Power Flow Study

Power ower Flow Study  Study Creation of a P Final Report Spring Semester 2007  by Ben Pilato Bryan Lake  Nick San Pietro Waylon Cash Andy Keller Vahram Stepanyan Department of Electrical and Computer Engineering Colorado State University Fort Collins, Colorado 80523

Abstract On August 14, 2003 a series of seemingly unrelated events conspired to produce a massive  power blackout, affecting an enormous swath of the northeastern United States and Canada. Shops and businesses closed, public transportation ground to a halt, and the economy lost  billions of dollars1. Blackouts are related to hidden vulnerabilities vulnerabilities that exist in the power system  but cannot be seen when everything is fully operational. These vulnerabilities are exposed during system disturbances. Through simulation analysis, disturbances can be modeled and accounted for to possibly prevent future power system failure.

The basic power-flow study starts with with a known system state. A comparison will be made from from this basic state. A predefined set of system disturbances are applied to to the benchmark case, and violations are documented. This establishes a benchmark from which to compare. From this known state proposed system changes can be introduced. Again, the same system disturbances disturbances applied to the benchmark case are applied to the altered altered case. Violations that are a direct result result of the system modifications are documented. These violations require a solution by the party party requesting system modifications. Basically, power-flow studies determine if system voltages remain within specified limits under various contingency conditions, and whether equipment such as transformers and conductors are overloaded. Power-flow studies are often used to identify the need for additional generation, capacitive, or inductive VAR support, or the placement of capacitors and/or reactors to maintain system voltages within specified limits. The above procedures have been documented and explained in the CSU wind farm system impact study provided in the beginning of this report. The process of performing a power-flow study using the Siemens software tool PSS/E (Power System Simulator for Engineering) is also  provided. Since power-flow studies require many steps and procedures, the process has been split into six, detail orientated, laboratories.

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Table of Contents Title…………………………….…………….………… Title……………………… …….…………….…………….…………….…………i ….…………….…………i Abstract…………...……………..……….………………….………….…………..1 Table of Contents…….……….…………………… Contents…….……….……………………………….………….…… ………….………….………...2 …...2 List of Figures…...…………….…………… Figures…...…………….……………………….……….…….…… ………….……….…….…………….3 ……….3 List of Tables..…...…………….………………… Tables..…...…………….……………………….…………….………… …….…………….…………….3 ….3 Introduction……………….…………………………….…… Introduction……………….……… …………………….……………..……………4 ………..……………4 Summary of Previous Work…………………… Wo rk…………………………….……………..……… ……….……………..……………5 ……5 Executive Summary...………………………… Summary...………………………………………………..……… ……………………..…………6 …6 Introduction……………………………………………… Introduction…………………… ……………………………………..…………7 …………..…………7 Study Objectives…………………………… Objectives………………………………………………….….…… …………………….….…………8 ……8 Methodology………………………………………………………..…………..8 Study Procedure…………………………………… Procedure………………………………………………….….………… …………….….………….8 .8 Study Approach……………………………… Approach…………………………………………………..….……… …………………..….………….9 ….9 Power Flow Results…………………………..……… Results…………………………..……………………….…….....10 ……………….…….....10 Cost for Upgrades………………………………………..………….………....11 Upgrades………………………………………..………….………....11 Conclusion………………………………………………..………….………...12 Results……………………………………………………..………….………..11 Appendix………………………………………………..…………….………..17 Lab Work Created…………..….……………… C reated…………..….……………………….……………….…..… ……….……………….…..……..29 …..29 Introduction to PSS/E……....….…………………… PSS/E……....….…………………………….……….………..30 ……….……….………..30 One Line Diagram ………….….…………………………….………..………45 ………….….…………………………….………..………45 Solving for Outages………….….…………………… Outages………….….………………………….……….….……...59 …….……….….……...59 Create ACCC Report………….….…………… Report………….….……………………….………………… ………….…………………...68 ...68 Multiple ACCC Report……….….……… Report……….….…………………………………… ……………………………………79 ………79 Addition of Generation……….….………………………….………………...91 Generation……….….………………………….………………...91 Conclusions and Future Work……………………………………………………108 Work……………………………………………………108 References…………………………………………………………………...…...109 Appendix…………………………………………………………………………110 Acknowledgments………………………………………………………………..111

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List of Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13

Existing transmission between CO and WY Archer-Stegall Example from Table 1 Drawing 0 Drawing 1 Drawing 2 Drawing 3 Drawing 4 Drawing 5 Drawing 6 Drawing 7 Drawing 8 Drawing 9 Drawing 10

7 11 18 19 20 21 22 23 24 25 26 27 28

List of Tables Table 1 Table 2 Table 3 Table 4 Table 5

ACCC Report Busses Utilized for N-1 Contingency Analysis Branches Monitored for Voltage Violations (System Intact & N-1) Itemized Cost for Plant Implementation One-Line Diagram Index

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13 14 15 16 17

Introduction

Our year long senior design project was based on the power industry. We worked with our industry advisor, Joe Liberatore, from Western Area Power Administration. At Western Area Power, a software tool made by Siemens is heavily utilized to perform system studies. The software is PSS/E (Power Systems Simulation Simulation for Engineering). In addition to Western, many other power companies use this software. The reason that so many companies rely on PSS/E is  because of the many features and abilities that it has to offer. The functionality and performance of PSS/E doesn’t come at a cheap price. The software costs roughly $90,000 per computer. Luckily, Siemens was kind enough to give us four free trial USB access keys and ENS was happy to install PSS/E on campus computers for our group to use. Each key was allotted 200 hours. The hardest part of our senior design project was actually learning how to use PSS/E. We were fortunate enough to have Joe guide us in times of need. We spent numerous hours outside of PSS/E just reading the help files that in our opinion are some what difficult to apply to create a  power-flow study. In fact, Joe has been working with PSS/E for three years and is still constantly learning new things. Since this software has barely any user tutorials, tutorials, it was requested by Dr. Collins and Joe’s boss at Western to create a series of laboratories to guide students and entry level power engineers through a power-flow study. In our first semester, we we were introduced to PSS/E and power-flow power-flow studies. We learned how to use PSS/E to perform a mock power-flow power-flow study. Our study involved adding a wind farm farm to the existing power grid. We were able to draw several conclusions about the feasibility of this addition. The system impact study can be seen in its entirety entirety in the following section of this report. Our second semester project was very unique because we actually went back and documented the entire process on how we performed our first semester project. This was very challenging  because we needed to bring a whole semester of work into a well written series of labs that could guide anyone through a power-flow study of their own. There are six lab manuals with questions that directly follow our last semester project in this report. report. The answers to the questions have  been omitted and turned into a solution manual that will only be provided to Dr. Collins. The labs are intended to be used in EE461 (Power (Power Systems) at Colorado State University. Dr. Collins is working on getting PSS/E installed on campus computers for students to perform these labs. The reason that these labs are so critical is because if they are utilized at Colorado Colorado State, this will be one of the only schools in the nation that will introduce students to PSS/E. This will, in turn, give Colorado States electrical engineering students interested in working in the power industry a major advantage with their future job opportunities.

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Summary of Previous Work

CSU WIND FARM System Impact Study for Request 2010-G1 December 3, 2006

Studies Conducted by: Waylon Cash Andrew Keller Bryan Lake Ben Pilato  Nick San Pietro Vahram Stepanyan

Colorado State University Power Corporation In Conjunction with the Western Area Power Administration

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Executive Summary

Colorado State University Power Corporation desires to add 150MW of wind generated power to the existing Western Area Power Administration network at the Colorado-Wyoming-Nebraska interface. The 150MW wind farm farm is intended to be used to meet the increasing demand for power in northern Colorado. Additional transmission capability must be explored to meet this this request. By applying computer analysis, transmission system topology is modeled with planned infrastructure improvements and/or modifications to reflect system configurations relative to this new addition. Simulations were run and deficiencies revealed. Simulations with current system topology show efforts to deliver new generation to the load further stresses the Colorado-Wyoming-Nebraska 230kV system, which is very close to its operating limits limits today. Reinforcing transmission capability with an additional 150MW, located in northern Colorado, will certainly assist in relieving system overloads in this area. However, additional measures will need to be taken to make sure that the transmission system can accommodate the generation upgrade. In order to effectively deliver the new wind generated power to the surrounding areas, some existing equipment will need to be upgraded to relieve stresses due to the increased generation. The underlying fact is that during the N-1 contingencies, the addition of a 150MW wind generation gen eration plant further stresses the existing power p ower grid. For an alternate course of action, this study has also explored the possibility of reducing the wind generation to 75MW. In summary, additional generation in the northern n orthern Colorado region will require additional upgrades to the the existing infrastructure. This study has included a detailed analysis of the desired 150MW wind generation, and has also proposed a more costeffective solution with the option to reduce the generation capacity to 75MW. This report does not take into consideration the geographical, environmental, financial, legal or contractual obligations which may exist and/or inhibit the ability to implement the proposed solution.

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I.

Introduction

This report will summarize the results of a transmission system study conducted by the Western Area Power Administration senior design project group at Colorado State University. The purpose of this study is to analyze analyze the impacts associated with the addition of a 150MW wind turbine generation facility, as well as the optional 75MW facility, located in in northern Colorado. The study will be conducted using Siemens PSS/E (Power System Simulator for Engineering) software to an alyze the power flow and the overall impacts to the existing power grid with the addition of the wind generation. The study assumes an in service date of June 2010. The power flow flow analysis used will utilize a Western Electricity Coordinating Council (WECC) 2010 Heavy Summer (2010HS) base case. Steady state analysis will not be performed due to a lack of accurate wind turbine turbine models. However, power flow flow and contingency analyses using a heavy summer base case were performed. A map of the major transmission lines near and around the area affected by the additional generation is included in figure1 below:

Figure 1 – Existing transmission between CO and WY

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II.

Study Objectives

A. B. C. D.

III.

Determine the feasibility of an additional 150MW of wind generation. Determine the feasibility of the alternative 75MW of wind g eneration. Determine system upgrades needed to accommodate the additional generation. Perform power flow studies to determine overall system impact.

Methodology

A. Base Case: The WECC 2010 heavy summer base case will be used in this study. The base case will be reviewed by all affected transmission providers in the area and will  be adjusted for known additions, corrections, and modifications to the Rocky Mountain Region to ensure proper case topologies. B. The study will take into consideration the increase delivery capability of the Colorado-Wyoming-Nebraska network. C. The N-1 contingencies will be applied to considerations outlined in B (above). IV.

Study Procedure

A. Criteria  NERC/WECC Planning Standards will be followed. System Intact (N-0): 1) Acceptable transmission line loading will be b e limited to 100% of thermal limits. 2) Bus voltages in the range of 0.95 to 1.05 per unit will be considered acceptable. 3) Acceptable transformer loading will be limited to 100% of thermal limits. 4) Power-flow solutions will allow all regulating items (i.e., transformer taps,  phase shifting transformers, area interchange, switchable shunt devices) to adjust for the “system normal” configurations. Single Contingency (N-1): 1) Acceptable line loading will be limited to 100% of thermal limits. 2) Acceptable transformer loading will be limited to not exceed the highest nameplate rating or appropriate owner’s maximum rating. 3) Transmission bus voltages will be maintained between 0.90 p.u. and 1.10 p.u. of nominal system voltage.

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V.

Study Approach

The power flow studies were conducted based on the 2010HS base case, which includes all the physical characteristics of each element contained within the Western Area Power Administration Administration controlled network. Elements include; transmission lines, busses, transformers, and any other components that make-up the power grid. A pictorial representation of the grid was obtained o btained by utilizing the drawing program included in the software to create a one-line diagram of the system. After a one-line diagram of a small portion of the grid was constructed, contingency, monitoring, and subsystem files were created. The contingency file is is programmed to remove one line at a time from from service; this is referred referred to as a contingency. When the system is fully operational, it has no outages, and is referred to as system intact or (N0). When a single line is taken out of service, the case is then referred to to as an (N-1) contingency. The monitoring files tell the the power flow simulator which branches branches to be supervised during (N-1) contingencies. Finally, the subsystem file file informs the power flow analysis to only look at a prescribed section, or zone, of the overall network. network. A sample of each file will now be given; Contingency file: TRACE CONTINGENCY DAV_STE TRIP LINE FROM BUS 65420 TO BUS 73190 END CONTINGENCY BRU_B.C TRIP LINE FROM BUS 70005 TO BUS 73013 END . . . . END

Trace starts the program. The next line names the (N-1) contingency. The third line describes which line will will be removed. The next line ends the contingency. Then the  process is repeated for all (N-1) contingencies that are desired. Monitor file: MONITOR BRANCHES IN SUBSYSTEM TOT3 MONITOR VOLTAGE RANGE SUBSYSTEM TOT3 0.90 1.10 MONITOR VOLTAGE DEVIATION SUBSYSTEM TOT3 0.5 0.5 MONITOR INTERFACE TOT3 RATING 1605 MW 73009 73011 73108 73012 73108 73193 73043 99200 73179 73150 73180 73143 END

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The first line informs informs which subsystem (zone) to monitor. The second line sets a per unit voltage range to monitor. The third line gives a +/- deviation from the prescribed prescribed values in line two. The fourth line indicates the power rating of the subsystem. The following six lines tell exactly which branches to monitor (from bus # to bus #). The final line ends that particular zone to be monitored. This is repeated for each additional zone that may be of interest. Subsystem file: SUBSYSTEM TOT3 BUS 70202 BUS 70209 BUS 70210 . . . . . . . . END

The first line names the subsystem and the following lines indicate which busses are to be included in the subsystem. The final line ends this file. These three files are utilized by b y the AC Contingency Calculation (ACCC) to perform p erform a power flow study of the zone in question. The ACCC produces an analysis of the  power system, from which the data was compiled and shown in Table 1 of the Results section. Each overload that occurred due to a contingency in Table 1, shown in the Results section, has been manually recreated and displayed in the one-line diagrams shown in the Appendix. VI.

Power flow Results

Simulations were constructed and ran based on the monitored busses and branches that are shown in the Results section, in Tables Tables 2 and 3 respectively. All of the  busses and branches represent a small portion of the overall power grid that may be affected by the addition of a wind farm. Before the wind farm farm was added, a simulation of the original (base) system was performed to reveal any power flow  problems that currently exist. This base case is shown in Table 1 in the Results section. Table 1 also shows the the positive and negative influences that a 75MW or 150MW wind farm brings to the existing system. The results of the addition of a wind farm are shown in the Results section, in Table 1. The monitored element is the branch that is overloaded when a disruption of service (or contingency) occurs. For example, when the line from from Ault to Laramie is taken out of service, an overload on the Archer-to-Stegall (230kV) line occurs. The  base case was overloaded, meaning above abo ve 100%, before the additions were made. It was operating at 103.3% of its rated rated capacity. Below the percentage shows the power level at the overload. With the addition of the wind farm, the operating levels levels for  both the 75MW and 150MW increased to 103.7% and 104.7% respectively. This

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means that the owner of the wind farm will need to make the necessary upgrades to the Archer-Stegall line, to relieve the overloads, before the wind farm can be added. See example portion of Table 1 in Figure 2.

Monitored Element 73009 ARCHER 73190 STEGALL

230 kV 230 kV

Contingency 1

AULT_LARAMIE

Base Case 103.3% 418MVA

 Wind Farm at 50% (75MW)

 Wind Farm at 100 % (150MW)

103.7% 420MVA

104.7% 424MVA

Figure 2 – Archer-Stegall example from Table 1.

If an overload occurs with the addition of a wind farm, but is less than the original overload within the base case, then the addition of the wind farm actually relieves the existing problem and the owner is not responsible for any upgrades. VII.

Cost for Upgrades

All of the projected costs for upgrades that will be given in this section are conceptual and can fluctuate by +/- 20%. In either case, for a 75MW or 150MW wind farm, farm, there is an initial cost of roughly $2.8 million for the construction of a new substation to connect the wind generation to the existing grid. The costs that will now be given are strictly for upgrades to the limiting components of the overloaded branches and the addition of the required substation, they do not include the cost for the wind generation plant itself. For the 150MW wind farm, four transmission lines, one transformer, and eighteen current transformers will need to be replaced, as well as the removal of one wave trap. The total cost for these these upgrades is $7,860,100 and the total cost for the substation and the upgrades is about $10.6 million. Please refer to the detailed costs analysis of the upgrades in Table 4 of the Results section. For the 75MW wind farm option, one o ne transmission line, and one transformer will need to be replaced, as well as the removal removal of one wave trap. The total cost for these upgrades is $3,662,200 and the total cost for the substation and the upgrades is around $6.5 million. Please refer to the detailed detailed costs analysis of the upgrades in Table 4 of the Results section. Table 4 was constructed based on the overflows calculated in Table 1 by PSS/E. Each overload that occurred as a direct result of the addition of a wind farm was further inspected to determine the limiting component or components on that  particular branch responsible for the overload. If the conductor was the limiting factor, the apparent power at the time of overload was obtained from Table 1, and the line-to-line voltage was found from our one-line diagrams. With these two pieces of data, the line current was found using the following equation: 3 V ll   I  VA . After the required line current was obtained, a corresponding Aluminum Conductor Steel ⋅

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⋅

=

Reinforced (ACSR) cable rated for greater than the required line current was found from a list of common ACSR conductors. The costs were then found by multiplying multiplying the length of the line in miles times the cost per mile of the conductor that was chosen. Other limiting components that were found in this study were transformers, current transformers, and wave traps. Transformers and current transformers need to be replaced by a new transformer with a rating that is greater than the apparent power at the time of the overload. The prices were obtained based on a list list of commonly used transformers in the Western Area Area Power Administration database. Wave traps are no longer used in the industry. Therefore, if a wave trap was found found to be the limiting factor, it will not be upgraded, but bu t rather removed from service. The total expenditure for the required upgrades to the existing network is the sole responsibility of the owner of the wind farm. VIII. Conclusion

After performing a detailed analysis of the system impact power flow study, it has  been shown that a wind generation plant can be added to the northern Colorado region with few negative impacts resulting resulting to the existing system. The studies of the  power flow models used in PSS/E have revealed that fewer stresses occur with the introduction of a 75MW wind farm, farm, in comparison to 150MW. However, it has been requested by the owner of the wind farm to build a 150MW plant. If the owner of the wind farm decides to build a 75MW plant, it can be fully upgraded to 150MW at a later date. The substation required for a 75MW plant is suitable for upgrades to allow for a 150MW plant. Furthermore, all of the upgrades that are required for a 75MW  plant would also be necessary upgrades for a 150MW 150 MW plant. Therefore, if the upgrade costs were considered to be the primary issue, the owner could install a 75MW plant now to be fully operational by the expected in service date of June 2010 and the capacity could be expanded to 150MW at a later date with relative ease.

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IX.

Results

Table 1 ACCC Report

Monitored Element 70470 WELD PS 70471 WELD PS

115 kV 230 kV

73009 ARCHER 73190 STEGALL

230 kV 230 kV

73020 BEAVERCK 73464 ADENA

115 kV 115 kV

73059 FLEMING 73478 GALIEN

115 kV 115 kV

73059 FLEMING 99000 CSU_WIND

115 kV 115 kV

73063 FRENCHCK 73080 HAXTUN

115 kV 115 kV

73063 FRENCHCK 73210 WAUNETA

115 kV 115 kV

73080 HAXTUN 99000 CSU_WIND

115 kV 115 kV

73179 SIDNEY 73180 SIDNEY

115 kV 230 kV

73191 STERLING 73478 GALIEN

115 kV 115 kV

73211 WELD LM 73212 WELD LM

115 kV 230 kV

73211 WELD LM 73212 WELD LM

115 kV 230 kV

Contingency

2

1

1

1

1

1

1

1

1

1

1

1

Base Case

WELD_WELD

102.4% 154MVA (1x)

AULT_LARAMIE

103.3% 418MVA (1x)

BEAVERCK_BRUSH

 Wind Farm at 50% (75MW)

 Wind Farm at 100 % (150MW)

103.7% 420MVA (1x)

104.7% 424MVA (1x)

103.0% 115MVA (1x)

107.2% 120MVA (1x)

HAXTUN_CSU

169.4% 141MVA (3x)

HAXTUN_CSU

112.4% 146MVA (2x)

FLEMING_CSU

107.1% 137MVA (3x)

FLEMING_CSU

144.6% 122MVA (3x)

FLEMING_CSU

112.5% 150MVA (3x)

N.YUMA_SIDNEY

113.7% 190MVA (1x)

105.6% 176MVA (1x) 161.3% 134MVA (3x)

HAXTUN_CSU 129.3% 194MVA (1x)

WELD_WELD

WELD_WELD

130.9% 196MVA (1x)

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128.0% 192MVA (1x)

Table 2 Busses Utilized for N-1 Contingency Analysis Anal ysis Bus # 400 450 70202 70209 70210 70240 70290 70311 70368 70469 70470 70471 70474 73003 73005 73008 73009 73011 73012 73013 73014 73015 73016 73020 73023 73031 73037 73038 73043 73046 73047 73059 73063 73065 73080 73092 73095 73096 73097 73136

Bus Name FLEMLOW CSU_LOW GODFRETP GREELEY GREELEY1 JOHNSTN MONFORT PAWNEE ROSEDALE WELD WELD PS WELD PS WINDSOR AKRON ALVIN ARCHER ARCHER AULT AULT B.CK PS B.CK PS B.CK TRI B.CK TRI BEAVERCK BIJOUTAP BRUSHTAP BUSHNELL BUSHNLTP CHEYENNE DALTON DEERINGL FLEMING FRENCHCK GARY HAXTUN JACINTO KERSEYTP KIMBALL KIOWA CK MESSEX

kV 34.5 34.5 115 115 46 115 115 230 115 46 115 230 230 115 115 115 230 230 345 115 230 115 230 115 115 115 115 115 115 115 115 115 115 115 115 115 115 115 115 115

Bus # 73140 73142 73143 73147 73150 73152 73158 73165 73166 73179 73180 73183 73190 73191 73192 73193 73199 73208 73210 73211 73212 73213 73224 73305 73309 73311 73355 73370 73378 73379 73464 73478 73480 73554 73558 90400 90450 94000 94200 99000

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Bus Name MYERS TP N.YUMA N.YUMA ORCHARD PEETZ PINEBLUF PROSPEC RAWHIDE REDWILLW SIDNEY SIDNEY SKYLINE STEGALL STERLING STORY STORY TIMBERLN WAGES WAUNETA WELD LM WELD LM WIGGINS WRAY EFMORGTP BARLOW FMS KIMBALLC LOSTCKTP FMN FMWEST ADENA GALIEN CROWCRK BOOMERNG WHITNEY CLR_1 CLR_1 FLEMWIND MARIAH CSU_WIND

kV 115 115 115 230 115 115 115 115 230 115 115 230 115 230 115 230 345 230 115 115 115 230 115 230 115 115 115 115 115 115 115 115 115 115 115 115 0.6 0.6 115 230 115

Table 3 Branches Monitored for Voltage Violations (System Intact & N-1) Bus #

From Bus

kV

Bus #

To Bus

kV

ID

Bus #

From Bus

kV

Bus #

65420

DAVEJOHN

230

73190

STEGALL

230

1

73020

BEAVERCK

115

73065

70005

BRUSHCPP

115

73013

B.CK PS

115

1

73020

BEAVERCK

115

70005

BRUSHCPP

115

73013

B.CK PS

115

2

73020

BEAVERCK

70192

FTLUPTON

230

70311

PAWNEE

230

1

73023

BIJOUTAP

70198

GILCREST

115

70202

GODFRETP

115

1

73023

BIJOUTAP

115

73379

FMWEST

115

1

70202

GODFRETP

115

70209

GREELEY

115

1

73031

BRUSHTAP

115

73305

EFMORGTP

115

1

70202

GODFRETP

115

70240

JOHNSTN

115

1

73037

BUSHNELL

115

73038

BUSHNLTP

115

1

70209

GREELEY

115

70290

MONFORT

115

1

73038

BUSHNLTP

115

73096

KIMBALL

115

1

70209

GREELEY

115

70470

WELD PS

115

1

73038

BUSHNLTP

115

73152

PINEBLUF

115

1

70240

JOHNSTN

115

70470

WELD PS

115

1

73043

CHEYENNE

115

73077

HAPPYJCK

115

1

70290

MONFORT

115

70439

UNC

115

1

73043

CHEYENNE

115

73480

CROWCRK

115

1

70311

PAWNEE

230

70343

QUINCY

230

1

73043

CHEYENNE

115

73504

PONNEQUI

115

1

70311

PAWNEE

230

73192

STORY

230

1

73043

CHEYENNE

115

99200

SYTECH

115

1

70368

ROSEDALE

115

70439

UNC

115

1

73046

DALTON

115

73179

SIDNEY

115

1

70368

ROSEDALE

115

70470

WELD PS

115

1

73046

DALTON

115

73236

GREENWOD

115

1

70410

ST.VRAIN

230

70471

WELD PS

230

1

73047

DEERINGL

115

73053

ECKLEY

115

1

70410

ST.VRAIN

230

70474

WINDSOR

230

1

73047

DEERINGL

115

73142

N.YUMA

115

1

70470

WELD PS

115

73211

WELD LM

115

1

73047

DEERINGL

115

73230

YUMA

115

1

70471

WELD PS

230

73212

WELD LM

230

1

73047

DEERINGL

115

73372

OTIS LM

115

1

70474

WINDSOR

230

73011

AULT

230

1

73059

FLEMING

115

73478

GALIEN

115

1

73003

AKRON

115

73020

BEAVERCK

115

1

73059

FLEMING

115

94000

FLEMWIND

115

1

73003

AKRON

115

73372

OTIS LM

115

1

73059

FLEMING

115

99000

CSU_WIND

115

1

73005

ALVIN

115

73175

SANDHILL

115

1

73063

FRENCHCK

115

73080

HAXTUN

115

1

73005

ALVIN

115

73210

WAUNETA

115

1

73063

FRENCHCK

115

73210

WAUNETA

115

1

73005

ALVIN

115

73304

CRETESWT

115

1

73065

GARY

115

73221

WOODROW

115

1

73008

ARCHER

115

73043

CHEYENNE

115

1

73078

HARMONY

230

73199

TIMBERLN

230

1

73008

ARCHER

115

73140

MYERS TP

115

1

73080

HAXTUN

115

94000

FLEMWIND

115

1

73008

ARCHER

115

73152

PINEBLUF

115

1

73080

HAXTUN

115

99000

CSU_WIND

115

1

73008

ARCHER

115

73183

SKYLINE

115

1

73087

WESTHILL

230

73190

STEGALL

230

1

73008

ARCHER

115

73480

CROWCRK

115

1

73088

HOYT

115

73464

ADENA

115

1

73009

ARCHER

230

73011

AULT

230

1

73092

JACINTO

115

73096

KIMBALL

115

1

73009

ARCHER

230

73190

STEGALL

230

1

73092

JACINTO

115

73179

SIDNEY

115

1

73009

ARCHER

230

94200

MARIAH

230

1

73095

KERSEYTP

115

73158

PROSPEC

115

1

73011

AULT

230

73165

RAWHIDE

230

1

73095

KERSEYTP

115

73554

BOOMERNG

115

1

73011

AULT

230

73199

TIMBERLN

230

1

73096

KIMBALL

115

73355

KIMBALLC

115

1

73011

AULT

230

73212

WELD LM

230

1

73097

KIOWA CK

115

73147

ORCHARD

115

1

73011

AULT

230

73212

WELD LM

230

2

73097

KIOWA CK

115

73158

PROSPEC

115

1

73012

AULT

345

73108

LAR.RIVR

345

1

73097

KIOWA CK

115

73213

WIGGINS

115

1

73012

AULT

345

79014

CRAIG

345

1

73098

KODAK

115

73558

WHITNEY

115

1

73013

B.CK PS

115

73020

BEAVERCK

115

1

73098

KODAK

115

73558

WHITNEY

115

2

73014

B.CK PS

230

73192

STORY

230

1

73103

L.MEADOW

115

73213

WIGGINS

115

1

73015

B.CK TRI

115

73020

BEAVERCK

115

1

73106

LAPORTE

230

73165

RAWHIDE

230

1

73016

B.CK TRI

230

73192

STORY

230

1

73107

LAR.RIVR

230

73190

STEGALL

230

1

73020

BEAVERCK

115

73031

BRUSHTAP

115

1

73108

LAR.RIVR

345

73193

STORY

345

1

73143

N.YUMA

230

73180

SIDNEY

230

1

73117

LOST CK

115

73370

LOSTCKTP

115

1

73143

N.YUMA

230

73192

STORY

230

1

73211

WELD LM

115

73558

WHITNEY

115

1

73143

N.YUMA

230

73224

WRAY

230

1

73305

EFMORGTP

115

73309

BARLOW

115

1

- 15 -

To Bus

kV

ID

GARY

115

1

73136

MESSEX

115

1

115

73464

ADENA

115

1

115

73097

KIOWA CK

115

1

Bus #

From Bus

kV

Bus #

To Bus

kV

ID

Bus #

From Bus

kV

Bus #

To Bus

kV

ID

73150

PEETZ

115

73179

SIDNEY

115

1

73305

EFMORGTP

115

73378

FMN

115

1

73150

PEETZ

115

73191

STERLING

115

1

73305

EFMORGTP

115

73379

FMWEST

115

1

73158

PROSPEC

115

73370

LOSTCKTP

115

1

73309

BARLOW

115

73310

FME

115

1

73165

RAWHIDE

230

73199

TIMBERLN

230

1

73311

FMS

115

73377

EXCEL

115

1

73165

RAWHIDE

230

73467

DIXON

230

1

73311

FMS

115

73379

FMWEST

115

1

73166

REDWILLW

115

73208

WAGES

115

1

73433

WINDSORT

115

73558

WHITNEY

115

1

73180

SIDNEY

230

73181

SIDNEYDC

230

1

73555

BRACEWLL

115

73558

WHITNEY

115

1

73180

SIDNEY

230

73190

STEGALL

230

1

73555

BRACEWLL

115

73558

WHITNEY

115

2

73183

SKYLINE

115

73188

STEGALDC

230

73375

WARRENLM

115

1

79039

HAYDEN

230

94200

MARIAH

230

1

73190

STEGALL

230

1

73136

MESSEX

115

73191

STERLING

115

1

73191

STERLING

115

73478

GALIEN

115

1

73139

MYERS

115

73140

MYERS TP

115

1

73208

WAGES

115

73210

WAUNETA

115

1

73140

MYERS TP

115

73154

POLE CK

115

1

73211

WELD LM

115

73554

BOOMERNG

115

1

73142

N.YUMA

115

73166

REDWILLW

115

1

Table 4 Itemized Cost for Plant Implementation Line Cost using Single Pole Steel Osprey Bittern Transmission Lines Beavercrk to Adena Flemming to CSU Wind Frenchck to Haxton Haxton to CSU Wind

k/mile

Line Reconductor Beavercrk to Adena with OSPREY Flemming to CSU Wind with Bittern Frenchck to Haxton with Bittern Xaxton to CSU Wind with Bittern Total Line Reconductor Cost

Cost $1,890,000 $1,267,875 $2,381,400 $422,625 $5,961,900

126 147 Miles 15 8.625 16.2 2.875

A 690 1200 KV 115 115 115 115

Substation Cost (2) Bus Section A 653 753 753 753

Bus Tie Steel Footings Bus System Control (3) Switches (3) Breakers Site prep Transformer Total Substation Cost

Single Cost 1 Bus $298,000 $359,000 $87,333 $69,000 $61,000 1 Switch $35,000 1 Breaker $72,000 $46,000 $1,258,000 $2,797,333

Multiple Cost 2 Bus Cost $596,000 3 Switches $105,000 3 Breakers $216,000 -

75MW Wave Trap Removal Transformer rated ≥ 200MVA Transformer Foundation 1% Transformer Installation 3%

Cost $25,000 $1,680,000 $16,800 $50,400

150MW Wave Trap Removal Transformer rated ≥ 200MVA Transformer Foundation 1% Transformer Installation 3%

Single Cost $25,000 $1,680,000 $16,800 $50,400

Multiple Cost -

Line Reconductor (Beavercrk to  Adena with Osprey) Total Substation Cost Total Cost

$1,890,000 $2,797,333 $6,459,533

Total Line Reconductor Cost

$5,961,900 1 150MVA $7,000 1 ≥160MVA $7,000 $2,797,333 $10,657,433

12 150MVA $84,000 6 ≥160MVA $42,000 -

(12) Current Transformer 150MVA (6) Current Transformer ≥ 160MVA 160MVA Total Substation Cost Total Cost

- 16 -

X.

Appendix

Table 5 One-Line Diagram Index Drawing # 0 1 2 3 4 5 6 7 8 9 10

Description No Wind Farm – System Intact-(Base Case w/ no wind farm) 150MW Wind Farm – System Intact (Base Case w/ 150MW) 150MW Wind Farm – Ault-Larimie Outage 150MW Wind Farm – Beaver Creek –Brush Outage 150MW Wind Farm –Haxton-CSU Outage 150MW Wind Farm –Flemming-CSU Outage 150MW Wind Farm – Weld-Weld Outage 75MW Wind Farm – System Intact (Base Case w/ 75MW) 75MW Wind Farm – Ault-Larimie Outage 75MW Wind Farm – Beaver Creek-Brush Outage 75MW Wind Farm – Weld-Weld Outage

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- 19 -

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- 21 -

- 22 -

- 23 -

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- 25 -

- 26 -

- 27 -

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Lab Work Created

Lab 1 provides an introduction to PSS/E and power flow studies. This lab explains the files used within PSS/E. Emphasizing the *.sav data file and its components. The data file is is a spread sheet representation of the power system being studied. This lab describes the different tabs used in the data file and their contents. Lab 2 introduces the-one line diagram, known as a slider file in PSS/E. This lab explains the components of a one-line diagram, including buses, branches, loads, etc. A one-line diagram is a three phase power system simplified and represented graphically with single lines. Lab 3 explains how to solve for outages in the power system. This lab will focus on performing performing a power flow study by manually taking lines out of service to create outages, solving the system and documenting each effect an individual outage has on the power system. Lab 4 provides an introduction to the contingency file, monitor file, and the subsystem files. This lab will explain how the three files are utilized by the AC Contingency C ontingency Calculation (ACCC) feature of PSS/E to perform perform a power flow study on a particular zone. An introduction to a power flow study is also given in this lab. A power flow study is performed in this lab by automatically taking contingencies and viewing the overloads due to the outages. Lab 5 explains how to modify the contingency file, monitor file, and the subsystem files  previously introduced. This lab introduces and explains how the Multiple AC Contingency calculation report feature of PSS/E is capable of creating a single report repo rt with the results of multiple ACCCs into one file. Lab 6 covers the introduction of a wind farm into a base case and analyzes the effects using PSS/E. A model of a wind farm based on characteristics of GE built wind turbine generators rated at 1.5 MW, 60 Hz, will will be added to the base case. From this a system impact study, or  power flow study can be performed and produced.

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LAB1 – INTRODUCTION TO PSS/E

EE461: POWER SYSTEMS COLORADO STATE UNIVERSITY

- 30 -

introduce the following PURPOSE: The purpose of this lab is to introduce PSS/E. This lab will introduce aspects of PSS/E:    

Introduction to PSS/E How to access PSS/E on campus computers Explanation of file types Explanation of tabs

Introduction to PSS/E

Power System Simulation for Engineering (PSS/E) is composed of a comprehensive set of  programs for studies of power system transmission network and generation performance in both steady-state and dynamic conditions. Currently two primary simulations are are used, one for steady-state analysis and one for dynamic simulations. PSS/E can be utilized utilized to facilitate facilitate calculations for a variety of analyses, including: • Power flow and related network functions • Optimal power flow • Balanced and unbalanced faults • Network equivalent construction • Dynamic simulation The lab manuals that will be considered throughout the duration du ration of this course will be primarily focused on power flow, dynamic simulations will not be explained. PSS/E uses a graphical user interface that is comprised of all the functionality of state analysis; including load flow, fault analysis, optimal power flow, equivalency, and switching studies. In addition, to the steady-state and dynamic analyses, PSS/E also provides the user with a wide rage of auxiliary programs for installation, data input, output, manipulation and preparation. Furthermore, one of the most basic premises of PSS/E is that the engineer can derive the greatest  benefit from computational tools by retaining intimate control over their application. Power Flow

A power flow study (also known as load-flow study) is an important tool involving numerical analysis applied to a power system. Unlike traditional circuit analysis, a power flow study usually uses simplified notation such as a one-line diagram and per-unit system, and focuses on various forms of AC power (ie: reactive, real, and apparent). Power flow studies are important because they allow for planning and future expansion of existing as well as non-existing power systems. A power flow study also can be used to determine the best and most effective design of power systems.

- 31 -

The PSS/E interface supports a variety of interactive facilities including: • Introduction, modification and deletion of network data using a spreadsheet • Creation of networks and one-line diagrams • Steady-state analyses (load flow, fault analysis, optimal power flow, etc.) • Presentation of steady-state analysis results Dynamics

The dynamic simulation program includes all the functionality for transient, dynamic and long term stability analysis. The dynamic simulation interface is operated as a separate program, currently independent of the PSS/E interface. This can be observed when going to a PSS/E  program and viewing the dynamics as a separate program. The purpose o f the dynamics is to facilitate operation of all dynamic stability analytical functions. The dynamics program, in addition to supporting the dynamics activities, also continues to support the traditional load flow interface through the LOFL activity. This lab will not address dynamic simulations. How to access PSS/E on campus computers

1. Log onto your computer 2. If an access key was provided, put USB access key in USB port of computer 3. In the start menu. Go to Start   Engineering Application   PSSE 30.2 (Power Flow) (This step is shown below):

- 32 -

  PSSE

 Note: The following error message will be displayed if PSS/E does not detect an access key:

Click OK. Continue clicking OK on any other error messages that may occur. PSS/E will close down and you will need to insert your access key into the USB  port before attempting to open PSS/E again. 4. PSS/E initial configuration After PSS/E opens, go to the top tool bar and in the Misc drop down menu select “Change program settings (OPTN)…

A screen like the one below will appear.

- 33 -

 Now change the Startup bus dimension to 150000 and select OK. This will allow PSS/E to load a case with up to 150000 busses.

 Now close out of PSS/E by clicking the in the upper right hand corner. Once PSS/E has shut down reopen reopen it and the the changes will be saved. This initialization  procedure will need to be performed before starting any lab in this course. 5. Loading a *.sav file - Re-launch PSS/E (Power Flow) application In the upper left hand corner of PSS/E click the open file icon.

- 34 -

 Now go to the folder that the *.sav file is located and click on it.

 Now click open in the lower right hand corner of the box and your *.sav file will be displayed. A sample of the screen that should be displayed is shown below:

- 35 -

 Note: If the startup bus dimensions are not changed and the *.sav file that you are attempting to open has more than the default 12000 busses an error message similar to the one shown below will be displayed. Click OK and make sure to follow step 4. PSS/E initial configuration above. Also Note: If PSS/E is not closed and reopened the message below will also be displayed when trying to open a *.sav file.

onl y) Explanation of file types  (This section is for reference only) PSS/E uses many types of files. Here is a brief description of important file types that may be used by PSS/E: *.sav – Saved case file The saved case file is a binary image image of the load flow working case. To conserve disk space and minimize the time required for storage and retrieval, saved cases (*.sav) are compressed in the sense that unoccupied parts of the data structure are not stored when the system model is smaller than the capacity limits of the program. The user may create as many saved cases as desired. Each saved case is a complete  power flow data set including analysis results that may be imported into PSS/E as a new  base case at any time.

- 36 -

*.raw – Power flow raw data file (input data file) A raw file is a collection of unprocessed data. This means the file has not been altered, compressed, or manipulated in any way by the computer. Raw files are often used as data files by software programs that load and process the data. These files contain power flow system specification data for the establishment of an initial working case. Several of these files may be read when a new power flow case is  being built up from subsystem data being provided by several different power companies or organizations *.sld – Slider file (Single Line Diagram) Dia gram) This file allows for performing network analysis studies s tudies on the grid. Sliders are visual displays of the grid. It includes buses, branches, lines, loads, generators, transformers etc... All components should be color coded based on voltage flow. The slider file can also show s how the operational ratings (power flowing across the component relative to the capacity) of the listed components. *.txt – Text file A text file (or plain text file) is a computer file wh ich contains only ordinary textual characters with essentially no formatting. Text files are commonly used throughout PSS/E. Soft code is often needed to complete tasks. This code can be written in a *.txt file to be loaded and processed appropriately. This will become more prevalent later when using the ACCC function. *.idv – Response file Comes from Unidata/UCAR, which is a Java J ava based software framework for analyzing anal yzing and visualizing geoscience data. *.idv is a response file. These files allow the user of PSS/E to automate the execution of a sequence of activities. A response file is an ordinary source file that is typed in by the user with a text editor before starting up PSS/E. *.dat – Input data file PSS/E must, from time to to time, accept large volumes of data data from external sources. Such large volumes of data could be typed directly into the PSS/E working case using the Spreadsheet View but this could be an onerous task. Voluminous data is best assembled in an input data file independent of PSS/E before PSS/E is started up. This file may then  be used as the input source for PSS/E to feed the data through the appropriate input activity into the PSS/E working case. Input data files may be obtained by reading from storage medium (i.e. CD’s) or e-mail attachments from external sources (other computer installations), ins tallations), or by the typing and file editing facilities of the host computer. In the case of power flow flow and dynamics data

- 37 -

input, the input data files may often be created by reading and reformatting data obtained from other computer installations. installations. While they are not a part part of the PSS/E activity structure, reformatting programs are available for translating several widel y used power flow and dynamics data formats into the PSS/E input format. Explanation of tabs

Once the *.sav file is opened, there are 19 tabs to choose from at the bottom of the data file (shown below). Each tab can can be accessed by clicking on it. There are six tabs that will be focused on in this section:

1. Buses

All equipment information associated with each bus in the system can be obtained by accessing the buses tab. Inside the buses tab there will be several parameters that can be set or adjusted. The important parameters will be described below: Displays the number assigned to a specific bus (1 through 999997). Alphanumeric identifier assigned to bus "#". The name may be up to twelve characters. The bus name may contain any combination of blanks, uppercase letters, numbers and special characters. The bus name is twelve blanks by default. Bus base voltage; entered in kV. Bus type code: 1 - Load bus (no generator boundary condition) 2 - Generator or plant bus (either voltage regulating or fixed Mvar) 3 - Swing bus 4 - Disconnected (isolated) bus 5 – Same as type 1, but located on the boundary of an area in which an equivalent is to be constructed Code = 1 by default. Bus voltage magnitude; entered in per unit, V = 1.0 by default. Bus data input is terminated with a record specifying a bus number of zero.

- 38 -

2. Branches

Each ac network branch to be represented in PSS/E as a branch is introduced by reading a branch data record. The important branch data records that will be considered are: Branch "from bus" number outside brackets with bus name and bus kV enclosed in brackets. Branch "to bus" number outside brackets with bus name and bus kV enclosed in  brackets. Branch resistance; entered in per unit. A value of R must be entered for each  branch. Branch reactance; entered in per unit. A nonzero value of X must be entered for each branch. Total branch charging susceptance (imaginary part of admittance); entered in per unit. B = 0.0 by default. First power rating; entered in MVA. Rate A = 0.0 (bypass check for this branch)  by default. Second power rating; entered in MVA. Rate B = 0.0 by default. Third power rating; entered in MVA. Rate C = 0.0 by default. Line length; entered in user-selected units. All lengths are in miles for for the  purposes of this lab. Branch data input is terminated with a record specifying a " from bus" number of zero.

- 39 -

3. Loads

Each network bus at which load is to be represented must be specified in at least one load data record. The load tab accesses the load data record. The important parameters for the load tab are described below:

This displays the Bus Number (where the load resides) outside of the brackets and displays the bus name as well as the bus voltage in kV inside the brackets. This is a one, or two, character uppercase, nonblank, alphanumeric load identifier. It is used to distinguish among multiple loads at the same "Bus Number/Name". At buses in which there is a single load present, the ID = 1. A check mark indicates that a certain load at a "Bus Number/Name" is fully operational. If for any reason a certain certain load at a "Bus Number/Name" needs to be taken out of service, simply un-check that particular one and click the line above or below to make your changes final. Active power component of constant MVA load; entered in MW. Reactive power component of constant MVA load; entered in MVAR.

4. Machines

Data entered in the spreadsheet view will be entered in the load flow working case (*.sav file). The source data records may be input from a Machine Impedance Data File or from the dialog input device (console keyboard or Response File). The machines tab can be used to:

- 40 -

1. Add machines at an existing generator bus (i.e., at a plant). 2. Enter the specifications of machines into the working case. 3. To divide and distribute the total plant output power limits proportionally among the machines at the plant. The important parameters for the machines tab are described below: This displays the Bus Number (where the machine is located) outside of the  brackets and displays the bus name as well as the bus voltage in kV inside the  brackets. This is a one, or two, character uppercase, nonblank, alphanumeric machine identifier. It is used to distinguish among multiple machines at a plant (i.e., at a generator bus). At buses in which there is a single machine present, ID = 1. A check mark indicates that a certain machine at a "Bus Number/Name" is fully operational. If for any reason a certain machine at a "Bus Number/Name" needs to be taken out of service, simply un-check that particular one and click the line above or below to make your changes final. This shows the active power that the generator is putting out; entered in MW. This shows the minimum active power that the generator can output; entered in MW. This shows the maximum active power that the generator can output; entered in MW. This shows the reactive power that the generator is putting out; entered in MVAR. This shows the minimum reactive power that the generator can output; entered in MVAR. This shows the maximum reactive power that the generator can output; entered in MVAR. 5. 2 Winding Transformer

- 41 -

Each transformer to be represented in PSS/E is introduced by reading a transformer data record  block. The transformer data record block can be accessed by clicking on the 2 Winding Transformer tab. The important parameters for this tab are explained below: This states the first bus number outside of the brackets with the bus name and bus kV enclosed in brackets. It is connected to winding one of the transformers transformers included in the system. The transformer’s magnetizing admittance is modeled on winding one. Winding one is the only winding of a two-winding transformer whose tap ratio or phase shift angle may be adjusted by the power flow solution activities. No default is allowed. This states the second bus number outside of the brackets with the bus name and  bus kV enclosed in brackets. It is connected to winding two of the transformers included in the system. No default is allowed. A check mark indicates that a certain two winding transformer between two buses is fully operational. If for any reason a transformer needs to be taken out of service, simply un-check that particular one and click the line above or below to make your changes final. The default is in service. 6. Switched Shunts

Shunts are used in the power system to improve the quality of the electrical supply and the efficient operation of the power system. There are two types of shunt compensation; shunt capacitive compensation and shunt inductive compensation. The shunt capacitive compensation is used to improve the power factor while the shunt inductive compensation is used to maintain the required voltage level, generally in the case of a very long transmission transmission line. Switched shunts are simply shunts that have the ability to be controlled. The “Switched Shunts” tab in PSS/E lists all of the shunt compensation in the overall system,  both capacitive and inductive, along with all of the pertinent information for the switched shunts: This displays the Bus Number outside of the brackets and displays the bus name as well as the bus voltage in kV inside the brackets. This is the bus to which the shunt is connected. This lists the bus, by number, whose voltage or connected equipment reactive  power output is controlled by this switched shunt. For example, if there is a bus number other than 0 in the remote bus column then that bus number is controlled

- 42 -

 by the shunt. If the value is 0 the bus in the column “Bus Number/Name” is controlled by the shunt. This lists the high voltage limits (in per unit) or the reactive power upper limit (in  per unit) of the total reactive power range of the controlled voltage controlling device of the switched shunts, depending on which control mode is selected. The control mode is an inherent characteristic of the shunt device and we won’t consider it much more than that. The default for VHI is 1. This lists the low voltage limits (in per unit) or the reactive power lower limit (in  per unit) of the total reactive power range of the controlled voltage controlling device of the switched shunts, depending on which control mode is selected. The default for VLO is 1. This lists the initial surge (or charge) admittance o f the connected shunt (in Mvar’s at unity voltage). Enter a (+) for for capacitance or (-) for inductance.

&

“Block # Step”, lists the number of steps in that block and “Block # Step BSTEP (MVAR)” lists the surge (or charge) admittance increment for each of the number of step for each of the number of blocks of the connected shunt (in Mvar’s at unity voltage). The switched shunt elements at a bus may consist consist entirely of reactors (each BSTEP is a negative quantity) or entirely of capacitor banks (each BSTEP is a positive quantities). In these cases, cases, the shunt blocks are specified in the order in which they they are switched on the bus. If the switched shunt devices at a  bus are a mixture of reactors and capacitors, the reactor blocks are specified first in the order they are switched on, followed by the capacitor blocks in the order they are switched on.

- 43 -

Questions Open the “sample.sav” data file to answer the following questions.

1) Go to the “Busses” tab. Find bus #3008. a) What is the name of this bus and its rated voltage? ___________________  b) Based on the code number, what type of bus is this? _______________  _________________ __ 2)  Now go to the “Branches” tab. Find the branch that connects bus #201 to bus #207. a) What are the names of the buses that are connected and the rated voltage of the  branch?  _  _______________  _______________________ __________ __  b) What is the rated resistance and reactance of this branch (both in per unit)?  _  _______________  _______________________ _______________ _______________ ________ _  3)  Now go to the “Loads” tab. Find load connected to bus #214 (LOADER, 230kV). a) What are the active (MW) and reactive (Mvar) components of this load?  _  _  ______________  ______________  b) Based on the results from above, what is the real power and power factor of this load?  _ ______________ __________________ ____ _ 4)  Now go to the “Machines” tab. Find generator connected to bus #402 500kV).

(COGEN-2,

a) What are the maximum and minimum active power ratings of this generator (in MW)?  _  _  _______  b) What are the maximum and minimum reactive power ratings of this generator (in Mvar)?  _  _ _______ 5)  Now go to the “2 Winding XFMR” tab. Find the transformer connected to bus #204 and  bus #205. a) What is the voltage rating of this transformer?  ______  b) Is this transformer in service?  ______________  ______________________ _____________ _____

 _  _

6)  Now go to the “Switched Shunt” tab. Find shunt compensator connected to bus #152 #15 2 (MID500, 500kV). a) How many steps are there to the shunt compensator and what are each of their values (in Mvar)? _____________  _____________________ ________________ _______________ ____________ _____  _______________  _______________________ _______________ _______________ _______________ _______________ ________________ _____________  _____   _______________  _______________________ _______________ _______________ _______________ _______________ _________ _  b) What type of shunt compensator is this (capacitive, inductive, or mixed)?  _  _  _______________  _______________________ _______________ _______________ ______________ ______

- 44 -

LAB2 – ONE-LINE DIAGRAMS

EE461: POWER SYSTEMS COLORADO STATE UNIVERSITY

- 45 -

PURPOSE: The purpose of this lab is to introduce the one-line diagram, also known as the Slider file in in PSS/E. This lab will introduce the following aspects:   

Introduction to a one-line diagram Explanation of the Slider (*.SLD) file Using the Slider file to create a one-line diagram

To properly perform this lab, lab, start PSS/E and open the sample.sav file. Refer to Lab 1 on how to do this. Introduction to one-line diagrams A one-line diagram is a simplified graphical representation of a three phase power system, used extensively in power flow studies. In power engineering, one can make the assumption that the three phases of a system are balanced and can therefore be examined as a single phase. The assumption can be made because what happens on one of the three balanced phases, theoretically, will happen to all three phases. This makes the evaluation of the system much less complicated without losing any information. Per unit is also also used extensively in one-line diagrams to further simplify the process.

The main components of a one-line (or single line) diagram are; Buses, Branches, Loads, Machines, 2 Winding Transformers, Switched Shunts, Reactor and Capacitor Banks. An explanation of these components will now be given: Buses

Buses are represented as a dot, circle or a thick line. The bus name (EAST500) and number (202) are given, as well as the voltage measured on the line (510.5kV and 1.021V in per unit). The final characteristic given is the angle angle (-26.1 degrees). The voltage is indicated by the color of the  bus. In this example, red indicates 500kV. Branches

Branches are represented as a thin line. The real power P, as shown on the branch above, flows from 478MW to -473MW and the reactive power Q, flows from 89.9MVA flow to -229.4MVA. In other words, the power flows from the positive number to the negative number, and the number on top is the real power while the number on the bottom is the reactive power. The voltage is indicated by the color of the branch. In this example, red indicates 500kV.

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Loads

Loads are represented as a triangle with the ID ID number located inside the triangle. triangle. The real  power, PLOAD, is denoted by the number on top (250MW), and the reactive power, QLOAD, is denoted by the number on bottom (100Mvar). The voltage is indicated by the color of the load. In this example, black indicates 230kV. Machines

Machines are represented as a circle with the ID ID number located inside the circle. The real  power, PGEN, is denoted by the number on top (321.0MW), and the reactive power, QGEN, is denoted by the number on bottom (142.3RMvar). The “R” indicates this machine is in voltage regulation mode, and it is controlling a specific bus to a voltage set point which requires it to generate 142.3Mvar. The voltage is indicated by the color of the machine. In this example, red indicates 500kV. Two Winding Transformers

Two winding transformers are represented as two separate windings with a gap separating them. The arrow pointing in at the connection reflects the primary side of the transformer. In this example, the primary voltage (1.0000V in per unit), is given on the primary side of the transformer and the secondary voltage (1.0000V in per unit), is given on the secondary side of the transformer. The voltage is indicated by the color of the transformer and is dictated by the  primary side voltage. In this example, purple indicates 21.6kV. Switched Shunts or Switched shunts are represented as either a capacitor or an inductor at the end of a line. The “SW” shown on top (or on the left if the shunt is shown vertical) indicates that this unit is a switched shunt compensator. If you see these symbols with a number in place of the “SW”, that  particular device is a permanently installed reactor or capacitor bank (see below). The number on  bottom (or on the right if the shunt is shown vertical) indicates the initial reactive charge admittance, BINIT (253.8Mvar or -599.6Mvar). The voltage is indicated by the color of the shunt. In this example, red indicates 500kV. Reactor Bank

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Reactor banks are represented as an inductor at the end of a line. The number on top (or on the left if the reactor is shown vertical) v ertical) indicates the real charge admittance, G SHUNT, of the line (3.6MW). If you see a “SW” instead of a number, you are looking at a switched shunt compensator (see above). The number on bottom (or on the right if the reactor is shown vertical) indicates the reactive charge admittance, BSHUNT, of the the line (490.0Mvar). (490.0Mvar). The voltage is indicated by the color of the reactor. In this example, red indicates 500kV. Capacitor Bank

Capacitor banks are represented as a capacitor at the end of a line. The number on top (or on the left if the capacitor is shown vertical) indicates the real charge admittance, GSHUNT, of the line (0.0MW). If you see a “SW” instead of a number, you are looking at a switched shunt compensator (see above). The number on bottom (or on the right if the capacitor is shown vertical) indicates the reactive charge admittance, BSHUNT, of the line (-1080.0Mvar). The voltage is indicated by the color of the capacitor.

The Slider File

As described in the previous lab, the Slider (*.SLD) file is a file that contains the one-line diagram. As can be see from the figure above, the one-line diagram can get pretty complicated. complicated.

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To simplify matters, all the physical data related to each element shown in the one-line diagram is linked to the data file (*.SAV). This way, a simple thin line represents represents all of the data located in the branch tab. All of this data is interconnected and linked so as to perform power flow analyses. Once a one-line diagram is created, it can be saved as a Slider (*.SLD) file. The Slider file can be amended and updated as necessary, as long as the amendments and updates correspond with the *.SAV file, since the two files are intertwined. Another advantage of the Slider file is that one can view the power flow and the operating levels of a branch. This allows a Power Engineer to quickly see potential trouble spots in a power system and correct them before problems occur. The process of performing a power flow flow analysis is the main objective of these labs. Using the Slider file to create a one-line diagram

As mentioned above, in order to properly perform this lab, PSS/E needs to be running and the data file “sample.sav” opened. Refer back to Lab 1 if problems problems arise in doing this.  Now go ahead and load a new file and get some buses b uses drawn! Load new slider (file  new  diagram) I. II. III.

First we need to load a file, and to accomplish this please do the following. Open PSS/E (it is shown on the previous lab) Go to file, and click new as shown:

IV.

After clicking new you will see the following:

V.

Select Diagram and click OK. A new diagram will be opened. This is where the future drawing will will be constructed.

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VI.

The color code for analyzing the one-line diagram will need to be programmed to distinguish the various voltage ratings for all the different components that the system consists of. This is done by selecting Diagram DiagramAnnotation).

This will display the Powerflow Powerflow Data Annotation window. Select the Diagram Range Checking tab shown below:

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Check “Use voltage level thresholds”. The voltage level thresholds with their corresponding colors can now be set. Set all values and colors to match the the following window.

Click on the color bar to set the width and color of the voltage level threshold. Click on the width drop down outlined in red to select the line pixel width. Click the color box outlined in red to select the color of the line. Click OK to return to the Power flow Data Annotation window.

(Threshold voltages from left to right: 12.47, 34.5, 69, 115, 138, 230, 345) (Colors from left to right: dark green, black, blue, blu e, bright green, yellow, orange, red,  purple) (Widths from left to right: 1, 1, 1, 2, 2, 3, 3, 4)  Note: all other values should be default Click OK to close window and return to blank diagram.

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VII.

A bus can be imported from the data (*.sav) file into the diagram. diagram. To do this select Auto Draw (located on the tool bar) as shown below:

Click on an open space in the blank diagram and the following window will be displayed:

 Next click select in the Select Bus window, or type the desired bus number, which comes from the *.sav file. (in this case, bus number 102 comes from the sample.sav file);

Click OK to return to the select bus window, which will show the bus selected.

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Click OK.  Note: As previously mentioned the bus can also be manually typed in to skip the  bus selection window.  Note: If a bus number is not in the *.sav data file the following error message will  be displayed:

Click OK and enter bus number 102 from the data file. Bus number 102 and all devices that are directly connected to it will now be displayed as shown below:

Click cancel to close out of the Select Bus window. Select the pointer from the tool bar to exit out of the auto draw function.

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***If needed, the toggle bus symbol feature can be applied to display buses as dots, circles, or lines. This is done by selecting a component by left clicking on it (the selected component will have a black square on each corner), and then right click on the bus symbol and selecting Toggle  bus symbol. Different bus symbols shown below; Dot:

Circle:

Line:

***For all purposes of this lab the line bus symbol will be used.

VIII. **IMPORTANT: The data file (*.sav) and slider (*.sld) diagram are interconnected, therefore deleting a bound item from a diagram removes it from the *.sav data file and will result in analysis corruption. This means that if a change is made to either of the files the other will be affected. To avoid possible corruption of the data file, the “bind items” feature should be turned off. This is done by right clicking on a bus and clicking on bind items as shown below:

IX.

Once the bind items have been unselected, it is safe to grow a small section of the data file into a one-line diagram. This is done by right clicking on a bus and selecting Grow.

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X.

Try to grow out bus number 151. This will display all the elements elements connected to bus number 151. The following will be produced:

 Notice how PSS/E automatically places the buses and branches in no particular layout. To allow for a legible display, manipulation to the above diagram is required. After growing out a bus, all the elements associated with the grow command will be selected. Click on a white space off the the drawing to deselect the grown items. Now it is possible to rearrange the drawing by selecting a bus and dragging it to the desired location. XI.

Try to rearrange the one-line diagram so that no wires or ratings ratings are overlapping. In other words, make the the diagram clean; meaning easy to read and understand. Notice how much clearer the diagram below is.

***If needed, a knee can be used to bend and manipulate a transmission line.

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To ‘bend’ a line, insert a knee point. This is done by selecting Knee Point from the tool  bar and then clicking on the line where the knee is desired. Multiple knees on a line may  be necessary in order to have more control of the design of the layout. Once the knee is  placed the line can be bent to any angle by grabbing and draggin g the point. An example of a line with two knees in it is shown below:

XII.

After a clean layout has been achieved the system is ready ready to be solved. Solving a system allows PSS/E to make all the necessary calculations used in a power flow analysis. This can be done by clicking on the solve icon on the toolbar. toolbar.

The following window will be displayed: displa yed: Configure the Loadflow solutions window to match the one displayed. This could include selecting the “Lock all” radial button under Switched shunt adjustments and uncheck “Adjust DC taps”.

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Click on solve and PSS/E will solve the system and store the results in the progress window. XIII.

After the system has been solved, the loading percentages can be displayed by clicking the current loadings icon on the tool bar. The following will  be displayed:

XIV.

Once the system has been solved, the Flow animation can be displayed by clicking the animate flows icon on the tool bar. The following will be displayed:

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Questions The “sample.sav” data file must be open to perform this section of the lab.

First, build out a one-line diagram to include the follow ten buses: 101 102 151 152 153 201 202 3004 3021 3022

NUC-A NUC-B NUCPLANT MID500 MID230 HYDRO EAST500 WEST WDUM EDUM

Solve for the system. Display the current loading percentages and the power flow animation. Print out the one-line diagram and include it in the report. Save the one-line diagram as “lab2.sld”, this will be needed for future labs. Using the one-line diagram, and answer the following following questions to include in the report. Turn off the loading percentages and the power flow flow animation for clarity. Make sure that the system has been solved. 1)

Looking at Bus #152 (MID500), what is the PLOAD and QLOAD of the load connected to this bus? ______________  _____________________ _______________ _______________ _______________ ___________ ___

2)

Find the two generators in this system. Which buses are they connected to? What is the PGEN and QGEN of the two generators?  _______________  ______________________ _______________ _______________ _______________ ________________ _______________ _______________ ____________  ____   _______________  ______________________ _______________ _______________ _______________ ________________ _______________ _______

3)

How many switched shunts are in this system? ______________  ______________________ ______________  ______  How many reactor banks are in this system? _______________  ______________________ _______________  ________  How many capacitor banks are in this system? _____________  _____________________ _______________  _______ 

4)

Looking at Bus #153 (MID230), what is the actual voltage of the bus and  per unit voltage? ______________  _____________________ _______________ ________________ _____________  _____ 

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what is the

LAB3 – SOLVING FOR OUTAGES

EE461: POWER SYSTEMS COLORADO STATE UNIVERSITY

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introduce how to solve for outages in the power PURPOSE: The purpose of this lab is to introduce system. This lab will focus on performing performing a power flow study by manually creating outages, solving the system and recording the effects of the individual outages. This lab will introduce the following aspects:    

Loading a Slider file (*.sld) Interpreting a power flow analysis Creating an outage Solving for outages

To properly perform this lab, lab, start PSS/E and open the sample.sav file. Refer to Lab 1 on how to do this. Loading a slider file (*.sld)

After the sample.sav file is displayed, select open on the toolbar.

The open dialog box will be displayed, and will automatically narrow the search to *.sav file types. To load a slider (*.sld) file, simply change the file type to a “Slider Binary File (*.sld)” and select the slider file created in Lab 2.

The slider file created in lab 2 should be displayed on the screen and should be similar to the figure shown below: If the data on the branches is grayed out, the system needs to be solved. PSS/E grays out the data to let the user know that the system needs to be solved. Simply solve the system as shown in Lab 2.

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Interpreting a power flow analysis

With the slider file open and the system solved, display the current loading percentages. percentages. This  process was explained in Lab 2. Once the current loadings are displayed and the system is solved the slider will be similar to the one below:

PSS/E automatically displays the current Creating and solving for outages

 Now take one line at the time, solve it, and display it with current loadings. Go ahead right click on the desired bus/line, from which you will see the following menu.

This view makes it possible to pinpoint where possible overloads and/or problems may exist in the system. By inspecting the branch between Bus #151 (NUCPLANT) (NUCPLANT) and Bus #201 (HYDRO), it can be seen that this branch is operating at 50% of its rated capacity. Looking at the branch between Bus#152 (MID500) and Bus #3021 (WDUM), it can be seen that the branch is operating at 127% of its rated rated capacity. Overloaded percentages are shown in dark red. This

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is because the branch is running much higher than its rated capacity and requires immediate attention to avoid permanent damage to the branch and/or the equipment. At the end of this lab, a results table is provided. Fill out the first row, labeled “No Outages”, with the current ratings of each branch from the figure above. Creating an outage

It is important to see how the system is reacting in its base case with everything fully functional. However, it is necessary to investigate how the system will react if an outage occurs. To do this, it is necessary to deliberately take a bus, branch or piece of equipment out of service and investigate its impact on the rest of the system. In order to switch out a bus, branch or piece of equipment, select the item to be switched out by right clicking on the device and selecting “Switch” from the menu box as shown in the image  below: **REMEMBER: The data file (*.sav) and slider (*.sld) diagram are interconnected, therefore deleting a bound item from a diagram removes it from the *.sav data file and will result in analysis corruption. This means that if a change is made to either of the files the other will be affected. To avoid possible corruption of the data file, the “bind items” feature should be turned off. This is done by right clicking on a bus and clicking on bind items.

 Now switch switch Bus #101 (NUCA) out of service.

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 Notice when a device is switched out of service it turns into dotted lines and the one-line diagram is grayed out. The dotted lines indicate that the items are are not in service and when the system has been grayed out it has been changed and needs to be solved again.

 Now solve the system. Record the current ratings for each branch in the second row, marked “101 NUC-A” in the table  provided at the end of this lab.

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In order to switch an item back into service, left click the switched out item to select s elect it, right click and select “Switch” just as before. Now, switch Bus #101 (NUC-A) back on and and solve the system. Everything should look as it did before the bus was switched out.

 Next, switch Bus #102 (NUC-B) out of service and solve the system.

Record all of the current ratings in the appropriate row of the results table and then switch the  bus back into service. Repeat this for each bus in the system and record all of the ratings in the Results Table.

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 Note: When some buses are switched out, you will receive the following error message.

Click OK and switch the device back into service. Fill in the corresponding corresponding row in the results table with N/A for each column on each of the buses that display this message upon being switched out. This is because; there can be multiple islands each of which contains a system swing bus, with DC links connecting them. PSS/E performs the required bus type code and branch status flag changes to disconnect all buses that were listed as not tied back to a swing bus. Any in service dc lines connected to such buses are blocked. Any in-service series FACTS devices connected to such buses are placed out-of-service. This process is repeated for each island.

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Questions The “sample.sav” data file as well as the “lab2.sld” slider file must be open to perform this section of the lab.

As was mentioned before, this process can be done on branches and equipment as well as on  buses. With all buses switched on and the system solved for, select the generator connected to Bus #101 (NUC-A), switch it out and solve for the system. 1)

What is the difference between just switching out the generator and switching out bus #101? Why  __________  __________ _____ ____ is this? ________ _ __ 

Switch the generator back on and solve for the system. Now, switch off the branch between Bus #151 and #201 and solve the system. You might need to remove the current rating rating boxes to do this, just turn them back on once the branch is switched off. 2)

What is the difference between just switching out the branch and switching out bus #201? Why is this? ________  __ ________ ________ _____ ____  _ __ 

 Now switch the branch back on and switch off the transformer between Bus #152 and #153 and solve. 3)

What is the difference between just switching s witching out the transformer and switching out bus #153? Why is  __________  __________ ____ ____ this? ________  ________ _ __ 

 Now switch the transformer back on and switch off the load connected to Bus #153 and solve. 4)

What is the difference between just switching out the load and switching out bus #153? Why is this? ________  ____ ______ ____ ____  ________  _ __

 Now switch the load back on and switch off the load connected to Bus #15 2 and solve. 5)

What is the difference between just switching out this load and switching out the load connected to bus #153? Why is  ____ _____ _ ___ there such a large increase of power flow on the branch between bus #152 and #153?  ________  ________ _ _

6)

Looking at the table you have completed, which bus being switched out had the most negative impact on the system? What ____ ____ ____ would indicate this? ____ __ __ __ Which bus being switched out had the least negative impact on the system? _ _  ____ _ _ What would indicate this? ____ __ __ __

7)

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Answer these questions and display the results in the table given below.

Results Table BRANCHES / OUTAGES  NO OUTAGES 101  NUC-A 102  NUC-B 151  NUCPLANT  NUCPLANT 152 MID500 153 MID230 201 HYDRO 202 EAST500 3004 WEST 3021 WDUM 3022 EDUM

101 151

GEN 101

102 151

GEN 102

151 152

151 152

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151 201

152 153

152 202

152 3004

152 3021

152 3022

LAB4 – CREATE AC CONTINGENCY CALCULATION REPORT

EE461: POWER SYSTEMS COLORADO STATE UNIVERSITY

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PURPOSE: The purpose of this lab is to introduce the contingency file, monitor file, and the subsystem files. This lab will explain how the three three files are utilized by the AC Contingency Calculation (ACCC) feature of PSS/E to perform a power flow flow study on a particular zone. This lab will introduce the following aspects:      

Introduction to power flow study Contingency file (*.con) Monitor file (*.mon) Subsystem file (*.sub) ACCC Using the *.con, *.mon, and *.sub to create an ACCC report

To properly perform this lab, lab, start PSS/E and open the sample.sav file. Refer to Lab 1 on how to do this. Introduction to power flow study The power flow study that will be conducted in this lab will be based on the sample.sav file. The  base case, or system intact, is a fully operational system in which everything is working the way it was intended to. However, in a real world world scenario the system is not always functioning within its operating limits. In addition, if a change to the system is required, it is desired desired to have a way to predict the positive and negative effects that may arise with the change. In lab 3, lines were manually switched out of service to simulate how the grid reacts due to the contingency. The slider file that was manipulated manipulated is just a piece of the whole system. It would be very hard to grow the whole system into a slider file to see all the overloads that may occur when a contingency is taken. This lab will explain how to automatically take contingencies and view all the overloads due to the outages. Contingency file (*.con) The contingency file is programmed to remove equipment, one piece at a time from service; this is referred to as a contingency. When the system is fully operational, it has no outages, and is referred to as system intact or (N-0). When a single line is taken out of service, the case is then referred to as an (N-1). (N-1). The easiest way to program how to do this is to see a portion of the code used in the *.con file and understand what everything everything does. Here is a portion of a contingency file. COM COM Contingency Description File for for SAMPLE Study, Outages COM TRACE CONTINGENCY NUC-MD5 TRIP LINE FROM BUS 151 TO BUS 152 END CONTINGENCY NUC-HYDR TRIP LINE FROM BUS 151 TO BUS 201 END END

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Trace starts the program. The next line names the (N-1) contingency. The third line describes which line will be removed. The next line ends the contingency. Then the process is repeated for all (N-1) contingencies that are desired. Monitor file (*.mon) The monitor file tells the power flow simulator which branches to be supervised during the (N-1) contingencies. A sample of the the monitor file will now be given: COM COM Monitored Element Description File File for SAMPLE Study, Study, Outage COM MONITOR BRANCHES IN SUBSYSTEM OVERAL MONITOR VOLTAGE RANGE SUBSYSTEM OVERAL 0.90 1.10 MONITOR VOLTAGE DEVIATION SUBSYSTEM OVERAL 0.5 0.5 MONITOR INTERFACE ZONE6H RATING 500 MW 152 3004 3002 3004 END END

The first line after the comments informs which branches to monitor in the subsystem named ‘OVERAL’. The second line sets a per unit voltage range for that subsystem. The third line gives a +/- deviation from the prescribed values in line two. The fourth line indicates the power rating for a defined set of lines. The following two lines tell tell exactly which branches to monitor (from bus # to bus #). The first END ends that particular zone to be monitored. This is repeated for each additional zone that may be of interest, and this file is completed with a final END to stop the monitor file. Subsystem file (*.sub) The subsystem file informs the power flow analysis to only look at a prescribed section, or zone, of the overall network. A sample of the subsystem file will will now be given: COM COM System discription file for SAMPLE FLOW STUDY COM SUBSYSTEM OVERAL BUS 101 BUS 102 BUS 151 BUS 152 BUS 153 BUS 154 BUS 155 END END

The first line after the comments names the subsystem ‘OVERAL’ as indicated in the monitor file. The seven bus number lines indicate which busses are to be included included in the subsystem. The first end stops the subsystem and the final end concludes the file.

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ACCC The contingency, monitor, and subsystem files are utilized by the AC Contingency Calculation (ACCC) feature of PSS/E to perform a power flow flow study on a prescribed zone. The ACCC  produces an analysis of the power system. Using the *.con, *.mon, and *.sub to create an ACCC report

For the purpose of this lab a sample.con, sample.mon and sample.sub file are provided as examples to perform an ACCC analysis. Start PSS/E and load the sample.sav file. To perform an ACCC analysis click on the “Power Flow” drop down menu and select “Solution”  “AC contingency solution (ACCC)”.

The AC Contingency Solution window will be displayed:

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A Distribution Factor Data File (DFAX) needs to be created by loading the provided sample.con, sample.mon and sample.sub files. Click on the “Create DFAX” button, and the “Build Distribution Factor Data File” window will be displayed: dis played:

Click on the three dots sample.sub file.

next to the “Subsystem description data” text field to load the

Locate the directory containing the sample files to select the Sample.sub file and click “Open”. The sample.sub file will be loaded in the Subsystem description data text field in the Build Distribution Factor Data File window.

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 Next, click on the three dots sample.mon file.

next to the “Monitored element data” text field to load the

Select the Sample.mon file and click “Open”. The sample.mon file will be loaded in the Subsystem description data text tex t field in the Build Distribution Factor Data File window.  Now, click on the three dots the sample.con file.

next to the “Contingency description data” text field to load

Select the Sample.con file and click “Open”. The sample.con file will be loaded in the Subsystem description data text field.

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 Next, a location for the DFAX output file needs to be assigned. This is done by clicking on the three dots next to the “Distribution factor data output file” text field.

Select the File name text field, type “sample.dfx” to name the DFAX output file, and click “Open”. This will create the output file in the directory listed in the window and can be created in a different directory if needed. The Th e sample.dfx file will be loaded in the Distribution factor data output file text field in the Build Distribution Factor Data File window. The Build Distribution Factor Data File window will look like the one below after all the sample files and Distribution factor data output file have been specified.

Click “OK” to return to the AC Contingency Solutions window, with the sample.dfx file loaded in the Distribution factor data output file text tex t field.

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Finally, a location for the ACCC output file needs to be assigned. This is done by clicking on the three dots next to the “Contingency output file” text field.

Select the File name text field, type sample.acc to name the ACCC output file, and click “Open”. This will create the output file in the directory listed in the window and can be created in a different directory if needed. The sample.acc file will be loaded in the Contingency Con tingency output file text field in the AC Contingency Solution window as shown below:

Click “Solve” to solve the system with the loaded sample files.

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 Now, click “Reports” to load the AC Contingency Reports window:

Leave everything set to the default values and click the “Go” button to run the ACCC report. Click close to exit the AC Contingency Reports window, click close again to exit the AC Contingency Solutions and return to the terminal window. Click on the report tab to view the completed ACCC Report.

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The monitored branch section shows all the branches that were overload due to a contingency. The contingency section shows which branch was automatically taken out of service by the ACCC, which resulted in an overload. The base case contingencies show the system intact overloads before any branches were removed from service. Scroll to the right on the report window to view the rating of the line in MWs, the power flow of the line in MWs, and the percent overload. At the bottom of the report the Monitored voltage report & Contingency legend can be seen, but is not of significant importance for this lab.

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Questions The “sample.sav” data file must be open to perform this section of the lab.

Using the “sample.con” contingency file, the “sample.mon” monitor file and the “sample.sub” subsystem file that have been provided, create a “sample.dfx” DFAX and a “sample.acc” AC contingency file. Solve the system with the loaded sample files and run the ACCC report as shown above. View the report generated by PSS/E and print print out the report, this print out will need to be included in the lab report. report. It will also be helpful in answering the following following questions. 1)

Which six branches suffer from overloads during the “BASE CASE” contingency and what is their percentage of overload? ______________ ________  _ ______________ ______________ _____ _____ _ 

2)

Looking at the “NUC-HYDRO” contingency, which branches suffer from overloads that did not suffer from overloads during the “Base Case”, and what is their percentage of overload? _________ _  Of the  ____ __ ____  Of  branches suffering from overloads during the “Base Case”, which one(s) got worse during this contingency, and by how much? ________ __  Did  ____ __ ____  Did any of these branches actually see a reduction in overload, if so, which ones and by how much were they reduced? ________ __  ____ __ ____ 

3)

Which of the contingencies created the highest number of overloaded branches? ___  ____ __ __ Which branch was taken out of commission in this contingency? __ _ ____  __ __ __ __

4)

Find the “DNTN-CAD” contingency. What is the rating of the branch between bus #202 and #203 (in MW) and what is the actual power flow (in MW) on this branch? __  What is the rating of the branch between bus #204 and #205 (in MW) and  __ __  What what is the actual power flow (in MW) on this branch? _ _  __ _ _  Assuming a power factor of 0.9, how much actual power (in MVA) must mus t the power company provide to each of these branches? _ _  __ _ How much actual power (in MVA) must the power company provide to each of these branches if the power factor was at 0.8, just 10% lower? _ _  _ _ 

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LAB5 – MULTIPLE ACCC REPORT

EE461: POWER SYSTEMS COLORADO STATE UNIVERSITY

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PURPOSE: The purpose of this lab is to gain an understanding of how to modify the contingency file, monitor file, and the the subsystem files previously introduced in lab 4. This lab will explain how the Multiple AC Contingency Con tingency calculation report feature of PSS/E creates a single report with multiple ACCCs into one file. This lab will introduce the following aspects:     

Modify contingency file (*.con) Modify monitor file (*.mon) Modify subsystem file (*.sub) ACCC Multiple AC contingency calculation report

To properly perform this lab, lab, start PSS/E and open the sample.sav file. Refer to Lab 1 on how to do this.

Open the sample.sld slider file included with PSS/E.

Make sure to select “Slider Binary File (*.sld)” file in the Files of type: drop down menu.

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The sample.sld slider file provided is shown below:

This slider file illustrates the sample grid broken up into 9 zones. The zones are shown within the dotted lines. From this point a *.con, *.mon and *.sub file need to be created for each zone to create an ACCC output file for that zone. The ACCC output files can then be implemented implemented in a multiple AC contingency calculation report. The *.con, *.mon and *.sub files were explained in lab 4, and can be referred to if needed. These files are created and edited in notepad then saved as their specified file types. Open a blank notepad document

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Complete the specific *.con, *.mon & *.sub files. The Zone6.con file is provided as an example.

The Zone6.con file is completed and ready to be saved.

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Select All Files in the Save as type drop down menu, type in the name of the specific file and click save. Examples of Zone6.con, zone6.mon and zone6.sub files are created in notepad, and provided.  Note: In order to edit *.con, *.mon and *.sub files notepad needs to be ass ociated to the file types.

Double click on the *.con, *.mon or *.sub file, choose the “Select the program from a list” radial  button and click OK. The “Open With” window is displayed.

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Scroll down and select “Notepad” from the list of programs. Next, check the box next to “Always use the selected program to open this kind of file” and click OK. OK. This will allow *.con, *.mon and *.sub files to be opened and edited in notepad by double clicking the files. Modify contingency file (*.con) Create the Zone#.con in notepad and save it. The Zone6.con file can be copied into notepad, edited and saved to the specific zone file as needed to help with the editing process. The zone6.con file is provided below as an example. COM COM Contingency Description File for for ZONE6 Study, Outages COM TRACE CONTINGENCY MD5-WMN TRIP LINE FROM BUS 152 TO BUS 3004 END CONTINGENCY MINE-SMN TRIP LINE FROM BUS 3001 TO BUS 3003 END CONTINGENCY EMN-WMN TRIP LINE FROM BUS 3002 TO BUS 3004 END CONTINGENCY SMN-WEST TRIP LINE FROM BUS 3003 TO BUS 3005

END END Modify monitor file (*.mon) Create the Zone#.mon in notepad and save it. The Zone6.mon file can be copied into notepad, edited and saved to the specific zone file as needed to help with the editing process. Notice in Zone6 there are two different monitor interfaces provided (listed as ZONE6H for the 500MW rating and ZONE6L for the 230MW rating) that will need to be edited or removed based on the ratings for different zones. The zone6.mon file is provided below as an example. COM COM Monitored Element Description File File for ZONE6 Study, Outage Outage COM MONITOR BRANCHES IN SUBSYSTEM ZONE6 MONITOR VOLTAGE RANGE SUBSYSTEM ZONE6 0.90 1.10 MONITOR VOLTAGE DEVIATION SUBSYSTEM ZONE6 0.5 0.5 MONITOR INTERFACE ZONE6H RATING 500 MW 152 3004 3002 3004 END MONITOR INTERFACE ZONE6L RATING 230 MW 3001 3003 3003 3005 END END

The monitor interface ratings are taken from the branches tab of the sample.sav data file as shown below:

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Modify subsystem file (*.sub) Create the Zone#.sub in notepad and save it. The Zone6.sub file can be copied into notepad, edited and saved to the specific zone file as needed to help with the editing process. The zone6.sub file is provided below as an example. COM COM System discription file for ZONE6 FLOW STUDY COM SUBSYSTEM ZONE6 BUS 3001 BUS 3002 BUS 3003 BUS 3004 BUS 3011 END END

The buses tab below shows the zone Number/Name that each particular bus belongs too:

ACCC An ACCC needs to be created for each zone. This is done after the *.con, *.mon and *.sub files for each zone are made. These are used to create the zone#.acc files required for for the multiple AC contingency calculation report. The ACCC function of PSS/E was covered in lab 4 and should  be referred to as needed. An example of what should be included when creating the Zone6.dfx file and Zone6.acc file is provided below:

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Click the “Solve” button to create the Zone#.acc output file.  Note: This process will need to be repeated for all 9 zones that are displayed in the sample.sld slider file. Multiple AC Contingency calculation report The multiple AC contingency calculation report utilizes the Zone#.acc output files created with the ACCC feature of PSS/E. A report is generated which includes includes the information from all the Zone#.acc files that are used. This is a very powerful tool when side by side study comparisons are needed.

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Once all of the Zone#.acc files have been created, the multiple AC contingency calculation report feature of PSS/E can be utilized. This is done by clicking on the “Power Flow” drop down menu and selecting “Reports”  “Multiple AC Contingency calculation report” as shown:

The AC Multiple Contingency Run Report window will be displayed:

Click on the three dots next to the text field at the bottom of the window, and load each Zone#.acc output file one at a time.

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After all nine zones have been loaded; Click the “Go” button to produce the multiple contingency report in the terminal window. Click the “Close” button to close the AC AC Multiple Contingency run report window and return to the terminal window. Click on the “Report” tab to view the multiple AC contingency calculation report.

This report contains a lot of important information, however it is not all needed for this lab. Scroll up to the AC CONTINGENCY C ONTINGENCY REPORT FOR 9 AC CONTINGENCY CALCULATION RUNS section on pages 8 and 9 of the report to view the table produced above. The monitored element section shows all the branches that were overload due to a contingency. Label shows which branch was automatically taken out of service by the ACCC, which resulted in an overload. Zones are categorized vertically vertically and display the the overload percentage on the monitored element. All 9 zones can be viewed by scrolling to the right and each monitored element can be viewed by scrolling down.

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Questions The “sample.sav” data file as well as the “sample.sld” slider file must be open to perform this section of the lab.

Inspect the “sample.sld” slider file and note which which buses are included in which zone. Also note which of the branches without transformers are contained within, or originate from, each zone. This information will be used to create “zone#.con”, “zone#.mon” and “zone#.sub” files for each of the nine zones. Zone 6 was given as an example in this this lab. Compare this example to what can be seen from the slider file. file. Notice that the subsystem file contains only the the buses contained within Zone 6. Also notice that the contingency file contains all of the branches that are not connected to a transformer that are either contained within or originate originate from Zone 6. In  particular, notice how the monitor file creates an interface for each of the different power ratings of the branches contained in the contingency file. Please note that when a redundant line occurs (multiple branches between the same two buses), the connection between those two buses is only listed once. This is exactly how the rest of the files will look for for each zone, except for with the appropriate buses and branches. A Multi-ACCC report will now be created. 

Create a contingency, a monitor and a subsystem file for Zone 1 through Zone 9. There will  be a total of 27 files created. Refer to Lab 4 if you have difficulties.



Create an ACCC and a DFAX file file for Zone 1 through Zone 9. There will be a total of 18 files created. Refer to Lab 4 if you have difficulties.



Create a Multi-ACCC report report by loading all nine “*.acc” file that were created. This process is laid out in detail earlier in this lab. Print out this report and include it in the lab write-up. All the information that this lab will focusing on will be in the AC CONTINGENCY REPORT FOR 9 AC CONTINGENCY CALCULATION RUNS section on pages 8 and 9. Just pages 8 and 9 can be printed by simply highlighting those pages and right-clicking the mouse to bring up the sub-menu and selecting print. This will only print the highlighted region and will save a few pages of unnecessary printing. Also, these reports tend to print nicer if they are printed in landscape mode.

Use the printed report to answer the following questions. Review the tables that were created created on  page 8 and page 9. The table on page 8 shows all of the overloads that occur in the “Base Cas e” contingency. The table on page 9 shows all of the overloads overloads that occur, or greater overloads then that occurred in the “Base Case” condition, in each of the contingencies. 1) Which zone contains the most overloads during the “Base Case” contingency?  __________   __________  Which zone contains the most overloads during the other contingencies?  ___ ___ 2) Which branch suffered from the largest overload (compared to the “Base Case”) and what is the overload?  _______ __  During what contingency did this occur (which branch was taken out)?  __________  __________

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3) What happens to the branch connecting the buses “SUB500” and “SUB230” when the branch  between bus #154 and bus #205 #20 5 is taken out of service?  __________  __________ 4) Which contingency causes the branch between “MINE_G” and “3WNDSTST1” to see an increase in the overage caused during “Base Case”? _________ _  How much of an increase occurred? _________ _ Were there any other overloads that occurred under this contingency? ______ ___ To which branch did this occur? _________ _  How much was the overload? ___ ______ 

Answer these questions and include the printed section of the Multi-ACCC report with your lab write-up.

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LAB6 – ADDITION OF GENERATION

EE461: POWER SYSTEMS COLORADO STATE UNIVERSITY

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PURPOSE: The purpose of this lab is to introduce a wind farm into a base case and analyze the effects using PSS/E.      

Introduction to Power Flow Study Load Slider File Adding New Buses Addition of Transformer Addition of Wind Generation Generation Multi ACCC Report

To properly perform this lab, lab, start PSS/E and open the sample.sav file. Refer to Lab 1 on how to do this. Introduction to Power Flow Study

As in previous labs, the base case used for this power flow study is the sample.sav data file. A  portion of this system will be visually represented by a slider file. A model of a wind farm based on characteristics of GE built wind turbine generators rated at 1.5 MW, 60 Hz, can be added to this case. From this a system impact study, or power flow study can be performed. Load Slider File

For this lab, load the sample.sld slider file, and use save as to save the sample.sld as sample1.sld. This will prevent the original sample.sld file from being corrupted during the process of this lab. Perform the same process to save the sample.sav data file as sample1.sav. Locate bus 154; this this  bus represents a central bus with a number of loads at a base 230 kV rating. Spread out the  branches and the other buses to better view the diagram and ratings, like in the diagram below:

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This will make more space for the addition of the wind generation. *NOTE: ITEMS ARE BOUND. SO WHEN MAKING A CHANGE TO A SLIDER, THAT CHANGE IS MADE MADE IN THE CASE. IF THIS CHANGE IS UNDESIRED, RIGHT CLICK AND UNCHECK BIND ITEMS. Adding New Buses

A new bus can be added between two existing buses by using the Tap line feature. To do this, select the branch between buses 153 and 154 by left clicking it as shown in the following diagram:

Two circles will appear at either end. Now right click on the branch and scroll down and select Tap line.

The following window will appear.

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Choose 75% for bus location as percent of line. This will tap the line 75% away from Bus 153 and 25% away from Bus 154. Choose a new bus number over 90000. This is done to distinguish between buses added for a study and those with lower bus numbers originally in the case.  Name the bus; in this case, it has been named CSU. CS U. The base kV should automatically say 230. If not, type in 230, and click OK. The new bus should now appear in the diagram diagram as shown  below:

 Notice that on the left side all the values are gray. This means that the file needs to be solved. Solve the case. After solving the case the values will darken as shown on the right in the figure above.  Next, add another bus by clicking on the “Sizable Busbar” button in the too ls menu.

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When the cursor is moved over the diagram, a star will appear as in the picture below. Click on an area near buses 153 and 154. A new bus will will appear. Then, click on Select in toolbar to get rid of the star. If the diagram is maximized, maximized, double click on the new bus and it will will locate the new bus in the sample1.sav data file.

Double click on the new bus or go to the buses tab in the sample1.sav data file, and a new line will appear with the new busses information. Click in the Bus Name field field and, rename it to CSU_ LOW. Then click in the Base kV field, and set it to 34.5. This is a typical typical value for wind generation. After making these changes, make sure to click off off of that line to make the the updates active. Bus CSU_LOW from the data file file can be seen in the figure below: Addition of Transformer

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To add a transformer between two buses, Click on the 2-Winding Transformer “button”.

When the cursor is over the diagram, diagram, a cross will appear. When moved over a bus, a familiar circle will appear. Click on the CSU bus when the circle circle is present then stretch the cursor over to the CSU_LOW bus and click on it. A dotted line will show up while doing this. In this case, a transformer will be added between CSU and CSU_LOW.

With the new transformer in place on the slider diagram, go to the 2-winding transformer tab in the data file and find the new transformer that was just added. In the Rate A slot, change the the rating from 0.0 to 25.0 MVA.

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Addition of Wind Generation

On the toolbar, select Run Automation File. File. Or, select I/O I/O Control  Run program Automation file.

For file type, select IPLAN IPLAN File (*.irf). Select the gewinda.IRF file provided and click open.

The following window will appear.

Click OK.

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The next window will ask to select the model of turbines to use. Select 1. GE1.5 MW, 60 Hz.

Click OK. The next window will ask for a *.dat file. Select collector_1buses.dat and click open.

The next window will ask how would you you like to dispatch the units? Type 2 into the command line and click OK.

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For the next window, type 30.0 for 30%, click OK. This is a typical output for wind generation.

In the next window, type 2 for voltage control mode and click OK.

 Next, type 1.05 and click OK.

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Another window will open asking for a *.dat file. Select the ge15f60a file provided and click click open.

 Next, select the ge15f50_ddispatch_vcontrol.dyr file provided and click open.

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After the ge15f50_ddispatch_vcontrol.dyr file is opened, the case should have the addition of the wind farm. It’s possible that a few windows will appear asking for more parameters parameters of the wind farm to be entered. If these windows appear, choose the default values. Type Y (yes), for a remote bus for windvar emulator.

Click OK.

Click OK. Type Y, for default.

Click OK.

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Click OK. Type 1 for the manufacturer suggested protection scheme with fault ride through capability.

Click OK.

Click OK.

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Click OK. Type 1 for the manufacturer suggested protection scheme.

Click OK.

 Now, solve the system. Right click on the CSU_LOW bus and grow. The new transformer, bus, and wind generator are now present on the slider diagram as well as in the sample1.sav data file. The *.IRF file that was just used added all the values and parameters for the wind generation. If the system does not solve, try selecting Lock all for Switched shunt adjustments, and apply immediately for VAR limits. The Loadflow solutions window shown on the right can  be access by selecting Power Flow  Solution  Solve.  Note: This window will not appear by clicking on the solve  button in the toolbar after the initial solve has been  performed.

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The new wind generation is shown in the one-line diagram below:

Multi ACCC Report

As explained in Lab 5, run the multiple AC contingency report.

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Select all the *.acc files for each zone and click Go to run the report.

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Questions The “sample.sav” data file as well as the “sample.sld” slider file file must be open to perform perform this section of the lab. NOTICE: Before continuing, make sure the “sample.sav” data file has been saved as “sample1.sav” and the “sample.sld” slider file as “sample1.sld”. It is very important not to overwrite the existing files in the process of completing this lab.

Add an 18MW (5.4MW @ 30%) wind farm to the system as described above. 

Tap the branch between Bus #153 (MID230) and Bus #154 (DOWNTN) and add a new 230kV bus. Give this new bus number 90000 and name it CSU. Bus #90000 (CSU) will be in Area #1 and Zone #3.



Add a new 34.5kV bus. This bus will be number 1 and name it CSU_LOW. Bus #1 (CSU_LOW) will be in Area #1 and Zone #1.



Add a branch between Bus #1 and Bus #90000 with a 25MVA, 34.5kV/230kV transformer.



Add a 18MW, 60Hz wind farm that is connected to Bus #1 (CSU_LOW).

Create a new Multi-ACCC report with the wind farm added to the system. 

Use the “*.con”, “*.mon” and “*.sub” files that were saved from Lab 5.



Revise the “Zone1.sub” file to to include Bus #1 and Bus #90001. The contingency and monitor files for this zone do not need to be revised because no branches without transformers have been added to this zone.



Revise the “Zone3.con” file. Remove the contingency “MD2-DNTN” “MD2-DNTN” which is the branch  between Bus #153 and Bus #154 (since it no longer exists). exis ts). Add the contingency “MD2CSU” which is the branch between Bus #153 and Bus #90000. Add the contingency “DNTNCSU” which is the branch between Bus #154 and Bus #90000.



Revise the “Zone3.mon” file. Remove the requirement to monitor the branch between Bus #153 and Bus #154 (again, since it no longer exists). Add the requirements to monitor the  branches between Bus #153 and Bus #90000 and between Bus #154 and Bus #90000. #90 000.

 

Revise the “Zone3.sub” file to include Bus #90000. Create a new ACCC and a new DFAX DFAX file for Zone 1 through through Zone 9. To reduce the  possibility of confusion, name the ACCC files “Zone#_wind.acc” and the DFAX files “Zone#_wind.dfx” for each zone. There will be a total of 18 files created. Refer to Lab 4 if needed.

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

Create a Multi-ACCC report report by loading all nine “*.acc” file that were created. This process is laid out in detail in Lab 5. Print out this report and include include it in the the lab write-up. write-up. As in Lab 5, all the information that this lab will focus on will be on pages 8 and 9.

Use the printed report to answer the following questions. Review the tables that were created created on  page 8 and on page 9 and compare these thes e tables with the tables obtained in Lab 5. Just as a reminder, the table on page 8 shows all of the overloads that occur in the “Base Case” contingency while the table on page 9 shows all of the overloads that occur, or greater overloads then that occurred in the “Base Case” condition, in each of the contingencies. 5) Which zone contains the most overloads during the “Base Case” contingency?  __________   __________  Which zone contains the most overloads during the other contingencies?  ___ ___  Has this changed from the results obtained in Lab 5?  __ _ ___ 6) Which branch suffered from the largest overload (compared to the “Base Case”) and what is the overload?  _______ __  During what contingency did this occur (which branch was taken out)?  __________   __________  Has this changed from the results obtained in Lab 5?  __ _ ___ 7) Compare the contingency “EMN-WMN” from Lab 5 and what was obtained for this lab. Each had two two overloads. How do they they differ?  __ _ __ _  8) Compare the “Zone 8” columns from page 9 of the Multi-ACCC report generated in this lab and from Lab 5. How do they differ?  __ _ __ _  9) If the addition of a wind farm (or an y other source of generation) creates more mo re overloads in the system during contingencies then without it, it is said to “hurt” the system. If it creates creates fewer overloads, it is said to “help” “help” the system. Based on the Multi-ACCC reports reports generated in this lab and in Lab 5, how does the addition of the 150MW wind farm affect this system? Does it hurt, help or make no discernable difference? __ _ _ _  10) If you were the engineer in charge of this region of the power grid you would be responsible for the stability of the grid if anything were w ere to be added to the grid (like a 150MW wind farm). Inspect the one-line diagram with the current loading percentages displayed. Based on what you see and the information you have obtain from compiling this Multi-ACCC report compared to the data from Lab 5, would you recommend this wind farm addition for approval and why or why not? __ _ _

Answer these questions and a nd include the printed Multi-ACCC report with the lab write-up.

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Conclusions and Future Work

Our year long senior design project was a success. Although the hardest part of our senior design project was learning PSS/E, PS S/E, all of our group members are now proficient in performing a  power-flow study with this tool. Through our dedication and hard work we have completed all of the tasks that were required required by not only our faculty advisor but also our industry advisor. We managed to use roughly 200 hours working within PSS/E this year. In addition, to the time spent working within PSS/E, countless hours of preparation went into  producing and editing each of the laboratories and system impact study that have been viewed in this report. We were very successful in creating a system impact study that actually portrayed the way that these studies are performed performed and created in the power industry. In addition, we developed laboratories that document the steps and processes involved in performing a powerflow study. The labs were created because there are barely any user tutorials available that will teach a power engineer how to perform power-flow power-flow studies using PSS/E. Each lab was laboriously tested and checked for errors to ensure that the point and purpose of each lab is plainly obvious. We feel that we have excelled in getting the point across so well that not just a power engineer would be capable in performing and understanding how to create a power-flow study using PSS/E, but any individual with the will and determination could easily follow the process that has been outlined in this report. As a direct result of the success of our senior design project, Western Area Power Administration as well as Colorado State University has immediate plans on implementing the lab manuals that have been created. Our project is complete and will not need any continuation. However, Joe has taken the initiative to lead another group of students interested in performing a senior design project in the  power industry next year. We have given these students permission to review our lab manuals and system impact study to further their understanding of PSS/E in their future senior design  project. Since our project was primarily software oriented, our group’s budget of $600 was not heavily utilized. We spent around $50 on our poster board for for E-days and binding of the labs and our  project. The only other budget that we had was to not use up all of our trial hours for PSS/E that was provided to us by Siemens. The remaining time that has been left left on the access keys will be  passed on to the future senior design group.

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References

John Moore. System Switching Diagram-Subsystem Index, April 6, 2000 PSS/E-Help Tutorial, [Online Document] cited August – November 2006, available www.ptius.com/pti/software/psse/index.cfm Sociey for Applied and Industrial Mathematics, “The Power Grid as Complex System,” [Online Document], Sara Robinson, December 1, 2003[cited April 25, 2007], available http://www.siam.org/news/news.php?id=377.. http://www.siam.org/news/news.php?id=377

Wind Energy, “Bare All Aluminium Conductor Cond uctor Steel Reinforced (ACSR),” [Online Document], cited November, 2 2006, available http://www.windnenergy.com/ACSR.htm

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Appendix

Abbreviations AC DC DFAX ACSR  p.u. WY CO HS WAPA CSU ACCC PSSE WECC  NERC USB VAR MVAR VA MVA W MW V kV FACTS mon con sub sld ENS Hz GE

Definition Alternating Current Direct Current Distribution Data Factor File Aluminum Conductor Steel Reinforced Per Unit Wyoming Colorado Heavy Summer Western Authority Power Administration Colorado State University Alternating Current Contingency Calculation Power System Simulator for Engineering Western Electricity Coordinating Councel North American Electric Reliability Corporation Universal Serial Bus Volt-Amperes Reactive Mega Volt-Amperes Reactive Volt-Amperes Mega Volt-Amperes Watt Mega-Watt Volt Kilo-Volt Flexible Alternating Current Transmission System Monitored File Contingency File Subsystem File Slider File (Single Line Diagram) Engineering Networking Services Hertz General Electric

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Acknowledgements

First and foremost we would like to thank our industry advisor, Joe J oe Liberatore from Western Area Power Administration, for all of his guidance and support throughout the duration of this senior design project. Without Joe, the success of this project would not have been possible. We would also like to thank our faculty advisor, Dr. Collins from Colorado State University, for initiating and overseeing this project from the beginning. We would also like to thank him for his influence and instruction in power engineering at CSU. Finally, we would like to thank Daniel Woo and Siemens for allowing the free use of Siemens PSS/E during the coursework.

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SIEMENS POWER SYSTEM SIMULATION FOR ENGINEERS® (PSS/E)

LAB1 INTRODUCTION TO SAVE CASE (*.sav) FILES

Power Systems Simulations Colorado State University

The purpose of ECE Power labs is to introduce students to fundamentals of power flow analysis utilizing PSS®E. Electrical engineers use PSS®E to analyze, design and run simulation on bulk electric system models. PSS®E has a large library of analysis tools and optional modules, including, but not limited to: Power Flow Optimal Power Flow Balanced or Unbalanced Fault Analysis Dynamic Simulation Extended Term Dynamic Simulation Open Access and Pricing Transfer Limit Analysis Network Reduction        

These labs will introduce the user to the application and develop the basics of power flow analysis. Introduction to PSS®E The lab manuals that will be considered throughout the duration of this course will be primarily focused on power flow, rather than dynamic simulations. PSS®E uses a graphical user interface that is comprised of all the functionality of state analysis; including load flow, fault analysis, optimal power flow, equivalency, and switching studies. A common line interface is also available and students are encouraged to explore this method. It will not be covered in these labs.

PSS®E provides the user with a wide range of assisting programs for installation, data input, output, manipulation and preparation. More importantly, PSS®E allows the user of having a control over the applications of these computational tools. Power Flow In the Electric Utility Industry, power flow analysis is used for real time system analysis as well as  planning studies. The user should be able to analyze the performance of o f power systems in both normal operating conditions and under fault (short-circuit) condition. The study in normal steady-state operation is called a power-flow study (load-flow study) and it targets on determining the voltages, currents, and real and reactive power flows in a system under a given load conditions. The purpose of power flow studies is to plan ahead and prepare for “system normal minus one” (N-1) (N-1) contingencies.

The PSS/E interface supports a variety of interactive facilities including: • Introduction, modification and deletion of network data using a spreadsheet • Creation of networks and one-line one-line diagrams • Steady-state Steady-state analysis (load flow, fault analysis, optimal power flow, etc.) • Presentation of steady-state steady-state analysis results.

I.

Create a folder

1- Create a folder in your drive. Name it PSSE Labs. 2- Go to C: Drive and navigate: C:\Program Files (x86)\PTI\PSSE32\EXAMPLE 3- Copy the following and paste p aste it in PSSE Labs folder: a. Sample.sav  b. Sample.sld c. exercise1.sld II. How to access PSS®E There are two ways to access PSS®E: P SS®E: 1-

On campu s Computer s:

a.  b. c.

Log onto Eng. Account computer. Click on Start icon. Type in the search box, PSS then select PSS®E 32

d.

2-

The window below appears:

Off Campus Campus::

a. Go to ENS webpage http://www.engr.colostate.edu/ens/

 b. c. d. e.

Choose Virtual Lab icon Then, follow the instructions in virtual lab page. Once it’s opened, click on Start and Type PSS in the search box. The program will launch and the window below will appear.

III.

Loading a *.sav file. The save case file (*.sav) is a binary image of the load flow working case. To conserve disk space and minimize the time required for storage and retrieval, save cases (*.sav (*.sav)) are compressed in the sense that unoccupied parts of the data structure are not stored when the system model is smaller than the capacity limits of the program.

A save case file (*.sav) will open through: a. Go to second toolbar. Click on

or Go to File, Open

 b. Navigates to your PSSE Labs folder. The window will appear. Choose Sample.sav  file. Make sure the description in the right box are Save Case File*.sav).

IV. Explanations of Tabs Once the sample.sav   file is opened, there are 19 tabs to choose from at the bottom of the data file (shown below). Each tab can be accessed by clicking the tab. There are six tabs that will be focused on in this section: Busses:

It is a node (remember in Circuit Theory Applications or in Basic Circuit Analysis) Busses connects components (machines, loads, transmission lines, etc.) in the circuit to one another.

All equipment information and characteristics associated with each bus in the system can be obtained by accessing the buses tab. In the buses tab there will be several parameters that can be set or adjusted. The important parameters will be described below:

Displays the number of each bus (1 through 999997).

Displays the name of each bus.

The voltage of each bus in KV unit.

They show up in numbers to 5 and it is usually set to 1 by default Here what each number means: 1 - Load bus (no generator boundary condition)

2 - Generator or plant bus (either voltage regulating or fixed MVar) 3 - Swing bus 4 - Disconnected (isolated) bus 5 –  Same  Same as type 1, but located on the boundary of an area in which an equivalent is to be constructed. Per unit voltage which is 1.0 by default. Bus data input is terminated with a record specifying a bus number of zero. Branches:

Branches represent transmission lines and they are characterized by impedance.

Each ac network branch to be represented in PSS/E as a branch is introduced by reading a branch data record. The important branch data records that will be considered are:

Shows number, name and KV voltage of each bus that is branching from.

Shows number, name and KV voltage of each bus that is branching to.

Branch resistance; entered in per unit. A value of R must be entered for each branch.

Branch reactance; entered in per unit. A nonzero value of X must be entered for each  branch.

Total branch charging susceptance (imaginary part of admittance); entered in per unit. B = 0.0 by default.

First power rating; entered in MVA. Rate A = 0.0 (bypass check for this branch) by default.

Second power rating; entered in MVA. Rate B = 0.0 by default.

Third power rating; entered in MVA. Rate C = 0.0 by default.

Line length; entered in user-selected units. All lengths are in miles for the purpose of this lab. Branch data input is terminated with a record specifying a " from bus" bus" number of zero. Loads:  loads are the elements which consume power, loads in AC systems consume real and reactive  power.

Data entered in the spreadsheet view will be entered in the load flow flow working case (*.sav file). The source data records may be input from a Machine Impedance Data File or from the dialog input device (console keyboard or Response File). The machines tab can be used to: 1. Add machines at an existing generator bus (i.e., at a plant). 2. Enter the specifications of machines into the working case. 3. To divide and distribute the total plant output power limits proportionally among the machines at the  plant.

The important parameters for the machines tab are described below: It shows the bus’s (number, name and KV voltage) where the machine is located.

This is a one, or two, character uppercase, nonblank, alphanumeric machine identifier. It is used to distinguish among multiple machines at a plant (i.e., at a generator bus). At buses in which there is a single machine present, ID =1

. A chec check k mark ark indi indica cattes that hat a cert certai ain n mach machin inee at a "Bus "Bus Numb Number er/N /Nam ame" e" is ful fully operational. If for any reason a certain machine at a "Bus Number/Name" needs to be taken out of service, simply un-check that particular one and click the line above or below to make your changes final.

This shows how much active power of particular p articular load is connected to this bus. This shows how much reactive power of particular load is connected to this bus. bu s. ** Buses can have more than one load attached to them and designed different by their “Id” Id” For instance, bus 154 has two loads attached as shown in load tap under

2 Winding Transformer:  two to one Transformer

Each transformer to be represented in PSS/E is introduced by reading a transformer data record block. The transformer data record block can be accessed by clicking the 2 Winding Transformer tab. The important parameters for this tab are explained below

This states the first bus number and the bus name with bus kV in their respective columns. It is connected to winding one of the transformers included in the system. The transformer’s magnetizing admittance is modeled on winding one. Winding one is the only winding winding of a two winding transformer whose tap ratio or phase shift angle may be adjusted by the power flow solution activities. No default is allowed.

This states the second bus number and the bus name with bus kV in their respective columns. It is connected to winding two of the transformers included in the system. No default is allowed.

A check mark indicates that a certain two winding transformer between two buses is fully operational. If for any reason a transformer needs to be taken out of service, simply un-check that  particular one and click the line above or below to make your changes final. The default is in service. Switched Shunts:   capacitive or inductive to reduce reactive power in the system. We will designate  both capacitors and inductors as “Reactive Elements “Reactive Elements”” when speaking in general terms.

Shunts are used in the power system to improve the quality of the electrical supply and the efficient operation of the power system. There are two types of shunt compensation; shunt capacitive compensation and shunt inductive compensation. Generally refers to in industry as capacitors or

inductors, the shunt capacitive compensation is used to improve the power factor while the shunt inductive compensation is used to maintain the required voltage level, generally in the case of a very long transmission line. Switched shunts are simply shunts that have the ability to be controlled.

The “Switched Shunts” tab in PSS®E lists all of the shunt compensation in the overall system, both capacitive and inductive, along with all of the pertinent information for the switched shunts: This displays the Bus Number and the bus name with the bus voltage in kV in their respective columns. This is the bus to which the shunt is connected.

This lists the bus, by number, whose voltage or connected equipment controls this switched shunt. For example, if there is a bus number other than 0 in the remote bus column then that  bus number controls the shunt.

This lists the high voltage limits (in per unit) and can be used as a trigger point to control or switch reactive elements. The default for VHI is 1.

This lists the low voltage limits (in per unit) and can be used as a trigger point to control or switch reactive elements.

This lists the initial surge (or charge) admittance of the connected shunt (in MVAR ’s ’s at unity voltage). Enter a (+) for capacitance capacitan ce or (-) for inductance.

Reactive (capacitors or inductors) elements are added incrementally utilizing a Block(#) steps that contain a number of steps per, or, Blk(#) Bstep. For example, if Blk1 has 5 steps containing Bstep of 10 MVar Blk2 has 10 steps containing Bstep of 5 MVar, the user could choose 2 x 10 (Blk1 contribution) + 1 x 5 (Blk2 contribution) MVar for a total 25 MVar of reactive compensation.

Refer to the highlighted line in the table above, the initial value of reactive compensation is 597.16MVar. Additionally, there are 4 steps of Blk1 with 100 MVar, 2 steps of Blk2 with 50 MVar, 4 steps of Blk3 with 25 MVar, 3 steps of Blk4 with 20 MVar and 2 steps of Blk5 with 20 MVar. In total, the system will have 700 MVar of additional compensation add to the initial 597.16 MVar which makes a total of 1297.16 MVar. * We will refer reactive element to both Capacitor and Inductor otherwise, we specify Capacitor as Positive or Negative and Inductor as Positive or Negative too.

** Formulas needed to answer Lab1 questions:

  ()     √    ()          ()        ** RealPower = ActivePower

 ()   ()

PSSE Lab # 1 Questions: Open the “sample.sav  ” data file to answer the following questions. 1) Go to the “Bus” tab. Find bus #3008. a) What is the name of this bus and its rated voltage? ___________________  b) Based on the code number, what type of bus is this? __________________ 2) Now go to the “Branch” tab. Find the branch that connects bus #201 to bus #207. a) What are the names of the buses that are connected and the rated voltage of the branch?  ______________________________________   ________________________ ______________   b) What is the rated resistance and reactance of this branch (both in [per unit])?  ______________________________________  ________________________ ______________  ____________________________________________________  ________________________ ____________________________________ ________ 3) Now go to the “Load” tab. Find load connected to bus #214 (LOADER, 230kV). 230kV). a) What are the active (MW) and reactive (MVAR) components of this load?  ________________________________________  ________________________ ________________  b) Based on the results from above, what is the real power and power factor of this load?  ________________________________________   ________________________ ________________ 

4) Now 4) Now go to the “Machine” tab. Find generator connected to bus #402 (COGEN-2, (COGEN-2, 500kV). a) What are the maximum and minimum active power ratings of this generator (in MW)?  ________________________________________  ________________________ ________________  b) What are the maximum and minimum reactive power ratings of this generator (in MVAR)?  ________________________________________  ________________________ ________________ 5) Now go to the “2 Winding XFMR” tab. Find the transformer connected to bus #204 and bus #205. a) What are the MVA ratings of this transformer? Rate A=_________________ Rate B=__________________ Rate C=_________________  b) Is this transformer in service? service? ________________________ _________________ _______ c) What is the High side Voltage? _______kV, What is the Low side Voltage? _______kV 6) Now go to the “Switched Shunt” tab. Find shunt compensator compensator connected to bus #154 (DOWNTN 230.000, 230KV). a) How many steps are there to the shunt compensator and what is each of their values (in MVAR)?  ____________________________________________________  ________________________ ____________________________________ ________  ____________________________________________________  ________________________ ____________________________________ ________

 b) What type of shunt compensator is this (capacitive, inductive, or mixed)?  ________________________________________   ________________________ ________________  7) While you are in the “Switched Shunt” tab, tab, Complete the missing Mvar values using the table below for BUS 3021? BLK# 1 2 3 4

Steps 2

Compensation/Steps# 200 100

2

Total in Mvar

100 Subtotal

Binit (Mvar) Totals

SIEMENS POWER SYSTEM SIMULATION FOR ENGINEERS® (PSS/E)

LAB2 INTRODUCTION TO SLIDER BINARY (*.sld) FILES

Power Systems Simulations Colorado State University

PURPOSE: The purpose of this lab is to introduce the one-line diagram, also known as the Slider files in PSS/E. This lab will introduce the following aspects: • Introduction to a one-line one -line diagram and its elements. • Explanation of the Slider (*.SLD) file • Using the Slider file to create a one-line one -line diagram To properly perform this lab, start PSS/E and open the sample.sav   file as we have done in LAB1.  file Introduction to One-Line Diagrams A one-line diagram is a simplified graphical representation of a three phase power system, used extensively in the electrical utility industry. In power engineering, if we assume that the three  phases of a system are balanced, the 3 phase system can be represent with a single line (I.E. one line diagram) which simplifies schematics. This makes the evaluation of the system much less complicated without losing any information. Per unit voltage used extensively in one-line diagrams to further simplify the process.

The main components of a one-line (or single line) diagram are; Buses, Branches, Loads, Machines, 2 Winding Transformers, Switched Shunts, Reactor and Capacitor Banks. An explanation of these components will be given later in this lab. Buses:

Buses are represented as a dot, circle or a thick line. The bus name (EAST500) and number (202) are given, as well as the voltage measured on the line (510.5kV and 1.021V in per unit). The final characteristic given is the angle (-26.1 degrees). The voltage is indicated by the color of the  bus. In this example, red indicates 500kV. Associating KV levels with *color is a user configurable option. Branches:

Branches are represented as a line connecting busses. The real power P, as shown in the above image of a branch, flows from 431.5MW to -429.8MW and the reactive power Q, flows from 158.7MVA flow to -238.8MVA. Notice when selecting the animation icon, MW and MVar are shown as green and yellow arrows respectively. In other words, the flows are from the positive number to the negative number shown below, and the number on top is the real power while the number on the bottom is the reactive power. The voltage is indicated by the color of the branch. In this example, red indicates 500kV.

Loads:

Loads are represented as a triangle with the ID number located inside the triangle. The real  power, PLOAD, is denoted by the number on top (250MW), and the reactive power, QLOAD, is denoted by the number on bottom (100Mvar). The voltage is indicated by the color of the load. In this example, black indicates 230kV. M achi achi nes: nes:

Machines are represented as a circle with the ID number located inside the circle. The real  power, PGEN, is denoted den oted by the number on top (321.0MW), and the reactive power, QGEN, is denoted by the number on bottom (142.3RMVAR). The “R” indicates this machine machine is in voltage regulation mode, and it is controlling a specific bus to a voltage set point which requires it to generate 142.3MVAR. The voltage is indicated by its color of the machine. Two Windin g Transformers: Transformers:

Two winding transformers are represented as two separate windings with a gap separating them. The arrow pointing in at the connection reflects the primary side of the transformer. In this example, the primary voltage (1.0000 in per unit voltage) is given on the primary side of the transformer and the secondary voltage (1.0000 in per unit voltage), is given on the secondary side of the transformer. The voltage is indicated b y the color of the transformer and is dictated b y the primary side voltage. In this example, purple indicates 21.6kV Switch Switch ed Shun ts: ts:

OR Switched shunts are represented as either a capacitor or an inductor on a bus. The “SW” shown on top (or on the left if the shunt is shown vertical) indicates that this unit is a switched shunt compensator. If you see these symbols with a number in place of the “SW”, “S W”, that particular that particular device is a permanently installed reactor or capacitor bank (see below). The number on bottom (or on the right if the shunt is shown vertical) indicates the initial reactive charge admittance, BINIT (253.8MVAR or -599.6MVAR). The voltage is indicated by the color of the shunt. In this example, red indicates 500kV.

Reacto Reactorr Ban k:

Reactor banks are represented as an inductor on a bus or line. The number on top (or on the left if the reactor is shown vertical) indicates the real charge admittance, G SHUNT, of the line (3.6MW). If you see a “SW” instead of a number, you are looking at an at an inductive switched shunt compensator (see above). The number on bottom (or on the right if the reactor is shown vertical) indicates the reactive charge admittance, BSHUNT, of the line (490.0MVAR). The voltage is indicated by the color of the reactor. In this example, red indicates 500kV. Capac Capacitor itor Bank:

Capacitor banks are represented as a capacitor on a bus or a line. The number on top (or on the left if the capacitor is shown vertical) indicates the real charge admittance, G SHUNT, of the line (0.0MW). If you see a “SW” instead of a number, you are looking at a capacitive switched shunt compensator (see above). The number on bottom (or on the right if the capacitor is shown vertical) indicates the reactive charge admittance, BSHUNT, of the line (-1080.0MVAR). The voltage is indicated by the color of the capacitor. The Sli Sli der der F il e:

The Slider (*.SLD) file is a file that contains the one-line diagram. As can be seen from the figure above, the one-line diagram can get pretty complicated. To simplify matters, all the  physical data related to each element shown in the one-line diagram is linked to the data file

(*.SAV). This way, a simple thin line represents all of the data located in the branch tab. All of this data is interconnected and linked so as to perform power flow analyses. Once a one-line diagram is created, it can be saved as a Slider (*.SLD) file. The Slider file can be amended and updated as necessary, as long as the amendments and updates correspond with the *.SAV file, since the two files are intertwined. Another advantage of the Slider file is that one can view the power flow and the operating levels of a branch. This allows a Power Engineer to quickly see potential trouble spots in a power system and correct them before problems occur. The process of performing a power flow analysis is the main objective of these labs. As mentioned above, in order to properly perform this lab, PSS/E needs to be running and the data file “sample.sav” opened. Refer back to Lab 1 if problems arise in doing doin g this. I.

How to open the *.sld *.sld –  *.sld  –  Slider   Slider file (Single Line Diagram) This file allows for performing network analysis studies on the grid. Sliders are visual displays of the grid. It includes buses, branches, lines, loads, generators, transformers etc... All components should be color coded based on voltage level. The slider file can also show the operational ratings (power flowing across the component relative to the capacity) of the listed components.

Once the PSS®E program opened, a.

Go to second toolbar. Click

 b. The window will appear. Choose Sample.sld   file. Make sure the description in the right  box are Slider Binary File (*.sld).

II. GROW Element In this method, you learn how to create *.sld file based on any *.sav file available to you. The *sld and *.sav files are interconnected **Important  . Therefore any actions to the either file result change the other and to avoid that you need to learn how to use “Bind items”. Finally, you learn how to grow element on one-line diagram. F ir st: cr eate new * .sld .sld

a. open PSS®E (refer to part II)  b. Go to second ond toolbar. Click on

c. The window will appear :

d.

Keep Diagram selected. Click OK. A new Diagram created.

Second: Second: Color code using Di agram An notation .

a. Go to third Toolbar. Click on

 b. Once you clicked on, Power Data Annotation window appears

c. Go to Diagram Range Checking tab and Check Use voltage level thresholds to edit it with their corresponding colors. Set all values and colors to match the following standards by clicking on each color bar: Colors from the left to the right on the window: Dark green - Black - Blue - Bright green - Yellow - Orange - Red –  Red –  Purple  Purple 





Widths from left to right on the window: 1 - 1 - 1 - 2 - 2 - 3 -3 –  -3 –  4  4  Now enter the threshold voltages as shown:

** If the diagram ranges checked, it should looks exactly as below, and then clicks OK.

Th ir d: D isplay a bus with in sample.s ample.sav av fil e.

This step will display a bus into the blank diagram using Auto Selected Draw: a. Open sample.sav  file  b. Return to blank diagram; go to third toolbar and Click on Auto Draw on the blank.

and go back click

c. Auto-Draw appears:

d. Click on select and choose the desired bus number from the sample.sav  file. In this practical example choose BUS 102. Then Click “OK ”.

e. Click on Auto-Draw OK, then all elements connected to BUS 102 will displayed on the blank diagram.

f. Exit Auto-Draw by clicking Esc key. F ourth: Un-Bi nd I tems tems.. **Important 

Because of the *.sav and *.sld are linked together (interconnected), any deleting of a bound item from a diagram removes it from the *.sav data file and will result in analysis corruption. This means that if a change is made to either files the other will be affected. This can be done by right unselect select  Bind Items or use Ctrl+B. click on a bus and un

 Note: Make sure there is no  Note: Make check mark!

F if th: Gr ow N L evel vel

a.

Once you deselect Bind items, right click on a bus and choose Grow N Levels.., Choose 1

The BUS 102 will grow out 1 level:

 b. Rearrange the grid. Click on black space in the diagram and select an element and drag it to desired place to avoid overlapping o verlapping in ratings or wires.

c. If needed, the toggle bus symbol feature can be applied to display buses as dots, circles, or lines. This is done by selecting a component by left clicking the component (the selected component will have a black square on each corner), and then right click the bus symbol and selecting Toggle bus symbol. Different bus symbols shown below; Dot:

Circle:

Line:

III. Solve a System Solving a system allows PSS/E to make all the necessary calculations used in a power flow analysis.

Go to fourth toolbar. Click on solve icon

The following window will display:

Configure the Load flow solutions window to match the one displayed. This could include selecting the “Lock all” radio button under Switched shunt adjustments and uncheck “Adjust DC taps”.

Click on button solve and PSS/E will solve the system and store the results in the progress window. IV. The loading percentages Go to third toolbar. Click on Current Loadings icon

The following will be displayed:

V.

Animation

Go to third toolbar. Click on Animate Flows icon

The following will be displayed:

VI.

Grow and Un-Bind in real application *.sld file

Open exercise 1.sld  from your PSSE folder; its hiding some elements that need to be grown.





 

Search for BUS 102 by zooming in and right click on the bus. un-select Bind items

Grow N Levels: right click and select Grow N levels. Choose the level that displays new element to the grid. Once there are no elements added to the grid, and then you are done. Zoom, Rearrange, and Deliver with Lab Questions. You should have exactly the sample.sld  file shown below:

PSSE Lab # 2 Questions: The “sample.sav  ” and “sample.sld  ” must be open to perform this section of the lab. First, build out a one-line diagram to include the following ten buses (and no others!): 101 NUC-A 102 NUC-B 151 NUCPLANT 152 MID500 153 MID230 201 HYDRO 202 EAST500 3004 WEST 3021 WDUM 3022 EDUM This is best done by typing “101” into the auto draw function, then right clicking the “151” bus; select grow. From here, right click the “152” bus and select grow. This should prevent you from ending up with extraneous buses. Solve for the system. Display the current loading percentages and the power flow animation. Print out the one-line diagram and include it in the report. Save the one-line one-line diagram as “lab2.sld”, this will be needed nee ded for future labs. Using the one-line diagram, and answer the following questions to include in the report. Turn off the loading percentages and the power flow animation for clarity. Make sure that the system has  been solved. 1) Looking at Bus #152 (MID500), what is the P LOAD and QLOAD of the load connected to this  bus? _______________  ______________________ ______________ _______________ ________________ __________  __  2) Find the two generators within this sub-system. Which buses are they connected to? What are the PGEN and QGEN of the two generators?  ________________  _______________________ _______________ _______________ _______________ ________________ _______________ _______________ ________________ _________ _  ________________  _______________________ _______________ _______________ _______________ ________________ _______________ _______________ ________________ _________ _ 3) How many reactive devices are in this system? _______________  _______________________ ________________ _________ _  _______________________ _______________ _______ How many capacitors are in this system? s ystem? _______________ How many inductors are in this system? s ystem? How many switched reactive devices (switch shunts) are in this system?  ________________  _______________________ ___________ ____ How many of the switched shunts are represented as a) inductors b) capacitors? 4) Looking at Bus #153 (MID230), what is the actual voltage of the bus and  _______________________ ________________ _______________ ___________  ____  What is the per unit voltage? _______________

SIEMENS POWER SYSTEM SIMULATION FOR ENGINEERS® (PSS/E)

LAB3 AUTO CREATION OF *.CON, *.MON, AND *.SUB FILES

Power Systems Simulations Colorado State University

Purpose of the lab: This lab is designed to represent a guide for the user to build the *.con, *.mon and *.sub files automatically according to sample.sav and sample.sld given files for this course. This lab will also explain how the three files are utilized by the AC Contingency Calculation (ACCC) feature of PSS/E to perform a power flow study on a particular zone.

Power Flow (PF) analysis is possibly the single most utilized tool in the power industry. PF analysis allows us to simulate unplanned (or forced) as well as planned outages. A power flow solution is often the starting point for many other types of power system analysis. In addition,  power flow analysis is at the heart of contingency analysis and the implementation of real-time monitoring systems. The creation of contingency (*.com), monitor and subsystem files will allow us to perform PF analysis. Important definition for better comprehension to this lab: *.sub (subsystem) file: · The subsystem file informs the power flow analysis to only look at a prescribed section, or zone, of the overall network. *.mon (monitor) file: · The monitor file tells the power flow simulator which branches to be supervised during the (N-1) contingencies *.con (contingency) file: · The contingency file is programmed to remove equipment, from service; this is referred to as a contingency. When the system is fully operational, it has no outages, therefore it is referred to as system intact or (N-0). When a single line is taken out of service, the case is then referred to as an (N-1). When two elements are taken out of the service, it referred to as (N-2) The easiest way to program how to do this is to see a portion of the code used in the *.con file and understand what everything does. ACCC: · The contingency, monitor, and subsystem files are utilized by the AC Contingency Calculation (ACCC) features of PSS/E to perform a power flow study on a prescribed zone. The ACCC  produces an analysis of the power system. DFAX (distribution factors file): · It is a measure of the impact of injections and network changes on the grid applied over the initial or base case power flow. DFAX represents a measure of the effect of each zone‘s load on the transmission constraint that requires the mitigating upgrade, as determined by power flow analysis. The source used for the DFAX calculation is the aggregate of all generation external to the study area. Sample.sav file: (described in lab 1) · The saved case file (*.sav) is a binary image of the load flow working case. To conserve disk space and minimize the time required for storage and retrieval, saved cases (*.sav) are compressed in the sense that unoccupied parts of the data structure are not stored when the system model is smaller than the capacity cap acity limits of the program. Sample.sld file: (described in lab 2) · *.sld –  *.sld –  Slider  Slider file (Single Line Diagram) This file allows for performing network analysis studies on the grid. Sliders are visual displays of the grid. It includes buses, branches, lines, loads, generators, transformers etc... All components should be color coded based on voltage flow. The slider file can also show the operational ratings (power flowing across the component relative to

the capacity) of the listed components. This network can be divided on several zones and areas  based on the need of the user. · Areas: Graphically, an Area typically represents an entire region, region, perhaps a state (Colorado) (Colorado) or small country (Bahrain). Areas can be utilized to represent a regional electric electric market, ie, the majority of load within an area is served with the majority of generation in in that same area. Load can be served with generation from another area. This is typically accomplished thru metering and schedules but is outside the scope of this lab. The only reason for a detailed explanation is to  present this concept and Bulk Electric System (BES) structural philosophy p hilosophy currently practiced in the real world to familiarize the future power engineer. · Zones: Typically, Areas (above) are represented as a collection of Zones. An Area could contain one or more Zones. The reasoning behind this is to allow Areas to have many subsets (Zones) such that detailed analysis and criteria can be applied to a particular Zone. For instance, one town may have a stricter pos-contingent per-unit voltage level. By breaking areas into zones, you will have the flexibility to apply different scenarios to avoid any outages or blackout when overloads occur and could be fixed fast and easy because you know which zones are affected. If the concept of Areas and Zones sees confusing, review the slider file (sample.sld) from lab two and consider the definition of Areas and Zones described above. Example: Figure1: Area 3 shown below in the picture has one zone.

Figure 2: Area 1 has two complete zones (1 and 3) and two partial zones (2 and 4) shown below.

1. Start PSS®E as it was shown in lab1. 2. Open the sample.sav file from your PSSE Labs folder as it was shown in lab1. 3. Open the sample.sld file from your PSSE Labs folder as it was shown in lab1. 4. Go to toolbar and and click on Subsystem-Area. Subsystem-Area. Write Write down the areas areas names. 5. Click Click on on the the Creat Create/M e/Modi odify fy Config Config File Filess icon icon . Also, Also, it can be acces accesss throu through gh Powe Powerr lowlowLinear Network- Create/Modify SUB, MON and CON configuration files...

6.

The following window will appear.

a) Uncheck the Append subsystem description to the existing file.  b) Enter Central  as the subsystem name. c) Click select from the select bus subsystem, a new window will ap pear as follows

d) Select on central then click on the arrow pointing to the right to have Central switched to  be in the Selected areas menu, hit Apply and Ok to close the window.

e) Click on (Subsystem description file) and type “area1” in the file name. Then save it. f) Uncheck the Append Monitored descriptions to existing file option. g) Verify the Bus voltage range is from 0.95 to 1.05 pu. h) Click on (Monitored element file) and type “area1” in the file name. Then save it. i) Uncheck the Append Contingency descriptions to existing file option.  j) Click on save it.

and (Contingency description data file) type “area1” in the file name. Then

The Configuration File Builder should look exactly like the given window below:

 j) Click on Go, then click DFAX and navigate to your folder location created in lab1 and type area1” in the File name box. box.

Click open and a new window will appear:

Click OK.  NOW: the *.con, *.mon, and *.sub files have created and can be opened using WordPad or  Notepad as shown in the picture below.

Items of note: “COM” denotes a comment line and all text following has no program implications. As in all  programming, commenting is good practice and should be implemented here. “END” statements will be requir ed ed for *.sub. *.mon and *.con files. The “area1.sub” file contains two “END” statements. Both, and sometimes more (and in future labs) are required. This to be explained in lab 4??.

area1.sub file:

The “area1.sub’ file has subsystem we called out (specified) (specified) as “central” and it contains all  buses in ‘area1’ as defined defined in the sample.sav database. area1.mon file:

The “area1.mon’ utilizes the subsystem we indicated as “central”. As such, we are now able to implement a wide variety of monitoring functions on this subsystem. The first line sets a per unit voltage range for the subsystem. Next, the line gives a +/- deviation from the prescribed values in first line. Then, the line comments inform which branches to monitor in the subsystem named “central”. Finally, Finally, the line tells that the monitor file is tied to “central” subsystem. area1.con file:

The “area1.con” is another file that is dependent on the subsystem. This file is utilized to simulate contingencies in power flow analysis for system-in-tact-minus-1 simulations, also known as N-1 simulations. The contingency operation will work in all of the elements in the specified area or zone. For instance, it plans to remove any single branch between two buses, double branches between two buses, or any single/double branch from one area/zone to another. AC Contingency Calculation (ACCC):

The three files area1.sub, area1.mon, and area1.con are utilized to by the AC Contingency Calculation (ACCC) feature of PSS®E to perform a PF study on a particular area or zone. After creating “area1” files, now it’s time it’s time to solve the system. Follow the steps below: 1- ACCC icon located on the Fourth Toolbar

Or there is always another long way to run the ACCC contingency solution:

1- Go to Toolbar and click on Power Flow menu 2- Scroll down to Solution. 3- Under Solution click on AC contingency solution (ACCC)

The widow of the ACCC will displayed as above place the files created earlier in the lab: Dis Distrib tribut utio ion n fa factor ctor dat data fil filee

: area1.dfx

Conti Conting ngen ency cy sol solut utio ion n outp output ut fil filee : type type in in the the fil filee name name area1 Leave Load throwover data file empty. “

”

Click on Solve. Don’t close the Window yet! Click on reports the window below will open and make sure you have the correct file name for *.acc file you created above.

Then hit GO to run the report for “area1” your report will appear in the ‘report’ tab. tab. Go over the reports and check all the files you created from AC Contingency are shown in the reports as the picture below.

 NOW after you have the appropriate files for this operation. the report contains three majors Section described below. 1-  M onitored onitored Br anch anch

* It shows all the branched double or single with its number and base voltage in kV that has been monitored by the contingency assigned to it. It also shows the machine identifier “ID”. * Under the contingency, the name of this contingency “BASE CASE” * Next column states the rating for the first power rating; ent ered in MVA * Under Flow indicates the amount of the power flow through this branch. * % shows the loads percentage which above 100% loads called overload.

2-  M oni tored voltage voltage r eport 

This section will sort the buses according to the subsystem name in this case “CENTRAL”

V-CONT: is the post contingency voltage. It indicates the voltage element under the specified network label. Ex: Single 5 V-INIT: it shows the initial voltage for this bus in deviation. V-MAX: indicates the maximum voltage deviation in the CENTRAL subsystem. (above V-initial) V-MIN: indicates the minimum voltage deviation in the CENTRAL subsystem. (below V-initial)

3-  Conti ngency Legends Legends

Sorts all the contingencies according to the network label and shows the action/event of this contingency. It runs contingency in every branch in all possible network choice and evaluates the overloads with each event.

These label networks can be explored in the “sample.sld” file by double-click double-click on the bus number as shown below:

PSSE Lab # 3 Questions: The “sample.sav” data file must be open to perform this section of the lab.

Using the “area1 “area1”” contingency file, the “area1 “area1”” monitor file and the “area1” area1” subsystem file that have been provided, create an “area1.dfx” area1.dfx” DFAX and an “area1.acc” area1.acc” AC contingency file. Solve Solve the system with the loaded AREA1 files and run the ACCC report as shown above. View the report generated by PSS®E and print out the report, this print out will need to be included in the lab report. It will also be helpful in answering the following questions. 1) Which branches suffer from overloads during the “BASE CASE” contingency and what is their percentage of overload? BRANCH Percentage overload

2) Looking at the “SINGLE “SINGLE 9” 9” contingency, which branches suffer from overloads that did not suffer from overloads during the “BASE “BASE CASE”, CASE”, and what is their percentage of overload? BRANCH Percentage overload

3) Of the branches suffering from overloads during the “BASE “BASE CASE”, CASE”, which one(s) got worse during this contingency (SINGLE 9), and by how much? BRANCH Percentage overload increase

4) Did any of these branches actually see a r eduction in overload, if so, which ones and by how much were they reduced? ______________ 5) Which of the contingencies created the highest number of overloaded branches?  ___________ 6) Find the “SINGLE 7” 7” contingency. a) What is the rating of the branch between bus #153 and #154 (in MW) and what is the actual  power flow (in MW) MW) on this branch? ______________   b) What is the rating of the branch between bus #152 and #3021 (in MW) and what is the actual  power flow (in MW) MW) on this branch? ______________ ___________________  _____   ____________ 7) Using the lab manual, run the ACCC for “ area2” and named the subsystem “EAST “. Printout the report and submit it with Lab #3 Questions.

SIEMENS POWER SYSTEM SIMULATION FOR ENGINEERS® (PSS/E)

LAB4 MANUAL CREATION OF *.CON, *.MON, AND *.SUB FILES

Power Systems Simulations Colorado State University

Purpose of the lab: This lab guides the user to create the *.con, *.mon, and *.sub files manually based on the completion of lab 3 and using these files sample.sav and sample.sld. Also, giving the user a deeper understanding of how to create and modify the three files which are necessary to perform the ACCC analysis for PF. Objectives of the lab:

• • • • •

Create & Modify subsystem file (*.sub) Create & Modify monitor file (*.mon) Create & Modify contingency file (*.con) Apply ACCC using the files above. ACCC report.

A Text file “*.txt” *.txt” is necessary to get familiar with Text files to do this lab. A text file (or plain text file) is a file which contains only ordinary textual characters with essentially no formatting. Text files are commonly used throughout PSS®E  because soft code contains commands often needed to complete tasks. PSS®E  utilizes specifically named .txt files to perform ACCC analysis. These files are named *.sub, *.mon and *.com (subsystem, monitor and contingency files respectively) Recap of some important definitions:

· *.sub (subsystem) file: The subsystem file informs the power flow analysis to only look at a prescribed section, or zone, of the overall network. · *.mon (monitor) file: The monitor file tells the power flow simulator which branches to be supervised during the (N-1) contingencies *.con (contingency) file: · The contingency file is programmed to remove equipment, one piece at a time from service; this is referred to as a contingency. When the system is fully operational, it has no outages, and it is referred to as system intact or (N-0). When a single line is taken out of service, the case is then referred to as an (N-1). The easiest way to program how to do this is to see a portion of the code used in the *.con file and understand what everything does. · ACCC The contingency, monitor, and subsystem files are utilized by the AC Contingency Calculation (ACCC) feature of PSS/E to perform a power flow study on a prescribed zone. The ACCC  produces power flow analysis of a system. DFAX (distribution factors file): · It is a measure of the impact of injections and network changes on the grid applied over the initial or base case power flow. DFAX represents a measure of the effect of each zone‘s load on

the transmission constraint that requires the mitigating upgrade, as determined by power flow analysis. The source used for the DFAX calculation is the aggregate of all generation external to the study area. · Areas: Graphically, an Area typically represents an entire region, perhaps a state (Colorado) or small country (Bahrain). Areas can be utilized to represent a regional electric market.ie; the majority of load within an area is served with the majority of generation in that same area. Load can be served with generation from another area. This is typically accomplished thru metering and schedules but is outside the scope of this lab. The only reason for a detailed explanation is to  present this concept and Bulk Electric System (BES) structural philosophy currently practiced in the real world to familiarize the future power engineer. The following steps are to help the user write the *.sub,*.mon, and *.con files manually for a modified area called “area1a “area1a” ” Using “central_1a” subsystem : 1. Start PSS®E as it was shown in lab1. 2. Open the sample.sav file from your PSSE Labs folder as it was shown in lab1 . 3. Open the sample.sld file from your PSSE Labs folder as it was shown in lab1. 4. Create a new folder in your PSSE Labs folder and name it “Lab4” 5. Once both files are opened, Go to toolbar and click on Subsystem. Or use the shortcut icon

6. Sel Select ect Bus  below

, then select ect central   area   area and and clic click k on arro arrow w

to sele select cted ed area areass box box as as show shown n

7. Click Apply and Ok to close the Bus Subsystem Selector window. 8. Go to sample.sav window and check you have Central area buses, branches ….etc. only. Notepad:  Subsystem file (*.sub): 1.  Now open the Notepad program. Save As and Name it “area1a.sub” in the file name  blank in “Lab4” folder.

2. It is time to start typing the text showing in the picture b ellow:

* *  M ake sur e f il e is identi identi cal to the fi le above above;; otherwise it may not r un properl properl y.

3. Save and close area1a.sub 

 Monitor file (*.mon): 1.  Now open the Notepad program. Save As and Name it “area1a.mon “area1a.mon”” in the file name  blank in “Lab4” folder.

2. Create and type area1a.mon with area1a.mon with exact command shown next page:

* *  M ake sur e f il e is identi identi cal to the fi le above above;; otherwise it may not r un properl properl y.

* In the monitor file you can determine the voltage range of a subsystem so no monitored elements exceed a specified range (V-Max, V-Min) of a specified subsystem. All voltagecontrolled buses in specified base voltage range will be including in your contingency plan. 3. Save and close area1a.sub 

Contingency file (*.con):

1. Go to Sample.sav. Click on

tab.

2. Use the above branches as reference of o f central area to create commands for area1a.con. area1a.con. 3.  Now open the Notepad program. Save As and Name it “area1a.con “area1a.con”” in the file name  blank in “Lab4” folder. 4. Type (Do (Do NOT copy the italic words) COM COM CONTINGENCY description file entry modified by CSU user COM TRACE starts TRACE starts the program 5. The next line names (N-1) contingency where specified and named the contingency for the following line. The following describes which lines will be opened (tripped). In the

end of area1a.con command you should end up with Two ENDS; one for last contingency plan and the other for the whole area1a.con. an example below shown this step: CONTINGENCY NUC_MID_1 OPEN LINE FROM BUS 151 TO BUS 152 CKT 1 END ends MUC_MID_1 contingency END ends area1.com REMARKS:  NUC_MID_1 name of the contingency for NUCPLNT and MID500 branch and with ID 1 CKT1 refers to the first NUCPLNT and MID500 branch in this area. CKT2 refers to the second NUCPLNT and MID500 branch in this area.

In or der der to finish the contingency file “area1a.con “area1a.con”, ”, the student must complete the remaining:  



Copy the first two contingency plans as explained and shown above. Fill “????” with Contingency name, “???” with Bus number in FROM_TO line, and “?” with ID # in the three contingencies followed. Write the remains 5 contingencies emulating the syntax structure of th e given examples.

Complete the necessary #’s describes DOWNTN and CATDOG CATDOG branch. Finish with Two ENDS. 6. By the end you will have 11 total contingencies. Save and close area1a.con. 

AC Contingency Calculation (ACCC): The three files area1a.sub, area1a.mon, and area1a.con are utilized to by the AC Contingency Calculation (ACCC) feature of PSS®E to perform a PF study on a particular area or zone. After

creating “area1a “area1a” files, now it’s time to solve ACCC:

the system. Follow the steps below to run

1- ACCC icon located on the Fourth Toolbar

Or there is always another long way to run the ACCC contingency solution:

a- Go to Toolbar and click on Power Flow menu  b- Scroll down to Solution. c- Under Solution click on AC contingency solution (ACCC)

d- Click on DFAX: Dist Distri ribu buti tion on fact factor or data data file file to crea create te area1a.dfx . A Distribution Factor Data File (DFAX) needs to be created by loading the provided area1a.sub, area1a.mon and area1a.sub files. Click on the “DFAX” button, and the “Build  “Build  Distribution Factor Data File” window will be displayed:

Use the navigation icon to choose the files area1a.sub, area1a.mon,  area1a.mon,  and area1a.con from area1a.con from “Lab4” folder respectively as shown below. below. Type “area1a ” in the Distribution factor data output file.

Click OK. Now you have created area1a.dfx file. area1a.dfx file.

** I f you make changes changes to your your * .sub, .sub, * .mon, or or * .con .con f il es, you you MUST   r e-buil -buil d the DF AX f il e. I t i s not nece necessary to gi ve it a new name, name, simpl simpl y ove over wri te the exi exi stin g f il e.

e- Con Conti ting ngenc ency y sol solut utio ion n outp output ut fil filee : type type in in the the file file nam namee “area1a“ Leave Load throwover data file empty. Click on Solve. Don’t close the Window yet! f- Click on reports the window in the next page will open and make sure you have the correct file name for *.acc file you created above.

g- Hit GO to run area1a report. Close. 2- Go over the report and check ch eck all the files created in this lab are in there.

PSSE Lab # 4 Questions: 1) 2) 3) 4) 5)

Printout area1a.sub file.  printout area1a.mon file Complete and Printout area1a.con file. Printout area1a report. Using the lab manual, run ACCC for “area2a” and named the subsystem “EAST_2a”.  printout the following: a) area2a.sub file.  b) area2a.mon file. c) area2a.con file. d) “area2a” area2a” report.

SIEMENS POWER SYSTEM SIMULATION FOR ENGINEERS® (PSS/E)

LAB5 MULTIPLE AC CONTINGENCY CALCULATION REPROTS

Power Systems Simulations Colorado State University

Purpose of the lab: This lab was designed to show the student how to adjust one-line diagram file (sample.sld) and then solve to reach better power flow with no overloads. The student is supposed to add another line (Branch) between bus 153 and bus 154. Then, solve the system and do the necessary adjustment to fix the overload in the system. This lab will explain how the Multiple AC Contingency calculation report feature of PSS®E creates a single report with multiple ACCCs into one file. This lab will introduce the following aspects: 

Add line in the data file (*.sav)



Add branch to the slider file (*.sld)



Create ACCC files



Run ACCC



Run Multiple ACCC

Important definition for better comprehension to this lab: · Sample.sld file: (described in lab 2) *.sld –  *.sld –  Slider  Slider file (Single Line Diagram) This file allows for performing network analysis studies on the grid. Sliders are visual displays of the grid. It includes buses, branches, lines, loads, generators, transformers etc... All components should be color coded based on voltage flow. The slider file can also show the operational ratings (power flowing across the component relative to the capacity) of the listed components. This network can be divided on several zones and areas  based on the need of the user.

The following steps are to guide student through this lab and assure them learning the skills of creating Multiple ACCC reports supposed to provide:

1. Start PSS®E as it was shown in lab1. 2. Open the sample.sav file from your PSSE Labs folder as it was shown in lab1. 3. Open the sample.sld file from your PSSE Labs folder as i t was shown in lab2. 4. Create a new folder in your PSSE Labs folder and name it “Lab “ Lab5 5” 5. Once both files are opened, Go to the sample.sav file and click on the Branch tab as shown  below.

Add Line to Sample.sav: A. From the far left of the sample.sav table click on the row which shows the branch from  bus #153 to bus #154 as shown.

B. Right click and select copy

C. Right click on the empty bottom row of the table and select paste

D. The new branch created between BUS#153 to BUS#154.

E.

Code has to be changed to 3 according to how many branches between the two  buses. Arrow Up will sort automatically below the original one.

F. To save the new sample file press on your keyboard Ctrl+S   and a save network data widow will open on the screen. Under the Case Data tab navigate to Lab5 folder and type “sampleL5  ” then Click OK using the pictures below:

G. Solv Solvee the the syst system em

on the the too toolb lbar ar show shown n bel below ow::

The following window will appear, make sure that you solve the system using the steps stated  below:

i. ii. iii.

Switched shunt adjustments, Choose En able able Al l  VAR limits, Choose Apply i mmediately  mmediately  Click Solve 

iv. v.

Switched shunt adjustments, Choose L ock ock All  Keep VAR limits as Appl y immediately immediately then click  Solve 

Image of the progress window with minimum number of iterations

H.  Now go to the Subsystem menu and select Area. Move “Central ” to selected areas areas on the right side of the box. I. Click Apply and close.

Add Branch to sample.sld:

1. Go to the sample.sld  and find bus number 153 2. Click on Bus#153 3. Once the bus selected use right click on the bus to open the list below.

4. Scroll down to Grow N levels  –  make   make sure that the number of level on the next box will be one and hit OK.

5. An image of the adjusted slider file is provided below; it shows that the added line is kind of hidden behind another element Zoom in. 6. Rearrange the branch to be visible.

J.

Changing the position of the line

The added line is hidden!!

The added line appears here

7. Save the new slider file and name it SampleL5.sld  Create ACCC files: ** Refer to LAB4 under Notepad section:  Create subsystem file and name it “area1c.sub”  Create monitor file and name it “area1c.mon”  be exactly the same as lab4.  be  The files Must   Create and Modify contingency file and name it “area1c.con”  Add the branch code Bus#153 to Bus#154 to area1c.con.  Save and close.

Run ACCC:

Use the three files created in the previous section to create DFAX file the ACCC reports “area1c.acc”   

Area1c.sub Area1c.mon Area1c.con

“area1c.dfx”

and name

Run Multiple ACCC reports:

The PSS®E Multiple AC Contingency reports feature can be used to perform. The multiple allows running ACCC reports contingencies within one run and compares up to nine contingency runs(Multiple *.acc) . This is a very powerful tool when side by side study comparisons are needed. Computational procedures in a contingency analysis shown in the diagram below:

a- Go to Toolbar and click on Power Flow menu  b- Scroll down to Reports. c- Under Reports click on Multiple AC Contingency run report…

This window will appear:

d- Go to Contingency solution output box and click e- Navigate to your LAB4 folder and choose area1a.acc f- Navigate to your LAB5 folder and choose area1c.acc

g- Hit Go. The Multiple ACCC reports display in the report window that contains 15 pages. Go to page 9 and check the changes on the Added line.

PSSE Lab # 5 Questions: 1) Print out the Multiple ACCC report “area1c.acc”? 2) After the impact of the contingencies and loads, explain how it affects area1? 3) Add transformer between Bus#152 and Bus#153, follow the same method of adding line in this lab and name the contingency output solution “area1T.acc”. Show the ACCC report “area1T.acc”?

4) Print and compare the three contingency report area1a.acc, area1c.acc, and area1T.acc in one report?

Appendix B2 How to draw PV curve in PSS/E: (The files needed for this part will be provided by the instructor. )

When you identify the maximum loading values at bus 5 and bus 6, please use the following steps: 1. In PSS/E, Click – Power Flow Solution PV analysis…This will open a “ PV Analysis” dialog box. 2. In the section of “ Transfer dispatch methods”, for the option of “ For study (“source”) system”, select “ Subsystem machines (MW)”; for the option of “ For opposing (“sink”) system”, select “ Subsystem load”. 3. For the option of “ Initial transfer increment (MW)” (which is in the middle-right part of the “PV Analysis” dialog box), select “ 30.00”. 4. In the section of “ Input data files”, click “ Create DFAX…” This will open a “ Building Distribution Factor Data File” dialog box. In the section of “ Input files”, for the option of “Subsystem description data”, click the right box with 3 dots on it to select the “ bus5.sub” file and then click “ Open”. For the option of “ Monitored Monitored element data”, click the right box with 3 dots on it to select the “ EE303.mon” file and then click “ Open”. For the option of “Contingency description data”, click the right box with 3 dots on it to select the “EE303.con” file and then click “ Open”. For the option of “ Distribution factor data output file”, click the right box with 3 dots on it to select the “ bus5.dfx” file and then click “ Open”. After finishing all selections above, click “ OK ” button at the bottom of “ Building Distribution Factor Data File” dialog box. 5.  Now back to “PV Analysis” dialog box, for the option of “ Output file (results)” (which is at the bottom of “PV Analysis” dialog box), click the right box with 3 dots on it to select the “bus5.pv” file and then click “ Open”. 6. Click “Go”. Then the “ PV Results” dialog box will be opened. 7. About the “ PV Results” dialog box, in the section of “ Type of results”, choose “ Bus voltages”. In the section of “ Contingencies”, choose “ BASE CASE 420.00 BASE CASE 0” such that this option becomes dark blue. 8. In the section of “ Buses”, you can choose bus 5 and then the PV Curve about bus 5 will be shown at the bottom of the “ PV Results” dialog box. From this PV Curve, you can find the maximum loading value at bus 5. 9. You can obtain the PV Curve about bus 6 by following following step1 step1 to step7. NOTE(important): (1) In step4, for the option of “ Subsystem description data”, click the right box with 3 dots on it to select the “ bus6.sub” file and then click “ Open”. For the option of Distribution factor data output file”, click the right box with 3 dots on it to select the “Distribution “bus6.dfx” file and then click “ Open”. (2) In step5, for the option of “ Output file (results)”, click the right box with 3 dots on it to select the “ bus6.pv” file and then click “ Open”.

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