EE2036 – FLEXIBLE AC TRANSMISSION SYSTEM
2 Marks And 16 Marks- Question Bank
UNIT-I -INTRODUCTION
TWO MARKS Q & A
1. What is flexibility of electric power transmission?
The ability to accommodate changes in the electric transmission
system or operating conditions while maintaining sufficient steady-state
and transient margins.
2. Define FACTS (or) Define FACTS as per IEEE (May/June 2012)
FACTS is defined by the IEEE as "A power electronic based system and
other static equipment that provide control of one or more AC transmission
system parameters to enhance controllability and increase power transfer
capability.
3. Write the difference between TSSC and TCSC? (May/June 2012)
TSSC (Thyristor Switched Series Capacitor), which permits a discrete
control of the capacitive reactance.
TCSC (Thyristor Controlled Series Capacitor) which offers a
continuous control of capacitive or inductive reactance.
4. How is reactive power controlled in an electrical network?
(Nov/Dec 2012)(May/June2007)
The reactive power can be compensated using VAR generators, avoiding
its circulation between the load (L or C) and the source, and therefore
improving voltage stability of the power system.
Reactive power compensation can be implemented with VAR generators
connected in parallel or in series.
Series controllers inject voltage in series with the line and the
shunt controllers inject current into the system at the point of
connection.
5. What are the objectives of FACTS? (May/June 2007), (May/June 2013)
(April 2014)
FACTS technologies allow for improved transmission system operation
with minimal infrastructure investment, environmental impact, and
implementation time compared to the construction of new transmission lines.
Provide advanced solutions to cost-effective alternatives to new
transmission line construction.
6. What is IPFC? (May/June 2011)
Interline power flow controller is a combination of two or more
independently controllable SSSC which are solid-state voltage source
converters which inject an almost sinusoidal voltage at variable magnitude
and couples via a common dc link.
7. What are the various categories of FACTS controllers? (Nov/Dec 2007)
i) Series FACTS Controllers
ii) Shunt FACTS Controllers
iii) Combined Series-Series FACTS Controllers
iv) Combined Series-Shunt FACTS Controllers
8. What are the applications of FACTS devices? (Nov/Dec 2007) (Nov/Dec
2014)
i) Power Transmission.
ii) Power quality
iii) Railway and Wind power grid connection
9. What are the different power electronic switching devices? (May/June
2010)
SCR, MOSFET, GTO, IGBT, BJT etc.
10. What is reactive power compensation?
Reactive power control for a line is often called reactive power
compensation.
11. What is compensator?
External devices or subsystems that control reactive power on
transmission lines are known as compensators.
12. What are the types of passive compensation?
a) Shunt compensation
b) Series compensation
13. What is the factors need careful for series compensation?
1) The voltage magnitude across the capacitor banks.
2) The fault current at the terminals of a capacitor banks.
3) The placement of shunt reactors to the series capacitors.
14. What is Series compensation?
If the effective reactance of a line is controlled by inserting a
series capacitor, and if the line terminal voltages are held unchanged.
15. What is shunt compensation?
A shunt capacitor is connected at the midpoint of the line so this is
called shunt compensation.
16. What is SVC? (May/June 2008, Dec-2008)
A shunt-connected static var generator or absorber whose output is
adjusted to exchange capacitive or inductive current so as to maintain or
control specific parameters of the electrical power system.
17. What is TCSC? (April 2014)
A capacitive reactance compensator which consists of series capacitor
bank shunted by a thyristor controlled reactor in order to provide smoothly
variable series capacitive reactance.
18. What is UPFC?
A combination of static synchronous compensator and a static
synchronous series compensator which are coupled via a common dc link, to
allow bidirectional flow of real power between the series output terminals
of the S3C and the shunt output terminals of the STATCOM, and are
controlled to provide concurrent real and reactive series line compensation
without an external electric energy source. The UPFC, by means of angularly
unconstrained series voltage injection, is able to control, concurrently or
s electively, the transmission line voltage, impedance, and angle or,
alternatively, the real and reactive power flow in the line. The UPFC may
also provide independently controllable shunt-reactive compensation.
19. What is FACTS controller?
A power electronics-based system and other static equipment that
provide control of one or more ac transmission system parameters.
20. What are the different types of compensation schemes? (May/June 2010)
a) Load compensation
b) System compensation
21. What is load compensation? (Nov/Dec2007)
It is possible to compensate for the reactive current Ix of the load
by adding a parallel capacitive load so that Ic = - Ix . Doing so causes
the effective power factor of the combination to become unity. This
condition is called load compensation.
22. What is system compensation?
To regulate the receiving-end voltage at the rated value, a power
utility may install a reactive power compensator.
23. What is a symmetrical line?
The voltage magnitudes at the ends of a line are equal, that is Vs =
Vr =V, the line is said to be symmetrical.
24. What is SIL?
Surge Impedance load is defined as P0 = V2nom / Z0
25. What is Active and Passive var control?
Fixed inductor and capacitor are employed to absorb or generate
reactive power is called passive control.
An active var control is produced when its reactive power is changed
irrespective of the terminal voltage to which the var controller is
connected.
26. Define Reactive Power (Nov/Dec 2014)
In electric power transmission and distribution, volt-ampere
reactive (var) is a unit in which reactive power is expressed in an AC
electric power system. Reactive power exists in an AC circuit when the
current and voltage are not in phase. Reactive power (measured in vars) is
present in a system containing reactive (inductive or capacitive)
components and can be either produced or consumed by different
load/generation elements. Though "imaginary", the reactive power has great
physical significance and is essential to the operation of the electrical
system as a whole. While the real power P is used to supply the energy
required to perform actual work (such as running a motor), the reactive
power regulates the voltage in the system. If the reactive power is too
low, inductive loads such as transformers will be unable to maintain
voltages necessary for the generation of electromagnetic fields, leading to
a "voltage collapse" that create blackouts .
UNIT 1
INTRODUCTION
Sixteen Marks Q & A
1. Explain in detail about series and shunt compensation in transmission
lines.
(April 2014) (Nov/Dec 2014) (May/June 2012) (Nov/Dec 2012) (May/June
2013)
2. Explain reactive power control in electrical power transmission lines.
3. Explain the objective of FACTS controllers in the power system netwotk.
(May/June 2007)
4. Derive the expression for active as well as reactive power flow in a
lossless transmission line and draw its necessary phasor diagram.
5. Explain briefly in a) IPFC (April 2014)
6. Explain in detail about the classifications of different types of FACTS
controllers.
(May/June 2007) (May/June 2013)
7. Discuss the principle of operation of thyristor controlled series
capacitor.
(Nov/Dec
2012)
8. Consider a two machine power system model. Explain the basic concepts of
shunt and series compensation in detail. Also comment about the effect of
degree of compensation on the system with a neat sketch.
(Nov/Dec 2012)
9. Explain the basic construction, working and characteristics of any one
type of SVC.
(May/June 2008)
(May/June 2012)
10. Explain Uncompensated Transmission Line. (Nov/Dec 2014)
11. List the advantages of SVC. (April 2014)
12. Give the complete analysis of lossless distributed parameter
transmission lines and derived
power equations for symmetrical case. (April 2014)
UNIT-II
SVC AND APPLICATIONS
TWO MARKS Q & A
1. Define the term Static Var Compensators SVC (May/June 2008,
Nov/Dec.2008)
What is the Objective of SVC? (Nov/Dec 2014)
A shunt-connected static var generator or absorber whose output is
adjusted to exchange capacitive or inductive current so as to maintain or
control specific parameters of the electrical power system.
2. What is linear range of SVC control?
This is the control range over which svc terminal voltage varies
linearly with SVC current or reactive power, as the latter is varied over
its entire capacitive to inductive range.
3. What is Slope or Current Droop?
It is the ratio of voltage magnitude change to current magnitude
change over the linear controlled range of the compensator.
4. State the advantages of slope in the SVC dynamic
characteristics.(May/June2011, May/June2008, May/June 2009 & 2012)
i) Substantially reduces the reactive-power rating of the svc for
achieving nearly the same control objectives.
ii) Prevents the SVC from reaching its reactive-power limits too
frequently
iii) Facilitates the sharing of reactive power among multiple
compensators operating in parallel.
5. What are the influences of the SVC on the system voltage?
i) Coupling transformer ignored
ii) Coupling transformer considered
iii) The system gain
6. Write the applications of SVC? (May/June 2007, Nov/Dec.2008) (Nov/Dec
2012)
i) Enhancement of transient stability
ii) Steady state power flow
iii) Enhancement of power system damping
iv) Prevention of voltage instability
7. What is overload range?
The SVC traverses outside the linear controllable range on inductive
side, the SVC enters the overload Zone. It behaves like a fixed inductor.
8. What is over current limit?
To prevent the thyristor valves from being subjected to excessive
thermal stress, the maximum inductive current in the overload range is
constrained to a constant value by an additional control action.
9. Draw V-I characteristics SVC. (May/June2009)
10. Define Voltage stability. (May/June 2010)
It is the ability of a power system to maintain steady acceptable
voltages at all buses in the system under normal operating conditions and
after being subjected to a disturbance.
11. What is the best location for SVC? Justify (Nov/Dec.2008)
Why the shunt compensation is attempted always at midpoint? (Nov/Dec
2012)
It has been proven that the midpoint of transmission line is the
optimal location of SVC. This proof is based on the linear load which is
not valid practically. For non-linear load model it was found that the best
location for advanced static var compensator close to the receiving end
where a wide range of reactive power could be controlled.
12. List the advantages of SVC.
1. Cheaper and simple operation.
2. Higher Capacity.
3. Faster & more reliable.
4. Improve steady state stability and transient stability.
5. Reduces transmission losses and increases power transfer capacity.
13. What are the 2 basic modes of SVC?
1. Voltage regulation mode
2. Var control mode
14. List out the prevention of voltage Instability.
* Placement of series and shunt capacitors.
* Placement of FACTS Controllers.
* Coordination of Multiple FACTS Controllers.
* Generation Rescheduling.
15. What are symptoms of voltage collapse?
The main symptoms of voltage collapse are low voltage profiles, heavy
reactive power flows, inadequate reactive support, and heavily loaded
systems.
16. Draw the power angle curve of SMIB system with midpoint SVC. (May/June
2013)
(Nov/Dec 2014)
17. Draw the block diagram of SVC voltage regulator in integrated current
droop form.
(May/June 2013)
18. Define: Effective Short circuit Ration (ESCR) (April 2014)
The usual measure of the strength of the system is the Short Circuit
Ratio, which is defined as
19. What are the factors that limits the power capacity of the line? (April
2014)
Bus voltage,
Line current,
Reactance
Susceptance
Unit 2
SVC AND APPLICATIONS
Sixteen Marks Q & A
1. Explain the basic construction, working and characteristics of SVC.
2. Explain the method of voltage control by SVC. (May/June 2007) (May/June
2012)
3. Discuss the advantage of the slope in SVC dynamic characteristics in
detail
(April 2014) (May/June 2007) (May/June 2013)
4. Discuss the method of improving transient stability with SVC.
(May/June 2007) (May/June 2012) (May/June 2013)
5. Discuss the role of SVC in the enhancement of power system damping.
(May/June 2008)
6. Explain the prevention of voltage instability in SVC. (April 2014)
7. Explain in detail about influence of SVC on system voltage.
8. Explain the static and dynamic characteristics of SVC. (Nov/Dec 2012)
9. Explain how SVC can be used to enhance the power transfer capacity of a
transmission line
(Nov/Dec
2012)
10. Explain the different applications of SVC. (Nov/Dec 2008)
11. Explain the design of voltage regulator in detail. (May/June 2008)
(Nov/Dec 2008)
12. Derive the voltage and power expression in SVC. (Nov/Dec 2014)
13. Explain the Prevention of Voltage instability. (Nov/Dec 2014)
14. Explain how an SVC can be used to enhance the steady state power
transfer capacity of a
transmission line. (April 2014)
15. Using Power angle curves, explain how SVC enhances transient stability
of a power system.
(April 2014)
UNIT-III
TCSC & APPLICATIONS
Two Marks Q & A
1. Draw the V-I capability cures for single module TCSC (May 2007, 2008)
2. What are the indications of voltage collapse points? (May/June 2012)
The main indications of voltage collapse are low voltage profiles,
heavy reactive power flows, inadequate reactive support, and heavily loaded
systems.
3. Draw the impedance Vs delay angle characteristics of TCSC. (Nov/Dec
2008)
4. What are the two basic approaches for controllable series compensation?
(Nov/Dec 2012)
TSSC (Thyristor Switched Series Capacitor), which permits a discrete
control of the capacitive reactance.
TCSC (Thyristor Controlled Series Capacitor) Which offers a
continuous control of capacitive or inductive reactance.
5. What are the modes of operation in TCSC? (May/June 2008) (Nov/Dec 2012)
i) Bypassed- thyristor mode.
ii) Blocked thyristor mode
iii) Partially conducting thyristor or vernier mode.
6. What is Bypassed- thyristor mode? (May/June 2012)
In this mode, the thyristors are made to fully conduct with an
conduction angle of 180 degree.
7. Write the applications of TCSC? (May/June 2010)
i) Improvement in system stability.
ii) Damping of power oscillation
iii) Prevention of voltage collapse
iv) Alleviation of sub synchronous resonance (SSR)
8. What is the indication of voltage collapse points? (May/June 2012)
The collapse points are indicative of the maximum load-ability of the
transmission lines or the available transfer capability.
9. What is the effect of TCSC in SSR problem? (May/June 2007)
At sub synchronous frequencies, the TCSC presents an inherently
resistive-inductive reactance. The sub-synchronous oscillations cannot be
sustained in this situation and consequently get damped.
10. How is the variation of capacitive reactance is achieved in TCSC?
(Nov/Dec 2008)
By varying the firing angle of the anti-parallel thyristors that are
connected in series with a reactor in the TCR, the fundamental frequency
inductive reactance of the TCR can be changed. This affects a change in the
reactance of the TCSC and it can be controlled to produce either inductive
or capacitive reactance.
11. How is voltge instability identified in the power system? (May 2007)
Insufficient reactive capacity of power system during disturbance
like line outage contingencies.
It is mathematically indicated when the system Jacobian becomes
singular
12. What is partially conducting thyristor or vernier mode?
This mode allows the TCSC to behave either as a continuously
controllable capacitive reactance or as a continuously controllable
inductive reactance. It is achieved by varying the thyristor pair firing
angle in an appropriate range.
13. What is Blocked thyristor mode?
In this mode, also known as waiting mode, the firing pulses to the
thyristor valves are blocked.
14. What is the modeling of the TCSC?
A TCSC involves continuous time dynamics, relating to voltages and
currents in the capacitor and reactor, and nonlinear, discrete switching
behavior of thyristor.
15. What are types of modeling of the TCSC?
Variable reactance model
Transient stability model
16. What is sub synchronous oscillation?
It is caused by interaction between the electrical network and the
generator torsional system. It is finally leads to the damage in the
generator shaft.
17. What is TCSC?
A capacitive reactance compensator which consists of series capacitor
bank shunted by a thyristor controlled reactor in order to provide smoothly
variable series capacitive reactance.
18. Write the difference of series and shunt capacitors?
"Sl.No "Series Capacitor "Shunt capacitor "
"1. "The reactive power "The reactive power is "
" "increases as the square of "generated proportional to the "
" "the line current "square of the bus voltage "
"2. "No such requirement exists"It must be connected at the "
" "for series capacitor "midpoint of the line. "
"3. "costly "economic "
19. What is need for variable series compensation?
i) Enhanced base-power flow and load ability of the series-
compensated line.
ii) Additional losses in the compensated line from the enhanced power
flow..
iii) Increased responsiveness of power flow in the series compensated
line from the outage of other lines in the system.
20. Write the advantages of TCSC?
i) Rapid, continuous control of the transmission line series
compensation level.
ii) Damping of the power swings from local and inter area
oscillations.
iii) Voltage support.
iv) Reduction of the short circuit current.
v) Enhance level of protection for series capacitor.
21. What is Bang-Bang Control in TCSC? (May/June 2013)
It is a discrete control form in which the thyristors are either
fully switched on (firing angle is 90 deg) or fully switched off (firing
angle is 180 deg). Thus the TCSC alternates between a fixed inductor and a
fixed capacitor, respectively, and it is advantageous that such control is
used not only for minimizing first swing but for damping any subsequent
swings as well. Bang-bang control is employed in face of large disturbances
to improve the transient stability.
22. Mention the disadvantages of fixed series compensation of the
transmission line.
(April 2014)
The reactive power increases as the square of line current.
Cost of series capacitors is almost twice as costly as shunt
capacitors because of their high operating voltage.
23. What is the function of Damping Control of a TCSC? (April 2014)
It prevents the power frequency oscillations
It improves the transient stability.
24. What are the methods for protection against Over Voltage? (Nov/Dec
2014)
Voltage Limits
Current Limits
Firing angle Limits
25. Define Transient Stability. (Nov/Dec 2014)
It is defined as the operating state of the system are not changing
during the transient time period and is concerned with whether the system
variables are within the correct limits.
Unit 3
TCSC and its APPLICATIONS
Sixteen Marks
1. Explain the variable reactance modeling for stability studies.
(May/June 2008) (Nov/Dec 2012) (May/June 2013)
2. Discuss the role of TCSC in enhancement of system damping. (Nov/Dec
2012)
3. What are the advantages of TCSC. Explain the modes of operation in TCSC.
(April 2014) (May/June 2007)
4. Explain with a neat sketch and waveforms the TCSC type of series
controller.
5. Enumerate the modeling of TCSC to enhance the system stability (May/June
2007)
6. Discuss the application of TCSC. (May/June 2008)
7. Explain the voltage collapse prevention in TCSC.
8. Explain the working and characteristics of TCSC. (May/June 2013)
9. Discuss the modeling of TCSC for various power system studies in detail
(Nov/Dec 2012)
10. Describe the capability of TCSC in improving transient stability, power
oscillation damping and voltage stability applications. (Nov/Dec 2012)
11. Explain the Operation of TCSC. (Nov/Dec 2014)
12. Explain the expression of TCSC for the time interval (-ß˂wt˂ß) (Nov/Dec
2014)
13. with a neat block diagram, explain the variable reactance model of the
TCSC and derive the transient stability and long term stability model.
(April 2014)
UNIT-IV
EMERGING FACTS CONTROLLERS
Two Marks Q & A
1. Draw the VI characteristics of STATCOM and SVC (May/June 2011)
2. What is the function of STATCOM? (May/June 2008) (April 2014)
i) Dynamic voltage control in T&D systems.
ii) Power oscillation damping in power transmission systems.
iii) Transient stability improvement.
iv) Ability control not only reactive power but if needed control
active power also.
3. How the reactive power compensation is done using STATCOM. (Nov/Dec
2008)
By controlling the magnitude of the STATCOM voltage, the reactive
power exchange between the STATCOM and transmission line and hence the
amount of shunt compensation can be controlled.
4. List the modes of operation of STATCOM.
i) voltage regulation mode
ii) Var control mode
5. State the salient features of UPFC? (May/June 2012) (May/June 2008)
(Nov/Dec 2008)
The UPFC is representative of the last generation of FACTS devices
which can control simultaneously all three parameters of line power flow
(line impedance, voltage and phase angle)
The UPFC combines together the features of STATCOM and SSSC.
6. Differentiate between STATCOM and SVC. (May/June 2012)
"STATCOM "SVC "
"It acts as a voltage source behind a"It acts as a variable susceptance. "
"reactance. " "
"It is insensitive to transmission "Harmonic resonance. "
"system harmonics. " "
"Large dynamics range "Smaller dynamic range "
7. Distinguish between UPFC and IPFC. (Nov/Dec 2012)
UPFC: It is typical shunt and series controller.
It is able to control the active and reactive power flow.
IPFC: Equalize both active and reactive power flow between the lines
Reduce the burden of overloaded lines by active power transfer
Compensate against resistive line voltage drops and the corresponding
reactive power demand.
8. What is the role of dc link in UPFC? (Nov/Dec 2012) (May/June 2007)
The real power is supplied from or absorbed by, the DC energy storage
device called dc link.
9. What is FACTS controller?
A power electronics-based system and other static equipment that
provide control of one or more ac transmission system parameters.
10. Write the few facts controller devices?
i) STATCOM (Static Synchronous Compensator)
ii) SVC(Static Var Compensator)
iii) SSSR (Static Synchronous Series compensator)
iv) UPFC (Unified Power Flow Controller)
v) TCBR (Thyristor controlled Breaking Resistor)
11. Write the few applications of STATCOM? (May/June 2013)
i) The dynamic voltage control in transmission and distribution
systems
ii) The transient stability
iii) The voltage flicker control
iv) It is control not only reactive power but also active power in
the connected line
12. What are the operating modes of UPFC?
i) The series injected voltage magnitude
ii) The line current through series converter
iii) The shunt converter current
iv) The minimum line side voltage of the UPSC
v) The maximum line side voltage of the UPSC
13. Write the Applications of UPFC?
i) It provides very significant damping to power oscillation when it
operates at power
flows within the operating limits
ii) Transient stability improvement.
iii) Enhancements in power oscillation damping.
14. What is UPFC? (Nov/Dec 2014)
A combination of static synchronous compensator and a static
synchronous series compensator which are coupled via a common dc link, to
allow bidirectional flow of real power between the series output terminals
of the S3C and the shunt output terminals of the STATCOM, and are
controlled to provide concurrent real and reactive series line compensation
without an external electric energy source. The UPFC, by means of angularly
unconstrained series voltage injection, is able to control, concurrently or
selectively, the transmission line voltage, impedance, and angle or,
alternatively, the real and reactive power flow in the line. The UPFC may
also provide independently controllable shunt-reactive compensation.
15. State the basic UPFC Power flow control function. (April 2014)
VAR Control Mode: The reference input is an inductive or capacitive
VAR request.
Automatic Voltage Control Mode: The goal is to maintain the
transmission line voltage at the connection point to a reference
value.
16. Define Linear Loads. (Nov/Dec 2014)
AC electrical loads where the voltage and current waveforms are
sinusoidal. The current at any time is proportional to voltage. Linear
Loads are:
POWER FACTOR IMPROVEMENT CAPACITORS, INDESCENT LAMPS, HEATERS
Unit 4
EMERGING FACTS CONTROLLERS
Sixteen Marks Q&A
1. Explain the basic construction, principal of operation and VI
characteristics of STATCOM.
(April 2014) (May/June 2007) (May/June 2008) (Nov/Dec 2008)
(Nov/Dec 2012)
2. With phasor diagram explain the different modes of operation of UPFC.
3. Explain the modeling of UPFC power flow studies.
4. Explain the operation of STATCOM and draw its output waveform.
5. Explain the application of UPFC and STATCOM.
6. Explain the basic operating principle of an UPFC. (Nov/Dec 2008)
7. Explain how a UPFC is different than a simple VSC.
8. Give the block diagram for a basic UPFC control scheme.
9. Explain in detail about the implementation of UPFC. (May/June 2013)
10. Explain the working of STATCOM. Compare its performance with SVC.
(May/June 2013)
11. Explain in detail about the modeling procedure of UPFC in power flow
studies
(May/June 2007) (May/June
2013)
12. Explain the protection of UPFC. (Nov/Dec 2014)
13. Derive the Expression of UPFC Connected at midpoint. (Nov/Dec 2014)
14. Draw the configuration of UPFC implementation using two back to back
connected VSC with a common DC Link. (April 2014)
15. Explain the steady state UPFC model for power flow studies. (April
2014)
UNIT-V
COORDINATION OF FACTS CONTROLLERS
TWO MARKS Q & A
1. List the possible combination of FACTS controller interaction?
(May/June 2013) (May/June 2012) (Nov/Dec 2012) (May/ June
2007)
FACTS controllers interact unfavorably with one another. Controller
interactions can occur in the following combination
i) Multiple FACTS controllers of similar kind.
ii) Multiple FACTS controllers of dissimilar kind.
iii) Multiple FACTS controllers and HVDC converter controllers.
2. What are the classifications of different frequency ranges of control
action? (Nov/Dec 2012)
i) 0HZ for steady state interaction
ii) 0-3/5 Hz for electromechanical oscillations
iii) 2-15 HZ for small signal or control oscillations
iv) 10-50/60 HZ for Sub synchronous resonance interactions
v) 15 HZ for electromagnetic transients, high frequency
resonance or harmonic resonance interactions.
3. What is steady state interaction?
Interaction between different controllers (FACTS-FACTS or FACTS-
HVDC) occur between their system related control.
4. What is electromechanical oscillation interaction?
Interaction between FACTS controllers also involve synchronous
generators, compensator machines, and associated power system stabilizer
controls.
5. What is a small signal or control oscillation?
Interaction between individual FACTS controllers and the network or
between FACTS controllers and HVDC links may lead to the onset of
oscillations in the range of 2-15 Hz.
6. What is Sub synchronous resonance interaction?
It caused by the interaction between the general torsional system and the
series compensated transmission lines, the HVDC converter controls, the
generator excitation control, or even the SVC.
7. What is High frequency interaction?
High frequency oscillation in excess of 15Hz are caused by large
nonlinear disturbances, such as the switching of capacitors, reactors,
transformers for which reason they are classified as electromagnetic
transients. For obviating such interactions may be necessary if the FACTS
and HVDC controllers are located within a distance of three major buses.
8. What is SVC-SVC interaction?
Interaction between multiple SVCs in a large power system.
9. What is meant by coordination of FACTS controllers? (May/June 2012)
(May/June 2007)
The term coordination does not imply centralized control; rather, it
implies the simultaneous tuning of the controllers to attain an effective,
positive improvement of overall control scheme.
10. Write the design procedure of controller?
i) Derivation of the system model
ii) Enumeration of the system performance specifications.
iii) Selection of the measurement and control signals.
iv) Coordination of the controller design.
v) Validation of the design and performance evaluation.
11. What is the need for coordination of different FACTS controllers?
(April 2014)
To attain an effective positive improvement of the
overall system control
scheme, coordination is much essential.
12. Why is it necessary to series compensate a power system network with
multiple of SVCs? (April 2014)
To provide the very good interaction,
To improve the short circuit ratio,
To prevent the SSR Problems
To improve stability and Damping.
Unit 5
COORDINATION OF FACTS CONTROLLERS
Sixteen Marks Q & A
1. Explain in detail about different control interactions.
2. Discuss about SVC-SVC interaction in a large power system.
(May/June 2013) (May/June 2012) (Nov/Dec
2012)
3. Explain the coordination of multiple controller using linear control
techniques.
(May/June 2013) (Nov/Dec 2012) (Nov/Dec
2008)
4. Explain the Quantative treatment of control coordination.
5. Explain the genetic algorithm based coordination of FACTS controllers.
(May/June 2007) (Nov/Dec 2008)
6. Explain in detail about different control interactions. (May/June
2012)
7. Explain the Linear Co-ordination technique. (Nov/Dec 2014)
8. Explain Quantitative Treatment in FACTS controller. (Nov/Dec 2014)
9. Explain the various kinds of control interactions occurs between
different FACTS controllers using their frequency response characteristics.
(April 2014)
10. Describe the following Linear Control Techniques used for coordination
of control of different FACTS Controllers. (4+4+6) (April 2014)
LQR Based Techniques
Global Coordination using Nonlinear constrained optimization
Control coordination using Genetic Algorithms.
Class-2 EE6004 FLEXIBLE AC TRANSMISSION SYSTEM IV YEAR/VII SEM
1. What is IPFC?
2. What are the applications of FACTS devices?
3. What is UPFC?
4. What is SIL?
5. What is the Objective of SVC?
6. Give the complete analysis of lossless distributed parameter
transmission lines and derived power equations for symmetrical case
(10)
7. Explain the method of voltage control by SVC (10)
