Typical Technical Specification for an Hvdc Transmission Project

TYPICAL TECHNICAL SPECIFICATION FOR AN HVDCLight ® Link TRANSMISSION PROJECT

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TYPICAL TECHNICAL SPECIFICATION FOR AN HVDC Light® LINK TRANSMISSION PROJECT

1JNL100098-754 Rev.00


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1. PROJECT DESCRIPTION........... ....................... ....................... ....................... ........................ ...................... ............... ....... .. 5 1.1 Scope of Supply........... ....................... ........................ ....................... ................... ............. .......... .......... .......... .......5 1.1.1Equipment,, Material and Services to be furnished by the 1.1.1Equipment Contractor............ ........................ ....................... .................... .............. .......... .......... .......... .......... ..... 5 1.1.1.2 Equipment and material ............................................. ............................................. 5 1.1.1.3 Services ........... ....................... ....................... ....................... ...................... ............... .......... .......... ..... 7 1.1.2Equipment,, Material and Services not included in the 1.1.2Equipment Scope of Supply ....................... ........... ....................... ....................... ........................ ....................... ................ .......... .......... ....... .. 7 1.2 Interface........... ...................... ....................... ........................ .................... ............. .......... .......... .......... .......... .......... ....... .. 8 1.3 Spare parts........... ....................... ........................ ....................... ..................... ............... .......... .......... .......... .......... .......8 1.4 Equipment and Services Furnished by the Owner................ ...................... ........ 8 1.5 Standards Standard s........... ....................... ....................... ....................... ........................ ....................... ....................... ................ .... 9 1.6 Quality and Environmen Environmental tal Assurance............ ...................... ............... .......... .......... ......... .... 9 2. GENERAL TECHNICAL SPECIFICATIONS ........................... ................... ............. .......... .......... .......... ....... ..10 2.1 Geographical Geographi cal location locati on of the converter converte r stations ..... .......... .......... .......... ......... .... 10 2.2 Environment.......... ...................... ........................ ....................... ................. ........... .......... .......... .......... .......... ....... .. 10 2.2.1 Elevation above sea level............ level ....................... ................... ............. .......... ......... .... 10 2.2.2 Ambient temperatures temperatu res........... ................. ........... .......... ......... ......... .......... .......... ........ ... 10 2.2.3Humidity 2.2.3Humi dity........... ....................... ....................... ....................... ........................ ................. .......... ......... .... 10 2.2.4Air pollution pollu tion........... ....................... ........................ ..................... .............. .......... .......... .......... ........ ... 10 2.2.5Isokeraunic 2.2.5Isok eraunic level level........... ....................... ........................ ....................... ..................... .............. .... 11 2.2.6Wind velocity veloc ity........... ...................... ....................... ........................ .................. ........... .......... ........ ... 11 2.2.7Seismic 2.2.7Seismi c requirements requi rements.......... ...................... ........................ ................... ........... ......... ....... ..11 2.2.8Other ambient amb ient conditions condi tions........... ....................... .................. ........... .......... .......... ....... ..11 2.2.9Topology ........... ...................... ....................... ........................ ....................... ................. ........... ......... .... 11 2.3 A.C. system sy stem characteristics characte ristics ........... ...................... ....................... ........................ ................... .......... ... 12 2.3.1 Voltages Vol tages........... ....................... ....................... ....................... ........................ ....................... .............. ... 12 2.3.2 A.C. system fault clearing ........... ....................... ........................ .................... .......... .. 12 2.3.3 Short-circuit Short- circuit characterist characteristics ics........... ....................... ..................... .............. .......... ..... 12 2.3.4 Frequency .......... ...................... ........................ ....................... ....................... .................. ........... ..... 13 2.3.5 A.C. system harmonic impedance characteristics character istics ... ...... ..... ..13 13 2.3.6 System voltage vol tage distortions distort ions........... ...................... ................. ........... .......... .......... ..... 13 2.3.7 System grounding ............ ........................ ................. .......... .......... .......... .......... .......... ....... ..14 2.3.8 A.C. system topology t opology............ ....................... ....................... ....................... ................ .......14 2.3.9 System equivalen equivalentt........... ....................... ....................... ..................... ............... ......... ....... ... 15 2.3.10 Torsional mode mod e frequencies ....... ............ .......... .......... .......... ......... ......... ........ ... 15 2.4 HVDC cable characteristi ch aracteristics cs........... ....................... ....................... ..................... ............... ......... ....... ... 15 2.5 Auxiliary Auxili ary power system........... ....................... ........................ ....................... ....................... ................ .... 15 2.6 Evaluation ............ ....................... ....................... ........................ ....................... ..................... ............... .......... ......... .... 16 2.6.1 Loss evaluation ............ ....................... ....................... ........................ ..................... .............. ..... 16 2.6.2 Availability Availabil ity evaluation evaluati on........... ...................... ................ ......... ......... .......... .......... ......... .... 16 2.7 Documentation ........... ....................... ........................ ....................... ................ .......... .......... .......... .......... .......16 2.8 Training of Owner’s personnel........... personnel ....................... ....................... ................ .......... .......... .......17 3. System REQUIREMENTS REQUIREME NTS............ ....................... ....................... ........................ ....................... ................ .......... .......... ..... 18 3.1 Power Transmission Transmis sion Capacity Capaci ty........... ...................... .................. ............ .......... .......... .......... ........ ... 18

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1. PROJECT DESCRIPTION........... ....................... ....................... ....................... ........................ ...................... ............... ....... .. 5 1.1 Scope of Supply........... ....................... ........................ ....................... ................... ............. .......... .......... .......... .......5 1.1.1Equipment,, Material and Services to be furnished by the 1.1.1Equipment Contractor............ ........................ ....................... .................... .............. .......... .......... .......... .......... ..... 5 1.1.1.2 Equipment and material ............................................. ............................................. 5 1.1.1.3 Services ........... ....................... ....................... ....................... ...................... ............... .......... .......... ..... 7 1.1.2Equipment,, Material and Services not included in the 1.1.2Equipment Scope of Supply ....................... ........... ....................... ....................... ........................ ....................... ................ .......... .......... ....... .. 7 1.2 Interface........... ...................... ....................... ........................ .................... ............. .......... .......... .......... .......... .......... ....... .. 8 1.3 Spare parts........... ....................... ........................ ....................... ..................... ............... .......... .......... .......... .......... .......8 1.4 Equipment and Services Furnished by the Owner................ ...................... ........ 8 1.5 Standards Standard s........... ....................... ....................... ....................... ........................ ....................... ....................... ................ .... 9 1.6 Quality and Environmen Environmental tal Assurance............ ...................... ............... .......... .......... ......... .... 9 2. GENERAL TECHNICAL SPECIFICATIONS ........................... ................... ............. .......... .......... .......... ....... ..10 2.1 Geographical Geographi cal location locati on of the converter converte r stations ..... .......... .......... .......... ......... .... 10 2.2 Environment.......... ...................... ........................ ....................... ................. ........... .......... .......... .......... .......... ....... .. 10 2.2.1 Elevation above sea level............ level ....................... ................... ............. .......... ......... .... 10 2.2.2 Ambient temperatures temperatu res........... ................. ........... .......... ......... ......... .......... .......... ........ ... 10 2.2.3Humidity 2.2.3Humi dity........... ....................... ....................... ....................... ........................ ................. .......... ......... .... 10 2.2.4Air pollution pollu tion........... ....................... ........................ ..................... .............. .......... .......... .......... ........ ... 10 2.2.5Isokeraunic 2.2.5Isok eraunic level level........... ....................... ........................ ....................... ..................... .............. .... 11 2.2.6Wind velocity veloc ity........... ...................... ....................... ........................ .................. ........... .......... ........ ... 11 2.2.7Seismic 2.2.7Seismi c requirements requi rements.......... ...................... ........................ ................... ........... ......... ....... ..11 2.2.8Other ambient amb ient conditions condi tions........... ....................... .................. ........... .......... .......... ....... ..11 2.2.9Topology ........... ...................... ....................... ........................ ....................... ................. ........... ......... .... 11 2.3 A.C. system sy stem characteristics characte ristics ........... ...................... ....................... ........................ ................... .......... ... 12 2.3.1 Voltages Vol tages........... ....................... ....................... ....................... ........................ ....................... .............. ... 12 2.3.2 A.C. system fault clearing ........... ....................... ........................ .................... .......... .. 12 2.3.3 Short-circuit Short- circuit characterist characteristics ics........... ....................... ..................... .............. .......... ..... 12 2.3.4 Frequency .......... ...................... ........................ ....................... ....................... .................. ........... ..... 13 2.3.5 A.C. system harmonic impedance characteristics character istics ... ...... ..... ..13 13 2.3.6 System voltage vol tage distortions distort ions........... ...................... ................. ........... .......... .......... ..... 13 2.3.7 System grounding ............ ........................ ................. .......... .......... .......... .......... .......... ....... ..14 2.3.8 A.C. system topology t opology............ ....................... ....................... ....................... ................ .......14 2.3.9 System equivalen equivalentt........... ....................... ....................... ..................... ............... ......... ....... ... 15 2.3.10 Torsional mode mod e frequencies ....... ............ .......... .......... .......... ......... ......... ........ ... 15 2.4 HVDC cable characteristi ch aracteristics cs........... ....................... ....................... ..................... ............... ......... ....... ... 15 2.5 Auxiliary Auxili ary power system........... ....................... ........................ ....................... ....................... ................ .... 15 2.6 Evaluation ............ ....................... ....................... ........................ ....................... ..................... ............... .......... ......... .... 16 2.6.1 Loss evaluation ............ ....................... ....................... ........................ ..................... .............. ..... 16 2.6.2 Availability Availabil ity evaluation evaluati on........... ...................... ................ ......... ......... .......... .......... ......... .... 16 2.7 Documentation ........... ....................... ........................ ....................... ................ .......... .......... .......... .......... .......16 2.8 Training of Owner’s personnel........... personnel ....................... ....................... ................ .......... .......... .......17 3. System REQUIREMENTS REQUIREME NTS............ ....................... ....................... ........................ ....................... ................ .......... .......... ..... 18 3.1 Power Transmission Transmis sion Capacity Capaci ty........... ...................... .................. ............ .......... .......... .......... ........ ... 18

1JNL100098-754 Rev.00


Page 3 Power direction and reversal........... reversal ....................... ..................... .............. .......... .......... ....... ..18 3.1.2 Transfer capabil capability ity............ ........................ ....................... ...................... ................ .......... ..... 18 3.1.3 Minimum Min imum transfer t ransfer capability capab ility ........... ...................... ..................... ............... ......... .... 18 3.1.4 Power level............ level ........................ ....................... ....................... ................. .......... ......... ......... .......18 3.2 Losses............ ....................... ....................... ........................ ....................... ....................... .................. ........... .......... ....... .. 18 3.2.1 Determination Determi nation of losses ............ ........................ ....................... ................. ........... ....... ..18 3.2.2 Losses to t o be included inclu ded........... ....................... .................... ............. .......... .......... .......... ..... 18 3.2.3 Verification Veri fication of losses losse s........... ...................... ....................... ........................ ................... ....... 19 3.3 Reliability and Availability Availabili ty ............................... ................... ........................ ...................... ............. ... 19 3.3.1.Availability 3.3.1.Availabi lity calculations calcu lations .......... ...................... ................... ............ .......... .......... ......... .... 19 3.3.2 Expected Availability Availabi lity ........... ...................... .................. ............ .......... .......... .......... ........ ... 19 4. SYSTEM PERFORMANCE........... ....................... ........................ ....................... ................ .......... .......... .......... .......... .......20 4.1 Compatibility Compatibi lity ............ ....................... ....................... ........................ ....................... ....................... .................... ........ 20 4.2 Main Circuit Ci rcuit Arrangement Arran gement.......... ...................... ........................ ...................... ............... .......... ......... .... 20 4.3 Active Power Capacity ............................. .................. ................... ............. .......... .......... .......... .......... ..... 20 4.4 Reactive Power Capacity ........... ...................... .................. ............ .......... .......... .......... ......... ......... .......20 4.4.1 Maximum reactive power exchange with converter blocked ............ ........................ ....................... ....................... ........................ .................... ............ .... 20 4.5 Filtering Filteri ng........... ...................... ....................... ........................ ....................... ....................... ........................ ................. ..... 21 4.5.1 A.C. Filterin Filtering g ........... ....................... ....................... ....................... ................... ............ .......... .......... .......... .......21 Calculated a.c. filter filte r performance shall comply with: ......... .............. .......... ....... ..21 21 4.5.2 D.C. filtering filterin g........... ....................... ....................... ................. .......... ......... .......... .......... ......... ...... ..21 4.5.3 Power line li ne carrier filtering fil tering ........... .................... .............. .......... .......... .......... ......... .... 22 4.5.4 Radio interference i nterference ............ ....................... ....................... ................. .......... .......... .......... .......22 4.6 Converter Control........... Control ...................... ....................... ................... ............ .......... .......... .......... .......... ......... .... 23 4.6.1 General............ General ........................ ....................... ....................... ........................ .................. ........... ........ ... 23 4.6.2 Redundancy Red undancy........... ....................... ....................... ....................... ........................ .................. ........ ..23 4.6.3 Self-supervision Self-su pervision ........... ....................... ....................... .................. ............ ......... ......... .......... ..... 24 4.6.4 Power control........... control ....................... ....................... ....................... ........................ .................. ...... 24 4.6.5 Reactive power control and a.c. voltage control.......... control ..........25 25 4.6.6 Recovery Rec overy after a.c. network faults........... ....................... .................. ......... ... 25 4.7 System protection ........... ....................... ........................ ....................... ....................... ..................... ............ ... 26 4.7.1 General............ General ........................ ....................... ....................... ........................ .................. ........... ........ ... 26 4.8 Insulation Insulati on Coordination Coordinati on........... ....................... ....................... ....................... .................. ........... .......... ..... 26 4.9 Acoustic Acousti c Noise ............ ....................... ....................... ........................ ....................... ....................... .................. ...... 27 4.10 Studies ............ ........................ ....................... ....................... ........................ ....................... ................. ........... ......... .... 27 5. EQUIPMENT AND SUB-SYSTEMS SUB- SYSTEMS........... ....................... ........................ ..................... .............. .......... .......... .......29 5.1 General Requirements Requ irements ............ ....................... ....................... ....................... ................ .......... .......... .......29 5.2 Filter Banks Ban ks............ ........................ ....................... ....................... ........................ ..................... .............. .......... .......30 5.2.1 A.C. Filters ........... ....................... ....................... ....................... ................ ......... .......... .......... ........ ... 30 5.2.2D.C. filters ........... ...................... ....................... ........................ ....................... ...................... ............. ..30 5.2.3D.C. valve capacitor .......... .................... ............... .......... .......... .......... ......... ......... .......... ..... 32 5.3 Power Transformers Tran sformers.......... ...................... ........................ ....................... ....................... ................. .......... ..... 32 5.4 Converter Valves.......... ...................... ........................ .................. ........... .......... .......... .......... .......... .......... .......32 5.5 D.C. Smoothing Reactor........... ...................... ....................... ........................ ....................... ............... .... 33 5.6 Phase Reactor ............ ....................... ....................... ........................ ....................... .................. ............ .......... .......33 5.7 Disconnectors, Grounding Groundi ng Switches and Interlocking Interlockin g..... .......... ......... ...... ..33 33 5.8 A.C. Breakers............ ........................ ....................... ....................... ....................... ................ ......... ......... .......... ..... 34

1JNL100098-754 Rev.00


Page 4 5.9 Insulators Insulat ors and Bushings Bush ings .......... ...................... ........................ ....................... .................... .............. ....... .. 34 5.10 Surge Arresters Arrester s........... ....................... ....................... ....................... ........................ ................. .......... ......... .... 34 5.11 Auxiliary Power System ............ ....................... ................... ............. .......... .......... .......... .......... ........ ... 35 5.12 Control, Protection Protecti on and Measuring equipment equi pment........... ...................... .............. ... 35 5.12.1General requirement requirements s........... ...................... ....................... ........................ ................ .... 35 5.12.2Operating 5.12.2Operatin g facilities ........... ...................... ................ .......... .......... .......... .......... .......... ....... .. 35 5.12.3Fault recording ............ ........................ ................... ............ .......... .......... .......... .......... ......... .... 36 5.13 Cooling System Syst em............ ........................ ....................... ....................... ..................... .............. .......... ......... ...... ..36 5.13.1General........... 5.13.1General ...................... ....................... ........................ ....................... ................. ........... ......... .... 36 5.13.2Water-cooling 5.13.2Water-cool ing equipment equipme nt........... ................... ............. .......... .......... .......... .......... ..... 37 5.14 Fire Protection Pr otection System........... ....................... ........................ ....................... .................. ............ ........ ... 38 6. TESTING AND TRIAL OPERATION .......... ...................... ........................ ....................... ................ .......... .......... ..... 39 6.1 General Requirements Requi rements............ ........................ ....................... ...................... ................ .......... .......... ....... .. 39 6.2 Equipment Tests ........... ...................... ....................... ........................ .................... ............. .......... .......... ........ ... 40 6.2.1 General............ General ........................ ....................... ....................... ........................ .................. ........... ........ ... 40 6.2.2 Converter valves ........... ....................... ................. .......... .......... .......... .......... ......... ......... .......40 6.2.3Power transformers transf ormers........... ...................... ..................... ............... ......... ......... .......... ......... .... 41 6.2.4Control system disturbance d isturbance tests.......... ................. ............ .......... .......... ....... ..42 6.2.5Control system verificati verification on........... ....................... ....................... ................. .......... .... 42 6.3 System Tests............ ........................ ....................... ...................... ................ .......... .......... .......... .......... .......... .......42 6.4 Trial Operation O peration and Acceptance Tests .......... ............... .......... .......... .......... .......... ......... .... 43 7. OPTIONS........... ...................... ....................... ........................ ....................... ....................... ........................ ..................... .............. ....... .. 44 7.1 Islanding Islan ding system s ystem operation operati on............ ....................... ....................... ........................ ................. ......... .... 44 7.2 Black start............ ....................... ....................... ........................ ....................... ....................... ...................... ............ .. 44 7.3 Standby operation ope ration for fast voltage support supp ort..... .......... .......... .......... .......... .......... .......44 7.4 Lower performances of acoustic noise noi se........... ...................... ....................... ................. ..... 44 7.5 Stabilization Stabiliz ation of the a.c. system ............................... ................... ...................... ............... ........ ... 44 7.6 Power runback ............ ........................ ....................... ....................... ..................... .............. .......... .......... ......... .... 45 7.7 Overload............ ........................ ....................... ....................... ....................... ................ ......... ......... .......... .......... ....... .. 45 7.8 Power flow fl ow control functions fu nctions ............ ........................ ....................... .................... .............. .......... ..... 45 7.9 Self-supporting Self-sup porting auxiliary auxil iary power............ ........................ ................. .......... .......... .......... .......... ..... 45 8. LIST OF APPENDIX .......... ...................... ........................ ....................... ....................... ..................... .............. .......... .......... .......46

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PROJECT DESCRIPTION

A short description of the project should be given, including a summary of the background of the project and the purpose of the HVDC Light ® Link (e.g. “enhance damping during transient conditions, perform steady state voltage control etc.”), the planned geographical and electrical connection points, etc. As an introduction, the text here should cover a general description of the surrounding transmission system and the network close to the proposed instal lation site in particular. Future planned changes to the network are also of interest for the contractor.

1.1 Scope of Supply 1.1.1

Equipment, Material and Services to be furnished by the Contractor 1.1.1.1

General

The works carried out under this Contract shall include the design, supply, construction, installation and commissioning of the following permanent plants: Converter station in (Station A) Converter station in (Station B) Cables between the stations: Distance (km)

Laying of the cable is included/ is not included in the Contractors supply.

Land cable Sea cable More details in Appendix 1.

The Contractor shall design, produce material, manufacture, test at the factory, transport and deliver to the sites, install, test, commission, put into operation and guarantee the attainment of certain performance criteria with respect to the plants as described in this Specification and/or shown in the drawings. The Contractor shall deliver to each converter station one complete set of special maintenance equipment and tools together with necessary measuring and testing equipment, which are needed for a proper maintenance of the converter stations. These special tools and maintenance equipment include all the equipment that is only available from the Contractor and his sub-suppliers. The maintenance, measuring and testing equipment may be used during installation, but any such tool or device that is damaged by the Contractor shall be repaired or replaced by the Contractor at no extra cost to the Owner. The Contractor shall organize and conduct, as part of the Scope of Supply, training programs and courses for operation and maintenance personnel prior to the test on site, see Section 2.8. Trainees' travel and living expenses will be born by the Owner. 1.1.1.2

Equipment and material

The Contractor’s Scope of Works shall include all equipment up to and including the terminals of the breaker connecting the HVDC Light® Link to the main bus at each station.

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Name

Main Bus Voltage (kV)

Station A Station B In particular the following is to be included in Contractor’s Scope of Works: All engineering, manufacturing and supply of the components of the HVDC Light® Link, their assemblies and accessories. 1.

2. The converters for reactive and active power control, including their protection, control, monitoring and cooling system. 3.

All reactors and capacitor banks as required by the design.

4.

Harmonic filters as required by the specified harmonic performance levels.

5.

All power transformers required by the HVDC Light® Link system.

6.

All instrument transformers as required.

7.

All circuit breakers, disconnect and grounding switches as required. All switchgear equipment on the primary side of the step-down transformer, incl. circuit breakers, disconnect switches, instrument transformers, surge arresters, etc., as required. 8.

All necessary equipment for the control, protection, signaling and measurement system of the HVDC Light® Link and its interface to the Owner network control, as required. 9.

10.

System for fault recording as required.

11.

Operator’s interface (HMI) as required. 12. Auxiliary a.c. and d.c. power distribution, including protection, batteries and chargers as required. Surge protection and overhead lightning protection of the HVDC Light® Link as required. 13.

14. All equipment support structures and foundations as well as trenches, as required. 15. All bus work including steel structures, foundations, insulators, connectors, joints, fittings etc., as required. A ground mat installed at the HVDC Light® Link, and connected to the existing substation ground mat. 16.

17.

All power and control cables for the equipment in the HVDC Light® Link. Complete HVDC Light® Link buildings with foundation, plumbing, lighting, fire protection and electrical outlets as well as facilities for ambient temperature and humidity control, as required. 18.

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The Owner can, after agreement, take over one or several subjects above. 1.1.1.3

Services

The following services shall be part of the Contractor’s Scope of Works: 1.

Delivery of all equipment under the Scope of Works to the Site at Substation A

Substation A

as well as the civil works, erection, installation, assembly, commissioning and field verification of all equipment supplied as required to form a complete HVDC Light® Link. Design and installation of a proper grounding mat at the site, to be connected to the existing grounding system in the substation (if applicable). 2.

3.

1.1.2

Commissioning of the complete HVDC Light® Link.

4.

Testing of individual components as well as the whole HVDC Light® Link system (field verification) as required.

5.

One week of on-site training of the Owner’s personnel, which will enable them to operate and maintain the HVDC Light® Link

Equipment, Material and Services not included in the Scope of Supply

The Owner should specify which equipment, material and services that are not included in the Scope of Supply under this Contract. This equipment may be supplied by the Owner or by other supplier(s). Examples are: -

A.C. switchyard for incoming lines

-

Auxiliary power supply

-

Telecommunication links between the two converter stations (if applicable) and between the converter stations and the remote dispatch control center(s)

-

Sewerage, drainage and particularly water supply

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1.2 Interface The following interfaces between the Contractor's Scope of Supply and equipment supplied by others must be specified: Converter Converter Converter Converter Converter Converter Converter

equipment stations stations stations stations stations stations

Telecommunication equipment A.C. networks A.C. auxiliary power supply Foundations civil works Grounding system for converter station Drainage D.C. transmission cables

1.3 Spare parts

The Scope of Supply shall include all spare parts necessary for safe operation and maintenance within the stated availability and reliability limits, and for scheduled maintenance of the two converter stations for the first __________ years (normally two years) of operation. If it is advisable, from economical or technical point of view, the spare parts may be divided into three groups: -

Spare parts for Station A

-

Spare parts for Station B

-

Common spare parts for both stations

In the Technical Specification the Owner should specify the requirement for spare Power transformer(s). This depends very much on the Owner's normal practice and the voltages of the a.c. systems connected to the converter stations. One spare unit of each type per station or, if the a.c. voltage is the same in both ends, common spare(s) for the two stations may be considered.

1.4 Equipment and Services Furnished by the Owner

The following equipment and services will be furnished by the Owner and is consequently not part of the Contractor’s Scope of Supply. 1. A dedicated piece of land in Substations where the HVDC Light® Link system will be installed. Layouts of the Substations showing the Sites can be found:

Substation

Appendix 2 3

Drawing

2. A cleared, graded, surfaced, compacted and fenced-in Site with properly designed and installed drainage as required. 3.

Two independent auxiliary a.c. feeders (400 V, or as required, three phase, ± 10%). Maximum load and quality of the supply will be as per the Contractor’s requirements. Se also section 7.9 Potable water, 400 V a.c. power, etc., for temporary use, as required for installation of the equipment and to facilitate reasonable working conditions for the Contractor’s personnel. 4.

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5.A dedicated telephone and modem line at site will be made available to the Contractor at start of installation work. 6.Access/right of entry to the Site 24 hours at any day of the week during civil works erection, installation and commissioning. This shall include an access road for transport of heavy equipment. 7.All permits necessary for the import, delivery to site and installation of the equipment. Available as-built reference data and drawings for the Contractor’s use in the design and interconnection of the HVDC Light® Link system. The Owner is responsible for the correctness of the delivered data. 8.

9.Temporary storage area for equipment, partly indoor or controlled environment. 10.

Storage area for spare parts, partly indoor.

1.5 Standards

The Contractor shall design and manufacture all equipment in accordance with metric standards. All documents, drawings, instruction manuals and test certificates shall use metric units. All Works connected with the supply of the HVDC Light® Link system shall be in accordance with the requirements of the appropriate IEC/ISO standards. Where no IEC/ISO standard exists the HVDC Light® Link system shall comply with recognized standards and design practices. If the requirements of this specification conflict with any of the above standards or practices, this specification shall apply. For special electric components for which no IEC standards are available, the Contractor shall propose applicable recommendations. 1.6 Quality and Environmental Assurance

The Contractor shall include a general description of the Management System, which could be a Quality Assurance Manual describing the quality and environmental assurance procedures. In connection with this the Contractor shall submit certificates according to Quality Standard ISO 9001:2000 and if applicable also Environmental Standard ISO 14001:1996/ or similar. The Contractor shall, in addition to the above, submit a Quality Plan for the proposed delivery. The Quality Plan shall define the systems and procedures that will be used by the Contractor to ensure that the delivery will comply with the requirements of the Owner as detailed in this specification.

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Page 10 2. GENERAL TECHNICAL SPECIFICATIONS 2.1 Geographical location of the converter stations

HVDC Light® station A

HVDC Light® station B

Located in Substation The substation is located in the town of The nearest larger city is Distance from the Site to the nearest larger city (km) The Site is placed in Region of The closest international sea port for import of goods is The distance from the international port to the Site (km) Transport of goods from the sea port to the Site can take place by truck with a maximum total load of (tonnes) Transport of goods from the sea port to the Site can take place by truck with maximum total dimensions of (m) In general, the Owner should specify particulars, affecting the way of transportation to the future HVDC Light ® Link sites.

2.2 Environment 2.2.1

Elevation above sea level

Station A

Station B

Station A

Station B

Station A

Station B

Station A

Station B

Meters above sea level

2.2.2

Ambient temperatures

Mean 24-hour temperatures, warmest month (Month) Mean 24-hour temperatures, coldest month (Month) Maximum temperature Minimum temperature Maximum temperature for guaranteed rated power

2.2.3

C C o C o C o C o

Humidity

Maximum wet bulb temperature Corresponding dry bulb temperature 2.2.4

o

o

C C

o

Air pollution

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Page 11

Environmental class (for instance: III-Heavy) According to IEC/TR 60815

2.2.5

Isokeraunic level

Strokes per km × year Strokes per km2 × year 2

2.2.6

Station B

Station A

Station B

Station A

Station B

Average Maximum

Wind velocity

Vs (serviceability limit) Vp (permissible stress limit) Vu (ultimate strength limit) 2.2.7

Station A

m/s m/s m/s

Seismic requirements As applicable.

2.2.8

Other ambient conditions

Snow depth Ice Load (radial thickness) Maximum combined snow and ice load Frost penetration Max Solar Constant 2.2.9

m mm kPa mm kW/m2

Topology

The Owner should describe surrounding buildings and if possible enclose a topologic map.

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Page 12 2.3 A.C. system characteristics

Single-line diagrams of the Substations are shown in Appendix. The single-line diagrams should indicate all major buses, power transformers, shunt reactors and shunt capacitors. Preferably, the diagrams show the prospective connection of the HVDC Light ® Link.

Substation

2.3.1

Single diagram in Appendix 4 5 Voltages

Nominal system voltage Normal operating voltage Maximum system voltage, steady state Minimum system voltage, steady state Maximum temporary system voltage, maximum duration Minimum temporary system voltage, maximum duration Maximum neg. sequence voltage during normal oper. Surge arresters in the surrounding systems (existing and planned) Rating SIPL/Current LIPL/Current 2.3.2

Station B

Station A

Station B

Station A

Station B

kV kV kV kV KV min KV min % kV kV/kA kV/kA

A.C. system fault clearing

AC System Fault Clearing Time, Normal AC System Fault Clearing Time, Breaker Failure Auto-reclosing time (1-phase) Auto-reclosing time (3-phase), Instantaneous Auto-reclosing time (3-phase), Delayed 2.3.3

Station A

ms ms s s s

Short-circuit characteristics

Maximum characteristics Short circuit current (Symmetrical, 3-phase) Asymmetrical, first peak Network X/R ratio Minimum characteristics Short circuit current (Symmetrical, 3-phase) Asymmetrical, first peak Network X/R ratio Minimum Post Contingency SCC (Short Circuit Capacity) Normal characteristics Short circuit current (Symmetrical, 3-phase) Asymmetrical, first peak

kA kA kA kA MVA kA kA 1JNL100098-754 Rev.00


Page 13

Network X/R ratio

2.3.4

Frequency

Station A Nominal frequency Maximum steady state variation Minimum steady state variation Maximum temporary frequency

Hz Hz Hz Hz sec

Duration Times per year Minimum temporary frequency

Hz sec

Duration Times per year

2.3.5

Station B

A.C. system harmonic impedance characteristics

The a.c. system harmonic impedances to be used for the design of the a.c. filters are given by the impedance logic of Figure in Appendix 6 (Station A) and Figure in Appendix 7 (Station B). Example: The harmonic network impedance Zn represents the power system network impedance as

seen from the bus to which the converter is connected. It can be given as harmonic impedance sectors, exemplified below: h

Zmin

Zmax

Φ

2-4

h Z min s.c.

hZ max s.c.

0° to 80°

5-10

h Z min s.c.

hZ max s.c.

± 75°

11-19

h Z min s.c.

hZ max s.c.

± 70°

20-34

h Z min s.c.

hZ max s.c.

± 60°

h Z min s.c.

hZ max s.c.

± 45°

--

--

35-50 51≤

Open Net

j X

Φ Z

+

i m n

R

Φ

Z m a

x

-

Where Zmin s.c. and Zmax s.c. are the min. and max. fundamental frequency short circuit impedances.

2.3.6

System voltage distortions

The Owner should specify existing individual harmonic voltage distortion (from measurements) and give the existing total voltage harmonic distortion. Note that system distortions typically follow daily and seasonal load variations.

Existing distortion in the a.c. system, maximum steady state harmonic distortion:

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Page 14

Unit [%] [%]

5 harmonic 7th harmonic th

Station A 1 1

Station B 1 1

Existing distortion in the a.c. system, maximum temporary harmonic distortion: Unit Station A Station B th 5 harmonic/duration [%]/[s] 1.5 / Steady state 1.5 / Steady state (for equipment rating) (for equipment rating) th 7 harmonic/duration [%]/[s] 1.5 / Steady state 1.5 / Steady state (for equipment rating) (for equipment rating)

2.3.7

System grounding

The existing system grounding system should be described.

AC network grounding reactance ratio, X1/X0

Unit pu

Station A

Station B

The Contractor shall calculate and design the grounding system for stations as well as for cables. The Owner will construct the grounding system

2.3.8

A.C. system topology

The Owner should give the topology of the surrounding a.c. system.

A.C. system topology

Station A Appendix 8

Station B Appendix 9

The information included in the above appendices should show the connections to other, electrically close, substations and the minimum in-feed of Short Circuit Capacity (SCC) from each connection. The transformer configurations should also be included. It should be possible to estimate both positive and zero sequence impedances at different system configurations from the information above. The models given will be used for all transient studies.

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Page 15 2.3.9

System equivalent

The a.c. system equivalents are given below: A.C. system equivalent

Station A Appendix 10

Station B Appendix 11

The network equivalents should represent the local transmission system near the HVDC Converter Stations and shall consist of 7-10 nodes each. Explicit line models should represent positive sequence series impedance and shunt capacitance. Explicit transformer models should represent winding configuration, and l eakage impedance. For simulations involving transformer energization or faults, explicit power and/or HVDC converter transformer models shall also represent saturation characteristics.

2.3.10 Torsional mode frequencies

The a.c. system contains the following Torsional Mode Frequencies: Unit Station A Inter area modes [rad/s] 2.4

Station B

HVDC cable characteristics

See Appendix 1. 2.5

Auxiliary power system

The Owner will provide the a.c. auxiliary power supply. Two separate supplies in each station will be provided. Unit Station A Station B A.C. voltage [kV] Figure Appendix 12 Appendix 13 Each supply will have sufficient capacity to supply the entire converter station, including the equipment not furnished by the Contractor. The power requirements of equipment not supplied by the Contractor are as follows: Unit Station A Station B Station name Load [kVA] The auxiliaries shall be capable of riding through all frequency and voltage conditions specified in sections 2.3 and 5.11 without loss of supply to the main power circuits or shut-down of any auxiliary system. In case of a permanent outage in one feeder all essential loads in the station should be transferred to the remaining feeder. When the faulty feeder is restored, the loads should be transferred back automatically. Both transfers shall not affect the power transmission capability of the converter station. Se also section 7.9

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Page 16 2.6

Evaluation 2.6.1

Loss evaluation Currency/kW

Capitalized no-load losses Capitalized load losses No-load losses and load losses are defined in Section 3.2. The equivalent total losses will be used for evaluation.

2.6.2

Availability evaluation Currency/percent

Capitalized Forced Energy Unavailability (FEU) Definitions of unavailability terms shall be according to "Protocol for reporting the operational performance of HVDC transmission systems" issued by CIGRE 14-97 (WG 04). EU per year is defined as the number of equivalent hours of outage per year (scheduled and unscheduled), divided by the total number of hours per year (8760) and multiplied by 100%.

2.7

Documentation

The Contractor shall submit the following documents for review by the Owner. The review period is maximum 14 calendar days from receipt of documents. Any request for changes from the Owner given outside the review period shall be considered but may be subject to time/price adjustment. The Contractor shall re-submit the revised documents within 21 calendar days from receipt of the comments from the Owner. The main design documents to be sent for review are: -

Single line diagram

-

Switchyard layouts

-

General layout and architecture of the buildings

-

Maintenance and service plan

-

Operation guidelines for the HVDC plant

-

Locking and interlocking

-

Nameplate drawings for main circuit apparatus

The Contractor shall submit the following documents for information: -

Type test reports

-

Routine test reports

-

Technical reports

-

Equipment specifications for main circuit apparatus

-

Dimension drawings for main circuit apparatus

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Page 17

-

Main circuit parameters

The instruction books for the equipment shall contain all information needed for operation and maintenance of the converter stations. The "as-built" plant documentation shall be delivered in a structured fashion no later than three months after start of commercial operation. 2.8

Training of Owner’s personnel

The Contractor shall organize and conduct, as part of the Scope of Supply, thorough training programs for operation and maintenance personnel prior to the commercial operation date. Trainee's travel and living expenses will be born by the Owner. The training courses shall also include training in the factory during the testing of the complete HVDC control system, Factory System Test. The training program shall run for such time as is required to enable the trainees to familiarize themselves with the operation and maintenance of the converter stations. Appropriate training documentation shall be included. It is also anticipated that the technical and maintenance personnel, for training purposes take part in the installation and testing work in cooperation with the Contractor's personnel. The Contractor is, however, to be responsible for the work. The participating persons shall have basic knowledge about switchgears and control system and basic computer know-how and have future participation in the plant’s operation and/or maintenance. The participating persons in the training program shall also participate in the commissioning activities.

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Page 18 3. SYSTEM REQUIREMENTS 3.1 Power Transmission Capacity 3.1.1 Power direction and reversal

The HVDC Light® Link shall be capable of power transfer in either direction and be capable of reversing power transfer direction automatically, at minimum power, without the requirement to block a converter or perform any high voltage switching. 3.1.2

Transfer capability

The HVDC Light® Link shall have a continuous active power transfer capability (Rated power) of not less than ______ MW. It shall also be able to deliver or consume reactive power at the connection point to the receiving a.c. network, as per the requirements stated in Sections 4.4. 3.1.3

Minimum transfer capability

The minimum continuous transfer capability of the HVDC Light® Link shall not exceed 0% of the continuous transfer capability, including at the completion of the start sequence. 3.1.4

Power level

The HVDC Light® Link shall be capable of continuous operation at any power level between minimum and continuous transfer capability. 3.2 Losses 3.2.1

Determination of losses

The Contractor shall determine the no-load losses and the load losses at nominal operation. The no-load losses are defined as the losses in stand-by operation with the transformers energized and the converter valves blocked. The load losses are defined as the total losses at nominal power, nominal a.c. voltage and frequency, at 0 MVAr produced from the converter and at an ambient temperature of 20oC, minus the no-load losses. For the calculation of losses, applicable parts of the guidelines given in IEC 61803 "Determination of power losses in High Voltage Direct Current (HVDC) converter stations" shall be followed. For calculation of harmonic losses the a.c. system shall be assumed to be an open circuit to all but the fundamental frequency component of the current. 3.2.2

Losses to be included

The losses of the entire main circuit equipment in the Contractor's supply shall be included for the determination of station losses. Furthermore, the Contractor's total active auxiliary power load for cooling equipment and control shall be included.

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Page 19 3.2.3

Verification of losses

For main circuit equipment, for which the losses that are established at factory test conditions can be considered equivalent to the losses in actual operation, the factory test results shall be used in the listing of station losses. For equipment where the operational conditions differ from the factory test conditions (which is the case where harmonics influence the losses), the losses shall be calculated. The losses shall be determined for Station A operating as rectifier and Station B as inverter. 3.3

Reliability and Availability

The Contractor shall perform a Reliability and Availability study of the HVDC Light® Link in accordance with sections 3.3.1 and 3.3.2. The study shall be used as the basis for determining the contract spare parts to meet the required availability of the HVDC Light® Link. 3.3.1. Availability calculations

The study shall use HVDC equipment category items as defined by Cigré Study Committee 14 – DC Links “Protocol For Reporting The Operational Performance of HVDC Transmission Systems”, revision 14-97 (WG-04), dated 1997, for calculation of the predicted availability. Random failures of one or more components within the HVDC Light® Link shall be considered in the calculations. However, damages that are caused by outage of another piece of equipment, or failures beyond the Contractor’s control will not be included in the calculations. As part of the study, and in addition to determining the required spare parts, the Contractor must: a.

Provide a list of tools and test equipment by type and quantity that are required at the site in order to meet the calculated availability.

b. Provide the annual maintenance plan, which was used for the purpose of calculating the predicted availability. c. Respect that the converter stations will be unstaffed and remote controlled from ___ (number)

power control center (-s), and assume that maintenance personnel will be dispatched by the operator (-s) in the power control center (-s) and will arrive on site within ____ (normally two) hours. 3.3.2

Expected Availability

Contractor shall state the expected Reliability and Availability quantities as per below: Number of Forced Outage Events, annually Energy Availability

Typically 5 Typically 98%

The Cigré Study Committee 14 – DC Links “Protocol For Reporting The Operational Performance of HVDC Transmission Systems” shall be used for definitions and for reporting and determination of the yearly Availability.

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Page 20 4.

SYSTEM PERFORMANCE

The Contractor shall fulfill the requirements for the overall performance of the system, as defined herein. Fulfillment of the requirements will be demonstrated by acceptance tests, as specified in Section 6.4. 4.1 Compatibility

The overall design of the converter station shall be compatible with the rest of the system as defined in Section 2, "General Technical Specification". 4.2 Main Circuit Arrangement

Suggested circuit configurations for the converter stations assuming a conventional converter circuit are provided in Figure ________________ appendix 14, for Station A and Figure ________________ appendix 15, for Station B. 4.3 Active Power Capacity

The active power transfer capability stated Section 3.1.2. refers to the a.c. line terminal at the receiving station. It shall apply to power transfer at the rated d.c. transmission voltage, with the a.c. network voltage and frequency within their steady state limits and at maximum ambient temperature. 4.4 Reactive Power Capacity

The converters shall be designed to meet the following reactive power requirements, during steady state operation as per clause 2.3.1 and 2.3.3, measured at a.c. line terminals: Active power direction A to B A to B A to B A to B A to B A to B B to A B to A B to A B to A B to A B to A

P [pu] 1.0 1.0 1.0 0.1 0.1 0.1 1.0 1.0 1.0 0.1 0.1 0.1

4.4.1

Q [MVAR] Generation Consumption

Uac [pu] max. steady state 1.0 min. steady state max. steady state 1.0 min. steady state max. steady state 1.0 min. steady state max. steady state 1.0 min. steady state

Maximum reactive power exchange with converter blocked

The maximum reactive power exchange with the a.c. system (at nominal system voltage) shall, with converters being blocked, not exceed the figures in the table below. Station A MVAr Station B MVAr

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Page 21 4.5 Filtering 4.5.1

A.C. Filtering

Calculated a.c. filter performance shall comply with:

• Individual harmonic distortion: Dh

=

U h

≤ 1%

U 1

• Total harmonic distortion: 2

 U  ≤ 2% THD = ∑  h   U h = 2  1  50

• Telephone influence factor: 2

 U TIF h   ≤ 40 TIF = ∑  h  U h = 2  1  50

Where: Uh: is the h:th harmonic (phase to ground) voltage, U1: is the nominal fundamental frequency (phase to ground) voltage. TIFh: is the weighting factor for the h:th harmonic according to EEI Publication 60-68 (1960). A.C. filter performance shall be calculated for expected steady state operating conditions as per clause 2.3, 2.3.5, 4.3 and 4.4. Individual harmonic distortion, Dh, shall be calculated using the worst-case value within the system harmonic impedance loci defined in Section 2.3.5 for each individual harmonic Total harmonic distortion and telephone influence factor, THD and TIF, shall be calculated using the worst case value within the system harmonic impedance loci defined in Section 2.3.5 for the single individual harmonic that contribute the most to these factors. For all other harmonics the system should be considered as an open circuit.

4.5.2

D.C. filtering

If the d.c. cable route shares the same right of way or runs close by subscribers telephone wires, rail road signaling wires or similar there is a possible exposure to harmonic interference from the d.c. cable. Under these circumstances and for conditions where a local preventive measure is not feasible, e.g. improving shielding of subscriber wires, the third party (telephone company, rail road company etc) should be consulted for permissible interference limits. The interference limits are often expressed as an equivalent weighted ground (common) mode current. As an example the performance requirement can be expressed as the psophometrically weighted, 800 Hz equivalent disturbing current, Ieq, fed into the cable pair at each station: I eq = (1 / P800 ) *

where:

∑ f ( Pf * I f ) 2

Ieq is the psophometrically weighted, 800 Hz equivalent disturbing current,

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Page 22

I f is the vector sum of harmonic currents in cable pair conductors and screens at frequency f, f is the frequency, ≤ 2500 Hz Pf is the psophometric weight at frequency f.

4.5.3

Power line carrier filtering

The converter station shall not, on the a.c. side, generate noise above the values below (0dBm = 0.775V, 1mW over 600Ω): Frequency Range (kHz) Noise Level (dBm) 150 - 500 < -30 The specified noise levels are referred to a measured value on the conventional PLC coupling. The bandwidth is 4kHz.

4.5.4

Radio interference

The radio interference from the HVDC Light® Link converters shall comply with the limits stated in ENV50121-5 (1996) in the frequency range 500kHz – 30MHz, and with the limits stated in CISPR11, group 1 and class A, in the frequency range 30MHz – 1GHz. The corona noise level from the outdoor yard and overhead lines in the vicinity of the HVDC Light® Link converters shall not exceed 100µV/m in the frequency range 500kHz-30MHz, along the contour lines shown in figure below. The 450-meter perimeter is measured from any energized component in the converter station or adjacent a.c. switching station.

1JNL100098-754 Rev.00


Page 23 4.5 km

450 m

150 m 30 m

4.6 Converter Control 4.6.1

General

Each converter shall be equipped with a control system that has been designed to operate satisfactorily under all system conditions specified. The design shall be flexible to allow for future adaptation of additional functions. The control system shall be able to operate under the condition that there is no telecommunication between the stations. Some additional control functions may require telecommunication to allow fast and safe operation. The HVDC Light® Link control system must be stable in all situations specified in this document. The control system shall not contribute with negative damping of sub synchronous oscillations in the a.c. system.

4.6.2

Redundancy

All essential parts of the control equipment shall be designed as duplicated systems acting as active or hot standby. At any time only one of the two control systems shall be active, controlling the converter and associated equipment. The other control system, the standby system, shall be in operation, but the “outputs” from that system shall be disabled. If a fault is detected in the active system, the standby system will take over the control, becoming the new active system. The faulty system (the previously active system) shall not return to operation as a standby system, unless the fault is cleared. This applies for, at least, the following systems: - Pole Control System - Valve Control System - Valve Cooling Control and Protection System The system switchover commands shall be manually or automatically initiated. The manual commands shall be initiated by a pushbutton in the active system or by an order from the Operator Work Station, OWS, while the automatic commands shall be initiated by internal supervision functions, or on protection system order. The switch over commands shall be initiated from the active system. By this switchover philosophy, a fault or testing activity in the standby system cannot result in an unintentional switchover.

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Page 24

A switchover to a faulty standby system shall not be possible. If the standby system detects a fault, it shall exit the standby mode. 4.6.3

Self-supervision

The control equipment shall, as far as possible, be built to avoid periodic maintenance and provide shortest possible repair times. The maintenance of the control equipment shall (due to the redundant design) not require any periodic shut down of any main circuit equipment. Maintenance shall be minimized by the use of self-supervision built into all microprocessor- based electronic units and the possibility to check all measured values during operation without disturbing the operation of the transmission link. The microprocessor-based systems shall include, but not be limited to, internal supervision functions like: - Auxiliary power supervision - Program execution supervision (stall alarm) - Memory test (both program and data memory) The operation of possible field busses shall be monitored by a supervisory function in the control and protection systems, continuously reading from each individual node of the system. Any detected faults shall generate an event record and shall initiate a switchover to the standby system. Integrated self-supervision of the high-voltage switchgear control units shall also be included to detect the following: - Failure of the output circuits to the breaker - Ground faults of the close/trip lines to the breaker - Close/trip coil failure of the breaker 4.6.4

Power control

Active power control shall be the normal mode of control in the receiving station. Changes in the amount of power transmitted shall be carried out automatically after a new power order and rate of change (in MW/minute) have been set and initiated. The initiation command shall start a continued regulation at the specified speed and in the direction of the sign-defined final value. The regulation shall cease when the final value is attained, or if a command to stop regulation is received. The control commands shall be absolute values and shall comprise: Sign of order value, positive power transfer defined Station A to Station B as from: Order value, Resolution [MW] 1 Rate of change, low limit [MW/min] Rate of change, high limit [MW/min] Rate of change, resolution [MW/min] 1 Initiation command Power control commands shall be given as one of the following alternatives: • Power control command from the local control room (local control) in the active power controlling station • Power control command from remote dispatch center (remote control)

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Page 25

It shall be possible to automatically superimpose modulation control on the power control (if applicable).

4.6.5

Reactive power control and a.c. voltage control

Each station shall be able to control the reactive power independently within given limits (4.4). It shall be possible to either control reactive power or a.c. voltage. 4.6.6

Recovery after a.c. network faults

The design target for the control system shall be to restore the power transfer to 90 percent of the prefault power within ____ ms after clearing a single-phase or three-phase a.c. fault at the rectifier side, and within ____ ms after clearing a fault at the inverter side. A stable and well-damped recovery shall have priority. 4.6.6.1 Irrecoverable Faults

The HVDC Light® Link System shall not be required to recover from the following: - faults within the protection zones of either converter station - faults on the HVDC high-voltage cable system - any event for which the short-circuit capacity in each respective network is reduced below the minimum post-contingency value as per clause 2.3.3

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Page 26 4.7 System protection 4.7.1

General

All protection equipment shall be suitably restrained or stabilized to prevent incorrect operation of the protections during system transients and a.c. system fault conditions. The protections shall be arranged so that suitable redundancy is obtained. Loss of one auxiliary power source shall not result in loss of the protection system. If suitable, protections should have selectivity between switchover order and trip and block order. The selectivity between switchover order and trip and block orders from a protection can be accomplished by setting a lower level criteria and a shorter pick-up delay for the switchover order.

4.8 Insulation Coordination

Surge arresters as per Section 5.10 shall protect the converter stations. The arrester scheme proposed by the Contractor shall be confirmed by the system studies during order stage. For lightning, multiple strokes shall be assumed as normal occurrence. As for multiple strokes, see Electra No. 69, March 1980, p. 65-102. Clearances shall be selected in accordance with the insulation levels, taking into account the safety and maintenance viewpoints as well as the requirements of the national authorities. The following insulation margins shall be selected for impulse voltages: IGBT valves, excluding redundant IGBT:s

10 %

for all stresses

Oil insulation

15 % 20 %

for switching surges for lightning surges

Other

15 % 20 %

for switching surges for lightning surges

For none of the equipment on the d.c. side or in the a.c. filters, test levels need to be rounded off upwards to the next IEC or ANSI standard level.

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Page 27 4.9 Acoustic Noise

Acoustic noise from the installation given as the equivalent, constant and corrected dB(A) Leq noise pressure level, shall not exceed the recommended emission values at typical locations provided in the table below. Typical Requirements:

Location Inside Station At the fence boundary line 150 m from equipment boundary line

Noise pressure level , Leq ; [dB(A)] < 90 < 65

Equipment boundary line

< 55

Station fence boundary line

In case the station is to be located close to residential properties, the acoustic noise from the installation, given as dB(A) L eq noise pressure level, shall not exceed the maximum required level which is to be provided by the local authorities, for all specified locations. The figure showing the surrounding of the station should specify the converter station area, give detail information about the topography around the station area, the existing buildings, distances to closest residences etc. It can preferably be as a 3D digital map (with height information), in common format such as *.dwg; *.dxf or shape file.

To fulfill the requirements, noise-reducing measures may be needed. Information about these measures shall be given to the Owner. The costs for such measures shall be born by the Contractor. For indoor areas the noise levels apply only for such areas that can be entered into during operation.

4.10

Studies

The Contractor studies shall include:

• • • •

Main circuit design, including definition of power transformer rating & taps A.C. harmonic filters design Over voltage performance Protection systems, including coordination with existing equipment (Owner to obtain applicable data from interconnecting utilities for Contractor design considerations).

• System Losses The Contractor shall write a technical report about losses. The report shall include losses of: - Filtering - Phase reactor - Converter valves - Transmission cable - Auxiliary power The losses shall be calculated according to active and reactive power levels presented in the table below. Power Transmitted Reactive Power Generation Reactive Power Consumption MW + MVAr - MVAr 1JNL100098-754 Rev.00


Page 28

0 (blocked) 100% The above calculation results shall be given including auxiliary power, fans, pumps, etc. The Owner can specify up to five more operations levels, as per his own choice. For these operational levels the nominal values of auxiliary losses should be used

• Reliability/Availability • Dynamic performance study, including a.c. disturbances, disturbance recovery, and equipment switching. The simulations included in the study shall be done in computer program EMTDC.

• Torsional Interaction (SSTI) if required by screening study. If there are generation facilities located in close proximity to the converter stations the potential risks of sub synchronous torsional interaction (SSTI) shall be evaluated. The procedure shall be as

follows:

a)

Evaluation of potential risk of SSTI (Screening Study)

The Unit Interaction Factor (UIF) as defined in the EPRI EL-2708 Research Project RP1425-1 Final Report 1982, will be used as a screening method to define conditions where the HVDC Light® Link system has potential risk of harmful interaction with a generator. The initial screening study shall be performed jointly by the Contractor and the Owner and shall determine any conditions requiring a more detailed study. b) Detailed SSTI study

If the Screening study indicates a need for a detailed SSTI study, the Owner will supply necessary data to Contractor, in a format to be provided by the Contractor, in order to determine the torsional modes of interaction. The Contractor shall provide a report to show that the HVDC control system design will not contribute to negative damping for the determined torsional mode frequencies.

1JNL100098-754 Rev.00


Page 29 5.

EQUIPMENT AND SUB-SYSTEMS

5.1

General Requirements

The Contractor undertakes to fulfill the following general requirements in the design of apparatus and sub-systems. Electrical equipment shall conform with the environmental requirements applicable to the location where it is to be used. Heating elements and insect protected ventilation devices shall be provided and mounted by the Contractor in all outdoor control cabinets within the Supply. Components containing PCB or similar materials will not be accepted. All electrical and electronic switchboards and cabinets shall be made of metal, and they shall be reliably grounded. If junction and terminal boxes are metal-enclosed, they shall be reliably grounded. Apparatus tests shall demonstrate that the equipment fulfills the specified requirements and has the ability to perform as intended. The converter equipment auxiliaries, and the equipment associated with the control of major apparatus or sub-systems, shall be designed such that a single contingency outage shall not cause loss of station capacity. Thus, for example, in the event of a failure of a cooling fan, the increased temperature at full load at maximum average ambient temperature shall still be within the maximum limit for the equipment. Redundant cooling pumps, cooling fans, heat exchangers etc., shall be provided as needed to obtain the required station reliability as defined in Section 3. The reliability of equipment shall be assured by incorporating the following design principles, where applicable: -

Use of the least complex design capable of performing the desired function. Use of components whose reliability has already been proven. Use of equipment capable of operating over a wide range of tolerance to reduce the necessity for matching replacement items to a specific operating condition. Use of duplicated components or sub-systems with automatic transfer between redundant systems as required, obtaining the required station reliability as defined in Section 3. Use of fail-safe and self-checking design features. Provision of adequate facilities for testing, fault indication and monitoring. Use of equipment that does not require special operating and maintenance environments or complex operating sequences. Use of modular construction to permit rapid replacement of modules containing failed components or subassemblies.

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Page 30 5.2

Filter Banks

5.2.1

A.C. Filters

5.2.1.1

General

The a.c. filter bank system shall consist of one or several banks. Each bank may consist of one or several branches and may include conventional shunt capacitors required for reactive power compensation. The design of the a.c. filter banks shall be fully compatible with the filtering and reactive power compensation requirements specified in sections 3.1, 4.3, 4.4 and 4.5. AC filter capacitors shall be designed and tested in line with applicable parts of IEC 60871-1. The capacitor units shall be of internal fuse, fuse-less or self-healing design. A.C. filter reactors shall be designed and tested in line with applicable parts of IEC 60289. 5.2.1.2 Component rating

The mechanical and thermal design of the filter components shall be such that no constraints are imposed on the operation of the plant in the voltage and frequency range given in Section 2.3.1 resp. 2.3.4. Rated voltage for a.c. filter capacitors shall at minimum be determined as

∑= U

U k +

2

h

h 1 h ≠ k

Where k denotes the maximum individual harmonic voltage across the capacitor bank. Rated current for all a.c. filter components shall at minimum be determined as

∑= I

2

h

h

1

Creepage distances for all a.c. filter components shall at minimum be determined as

∑= U

2

h

h

1

5.2.1.3 Protection

Adequate protection and/or supervision shall be provided for the filter components. The protection system shall include but not be restricted to capacitor unbalance protection.

5.2.2

D.C. filters

5.2.2.1 General

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Page 31

The d.c. filters (if any) may consist of one or several branches. The design shall be fully compatible with the filtering requirements specified in Section 4.5.2. D.C. filter capacitors shall be designed and tested in line with applicable parts of IEC 61071-1. The capacitor units shall be of internal fuse or self-healing design. D.C. filter reactors shall be designed and tested in line with applicable parts of IEC 60289. 5.2.2.2

Component rating

The mechanical and thermal design of the filter components shall be such that no constraints are imposed on the operation of the plant in the voltage and frequency range given in Section 2.3.1 resp. 2.3.4. Rated voltage for d.c. filter capacitors shall at minimum be determined as U dc

+ 2 ∑ U h h =1

Rated current for all d.c. filter components shall at minimum be determined as

∑= I

2

h

h

1

Creepage distances for all d.c. filter components shall at minimum be determined as 2 U dc

+ ∑ U h 2 h =1

5.2.2.3 Protection

Adequate protection and/or supervision shall be provided for the filter components. It is foreseen that element failures in a d.c. filter capacitor is detected by capacitance measurement during the maintenance stops. An adequate interval for these measurements shall be given.

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Page 32

5.2.3

D.C. valve capacitor

D.C. valve capacitors shall be designed and tested in line with applicable parts of IEC 61071-1. The capacitor units shall be of internal fuse or self-healing design. 5.3

Power Transformers

Insulation withstand voltage levels on the a.c. line side of the transformers shall be equal to or exceed those given in the Table below: Separate-source voltage test Internal insulation kV Phase Neutral point (1)

Bushings (wet) kV

Switching impulse test

Full-wave Lightning impulse test

Induced over voltage test (5sec.) L-L

L-N

L-L

kV

kV

kV

kV

NA

NA

(1)

NA

An indirect test (+ and -), note the wave shape.

Bushings of the same voltage and current rating shall be interchangeable for all transformers. The transformers shall be provided with the necessary instrumentation and at least the following protections: Gas detection relays Oil and winding temperature indication Differential protection Over-current protection Oil level gauge Testing of the transformers shall be performed as specified in Section 6. 5.4

Converter Valves

The IGBT valves shall be of indoor, air insulated and water cooled design. It shall consist of a number of series connected IGBT positions with semiconductors, voltage dividers and gate control units. The semiconductor device shall consist of an IGBT part and an anti parallel diode part to be able to conduct the current in both directions. For large valves, the IGBT positions can be distributed in a number of mechanical subunits (stacks). The valve shall be designed for a creepage distance of 14 mm/kV based on an rms voltage applied during switching operation. The valve shall be built in a low inductive way, to minimize the voltage spikes at commutation within each phase. No auxiliary power shall be needed for the electronics in gate control units. They shall receive the power from the main circuit. Communication to and from the valves shall be done with high communication speed by means of optical cables, for insulation from ground potential.

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Page 33

No standards for testing of high voltage HVDC Light® Link valves are available. However, similar standards for testing of conventional HVDC valves and self-commutated converters in low voltage applications are available. Where applicable, the principles of standard IEC 60700 for dielectric testing and IEC 60146-2 for operational testing are followed.

5.5

D.C. Smoothing Reactor

The d.c. smoothing reactor, if needed, shall be designed to ensure the requirements for emissions of disturbances from the HVDC transmission. The design of the reactor shall consider any disturbances in the transmission system, which may cause transient over voltages or over current stresses on the reactor. The d.c smoothing reactors shall be of air insulated design. They shall be designed and tested in line with applicable parts of IEC 60289.

5.6

Phase Reactor

The phase reactor shall be designed to ensure satisfactory operation according to the overall performance requirements for the HVDC transmission system. The design of the reactor shall consider any disturbances in the transmission system, which may cause transient over voltages or over current stresses on the reactor. The Contractor, considering reactive power requirements, harmonic currents and fault currents, shall select the inductance of the reactor. The reactor shall preferably be dry type, air cooled, or water/air cooled cable winding. Dry type reactors shall be designed and tested in accordance with IEC 60289 and temperature class Y according to IEC 60085.

5.7

Disconnectors, Grounding Switches and Interlocking

All disconnectors and grounding switches shall be designed to ensure satisfactory operation and maintenance. All disconnectors shall be motor-operated, but with provision for manual operation. All disconnectors and grounding switches shall have a clearly visible position-indicating device. An interlocking scheme shall prevent un-permitted operation. The interlocking system shall include: -

The a.c. disconnectors and grounding switches for the Power transformers.

-

All disconnectors, grounding switches etc., within the Scope of Supply.

-

Door or gate leading into areas with live parts.

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Page 34 5.8

A.C. Breakers

The breakers shall comply with IEC 62271-100 and be able to perform, at least, at the maximum voltage, short circuit current and insulation data given in section 2. If for any reason other (higher) data are required by the Owner these should be amended.

5.9

Insulators and Bushings

To the extent possible, the Contractor shall select insulators and bushings of a type that is, or will become, a manufacturer's standard item. Mechanical strength shall be in accordance with conventional practice for high voltage a.c. insulators. Insulators subjected to direct voltage shall be of a type that by tests or otherwise have proven to be suitable for direct voltage application. Creepage distances, based on rms terminal-to-flange voltage, shall be as follows: Outdoor insulators and bushings subjected to: Ceramic insulators Silicone insulators Minimum, mm/kV Minimum, mm/kV A.C. voltage D.C. voltage D.C. voltage with a.c. component All indoor insulators and bushings subjected to: D.C. voltage D.C. voltage with a.c. component

Minimum, mm/kV 14 14

For all outdoor bushings, excluding capacitor bushings, mounted in a horizontal position (± 30 degrees), all creepage distances shall be increased by 20%.

5.10

Surge Arresters

Only arresters of metal-oxide type will be accepted except where unfeasible. The protective characteristics of the arresters shall be selected by the Contractor, in order to coordinate system protection, subject to approval by the Owner. Since there are no IEC standards for arresters for d.c. applications, test procedures shall be based on the guide prepared by CIGRÉ, Publication 43, 1989, and IEC 60099-4, where relevant.

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Page 35 5.11

Auxiliary Power System

The low voltage auxiliary power system within the Scope of Supply is envisaged to comprise: 3 x ______ V ________Hz, with neutral and PE (Protected Earth) wire, and directly grounded neutral point Two redundant _____ V batteries Variation in a.c. voltage is (+10%, -10%) of rated voltage. Variation in d.c. voltage is (+10%, -10%) of rated voltage. The normal operating voltage is the upper value. The a.c. supply will be provided from two _____________ V independent supplies. Each supply will have sufficient capacity to supply the entire station including the equipment not furnished by the Contractor. The auxiliary power system shall be designed to fulfill the following requirements: -

Operation of the converters shall not be affected by loss of one source of the main a.c. auxiliary supplies, i.e. the auxiliary power system shall be able to overlap the time required for switching all loads over from the failing supply to the operating supply.

-

With loss of the entire a.c. auxiliary power system, automatically controlled shutdown of the converters shall take place. Immediately after recovery of the auxiliary power supply, start-up of the converters shall be possible.

-

The d.c. supply batteries shall be able to operate the necessary equipment for control for at least 12 hours.

5.12

Control, Protection and Measuring equipment

5.12.1 General requirements

The design of the control system shall be flexible enough to enable changes as required by application development. A computer based control system will be preferred. A high reliability is required regarding control system hardware and software. The control system shall be duplicated and shall be designed so that the control system not in use can be tested and serviced during normal operation of the transmission link. The control and protection systems shall be designed so that loss of one auxiliary power source does not result in loss of the control or protection systems. The Owner will provide two independent auxiliary power supplies. Terminal blocks and other components for connection of external cables shall be located in the lower part of the control system cabinets, or in separate termination cabinets. All control cables shall be shielded. All cabling for converging low level analogue signals shall use individually shielded and twisted pairs in overall shielded cables. The shielding of signal cables shall be insulated when taken through junction boxes. 5.12.2 Operating facilities

The control system shall be designed to permit control and monitoring of the HVDC Light® Link converter stations either from a local control room within each station or from a remote dispatch center.

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Page 36

A local operator workstation (LOWS) shall be located at both converter stations. Any change in control settings carried out from the dispatch center shall be monitored in the LOWS at the concerned converter station and vice versa. Switching between local and remote control shall be made from the LOWS. The local control room shall be equipped with monitoring facilities so that the operator can easily survey the state of the converter station. It shall be possible to initiate all control actions necessary for the daily operation, including shutdown and start-up of the converter station, locally as well as from the remote dispatch center , if any . In the operator workstation environment all necessary tools for configuration and operation shall be included. The LOWS shall be provided with, but not be limited to, the following functions. - Logon/logoff - Control window - Event recorder - Alarm and Fault list - Trend window Different users with different access levels shall be able to logon to the LOWS. The Event recorder shall store all events generated in the HVDC Light® Link station and have possibilities to show events as they appear and for a specified historical time span. The Alarm list shall show all alarms generated in the station and it shall be possible to acknowledge the alarms one by one or all at once. The Fault list shall show the actual status of the station with all present alarms. It shall be possible to see variations in specified signals in a real time Trend window. It shall also be possible to store information regarding specified signals and view them later, or export the data to a file center. 5.12.3 Fault recording

To facilitate the analysis of malfunctions and system disturbances, the Contractor shall provide equipment for high speed, analogue and digital fault recording of significant quantities, i.e. d.c. and a.c. voltages, currents, and selected control and protection signals. Measuring and event indication devices suitable for cooperation with the fault recorder, and devices for starting the fault recorder in the event of faults and major disturbances shall be provided. Transmission of the recorded digital data to a remote control center shall be possible. The fault recorder shall be equipped with a clock that can be synchronized from a central time source. 5.13

Cooling System

5.13.1 General

All cooling systems shall be provided with stand-by operation. The cooling system for the valves shall be capable of removing all the heat produced by the valves in any specified mode of operation. 1JNL100098-754 Rev.00


Page 37 5.13.2 Water-cooling equipment

The Contractor shall provide a complete cooling plant. Redundant components/units shall be provided where needed in order to fulfill the availability requirement, as well as for easy maintenance. Full redundancy is required for circulating pumps and 3-way shunt valves. One redundant heat exchanger shall be included, if applicable, in each cooling system. Each cooling system shall be equipped with a water treatment circuit in order to maintain a required conductivity level of the fine water (de-ionized water). Equipment for chemical treatment of the raw water shall be included if needed. The system must be designed to eliminate the risk of damage because of freezing. Arrangements, such as frequency converters, two speed motors etc, shall be available to achieve low power consumption during standby periods. All fine water circuit components, i.e. piping, valves, heat exchangers, filters etc., shall be made of stainless steel of quality standards SS2352 (ANSI 304L) or SS2353 (ANSI 316L). The control system for operation and monitoring of the cooling plant shall be included in the delivery. It shall be possible to operate and monitor the cooling process from the control room.

1JNL100098-754 Rev.00


Page 38 5.14

Fire Protection System

The Contractor of the converter stations has a primary function to analyze the different structures, systems and components, and introduce fire preventions in the early stages of the design, and carry them through the stages of civil works and installation. When considering the general fire load density in different areas of the plant, an inventory must be done of combustibles and their potential for causing adverse secondary effects due to a fire. This should reveal where, and how much of these materials, as well as in which form and for what purpose they are stored or being used. The Contractor shall submit detailed descriptions, arrangements, locations, types of equipment etc. regarding the whole fire protection system. In order to facilitate the detection of a fire in its incipient stage, the converter stations are to be equipped with an automatic fire alarm device monitoring the enclosed areas. The fire alarm device shall monitor all spaces in the areas concerned. In the event of a fire being discovered, a fire alarm signal is to be transmitted: -

locally in all enclosed areas

-

to the remote control center

-

to the local fire brigade (if applicable)

The fire alarm device shall be designed in such a way that: -

it operates automatically, i.e. itself discovers and indicates an incipient fire.

-

it is self-monitoring, i.e. important functions are monitored in such a way that a fault affecting the function of the installation triggers off a fault alarm, which is indicated locally and in the monitoring center.

Detectors are to be connected to the fire alarm center in such a way that, in the event of an alarm being given, the fire alarm center will clearly indicate where the fire has started. In case of fire, indication shall be given in which fire cell the fire is detected. For buildings (if any) the fire protection shall follow the local regulations. The Owner shall provide the required information about local regulations.

1JNL100098-754 Rev.00


Page 39 6. TESTING AND TRIAL OPERATION 6.1 General Requirements

All equipment within the Scope of Supply of the Contractor shall be comprehensively tested in order to demonstrate that they meet the specified requirements. The Contractor is responsible for the performance of the tests required in these Specifications. The tests shall be conducted at a sufficiently early stage so that rectification of possible non-conformities will not delay completion of the work. The tests shall be divided into three main groups: 1.

Factory tests To the extent possible, equipment shall be assembled in large units or sub-systems in the Contractor's factory and be tested prior to shipping. The test reports shall be forwarded to the Owner immediately upon completion of the tests.

2.

Sub-system and component tests after mounting and installation This test program shall include verification tests of components and sub-systems that can be carried out prior to the final testing of the complete Scope of Supply.

3.

System and acceptance tests This test program shall be carried out after sub-system and component tests, and be performed according to the Contractor's proposed test program.

The Contractor shall submit a list of tests with a preliminary time schedule for system tests and acceptance tests. The Owner shall approve the test programs. Two months before the start of the system test period, the Contractor shall provide a test time schedule and final test program for the tests. The test program shall indicate the need for power supply, connection of main circuits, and other information necessary for the system planning and operation. The Owner reserves the right, in collaboration with the Contractor, to make alterations in the test program. The Contractor shall initiate all tests. Within the Scope of Supply, the Contractor shall establish the measuring points necessary for the testing. The Contractor shall provide all instruments, equipment and wirings, as well as the necessary skilled personnel, for carrying out these tests.

1JNL100098-754 Rev.00


Page 40 6.2 Equipment Tests 6.2.1

General

All individual components shall, without any additional cost to the Owner, be subjected to manufacturing tests according to: 1.

Specifications in this Section

2.

Applicable IEC (or ANSI) standards

Type tests shall be performed on one unit of each design with the specific design and rating used for this project. Type tests proved by certified test reports on tests previously performed on a component with similar design and rating may be accepted as type tests. 6.2.2

Converter valves

Valve tests shall consist of type tests and production tests 6.2.2.1

Type tests

Type tests consist of dielectric tests, operational tests and temperature cycling. They shall be performed according to specific Inspection and Test Plan, ITP. Reference can be made to earlier, already performed tests on similar valves. 6.2.2.1.1

Dielectric tests

For dielectric testing, the test program follows the principles of IEC 60700. When atmospheric correction (k atm ) is to by applied in a test, it shall be based on a valve enclosure temperature of 60 °C, project specific altitude above sea level and a relative humidity of 10% (at 60°C and an air pressure of 101.3 kPa) The following tests are to be carried out: Stack to stack with IGBT:

• a.c./d.c. test • fast transient test • d.c. test Stack to earth:

• switching impulse test • d.c. test • a.c. test Capacitor structure to earth:

• switching impulse test • d.c. test

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Page 41 2.1.1.2

Operational tests

For operational tests, a scaled demonstration of the capability to operate at maximum and minimum power shall be done. Protection functions shall be verified and a temperature cycling test from minimum to maximum current shall be carried out. This test program follows the principles of IEC 60146-2, for semiconductor self-commutated converters in low voltage application. The following tests are to be carried out: • Turn-off at maximum current • Valve short-circuit protection • Operational test during normal, high and low d.c. voltage 6.2.2.1.3

Temperature cycling

A static temperature cycling with maximum temperature variation on semiconductor junction shall be done on a complete mechanical IGBT stack assembly. 6.2.2.2 Production tests

Production tests consist of routine tests and sample tests. 6.2.2.2.1

Routine tests

Routine tests shall be performed on the actual delivery according to the specific ITP. The consist of the following:

• Complete IGBT position test • Check of assembly of stack • Tests on assembled valve housing, if applicable 6.2.2.2.2

Sample tests

After manufacturing of the IGBT positions in continuous production a sample of 1% shall be taken to a sample test:

• Operational test during normal, high and low d.c. voltage. 6.2.3

Power transformers

Beside the tests stated in the above-mentioned standards, the following tests shall be performed: Routine tests - According to IEC 60076-1 clause 10.1.2 Type tests - Heat Run test according IEC 60076-1 Clause 10.1.2.a

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Page 42 6.2.4

Control system disturbance tests

Disturbance type tests shall be performed according to EN 50082-2 (EN 61000-62), including the following:

IEC 61000-4-2, (IEC 60801-2) IEC 61000-4-3, (IEC 60801-3) IEC 61000-4-4, (IEC 60801-4) IEC 61000-4-5, (IEC 60801-5) IEC 61000-4-6 IEC 60255-4, (IEC 61000-4-12) IEC 61000-4-16

6.2.5

Electrostatic discharge, Performance Criterion A Radio Interference Immunity, Performance Criterion A Electrical fast transient/burst, Performance Criterion A Surge immunity 1,2/50, Performance Criterion A Conducted disturbances High frequency disturbance test Electromagnetic compatibility

Control system verification

Functions and performance of the control and protections system will be subjected to verification for each function. The Contractor shall: - Present a verification plan covering time, place, and functions to be verified. - Produce verification procedures covering step-by-step activities for each function to be verified.

6.3 System Tests

Prior to trial operation there shall be a testing period. The purpose of this test period is to permit: -

Equipment inspection and verification at the site (on site equipment test).

-

Functional tests and final adjustment of sub-systems and systems.

-

Tests at rated voltage

-

Tests at rated current and specified overload

During the high voltage energization and on load testing period, normal operating procedures shall be followed regarding switching, power dispatching and access to high voltage areas. The Owner will provide the staff necessary for performing these tasks. When the high voltage energization tests have started, all temporary connections or similar arrangements in the high voltage circuiting are to be performed by the Owner's personnel. The correctness of the measures to be taken on high voltage equipment shall, however, be the responsibility of the Contractor.

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Page 43 6.4 Trial Operation and Acceptance Tests

As soon as commissioning and system tests are completed, the Contractor shall advise the Owner in writing that the equipment is ready for service. From the time the Contractor has stated in writing that the equipment is ready for service, trial operation shall start and last for a minimum of two week, to confirm to the Owner that the system is working satisfactorily. During the trial operation, the Contractor shall on his own account provide sufficient supervising engineers and service personnel on site. The Contractor's engineers shall supervise the equipment on site and instruct the Owner's operating personnel, and at the same time assist the Owner in testing etc. The trial operation shall contain a 7-day period, any consecutive 7 days, without interruption by a failure for which the Contractor is responsible. The testing shall continue until such an interruption-free 7-day period has elapsed. During the interruption-free period the power transmission capacity shall not be less than the rated power, see Section 4.3. The actually transmitted power may, however, be lower due to lower demand, or restrictions from the dispatch center or other limitations in the electrical grid systems. When trial operation has been successfully completed and documented in accordance with the Contract, the equipment within the Scope of Supply is ready for the acceptance tests (if not already performed during system test and trial operation), and for the taking-over procedure, as defined in the commercial contract. The acceptance tests shall be carried out in such a way that a satisfactory approval of guaranteed values and system performance is achieved.

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Page 44 7. OPTIONS

The Owner reserves the right to choose from the following optional functions, provided that a fast communication between the stations is established. The possible additional functions shall not be limited to the following. Other additional functions have to be specified separately. 7.1 Islanding system operation

This option shall give the HVDC Light® Link plant performances for frequency control and for going from synchronous operating to islanding operation. 7.2 Black start

This option shall make it possible for one of the stations to start up a passive network to normal islanding system operation. The specific conditions for each site concerning auxiliary power have to be defined. 7.3 Standby operation for fast voltage support

From a state with the converter blocked and in a case of a network disturbance, the plant shall give fast support to the network within a certain time after an event. The triggering condition can be a pre-defined voltage dip. 7.4 Lower performances of acoustic noise

The Contractor may specify lower acoustic noise levels than those recommended in section 4.9. 7.5 Stabilization of the a.c. system

Modulation control shall be superimposed on the normal active and reactive power control so that oscillations in the a.c. network can be damped. The modulation signal may be derived from remote or local sources. Its origin may be local frequency, a.c. line power, etc. The modulation control shall fulfill the following requirements: 1.

It shall be possible to compose signals by adding or subtracting signals from the other station via telecommunication to signals in the power controlling station.

2.

Total time delay for the signal processing shall be less than 100 ms. It is necessary to have a fixed well-defined time delay to enable correct signal comparisons.

It shall be possible to manually release/suspend modulation control. It shall be possible to set an upper as well as a lower limit for the power order output from the modulation control equipment (e.g. dXXX MW and DYYY MW). The maximum contribution from the modulation control will thereby be limited to the specified range.

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Page 45 7.6 Power runback

The power runback function is a control mode that may be helpful in some situations to support a power system in case of a disturbance. The value of this control mode has to be investigated for each individual case before deciding whether it should be included or not. The conditions vary from project to project. Therefore only a general description is given below. Contingencies involving loss of generation or load may require an automatic reduction in the d.c. power transfer. The Contractor shall design and supply a runback control system, which shall include the following features: -

At least ___ preset levels of runback shall be provided. The values of the preset levels will be determined during the design studies.

-

The facility shall be provided to initiate any of the runback levels using external signals provided by the Owner and from signals that may be derived from within the control system.

-

The runback function shall act on the power order or current order, and shall reduce the power at a rate of ____ MW/min.

The above settings facilities are examples of what can be used. The specific entries to be implemented for the power runback control need to be studied and specif ied for each individual project.

7.7 Overload

The Contractor shall specify any conditional amount of overload capacity. 7.8 Power flow control functions

In order to facilitate the operation of the plant, an automatic function for adjustment of the transmitted power, the a.c. voltage level and the reactive power, shall be provided. The specific conditions shall be defined during the design stage. 7.9 Self-supporting auxiliary power

An auxiliary power winding, 400 V, phase-phase, for feeding of the auxiliary power shall be provided on the power transformer.

1JNL100098-754 Rev.00

Typical Technical Specification for an Hvdc Transmission Project

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