VSC Transmission. Presentation Overview. CIGRE B4 HVDC and Power Electronics HVDC Colloquium, Oslo, April LCC HVDC Transmission

Transcription

1 CIGRE B4 HVDC and Power Electronics HVDC Colloquium, Oslo, April 2006 VSC Transmission presented by Dr Bjarne R Andersen, Andersen Power Electronic Solutions Ltd Presentation Overview - Basic Characteristics of VSC Transmission, - Comparison of VSC Transmission and LCC HVDC technology, - VSC Transmission Applications, - Components of a VSC Transmission Scheme, - System Issues, - Overview of VSC Transmission schemes, - Future Trends. 18/09/2005 VSC Transmission Tutorial 1 3rd April 2006 CIGRE B4 Meeting Oslo, April, LCC HVDC Transmission The Voltage Sourced Converter In use since Long Distance transmission - Asynchronous Interconnections - >60GW in service, Voltage up to ±600kVdc Uses Thyristors, - Line Commutated Converters - Converter absorbs reactive power - AC harmonic filters are used to achieve satisfactory waveshape and power factor - DC Voltage source - Semi-conductors capable of turn-on AND turn-off are used - An ac voltage with controllable amplitude and phase angle is produced. 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April,

2 VSC Transmission Based on Motor Drive technology, - Voltage Sourced Converter, - IGBTs, capable of turning on and off, providing a self commutated converter, - 4 Quadrant capability (P & Q). Demonstrator went into service in 1997, ±10kVdc, 3MW. Now 7 schemes in service, total rating 900MW. 3rd April 2006 CIGRE B4 Meeting Oslo, April, Simplified VSC Transmission Scheme - Power flow dictated by the voltage difference and dc resistance: I dc = (U da -U db )/ R dc - Power flow can be controlled very quickly and accurately - No reactive power flow on the dc side 3rd April 2006 CIGRE B4 Meeting Oslo, April, Simplified VSC Transmission Scheme Voltage Sourced Converter 2-level converter d d 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April,

3 VSC Start Up - 1 VSC Start Up - 2 Diodes act as an uncontrolled rectifier. Diodes act as an uncontrolled rectifier. 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April, VSC Operation - 1 VSC Operation - 2 IGBT Conducting - Inverter Operation. IGBT Turned off - Diode picks up current What happens when we turn-off the IGBT?? 3rd April 2006 CIGRE B4 Meeting Oslo, April, There will be a delay before the ac current changes polarity because of L 3rd April 2006 CIGRE B4 Meeting Oslo, April,

4 VSC Operation - 3 Inverter Operation - Blanking Period has passed and current has reversed. VSC Operation - 4 Rectifier Operation How do we turn off the diode? 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April, VSC Operation - 5 Turning Off Diode - IGBT Conduction causing a temporary short circuit VSC Operation - 6 The diode turns off because of the short circuit current 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April,

5 VSC Operation - 7 Full Wave Conversion When the current in L reverses the IGBT turns off and the diode turns on Advantages dc ac - Low Power Loss Disadvantages - AC and DC voltage relationship fixed - makes it unsuitable for dc transmission - High magnitude of low order harmonics - large ac harmonic filters are required dc 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April, Pulse Width Modulation PWM Control Carrier at 9 times fundamental frequency 3rd April 2006 CIGRE B4 Meeting Oslo, April, Disadvantage - Power loss larger because of more frequent switching Advantages - Gives additional degrees of freedom - e.g. independence of converters, and control of ac voltage amplitude with fixed dc voltage - Reduces lower order harmonics - smaller filters - Higher speed of response 3rd April 2006 CIGRE B4 Meeting Oslo, April,

6 Simplified Representation Four Quadrant Control The Reactive Power output depends on the voltage amplitude: U P = U Q = conv ( 1).U L(1) X ( U U cosδ ) L( 1) L(1) sin δ X conv(1) 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April, Four Quadrant Control Four Quadrant Control The Active Power output depends on the converter voltage Phase Angle: U = U conv L U L - U conv U conv U L I conv Simplified PQ Diagram Rectifier Mode P conv Desired Reactive Power Desired Active Power Q conv Inductive Capacitive I conv P conv = 0 P conv< 0 Rectifier operation P > 0 conv Inverter operation Inverter Mode U ac = Max U ac = Nom U ac = Min 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April,

7 Presentation Overview Comparison - Experience - Basic Characteristics of VSC Transmission, - Comparison of VSC Transmission and LCC HVDC technology, - VSC Transmission Applications, - Components of a VSC Transmission Scheme, - System Issues, - Overview of VSC Transmission schemes, - Future Trends. 3rd April 2006 CIGRE B4 Meeting Oslo, April, LCC HVDC VSC Transmission In service since 1954 In service since 1997 Installed Capacity >60GW Largest Scheme 6300MW Highest Voltage +/-600kVdc Reliability/Availability proven Installed Capacity 930MVA Largest Scheme 346MVA Highest Voltage +/-150kVdc No formal records available at present 3rd April 2006 CIGRE B4 Meeting Oslo, April, Comparison - Converter Technology LCC HVDC Uses 8.5kV, 4kA Thyristors, a latching device Turn on by control, turn off when current tries to reverse Requires AC network voltage for commutation Faults and switch operations in the network can cause commutation failure VSC Transmission Uses 2.5kV, 2kA IGBTs, a transistor type device Turn on by control and turn off by control, irrespective of the current flow at the time Is self commutating Can be the sole supply to a passive network No Commutation Failures Faults on the dc line cleared by The diodes feeds current into thyristors through control fault on dc side AC Circuit action breaker action needed to clear 3rd April 2006 CIGRE B4 Meeting Oslo, April, Comparison - Harmonics LCC HVDC 12-pulse harmonics (12n±1), plus non-characteristic (2, 3, 4, 5, 7 etc )harmonics Requires large filters to limit harmonics typically on HV bus or on tertiary winding Possibility of magnification of pre-existing harmonics Switchable AC Harmonic Filters also used for Q Control VSC Transmission PWM moves characteristic harmonics to higher orders Smaller and higher frequency filters required typically between converter reactor and interface transformer Risk of magnification of preexisting harmonics may be smaller, but needs evaluating Filter not normally switchable 3rd April 2006 CIGRE B4 Meeting Oslo, April,

8 Comparison - Reactive Power Comparison - Other LCC HVDC Converters absorb reactive power (~55% of Real Power) Switchable AC Harmonic Filters for Q Control Large overvoltages can occur during load rejection Site area is relatively large because of need for switchable harmonic filters and shunt capacitors VSC Transmission Converters can operate at any leading or lagging power factor. Reactive Power can be controlled by the converter Load rejection overvoltage is small Site area is compact because of small unswitchable filters and simple ac switchyard LCC HVDC Used with overhead lines, cables and mixtures thereof. Relatively low capital cost when used at large power and relatively strong ac networks Multi-terminal operation is challenging for small taps in weak ac network areas VSC Transmission All commercial installations have used cables so far. Competitive capital cost at power <350MW, particularly when ac networks are weak Multi-terminal operation seem easy, as the converter tap will not suffer commutation failures, and dc voltage polarity is not changed Low power loss (~0.8% per terminal at full power) Higher power loss (~1.9% per terminal at full power) 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April, Comparison - Power Loss Presentation Overview Converter losses 2-level Triangular PWM Line commutated HVDC level, or comparable topologies, or 2-level with OPWM Year 3rd April 2006 CIGRE B4 Meeting Oslo, April, Basic Characteristics of VSC Transmission, - Comparison of VSC Transmission and LCC HVDC technology, - VSC Transmission Applications, - Components of a VSC Transmission Scheme, - System Issues, - Overview of VSC Transmission schemes, - Future Trends. 3rd April 2006 CIGRE B4 Meeting Oslo, April,

9 Benefits of Interconnections Interconnection Benefits: - Better utilisation of installed generation. - Reduction in overall spinning reserve. - Emergency power support The benefits from the use of HVDC include: - The power flow is fully controlled. - Asynchronous networks can be connected. - HVDC is more economic when distance is large, e.g. >800km overland or >70km submarine. 3rd April 2006 CIGRE B4 Meeting Oslo, April, Benefits of the use of cable connections It may be more expensive than an overhead line but: - It is less intrusive on the landscape. - It does not produce electric fields or varying magnetic fields, - More acceptable to the public, resulting in planning approval being granted more quickly. - It is not subject to flashover due to pollution problems, - More reliable than an overhead line, 3rd April 2006 CIGRE B4 Meeting Oslo, April, Interconnection to Small Isolated network - 1 Interconnection to Small Isolated network - 2 Reasons for Interconnection: - No Electrical Power at present - Small diesel generation at present Expensive MWhr cost, Maintenance requirement, Reliability/Availability, Damaging for the environment 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April,

10 Interconnection to Small Isolated network - 3 Interconnection between weak networks - 1 Benefits from Using VSC Transmission: - No need for Synchronous Compensators - Converter can dynamically control the ac system voltage - Economic and environmental benefit by using main network generation - Less Maintenance - Cable connection has low visual impact ~ = HVDC Line = ~ 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April, Interconnection between weak networks - 2 Re-inforcement of Weak AC tie Lines - 1 Reasons for Interconnection: - Weak areas are likely to be remote from main network. Provide damping control - improved security of supply (fewer trips of ac line to main network) - Asynchronous connection may be more acceptable politically -(HVDC as Firewall) - Converter can dynamically control the ac system voltage - improved system stability. = HVDC Line ~ = ~ 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April,

11 Re-inforcement of Weak AC tie Lines - 2 Reasons for Re-inforcement: - More capacity needed. - As load grows, instabilities may cause frequent trips. - Power oscillations may reduce useable power capacity. - Unacceptable loop power flows. - Controlability of HVDC may add substantial benefits Re-inforcement of Weak AC tie Lines - 3 Benefits from Using VSC Transmission: - VSC Transmission can significantly increase the available capacity on the ac Tie Line. - Powerful damping control, through control of active and reactive power. ABB have shown that the capacity of a weak ac Tie line can be increased by more than the rating of the parallel VSC Transmission scheme 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April, Connection of Offshore loads - 1 Connection of Offshore loads - 2 Reasons for Connection: - More capacity needed for extraction and transport. - Reduction of maintenance compared with GTs, - Reduction of CO2 emissions - Reduction of fire risks 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April,

12 Connection of Offshore loads - 3 Connection of Remote Wind Farms - 1 Benefits from Using VSC Transmission: - Does not require synchronous compensators, - Much lighter and more compact than LCC HVDC, - Can operate as a variable speed drive, for large motors. 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April, Connection of Remote Wind Farms - 2 Reasons for Connection with HVDC: - Transmission distance is large, - De-coupling required between ac grid and wind farm ac network, faults power quality - Enabling variable frequency of wind farm network, for greater efficiency, 3rd April 2006 CIGRE B4 Meeting Oslo, April, Connection of Remote Wind Farms - 3 Benefits from Using VSC Transmission: - Connection can be made to weaker point in ac network, - Improved stability of the wind farm ac network, - Reduction of flicker on wind farm network - Smaller site area required than for LCC HVDC - Power can be transmitted to wind farm network when the wind does not blow, Auxiliary Power - Control & Protection, Telecommunication, Navigation, Safety. 3rd April 2006 CIGRE B4 Meeting Oslo, April,

13 Presentation Overview Components of a VSC Transmission scheme - Basic Characteristics of VSC Transmission, - Comparison of VSC Transmission and LCC HVDC technology, - VSC Transmission Applications, - Components of a VSC Transmission Scheme, - System Issues, - Overview of VSC Transmission schemes, - Future Trends. 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April, VSC - 3 phase implementation PWM Control 3 phase 2-level Voltage Sourced Converter d Different PWM control methods: - Triangular carrier, pure sinewave for control - Triangular carrier, sinewave with 3rd harmonic for control - Optimised PWM - Selective harmonic elimination d 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April,

14 PWM - Waveshape & Harmonics -2 OPWM / SHEM AC Voltage phase to - Neutral Fundamental frequency component Fourier Analysis of Phase to Phase voltage Eliminates specific harmonics, but switching instants change with operating conditions. - Pre-calculated or determined as you go Can arrange to minimise switching at maximum current Results in a reduction in power loss, compared with simple triangular carrier wave. Triangular carrier at 21st harmonic, sinewave with 3rd harmonic as control 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April, AC Voltage phase to - Neutral PWM - Waveshape & Harmonics -3 3-level (NPC), 3-phase VSC Waveshape shown for full wave switching Fundamental frequency component Fourier Analysis of Phase to Phase voltage Optimised PWM or Selective Harmonic Elimination 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April,

15 Advantages of multi-level converters Fewer switch operations for similar harmonic performance. Lower voltage per switch. Amplitude of fundamental frequency voltage can be adjusted even with full wave switching - giving additional degree of freedom. Lower power loss. Line-to-neutral voltage (pu) 2-Level VSC 3-Level VSC Pulse Width Modulation PWM switching at 21 times fundamental frequency Line-to-neutral voltage (pu) Degree rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April, Degree Series connected 2-level converters (HVDC Plus) Components of a VSC Transmission scheme Converter Topology VSC Valves DC Capacitor Controls Converter Reactor AC Filters Interface Transformer DC Cables Converter Transformer 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April,

16 VSC Valves - Device choice IGBT Press Pack Currently the device of choice is the IGBT - Can be turned off in short circuit conditions. - Active control of the voltage across the device, - Low power control of the device (Voltage control - MOSFET device). - High switching speed capability. - Valve operation with failed devices, - Pack includes IGBTs and Diodes - 6kV designs available, but 2.5kV, 2kA devices generally used, - Multi-chip design. 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April, VSC Valve design - 1 VSC Valve design -2 Coherency of switch on and off is essential. Voltage distribution controlled by IGBT transistor action Stray inductance kept as low as possible Voltage divider and surveillance circuits for device monitoring Energy for gate electronics obtained from main circuit via voltage divider Fibre optic interface with ground level control A valve for ± 150kVdc may contain >300 series levels. IGBTs and diodes are water cooled Devices mounted with great pressure against heatsinks Valves housed in metallic enclosure - contains EMF 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April,

17 VSC Valve for ± 150kVdc Components of a VSC Transmission scheme Converter Topology VSC Valves DC Capacitor Controls Converter Reactor AC Filters Interface Transformer DC Cables Photo Courtesy of ABB 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April, DC Capacitor Design DC Capacitor Provides energy storage on the dc side, acting as a dc voltage source. Capacitor must have low inductance Capacitor placed close to VSC Valves to minimise stray inductance in commutating loop Capacitance must be large enough to limit harmonic ripple to design limit - Ripple depends on direct current amplitude and on the switching strategy long pulses of high current causes more ripple Voltage variations during faults in ac networks also need to be taken into account. 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April,

18 DC Capacitor Design Components of a VSC Transmission scheme Dry type capacitors used - minimises fire risks Self healing metalised film design used Plastic Housing Compact Converter Topology VSC Valves DC Capacitor Controls Converter Reactor AC Filters Interface Transformer DC Cables Photo Courtesy of ABB 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April, Controls Control System Block Diagram Determines the instant at which each individual VSC valve is switched on or off to meet the operational requirements. Typically: - One station controls the direct voltage. - One station controls the active power - Both stations can also control ac voltage or reactive power Implemented as a duplicated digital control system. 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE Figure B4 Meeting Courtesy Oslo, April, of ABB

19 Components of a VSC Transmission scheme Converter reactor Converter Topology VSC Valves DC Capacitor Controls Converter Reactor AC Filters Interface Transformer DC Cables Provides constant fundamental frequency impedance for the control of the VSC active and reactive power output. Provides a high frequency blocking filter between the VSC and the ac network. Limits rate of rise of short circuit currents. 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April, Converter reactor for 65MVA, ±80kVdc VSC Transmission scheme Components of a VSC Transmission scheme Dry type air-insulated air-cored reactor Typical impedance of 15% Low stray capacitance Metallic screen to eliminate external magnetic fields Forced air cooling Converter Topology VSC Valves DC Capacitor Controls Converter Reactor AC Filters Interface Transformer DC Cables Photo Courtesy of ABB 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April,

20 AC Harmonic Filter - 1 Components of a VSC Transmission scheme Characteristic harmonics tend to be at higher orders. Must check non-characteristic harmonics, when the ac system can be unbalanced. Design methods similar to those for LCC HVDC scheme Typical rating of the ac harmonic filter is 15%. Typically includes tuned and high pass branches. Converter Topology VSC Valves DC Capacitor Controls Converter Reactor AC Filters Interface Transformer DC Cables 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April, Interface Transformer - 1 Interface Transformer - 3 Enables the VSC to be designed independently of the ac connection voltage. Blocks zero sequence current Provides additional series reactance - beneficial for harmonics - adds to converter reactor reactance Typically does not have dc stress or significant harmonic stress. - Ordinary substation transformer can be used. A converter winding tapchanger can achieve: - larger steady state rating - lower power loss A tertiary winding may be used for auxiliary power supply Typical impedance of 10-15% 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April,

21 Interface Transformer - 3 Components of a VSC Transmission scheme Converter Topology VSC Valves DC Capacitor Controls Converter Reactor AC Filters Interface Transformer DC Cables Photo Courtesy of ABB 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April, DC Cables Land Cables Extruded polymeric cables can be used, as the dc voltage does not change polarity. - Lighter - Smaller bending radii - No significant environmental risks. These features make them easier and quicker to install. This type of cable has been proven in service at voltages up to ± 150kVdc. Installed lengths of 1-2km are joined in the field. Depending on the ground conditions, cable can be buried using direct ploughing methods. 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April,

22 Laying a Land Cable Deep Sea Submarine Cables Can be manufactured and laid in continuos lengths of > 100km, depending on rating. Illustration Photo Courtesy Courtesy of ABB of ABB 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April, Components of a VSC Transmission scheme Converter Topology VSC Valves DC Capacitor Controls Converter Reactor AC Filters Interface Transformer DC Cables Other equipment/components Other equipment in a VSC Transmission substation AC circuit breakers. RFI and PLC filters. Voltage and Current measuring transducers. Surge arresters. Disconnectors and earth switches. Auxiliary power supplies. Fire Protection. Civil works. 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April,

23 Physical Layout, 65 MVA HVDC Light TM Converter Station Presentation Overview Building 45 x 18 m Phase A, B and C valve enclosures Auxiliary Power System & Cooling Control Cooling towers Phase Reactors AC Yard & Harmonic filters DC Yard Equipment 3rd April 2006 CIGRE B4 Meeting Oslo, April, Basic Characteristics of VSC Transmission, - Comparison of VSC Transmission and LCC HVDC technology, - VSC Transmission Applications, - Components of a VSC Transmission Scheme, - System Issues, - Overview of VSC Transmission schemes, - Future Trends. 3rd April 2006 CIGRE B4 Meeting Oslo, April, System Issues - 1 System Issues - 2 Protection in ac network. - During ac faults the current delivered by a VSC Transmission scheme is limited to rated. - Conventional over-current protection may not work. - However, low current may permit longer fault detection - Protection needs careful consideration - VSC Transmission does not add inertia Frequency tripping limits may need to be reassessed 3rd April 2006 CIGRE B4 Meeting Oslo, April, Feasibility Studies can use third party commercially available models. - However, these models may not reflect full capability and/or limitations of the VSC. - When specifying a scheme make the specification functional, and provide necessary system data. - Studies done during feasibility phase typically has to be repeated by the manufacturer during the implementation phase 3rd April 2006 CIGRE B4 Meeting Oslo, April,

24 System Issues - 3 Presentation Overview When comparing options during feasibility studies all issues must be considered: Capital cost Ancillary service Benefits: Power Loss Reactive Power control, Black Start Capability Maintenance Environmental Impact Reliability Visual Impact Availability EMF Operation cost Time to In-service Public Enquiry Time to implement 3rd April 2006 CIGRE B4 Meeting Oslo, April, Basic Characteristics of VSC Transmission, - Comparison of VSC Transmission and LCC HVDC technology, - VSC Transmission Applications, - Components of a VSC Transmission Scheme, - System Issues, - Overview of VSC Transmission schemes, - Future Trends. 3rd April 2006 CIGRE B4 Meeting Oslo, April, Gotland - the first commercial HVDC Light TM project Gotland HVDC Light Technical Data Commissioning year: 1999 Power rating: 50 MW AC Voltage: 70 kv both ends DC Voltage: ± 80 kv DC current 350 A Length of DC cable: 2 x 70 km Main reasons for choosing HVDC system: Wind power (voltage support). Easy to get permission for underground cables. Gotland HVDC Light converter station at Näs, exterior view 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April,

25 Gotland HVDC Light Eagle Pass HVDC Light link The HVDC Light installation in Eagle Pass mitigates voltage instability, and at the same time allows power exchange between the U.S. and Mexico. Converter station at Näs blends in well with surrounding farms. Technical Data Commissioning year: 2000 Power rating: 36 MW AC Voltage: 132 kv (both sides) DC Voltage: ± 15,9 kv DC current 1,1 ka Configuration: Back-to-back Illustration Courtesy of of ABB ABB 3rd April 2006 CIGRE B4 Meeting Oslo, April, Main reasons for choosing HVDC system: Controlled asynchronous connection for trading. Voltage control 3rd April 2006 CIGRE B4 Meeting Oslo, April, Eagle Pass HVDC Light, simplified SLD Eagle Pass Eagle Pass converter station, AC yard. 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April,

26 Murraylink Murraylink - valve enclosures Technical Data Commissioning year: 2002 Power rating: 200 MW AC Voltage: 132/220 kv DC Voltage: ± 150 kv DC current: 739 A Length of DC cable: 2 x 180 km At factory Placed on foundation Inside building Main reasons for choosing HVDC system: Controlled asynchronous connection for trading. Easy to get permission for underground cables. 3rd April 2006 CIGRE B4 Meeting Oslo, April, Illustrations Courtesy of ABB 3rd April 2006 CIGRE B4 Meeting Oslo, April, Murraylink Cross Sound Cable Murraylink, the Berri converter station. Technical Data Commissioning year: 2002 Power rating: 330 MW AC Voltage: 345 kv at New Haven 138 kv at Shoreham DC Voltage: ± 150 kv DC current 1175 A Length of DC cable: 2 x 40 km Main reasons for choosing HVDC system: Controlled connection for trading. Submarine cables without oil. 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April,

27 Cross Sound Converter Layout Dynamic Response to Network Faults March 17, 2005 Cross arm fault on 353 Line (345kV) Building 90 x 18 m 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April, Dynamic Response to Network Faults Troll A HVDC Light TM link The HVDC Light TM installation between the Norwegian main land and the Troll A oil platform consists of two circuits, each feeding a 40 MW compressor motor Technical Data Commissioning year: Planned 2004/2005 Power rating: 2 x 42 MW AC Voltage: 132 kv/56 kv DC Voltage: ± 60 kv DC current 350 A Length of DC cable: 4 x 70 km Cross arm fault on 353 Line (345kV) 3rd April 2006 CIGRE B4 Meeting Oslo, April, Main reasons for choosing HVDC Light TM system: Environmental improvement by elimination of gas turbines on platform. Low weight and small space on platform. Ability to feed and black-start motors, without local generation. 3rd April 2006 CIGRE B4 Meeting Oslo, April,

28 Troll A HVDC Light TM link Troll A Troll A SM 56kV ~ 70 km +/- 60kV = Kollsnes 138kV MotorFormer 4-pole, 40MW 0-65 Hz = HVDC Light ~ Illustrations Courtesy of ABB 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April, Presentation Overview VSC Transmission Outlook - Basic Characteristics of VSC Transmission, - Comparison of VSC Transmission and LCC HVDC technology, - VSC Transmission Applications, - Components of a VSC Transmission Scheme, - System Issues, - Overview of VSC Transmission schemes, - Future Trends. VSC Transmission has many technical advantages over LCC HVDC WG-37 has not identified any technical reason why VSC Transmission cannot be developed for very high voltage and power, say 500kVdc, 3000MW Main drawbacks relative to LCC HVDC are its presently limited power rating and higher power losses. 3rd April 2006 CIGRE B4 Meeting Oslo, April, rd April 2006 CIGRE B4 Meeting Oslo, April,

29 VSC Transmission trends Recommended Further reading Future Developments - Increased dc voltage (higher power, longer distances) - Increased dc current (higher power) - New topologies (lower losses) - New Semi-conductor devices (lower losses and cost) Resulting in: - VSC Transmission competing head on with LCC HVDC in more and more applications. 3rd April 2006 CIGRE B4 Meeting Oslo, April, VSC Transmission, Cigre Brochure 269, Working Group B4.37, April It s Time to Connect, Technical Description of HVDC Light technology, ABB website, 3rd April 2006 CIGRE B4 Meeting Oslo, April, Thank you for your Attention! Any Questions? Bjarne@AndersenPES.com 18/09/2005 VSC Transmission Tutorial 115