Wind Generators Evolving Technology

Transcription

1 Wind Generators Evolving Technology Transmission Advisory Group Ray Brown Transmission Manager - Meridian Energy April 2008

2 Overview of Presentation 3 Different Wind Farms 3 Different Technologies Te Apiti Wind Farm 55 x NEG Micon 1.65MW, Simple Induction generators (90MW total) White Hill Wind Farm 29 x Vestas V80 2MW, DFIG (58MW total) Project Westwind development 62 x Siemens 2.3MW, Full converter output (142.6MW total)

3 Overview of Presentation Disclaimer Power system integration capability is improving rapidly as new technologies immerge, however some caution is required in assuming which Wind Turbine Generator (WTG) type will be used in future projects as generators generally choose the (WTG) based on its productivity/cost :economics and robustness. Power system integration is generally not the main issue influencing WTG choice. So we might not always select the best WTGs from a power system integration perspective on future wind farm developments.

4 Te Apiti Simple Induction Generators Te Apiti first wind farm subjected to grid connected EGR requirements 90 MW connected to 110 kv NEG Micon Simple Induction Generators (SIG)

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6 Te Apiti 22kV On Site Reticulation

7 Te Apiti 22kV On Site Reticulation 48km of underground cables 22kV, XLPE

8 Te Apiti - Substation 100MVA 22kV / 110kV Transformer Outdoor capacitor banks 22kV indoor SF6 Switchgear Indoor Statcon

9 Te Apiti - STATCON First such device in NZ Power electronic device using Insulated Gate Bipolar Transistors (IGBT) Provides reactive power - Voltage support - Fault ride through Fast operating (milliseconds) Rated ± 9.6MVAr 8x 1200 kvar units - watercooled, modular Water Cooled

10 Te Apiti - Transmission Line Te Apiti to Woodville substation 110kV, 5km Owned by Meridian Steel monopoles Comms OPGW

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12 Te Apiti Simple Induction Generators (SIG) Squirrel Cage Induction Generator Gearbox Capacitor Bank Dynamic Reactive Support Capacitor Bank Grid Fixed Speed Induction Generator e.g. Te Apiti Inductive! Reactive power support Optional (but non-compliant with EGRs if none) Requires dynamic reactive power support for Low Voltage fault ride thru i.e. STATCONs Somewhat chunky control of reactive power compared to synchronous machines Provides inertia but no governor control Provides some damping to synchronous power oscillations Few WTG suppliers offer this technology now, but can provide good economic solution

13 Te Apiti - Fault Ride Through Transpower provided minimum requirements Power system fault studies performed by turbine manufacture Woodville 110 kv Point-of-Connection Voltage Profile - Individual 3-phase Grid Faults (Distribution faults final voltage = 0.95 p.u., Transmission faults final voltage = 0.9 p.u.) Voltage (p.u.) Remote, BPE 110 kv - Trip remote (Zone 1) Local 110 kv - Trip WDV(Zone 1), BPE (Zone 2) Remote BPE 110 kv - Trip BPE (Zone 1), WDV (Zone 2) Remote, BPE 220 kv - Trip remote (Zone 1) Remote, BPE 33 kv Feeder (0 Ohm) Remote, BPE 33 kv Feeder (2 Ohm) Remote BPE 33 kv bus Remote, WPW 33 kv Feeder (0 Ohm) Remote, WPW 33 kv Feeder (5 Ohm) Remote, WPW 33 kv Bus Time (sec)

14 Te Apiti - Reactive Power Support Te Apiti Reactive Power provided by: 1. Thyristor switched capacitor banks at turbine generator (850kVAr total each WTG) 2. Three substation capacitor banks (9MVAr, 6MVAr, 3MVAr) 3. Statcon (8 individual units totalling ± 9.6MVAr) Wind farm de-rating of 2.5MW for every statcon not in service EGR Requirements System Operator Agreed Requirements Export (Capacitive) 50% (45.4 MVAr) 30% (27 MVAr) Import (Inductive) 33% (30 MVAr) 33% (30 MVAr) EGR Dispensations: Limited Reactive Power Range and No Governors

15 White Hill Deeply embedded large wind farm testing limits of technology (ESR 1) 58 MW connected to 66 kv 29 Vestas V80 2 MW DFIGs

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17 White Hill > 70 MW WTG site Te Anau 40 MW GXP 70km away 1. Vestas Latest WTGs 2. 6 MVA STATCON 3. Intertrip 4. Runback 5. Protection Upgrades 6. HED Capacitor Banks 7. Ripple Blocking Filters 8. New line NMA-WIN N Manapouri 220kV Monowai Orawia Otautau Ohai Heddon Bush 3,4 White Hill Mossburn 5,6 9 8 ~ 10 1,2 Dipton Lumsden Centre Bush Winton North Makarewa Riversdale Go 9. Connect Redundant HED-WIN line 10. NMA Capacitor Banks 220kV 110kV 66kV 33kV

18 White Hill - Substation WHL HED Line Bay & Gantry Structure WHL TEA Line Bay & Gantry Structure D-VAR Statcon Modules NER TPCL MEL Oil Separator & Containment System 66/22 kv 65 MVA Transformer, T1 Switchroom 22 kv Switch Board and Control Cabinets

19 White Hill Transmission Line

20 White Hill - DFIGs Partial Scale Frequency Converter Gearbox Wound Rotor Induction Generator Dynamic Reactive Support Capacitor Bank Grid Doubly Fed Induction Generator e.g. White Hill Variable Speed (slip -40% to +30%) Better reactive power, voltage support and fault ride through Might need some reactive power support for EGR compliance depends on WTG reactive power range Might need dynamic reactive power support for LV ride thru depends on system strength Good control of reactive power similar to synchronous machines depends on control system Generally improves power system synchronous stability compared to conventional generators Theoretically - significant improvements to synchronous stability could be achieved with high spec controls Governor control dependent on WTG supplier White Hill EGR Governor Dispensations required

21 Good & Bad Days at White Hill On a bad day... On a good day...

22 Westwind Location Makara/Terawhiti, Wellington Size MW, 573 GWh Turbines 62 x Siemens S82 2.3MW Stage Civil works Commissioning Tx Late mid kV Tees to CPK-WIL B

23 Westwind Full Converter Output Full Scale Frequency Converter Capacitor Bank? Gearbox Generator? Grid Full Scale Frequency Converter e.g. Westwind Variable Speed, gearbox optional, speed variability depends on WTG Reactive power, voltage support and ride through can be superior to conventional generators Synchronous condenser option possible (at no / high wind) - depends on WTG Might need minimal capacitor banks for EGR compliance depends on WTG reactive power range Better than conventional generators re ride through e.g. simulations suggest WWD should survive >1 sec 3phase fault zero impedance on 110 kv transformer connection. Special protection needed to trip off WTGs when required e.g. auto-reclose events (conventional generators can not ride through auto-reclose on their grid connection) Very fast voltage support similar to STATCONs (better than conventional generators) Theoretically - Large improvement to power system synchronous stability compared to conventional generators (extent of support depends on wind farm control system) Good control of reactive power similar to synchronous machines depends on control system Governor control and frequency support dependent on WTG supplier

24 West Wind EGR Compliance Westwind Reactive Power to be provided by: 1. Wind Turbine Generators 2. Two substation capacitor banks (2 10 Mvar?) for compliance only Note there are outstanding questions on whether a STATCON will be needed instead to ensure dynamic stability between the HVDC non-linear control response and the WTG non-linear control response, so we are holding off ordering the capacitors. However this is a special case because of the HVDC s proximity. Normally no STATCON would be needed with this WTG technology Governor and Frequency Response? May be fully EGR compliant. No dispensations sought Ability to provide Ancillary Services?

25 Westwind - Power Quality Requirements Ride Through Under Voltage and Over Voltage Events (WWD must ride through these faults)

26 Westwind Preliminary Power Quality Results Low Voltage Fault Test extreme (power system protections disabled) case to test the performance of the WTGs. (Actual zero voltage faults will clear within approximately 200 ms) Zero volts for 1.5s on wind farm 110 kv connection. Conventional generators would trip well before this. Westwind simulations suggest ride through with no issues. Special Protections (intertrips) are being installed to ensure the appropriate half of WWD trips quickly on spur line faults as we do not want WWD to feed into Central Park while disconnected from Wilton

27 Westwind Potential Synchronous Compensate Mode?? Real Fault Scenario 1) Haywards 220 kv Fault 2) West Wind 33 kv voltage ramps up quickly due to WTG reactive power support 3) This improves the Wellington 110 kv voltages

28 Wind Technology Is New and Is Still Changing! Unconventional - Potential Effects: Engineers need re-educating e.g. short circuit contribution, no sync checks Low voltage ride thru can be miserable (SIG WTGs), but can be better than conventional generators (full converter output WTGs). e.g. may need intertrips to ensure WTGs trip when required. Low frequency ride through similar to international grid codes but not the SI standard Voltage control OK if EGR compliant, and can be slower/faster than conventional generators Frequency support the next challenge. Theoretically can be better than conventional generators (faster). Good support needs wind spill (similar to CCGTs) Generally improves dynamic and transient stability e.g. Hayes. Can provide STATCON-like support i.e. better than SVCs and potentially better than conventional generators Market signals required if penetration levels high if frequency support procured for wind. Wind may provide its own frequency support in the future if penetration high and signals correct.

29 Where to next with wind? Better Forecasting! Improved diversity of fuel source Better understanding of output variability (630 MW Hayes!? and its effects) Fast Governor control (hopefully on MEL s next wind farm Mill Creek?) Wind farms provide frequency support services Power boost from full power? Power System Stabilisers??? Storage when high penetration levels require wind spill, it might become economic to store energy rather than spill it Some of these will need market rule changes and tools?

30 Conclusion Continuing development in wind turbine technology and performance is demonstrating that the often pessimistic predictions associated with aspects of integrating wind generation into the power system can be largely disregarded. Studies: Are based on the most basic technology Pessimistic performance assumptions Focus on negative impacts Do not identify the possible benefits Wind technology is likely to surpass conventional generator power system performance in the future.

31 Wind Integration in NZ (for discussion if time) What is the highest penetration level for wind in NZ The engineering answer is we could supply 100% of NZ's electricity needs from wind and existing renewables. The technology is coming available to do this. Germany is discussing the ability to go 100% renewable and they do not have a hydro base like NZ But - not economic (e.g. storage, lower tier wind sites) &, insufficient consentable sites Future generation development will include a number of competing technologies, not just wind.

32 Discussion?