Operation of offshore wind power plants connected with HVDC

Transcription

1 Operation of offshore wind power plants connected with HVDC Trondheim, February 2015 O. omis-bellmunt (IREC / CITCEA-UC) with support from M. de-rada, A. Egea, J.L. Dominguez, E. rieto, J. Sau, F. Diaz and M. Aragüés

2 Agenda Context. Offshore wind power plants connected with VSC-HVDC. Functional requirements for offshore W connected with VSC-HVDC. Coordinated control for power reduction. Conclusions. 2

3 Context. Offshore wind power plants connected with VSC-HVDC. Functional requirements for offshore W connected with VSC-HVDC. Example of coordinated control for power reduction. Conclusions. 3

4 Fix Speed onshore W Energy capture Fault ride-through rid support Other WTs LV 50 Hz MV 50 Hz LV 50 Hz Main grid Other WTs LV 50 Hz MV 50 Hz LV 50 Hz Main grid Variable Speed onshore W Other WTs LV 50 Hz MV 50 Hz LV 50 Hz HVAC Offhore W HV 50 Hz HVAC cable HVAC cable Compensation required Long cables (>50-80 km) not possible Main grid HV 50 Hz Other WTs LV 50 Hz MV 50 Hz HV 50 Hz Same WT DC cables VSC-HVDC technology VSC-HVDC, Offhore W HVDC cable Bard Offshore 1 (BorWin 1) 400 MW First offshore W with VSC-HVDC First WT in 2010 To be completed in 2013 Main grid HV 50 Hz 4

5 Multiterminal VSC-HVDC Other WTs LV 50 Hz MV 50 Hz HV 50 Hz AC grid HV 50 Hz Other WTs LV 50 Hz MV 50 Hz HV 50 Hz Multiterminal HVDC system AC grid HV 50 Hz 5

6 VSC-HVDC grid Other WTs LV 50 Hz MV 50 Hz HV 50 Hz AC grid HV 50 Hz Other WTs LV 50 Hz MV 50 Hz HV 50 Hz HVDC grid AC grid HV 50 Hz 6

7 oint to point VSC-HVDC with an offshore AC hub Mainstream Renewable ower Other WTs LV MV HV oint to point HVDC AC grid HV 50 Hz AC hub AC cable Other WTs LV MV HV oint to point HVDC AC grid HV 50 Hz 7

8 HVDC technology concepts for future transmission systems for offshore wind oint to point HVDC Multiterminal HVDC HVDC grid Offshore AC hubs AC systems with HVDC links All the previous combined ermany Takes the Lead in HVDC, IEEE Spectrum 2013 Siemens Friends of the Supergrid 8

9 W concepts AC W standard/nonstandard frequency AC W variable frequency Cost? Efficiency? Reliability? Availability? Maintainability? DC W Hybrid DC-AC 9

10 AC collection W AC voltage ratings 33 kv 66 kv? 50/60 Hz? non-standard frequency? Variable frequency? Normally with Type 3 (DFI) and Type 4 (FC) Wind Turbines HVDC transmission AC Export cable AC DC Offshore latforms AC DC Mikel de-rada et al. Analysis of DC Collector rid for OW 12th Wind Integration Workshop, London, October 2013 DC AC 10

11 Cluster 1 Substation Offshore Wind Farm 1 rid Connection System Converter Station To WTs Export Cable String 1 String 2 Substation Offshore Wind Farm 2 Converter Tx Rectifier ~ = Inverter ~ = AC rid Emergency ower ONSHORE OFFSHORE Cluster 2 Cigré W B4-55 HVDC connection of offshore wind power plants (under development) 11

12 rojects (W with VSC-HVDC) with AC collection 50 Hz Borwin 1 (Transpower offshore, 2009, +/- 150 kv, 400 MW, km) for BARD Offshore 1-2x1 km DolWin 1 (TenneT, 2013, +/- 320 kv, 800 MW, km) for Meg Offshore 1-2x13 km and Borkum West II - 2x7.5 km DolWin 2 (TenneT, 2015, +/- 320 kv, 900 MW, km) for ode Wind I - 7 km and ode Wind II - 12 km Borwin 2 (Transpower offshore, 2014, +/- 300 kv, 800 MW, km) for Veja Mate 2x10 km and lobaltech 1 2x30 km Helwin 1 (Transpower offshore, 2014, +/- 250 kv, 576 MW, km) for Nordsee Ost 2x4.2 km, Meerwind phase 1 2x7.6 km and 2 2x 20 km Sylwin 1 (TenneT, 2014, +/- 320 kv, 864 MW, km) for Dan Tysk 2x9.7 km, Butendiek 2x40 km and Sandbank 24 2x35 km Helwin 2 (TennetT, 2015, +/- 320 kv, 690 MW, km) for Amrumbank 3x8 km, Hochsee Testfeld Helgoland 2x4 km and Kaskasi 2x3.5 km DolWin 3 (TenneT, 2017, +/- 320 kv, 900 MW, km) for OW Borkum Riffgrund West 1, OW Borkum Riffgrund West 2 and OW Borkum West 2 12

13 Context. Offshore wind power plants connected with VSC-HVDC. Functional requirements for offshore W connected with VSC-HVDC. Example of coordinated control for power reduction. Conclusions. 13

14 W connected to VSC-HVDC Functional requirements Collect the wind power and inject it in the VSC- HVDC cable rovide support to the main AC grid rovide support to the DC grid (if exists) Ensure the proper offshore grid operation Maintain stability in normal and fault conditions 14

15 Specific requirements: W connected to VSC-HVDC Functional requirements Reactive power management. Offshore grid voltage control (HVDC rectifier + WTs) Active power management Offshore grid frequency control (VSC-HVDC rectifier) Start/stop sequence Fault ride-through capability Main grid support: Voltage support Frequency support may be required Virtual (synthetic inertia) may be required ower oscillation damping may be required Control coordination between W control and VSC-HVDC control Operation under communication failure rovide auxiliary power to the W when there is no available generation (no wind or excessively high wind) 15

16 Normal operation Substation Converter Station Emergency ower Offshore Converter ~ = Converter = ~ AC rid Transformer latform 1 Draft from Cigré B4-55 W HVDC connection of offshore W 16

17 Restricted operation Draft from Cigré B4-55 W HVDC connection of offshore W 17

18 Main AC grid fault Substation Converter Station Emergency ower Offshore Converter ~ = Converter = ~ HVDC chopper actuation AC rid Fault Transformer latform 1 Draft from Cigré B4-55 W HVDC connection of offshore W 18

19 W fault Substation Converter Station Emergency ower Offshore Converter ~ = Converter = ~ AC rid Fault Transformer latform 1 Draft from Cigré B4-55 W HVDC connection of offshore W 19

20 Export cable fault Substation Converter Station Fault Emergency ower Wind turbine power reduction Offshore Converter ~ = Converter = ~ AC rid Transformer latform 1 Draft from Cigré B4-55 W HVDC connection of offshore W 20

21 Frequency response using W control ower reduction Substation W CONTROL frequency / W required active power RID OERATOR Converter Station Emergency ower Offshore Converter ~ = Converter = ~ AC rid Transformer latform 1 Draft from Cigré B4-55 W HVDC connection of offshore W 21

22 Frequency response using VSC-HVDC converters Transformer latform 1 Substation Converter Station frequency / W required active power Emergency ower Offshore Converter ~ = Converter = ~ AC rid Frequency Change Draft from Cigré B4-55 W HVDC connection of offshore W 22

23 Context. Offshore wind power plants connected with VSC-HVDC. Functional requirements for offshore W connected with VSC-HVDC. Example of coordinated control for power reduction. Conclusions. 23

24 Example coordination for power reduction How can we provide power reduction (without fast communication between offshore and onshore VSC-HVDC)? VSC-HVDC DBR, fast but available limited time. (not offshore ->footprint!) Wind turbine DBR, fast but available limited time. itch angle. Slow response but good for steady-state. Fast wind turbine torque reduction with the power converter? Electrically possible, but not allowed. (Turbine loads) itch angle Wind turbine DBR VSC-HVDC DBR 24

25 Example coordination for power reduction θ g d/dt i wtabc. θ g T[θ] i wtabc v wtabc v wtqd i wtqd β pitch itch controller WC T[θ] -1 Inner loop * iwtqd MT * wt wt E wt v pabc T[γ] -1 v pqd Inner loop i* pqd DC loop i pabc hd thesis, Agustí Egea (CITCEA-UC) wt-ch ower reduction WTC v pabc v rabc γ LL γ v rqd i pqd E* wt E wt T[γ] v rabc v rqd i pqd wt DETAILED WIND TURBINE COMMUNICATION BUS min E 2 min E 1 E DC max E 2 max E 1 OFFSHORE LATFORM i nabc i cabc vcabc i cabc i nabc red WF ω δ δ v cabc T[δ] δ WFC v tabc T[δ] -1 v i tqd cqd v cqd Inner loop i* cqd i nqd Voltage v cqd * loop min E 1 WF power controller E 1 WINF FARM CONTROL Cable 1 E 1 2ch SC chopper E 2 SC-DBR CONTROL I 1 E 2 v labc v lqd SC Inner loop i lq * Droop control v lqd i lqd * E 2 E 2 ONSHORE STATION i labc v labc ϕ T[ϕ] -1 LL ϕ T[ϕ] SC CONTROL v zabc vlabc i labc v zabc nom E 2 E 2 DC 25

26 Example coordination for power reduction θ g d/dt i wtabc. θ g T[θ] i wtabc v wtabc v wtqd i wtqd β pitch itch controller WC T[θ] -1 Inner loop * iwtqd MT * wt wt E wt wt-ch ower reduction v pabc WTC T[γ] -1 v pqd Inner loop i* pqd DC loop i pabc v pabc v rabc γ LL γ v rqd i pqd E* wt E wt T[γ] v rabc v rqd i pqd wt DETAILED WIND TURBINE COMMUNICATION BUS OFFSHORE LATFORM i nabc i cabc vcabc i cabc i nabc red WF ω δ δ v cabc T[δ] δ WFC v tabc T[δ] -1 v i tqd cqd v cqd Inner loop i* cqd i nqd Voltage v cqd * loop min E 1 WF power controller E 1 WINF FARM CONTROL Cable 1 E 1 2ch SC chopper E 2 SC-DBR CONTROL I 1 E 2 v labc v lqd SC Inner loop i lq * Droop control v lqd i lqd * E 2 E 2 ONSHORE STATION i labc v labc ϕ T[ϕ] -1 LL ϕ T[ϕ] SC CONTROL v zabc vlabc i labc v zabc hd thesis, Agustí Egea (CITCEA-UC) 26

27 Context. Offshore wind power plants connected with VSC-HVDC. Functional requirements for offshore W connected with VSC-HVDC. Example of coordinated control for power reduction. Conclusions. 27

28 Conclusions Offshore wind power plants connected with VSC-HVDC have special characteristics: The VSC-HVDC converter needs to create an offshore grid where the frequency can be freely chosen. As the offshore grid is an only power electronics grid, the protections need to be carefully designed. Standard approaches may not be useful. The interactions between wind turbines and VSC-HVDC converters need to be studied. Offshore wind power plants need to: Collect the wind power and inject it in the HVDC cable rovide support to the main AC grid and DC grid. Maintain stability in normal and fault conditions 28

29 Thanks for your attention!