FACTS and HVDC for Grid Connection of Large Wind Farms

Transcription

1 David Larsson Power-Gen Europe 2005 Milan, Italy FACTS and HVDC for Grid Connection of Large Wind Farms

2 FACTS Agenda Wind Generators Response to Grid Faults PICTURE JPG-FORMAT WEB OPTIMIZED RESOLUTION SVC and STATCOM HVDC HVDC Light Date 25-Nov Closing Remarks

3 Generator FACTS The Double-fed Induction Generator turbine gearbox double-fed induction generator IG grid transformer slip-rings = Date 25-Nov = rectifier inverter

4 Generator FACTS Equivalent Circuits (for Positive-sequence) i s r S x S x R Shortcircuited induction generator u S x m r R /s i s r S x S x R Date 25-Nov Doublyfed induction generator u S x m r R /s u R /s

5 Generator FACTS Magnetising of Rotor stator flux s 0 conn bus r S x S x R rotor flux x m r R /s weak network induction generators s<<0 conn bus r S x S x R x m r R /s Date 25-Nov weak network induction generators

6 Generator FACTS Typical Fixed Rotor Flux 5 Stator current (pu) 4 is (pu) Electrical torque (pu) Date 25-Nov Tel (pu) rotor freq (Hz)

7 Generator FACTS Mechanical System Turbine Generator Date 25-Nov

8 FACTS Agenda Wind Generators Response to Grid Faults PICTURE JPG-FORMAT WEB OPTIMIZED RESOLUTION SVC and STATCOM HVDC HVDC Light Date 25-Nov Closing Remarks

9 Fault FACTS Recovery Generic System Wind Farm 35 km Main Grid 66 kv SVC Minor Load Date 25-Nov s. 3psg at 1.0 s.

10 Fault FACTS Recovery Fault Recovery, Without SVC 1.2 Stator & rotor flux stator rotor 1 per unit Wind turbine & induction generator speed turbine generator 1.1 per unit Date 25-Nov time (s)

11 Fault FACTS Recovery Fault Recovery, With SVC 1.2 Stator & rotor flux stator rotor 1 per unit Wind turbine & induction generator speed turbine generator 1.1 per unit Date 25-Nov time (s)

12 FACTS Agenda Wind Generators Response to Grid Faults PICTURE JPG-FORMAT WEB OPTIMIZED RESOLUTION SVC and STATCOM HVDC HVDC Light Date 25-Nov Closing Remarks

13 SVC & FACTS STATCOM Combined VSC and TSC Scheme 132 kv 150 MVA ~ = FC 3 Mvar Date 25-Nov VSC +/- 53 Mvar TSC 94 Mvar

14 SVC & FACTS STATCOM SVC Vs. STATCOM Comparison SVC / MVAR STATCOM - 90 / MVAR XFMR 220 MVAR XFMR 170 MVAR HF HF 20 MVAR 20 MVAR HF 54 MVAR TCR MVAR TSC 166 MVAR VSC ± 65 MVAR VSC ± 65 MVAR Date 25-Nov Capacitive MVAR Output vs Voltage Voltage (p.u.) 1,0 0,9 0,8 0,7 SVC -100 / STATCOM -90 / each case is unique considering footprint, transmission situation, losses, etc

15 SVC & FACTS STATCOM Example SVC Installation, outline 220 kv 220/20 kv 200 MVA 20 kv Date 25-Nov TCR1 135 Mvar TCR2 135 Mvar TSC 130 Mvar 5 th 7 th 40 Mvar 30 Mvar

16 SVC & FACTS STATCOM Example SVC Installation, Picture Control Building TSC Power Transformer TCR1 TCR2 Date 25-Nov Filter

17 SVC & FACTS STATCOM Example SVC Installation, layout Date 25-Nov

18 FACTS Agenda Wind Generators Response to Grid Faults PICTURE JPG-FORMAT WEB OPTIMIZED RESOLUTION SVC and STATCOM HVDC HVDC Light Date 25-Nov Closing Remarks

19 FACTS HVDC Why HVDC? Part 1 One reason for choosing a High Voltage Direct Current (HVDC) trans-mission system for the connection of an offshore wind farm might be a long distance between the wind farm and the grid connection point, where HVAC cables can not be used due to their charging current. Date 25-Nov

20 FACTS HVDC Why HVDC? Part 2 An HVDC connection separates the two systems electrically. As an example: A contingency in the on shore grid doesn t affect the voltage level at the off-shore installation. Off-shore Wind farm On-shore Main Grid ± 150 kv DC cable Date 25-Nov

21 FACTS HVDC Why HVDC? Part 3 It is possible to operate of the wind farm at different and/or varying frequency, e.g. for optimum use of the wind energy. Assuming VSC technology, both the off-shore installation and the on-shore grid can be supported with dynamic reactive power. Lower resistive losses in the interconnecting cable. Date 25-Nov

22 FACTS Agenda Wind Generators Response to Grid Faults PICTURE JPG-FORMAT WEB OPTIMIZED RESOLUTION SVC and STATCOM HVDC HVDC Light Date 25-Nov Closing Remarks

23 FACTS HVDC Light HVDC Light is a DC transmission system based on voltage source converter (VSC) technology. In a VSC, the current in the valves can be switched on and off at any time - the converter is self-commutated. Date 25-Nov

24 HVDC Light FACTS HVDC Light Valve: IGBT + Diode DC-Cable AC Phase- Reactance DC-Capacitor +/- 150 kv Date 25-Nov AC- Filter DC-Cable

25 HVDC FACTS Light HVDC Light, P-Q Characteristic Limits maximum Current maximum DC Voltage maximum DC Power Q U ac = 0.9 pu U ac = 1.0 pu U ac = 1.1 pu P Date 25-Nov

26 HVDC FACTS Light HVDC Light Offshore Installation HVDC Light offshore module, MVA (W L H) m Including Transformer Date 25-Nov

27 FACTS Agenda Wind Generators Response to Grid Faults PICTURE JPG-FORMAT WEB OPTIMIZED RESOLUTION SVC and STATCOM HVDC HVDC Light Date 25-Nov Closing Remarks

28 FACTS Conclusion 1 Both AC and DC are available and feasible for connecting large wind power plants to the grid. The selection of technology depends on several parameters, a supplier with experience of both technologies should be able to advice. Date 25-Nov

29 FACTS Conclusion 2 Date 25-Nov An SVC at the PCC provide reactive power support to the grid at all operating scenarios and mitigates problems with flicker, stability and other quality issues. HVDC Light is an alternative when the connection is long and/or the grid connection point is weak. With HVDC Light it is possible to operate of the wind farm at different and/or varying frequency.

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