1. 2007-05-09Antje Orths - EWEC 2007, Milano, Italy Experience with Voltage Control From Large Offshore Windfarms for Transmission Systems Vladislav Akhmatov Antje Orths Peter Børre Eriksen NORDEL UPS UCTE

2. 2007-05-09Antje Orths - EWEC 2007, Milano, Italy AGENDA Introduction Danish Grid Connection Specifications Limiting Factors Summary

3. 2007-05-09Antje Orths - EWEC 2007, Milano, Italy Power Balance 2005 Two synchronous areas: Central power plants Local plants Wind turbines 1000/950 MW 460/490 MW 550 MW 800/1200 MW Consumption1250 - 3700 MW Central power plants 3400 MW Local CHP units 1700 MW Wind turbines 2400 MW Consumption 880 - 2600 MW Central power plants 3800 MW Local CHP units 650 MW Wind turbines 750 MW West: East: 4100 MW 1400 MW penetration Wind: 65 … 200% CHP: 46 … 136% penetration Wind: 30 … 85% CHP: 25 … 74% ex: 40 of prod. im: 70 of cons. ex: 43 of prod. im: 70 of cons. 1300/1700 MW im-/ export [MW]

4. 2007-05-09Antje Orths - EWEC 2007, Milano, Italy The Danish transmission system Discussed Future Locations Areal ca. 44 km 2 Power ca. 200 MW Discussed Future Locations Areal ca. 44 km 2 Power ca. 200 MW Governmental Energy Strategy 2025: + 3,000 MW Governmental Energy Strategy 2025: + 3,000 MW … and offshore windparks German plans (DENA study) 2020: + 20,000 MW (North & Baltic Sea) German plans (DENA study) 2020: + 20,000 MW (North & Baltic Sea)

5. 2007-05-09Antje Orths - EWEC 2007, Milano, Italy The Danish transmission system … need for a stronger grid existing planned discussed

6. 2007-05-09Antje Orths - EWEC 2007, Milano, Italy Absolute Production Constraint Power Gradient Constraint Delta Production Constraint Grid Connection Specifications Stop regulation 3 5 6 7

7. 2007-05-09Antje Orths - EWEC 2007, Milano, Italy Example Horns Rev 1

8. 2007-05-09Antje Orths - EWEC 2007, Milano, Italy Dimensioning Voltages and Frequencies Reactive Power Regulation 47,549,7 49,550,5 ULUL U LF UNUN U HF UHUH Voltage 51,0 53,0f [Hz] Grid Connection Specifications dotted lines: rules before 2004

9. 2007-05-09Antje Orths - EWEC 2007, Milano, Italy 2400 Load shedding [MW] 1500 800 1050 500 5200 400 European ”System Test”, November 4, 2006

10. 2007-05-09Antje Orths - EWEC 2007, Milano, Italy Georg Christoph Lichtenberg`s Comment: ”A banging physical experiment is actually more valuable than a silent one…” (1742 – 1799)

11. 2007-05-09Antje Orths - EWEC 2007, Milano, Italy Limit 1: Converter Power Rating Qualitative PQ-Chart of DFIG-Wind Turbines

12. 2007-05-09Antje Orths - EWEC 2007, Milano, Italy Connection of Horns Rev 2 offshore park: ~15 km ~ 45 km Limit 2: Long AC Cables Platform SeacableLandcable 56 km 35 km

13. 2007-05-09Antje Orths - EWEC 2007, Milano, Italy What makes a difference… 80 km cable 25 km cable Qualitative Example

14. 2007-05-09Antje Orths - EWEC 2007, Milano, Italy 164 166 168 170 0.40.81.21.62.00.0 [s] Voltage offshore platform Voltage Onshore Voltage at Cable Ends increase of Q [MVar]: 4  20 HRA: ~ rated power V > 170 kV ! => Cable sets limit for Q-Deliverance Voltage offshore platform Voltage Onshore 164 166 168 170 172 0.40.81.21.62.00.0 [s] decrease of Q [MVar]: 4  -25 V < 165 kV ! => Cable sets limit for Q-Absorbtion

15. 2007-05-09Antje Orths - EWEC 2007, Milano, Italy Summary Today: control of the power system is based on control of conventional power plants Ambitious plans for additional wind power in EU and DK => Wind Farm`s Contribution to System Services is essential Possible Limiting Factors ­Power- and Current Rating Limits of Power Electronic Converters ­Long AC Cable Connections These limits should be considered during planning phase

16. 2007-05-09Antje Orths - EWEC 2007, Milano, Italy Horns Rev Thank you !  www.energinet.dk