Antje 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

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

Antje 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 Consumption MW Central power plants 3400 MW Local CHP units 1700 MW Wind turbines 2400 MW Consumption 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]

Antje 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)

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

Antje Orths - EWEC 2007, Milano, Italy Absolute Production Constraint Power Gradient Constraint Delta Production Constraint Grid Connection Specifications Stop regulation

Antje Orths - EWEC 2007, Milano, Italy Example Horns Rev 1

Antje 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

Antje Orths - EWEC 2007, Milano, Italy 2400 Load shedding [MW] European ”System Test”, November 4, 2006

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

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

Antje 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

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

Antje Orths - EWEC 2007, Milano, Italy [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 [s] decrease of Q [MVar]: 4  -25 V < 165 kV ! => Cable sets limit for Q-Absorbtion

Antje 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

Antje Orths - EWEC 2007, Milano, Italy Horns Rev Thank you ! 