Onshore solution for offshore wind
Danish utility installs a static VAR compensator to prevent voltage instability.
In 2003, the Nysted Offshore Wind Farm, with an Installed Capacity of 165.6 MW, was commissioned on the island of South Zealand in southern Denmark. The wind turbines are equipped with asynchronous generators with squirrel-cage rotors. Studies supported by operational experience have confirmed the wind farm was the source of unacceptably large and frequent voltage fluctuations on the 132-kV transmission system.
The voltage disturbances were due to a combination of a weak 132-kV transmission system and large variations in the reactive power-flow exchange between the wind farm and the transmission system. The reactive power flow at the Radsted substation was due to the absorption of the reactive power in the magnetisation of the wind turbines, transmission cable and 132/33/33-kV transformers. The grid interconnection at Radsted was more than 100 km (62 miles) from the nearest conventional power plant and the country’s strong 400-kV transmission system.
To reduce the voltage fluctuations, SEAS-NVE (Svinninge, Denmark) decided in the spring of 2005 to install a static VAR compensator (SVC).
TRANSMISSION SYSTEM IN EASTERN DENMARK
The transmission system in eastern Denmark comprises 400-kV and 132-kV transmission lines, cables and existing interconnectors with southern Sweden and Germany, with plans in the works for yet another interconnector to the Danish island of Funen.
The Swedish interconnector — which includes four AC cables, comprised of two 400-kV cables and two 132-kV cables — has a transfer capacity of 1900 MW and links Denmark to the Nordic grid. The interconnector to Germany is a 400-kV high-voltage direct current (HVDC) transmission system with a transfer capacity of 600 MW. The planned interconnector to Funen will be a 600-MW HVDC transmission system. Currently, in eastern Denmark, the installed generating capacity is 4360 MW supplying a maximum demand of some 2870 MW.
[Click here for complete article from Transmission & Distribution World.]
Sep 1, 2009
By Niels Andersen and Michael B. Hansen, SEAS-NVE
Tags: Wind power, Wind energy
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