ECN publication
Electrical and Control Aspects of Offshore Wind Farms II (Erao II). Volume 2: Offshore wind farm case studies
Published by: Publication date:
ECN Wind Energy 1-6-2004
ECN report number: Document type:
ECN-C--04-051 ECN publication
Number of pages: Full text:
132 Download PDF  


In The Netherlands offshore wind power is on the brink of implementation. Specific plans exist for two offshore wind farms of about 100 MW, located 12 and 25 km from the coast of the province of North Holland. The effects of the incorporation of 6000 MW offshore wind power in the Dutch high voltage grid are currently investigated. Only the steady state behaviour has been considered, resulting in suggestions for grid reinforcement. This investigation needs to be complemented by a study on the dynamic interaction of wind power and grid. Tools for this investigation, viz. dynamic models of wind farms including all relevant electrical components, have been developed in the Erao-2 project. This report describes the wind farm dynamic models (Volume 1) and emonstrates their use in a number of case studies (Volume 2). Special concern exists about wind farm behaviour during extreme wind speed changes and abnormal grid conditions (voltage and frequency dips); these may cause complete wind farms to shut down instantaneously. Assisting grid voltage and frequency control is also an issue. In the case studies the models have be used to compare four types of wind farms: (1) constant speed stall with directly coupled induction generators and (2) with cluster control, (3) variable speed with double fed induction generator and (4) with permanent magnet generator. The case studies compare normal dynamic behaviour, flicker contribution, responses to grid faults and wind farm control has been developed to support the grid frequency and voltage.

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