Patent ID: 8451573

Claim:
An overvoltage protection device for protecting a wind turbine against overvoltage, the wind turbine including an electrical transformer for transforming electrical power generated by a generator of the wind turbine from a low voltage region to a medium voltage region, the electrical transformer comprising: a secondary winding electrically connected to the generator of the wind turbine; and a primary winding electrically connected to an electrical utility grid receiving the generated electrical power, wherein the overvoltage protection device comprises: a detection unit configured to detect overvoltage at the electrical transformer; a determination unit configured to determine a counter-current on basis of the detected overvoltage; a counter-winding having a winding direction opposite to a winding direction of at least one of the primary winding and the secondary winding; and a current driver unit configured to feed the determined counter-current through the counter-winding.