Patent ID: 8692419

Claim:
A method for operating a wind power plant ( 15 - 19 ) with a rotor-driven ( 25 - 29 ) electric generator ( 30 ) for delivering electric power to an electric grid ( 31 ), which provides a grid voltage, comprising the steps of: when excess voltage prevails in the grid ( 31 ), idle power from the wind power plant ( 15 - 19 ) is fed to the grid ( 31 ) in order to lower the voltage, monitoring whether within a predeterminable time the voltage was lowered to a predeterminable voltage reference value, and monitoring whether an idle current is delivered which is greater than or equal to a predeterminable idle current reference value, wherein for the case that the predeterminable voltage reference value and/or the predeterminable idle current reference value is not achieved within the predeterminable time, a signal for separating the wind power plant ( 15 - 19 ) from the grid ( 31 ) is triggered, and wherein a first time (t) dependent limit function ( 42 ) of predetermined voltage reference values and a second limit function of time (t) dependent predetermined inductive idle current reference values is provided.