A method is provided 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 in which, 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. A wind power plant is provided (15-19) with a rotor-driven electric generator (30) for delivering electric power to an electric grid (31) in which when excess voltage prevails in the grid idle power from the wind power plant (15-19) is fed to the grid (31) in order to lower the voltage. Monitoring occurs to determine whether within a predeterminable time a voltage was lowered to a predeterminable reference value and/or an idle current is delivered which is greater than or equal to a predeterminable idle current reference value.