Method for operating a wind turbine, and a power plant

Abstract

A method () for operating a wind turbine () including a rotor () having rotor blades () and a power conversion system () mechanically connected with the rotor (), configured to convert input motive power into electrical output power, and electrically connected to a network () for feeding the electrical output power (P) to the network is provided. The method includes initializing (), at a first time (t), the wind turbine to operate in an overproduction operating mode in which the electrical output power (P(t)) of the power conversion system is increased from an initial electrical output power of the power conversion system by providing kinetic energy stored in the rotor. At a second time (t), decreasing () the electrical output power, and integrating a reference power (P, P) to determine an energy recovery value (E) are started. An energy response value (E) corresponding to a product of the reference power (P) with a time difference (T) between the second time and the first time is determined (). The wind turbine is operated () in a recovery operating mode from a third time (t) at which the electrical output power (P) reaches or crosses the reference power (P, P) until the energy recovery value becomes at least equal to the energy response value or until the electrical output power reaches or crosses the reference power again from below. In the recovery operating mode, the electrical output power is, limited upwards depending on the reference power and a currently available maximum electrical power output without reducing a speed of the rotor.