Abstract: A method for operating a wind turbine when a grid fault with a voltage drop occurs. The turbine has a rotor with a rotor blade having an adjustable blade pitch angle, a generator connected to the rotor for generating power for a power grid and a converter connected to the generator and the power grid. The grid fault is identified and a present value of a turbine variable representing a power is detected and a hold setpoint for the variable representing a power of the turbine is preset. A maximum and/or minimum permissible setpoint for the variable of the turbine is determined. The setpoint is increased or reduced once the hold time has elapsed. The turbine is driven with a setpoint preset which corresponds to the rotational speed. A presetting of the maximum permissible setpoint is ended when the rotational speed-dependent setpoint is lower than the maximum permissible setpoint.

Abstract: A method for operating a wind turbine when a grid fault with a voltage drop occurs. The turbine has a rotor with a rotor blade having an adjustable blade pitch angle, a generator connected to the rotor for generating power for a power grid and a converter connected to the generator and the power grid. The grid fault is identified and a present value of a turbine variable representing a power is detected and a hold setpoint for the variable representing a power of the turbine is preset. A maximum and/or minimum permissible setpoint for the variable of the turbine is determined. The setpoint is increased or reduced once the hold time has elapsed. The turbine is driven with a setpoint preset which corresponds to the rotational speed. A presetting of the maximum permissible setpoint is ended when the rotational speed-dependent setpoint is lower than the maximum permissible setpoint.

Abstract: A method for the active damping of a drive train in wind energy plant, with the following steps: the actual value of the generator rotational speed is acquired and amplified via an oscillatory delay element, the oscillatory delay element has a predetermined natural oscillation frequency (?E), which is smaller than the smallest natural frequency of the drive train, and a difference between the actual value of the rotational speed and the amplified value for the rotational speed is connected to a controller as actuating variable, which determines a correction moment for a generator control.

Abstract: A method for the active damping of a drive train in wind energy plant, with the following steps: the actual value of the generator rotational speed is acquired and amplified via an oscillatory delay element, the oscillatory delay element has a predetermined natural oscillation frequency (?E), which is smaller than the smallest natural frequency of the drive train, and a difference between the actual value of the rotational speed and the amplified value for the rotational speed is connected to a controller as actuating variable, which determines a correction moment for a generator control.