Abstract: A method for operating a wind turbine (WEA), which has a generator for supplying electric power to an electric supply grid, is provided. After being operated in a first operating state with a first power output and a first rotational speed, the wind turbine is set to a second operating state with a second power output and a second rotational speed. In order to set the wind turbine to the second operating state, an aerodynamic power output which is available for supply is determined, a target rotational speed is determined from the available output, and a target output to be set for the generator is specified from the target rotational speed.

Abstract: A method for recording the magnitude and phase of the electrical voltage in an electrical three-phase supply network for a fundamental and at least one harmonic is provided. The method includes measuring an electrical three-phase voltage of the supply network, transforming the measured voltage values into polar coordinates using a rotating voltage phasor for the fundamental as a measured reference phasor, and respectively observing values of at least one voltage phasor for the fundamental and of at least one voltage phasor for at least one harmonic to be recorded with the aid of a state observer, and tracking the observed values on the basis of the measured reference phasor.

Abstract: A method for controlling a synchronous generator of a gearless wind turbine is disclosed. The synchronous generator has an electrodynamic rotor and a stator for producing electrical power by rotating the rotor relative to the stator. The method includes generating a multiphase output current at the stator, supplying the output current to a rectifier, and controlling the output current using the rectifier in such a manner that a torque ripple of the generator is reduced.