Abstract: Provided is a method for heating a generator of a wind power installation during or before starting the installation. The generator is a permanent magnet synchronous generator configured to generate a stator current comprising at least one three-phase current. The installation is configured as a gearless installation and is connected to an electrical supply network for feeding electrical power into the network. The installation comprises a converter, connected to the generator, to control the generator to feed electrical power into the network. The method comprises rotating the rotor with a low rotational speed below a first limit and operating the converter such that the generator generates the stator current and electrical power, and no electrical power is fed into the electrical supply network. At least one portion of the stator current substantially circulates through the generator and the converter to consume power in generator windings to heat the generator.

Abstract: Provided is a method for controlling a current converter, in particular an inverter, preferably a frequency converter comprising an inverter, in particular of a wind power installation.

Abstract: A wind power installation and a method for feeding a filtered alternating current into an electrical supply grid by the wind power installation are provided. The wind power installation includes at least one inverter having an inverter output for providing an inverter current. The at least one inverter is coupled at its inverter output to an active filter. The active filter filters the inverter current provided at the inverter output and provides the filtered alternating current for feeding into the electrical supply grid. The method includes providing the inverter current at the inverter output by switching at least one switch of the inverter, sensing the switching, and controlling the active filter based on the sensed switching to filter the inverter current provided at the inverter output and produce the filtered alternating current.

Abstract: A wind power installation and a method for feeding a filtered alternating current into an electrical supply grid by the wind power installation are provided. The wind power installation includes at least one inverter having an inverter output for providing an inverter current. The at least one inverter is coupled at its inverter output to an active filter. The active filter filters the inverter current provided at the inverter output and provides the filtered alternating current for feeding into the electrical supply grid. The method includes providing the inverter current at the inverter output by switching at least one switch of the inverter, sensing the switching, and controlling the active filter based on the sensed switching to filter the inverter current provided at the inverter output and produce the filtered alternating current.