Method for controlling an electrical generator of a wind turbine

A wind turbine comprising a generator including a rotor and a stator, wherein the wind turbine is configured to be controlled such that the stator is controlled by a stator current, wherein the stator current has a main component having a fundamental signal with a fundamental frequency and a fundamental phase angle, and a fractional harmonic current component having a fractional harmonic signal having a fractional harmonic frequency and a fractional harmonic phase angle, the wind turbine being configured to:

• provide a compensation current having a compensation amplitude and a compensation phase angle, and
• determine the compensation phase angle depending on an absolute rotational position of the rotor, wherein
• the fractional harmonic phase angle or the compensation phase angle is determined with respect to a phase angle of a reference period of the fundamental signal,
• the fundamental signal has a plurality of periods per revolution of the rotor or per segment of the rotor,
• the reference period is selected from the plurality of periods depending on the absolute rotational position of the rotor,
• in a starting step, at least one of the fractional harmonic signal or the fractional harmonic phase angle is determined based on the absolute rotational position of the rotor,
• a corresponding period of the fundamental signal having a zero crossing closest to a zero crossing of the fractional harmonic signal determined in the starting step is selected as the reference period, and
• the zero crossing of the fundamental signal of the reference period is used as a reference point and the fractional harmonic phase angle or the compensation phase angle is determined with respect to the reference point.