Method for detecting an accretion of ice on a wind turbine

The method as claimed in claim 21, comprising:

• recording the operating deviations as standard deviations;
• combining the operating deviations as a deviation band, and selecting or changing the deviation curve to be below the deviation band relative to the operating variable;
• and/or
• setting a respective minimum deviation or the deviation curve during operation of the wind turbine based on the characteristic operating curve and/or the recorded operating deviations.

A wind turbine, comprising:

• at least one rotor operable at a variable rotational speed and having at least one rotor blade;
• a wind speed measuring device configured to record a wind speed of wind acting on the rotor;
• and
• a controller configured to:
• record an operating variable that is dependent on the wind speed;
• compare the recorded operating variable or the recorded wind speed with a reference variable of a characteristic operating curve of the wind turbine, wherein the characteristic operating curve indicates an operating variable based on the wind speed;
• and
• detect an accretion of ice on the rotor blade in response to the recorded operating variable or the recorded wind speed deviating from the reference variable by at least a minimum deviation,
• the minimum deviation being set depending on the wind speed.