Method for operating a wind turbine in the event of a grid error and a wind turbine for carrying out said method

A method for operating a wind turbine in the event of a grid error, wherein the wind turbine has a rotor having at least one rotor blade which can be adjusted in its blade pitch angle, a generator connected to the rotor for the generation of electrical power (P) and at least one unit for capturing an actual value of the rotational speed of the generator (na), a value for the blade pitch angle (βa, βs) and an actual value of a variable which is representative of a generator torque (MG), said method comprising the steps of:

• recognizing a grid error;
• capturing an actual value of the variable representative of the generator torque (MG) and the actual value of the rotational speed of the generator (ns) when a grid error is recognized;
• determining a change in the generator torque (ΔMG);
• capturing the value for the blade pitch angle βa, βs);
• determining a corrective value for the blade pitch angle in dependence upon the change of the generator torque (ΔMG) and the value for the blade pitch angle (βa, βs);
• and,
• determining a corrected set-point for the blade pitch angle which results from a rotational speed dependent set-point for the blade pitch angle during a regular operation and the determined corrective value for the blade pitch angle.