Method for operating a wind turbine having a rotor hub supporting at least one rotor blade

A method for operating a wind turbine which includes a rotor hub supporting a rotor blade, the method comprising:

• a) detecting changes in the aerodynamic performance of the rotor blade of the wind turbine;
• b) determining a first control rule of the wind turbine being related to power output of the wind turbine;
• c) determining a first power output information indicating a first power output of the wind turbine based on the first control rule;
• d) changing at least one operational parameter of the wind turbine and choosing at least one second control rule in such a manner that the first control rule is replaced by the second control rule being related to power output of the wind turbine;
• e) determining a second power output information indicating a second power output of the wind turbine based on the second control rule;
• f) comparing the first and second power output information;
• g1) when the second power output of the wind turbine exceeds the first power output of the wind turbine, repeating a)-f) with the second control rule being used as the first control rule in b);
• g2) otherwise repeating a)-f), whereby a different second control rule is applied in d).