CONTROL METHOD FOR A WIND TURBINE

The invention relates to a method of controlling a wind turbine having a rotor with pitchable wind turbine blades and a generator for producing power, where a pitch reference value for the wind turbine blades is determined, and an operational parameter representing a loading on the wind turbine rotor exerted by the wind is measured at time intervals. A variation parameter reflecting a variation of the operational parameter over time is determined and used in the determination of a minimum pitch limit value of the pitch reference value. The wind turbine is then controlled according to the pitch reference value only if the pitch reference value is above or equal to the minimum pitch limit value, and otherwise according to the minimum pitch limit value. The invention further relates to a method of controlling the change in the operational parameter as measured in two successive time steps is determined and the turbine then being controlled according to a safety control strategy if the difference between the operational parameter change and the variation parameter is above a certain alert threshold. The invention further relates to a control system configured to perform the above control method, and a wind turbine comprising such system.