Abstract: A system includes a wind turbine a wind and a first control device for controlling the wind turbine. The first control device is configured to acquire a yaw misalignment of the wind turbine, which yaw misalignment is a difference between the actual yaw angle and a wind direction at the wind turbine; and to determine at least one of a target pitch angle of the blade and a target torque of the generator based on the yaw misalignment to optimize a power output from the wind turbine. Further, a wind farm includes the system and a method of controlling a wind turbine.

Abstract: A method for alleviating rotor asymmetric loads in a variable-speed wind turbine having pitch and torque control means comprising the following steps: providing a control law that determines the pitch to be applied individually to each wind turbine blade for counteracting rotor asymmetric loads (such as wind shear, upflow, yaw misalignment) using wind speed and wind direction measurements at the wind turbine, values of the wind features that cause rotor asymmetric loads and configuration parameters of the wind turbine (whether real-time values or statistical values at the wind turbine site), said pitch to be added to the collective pitch ?0; implementing said control law in the wind turbine control means. The invention also refers to a wind turbine control system arranged for implementing said method.

Abstract: Method for the identification in operation of the drive train main vibration frequency of a wind turbine, comprising online steps of: a) obtaining a input signal (r) of the generator speed (?); b) filtering the generator speed input signal (r) for obtaining a generator speed signal (r1) in a suitable band for representing the oscillating signal (o) comprised in the input signal (r) of the generator speed (?); c) extracting the drive train main vibration frequency (f) from said filtered signal (r1). The invention also comprise a method of damping the drive train vibrations of a wind turbine comprising steps of setting the generator torque reference (Trref) as a function of the generator speed (?) and of the drive train main vibration frequency (f) identified by the above mentioned method and wind turbine control system implementing said damping method.

Abstract: Method for the identification in operation of the drive train main vibration frequency of a wind turbine, comprising online steps of: a) obtaining a input signal (r) of the generator speed (?); b) filtering the generator speed input signal (r) for obtaining a generator speed signal (r1) in a suitable band for representing the oscillating signal (o) comprised in the input signal (r) of the generator speed (?); c) extracting the drive train main vibration frequency (f) from said filtered signal (r1). The invention also comprise a method of damping the drive train vibrations of a wind turbine comprising steps of setting the generator torque reference (Trref) as a function of the generator speed (?) and of the drive train main vibration frequency (f) identified by the above mentioned method and wind turbine control system implementing said damping method.

Abstract: A method for alleviating rotor asymmetric loads in a variable-speed wind turbine having pitch and torque control means comprising the following steps: providing a control law that determines the pitch to be applied individually to each wind turbine blade for counteracting rotor asymmetric loads (such as wind shear, upflow, yaw misalignment) using wind speed and wind direction measurements at the wind turbine, values of the wind features that cause rotor asymmetric loads and configuration parameters of the wind turbine (whether real-time values or statistical values at the wind turbine site), said pitch to be added to the collective pitch ?0; implementing said control law in the wind turbine control means. The invention also refers to a wind turbine control system arranged for implementing said method.