Abstract: A method for controlling a wind turbine, and an associated wind turbine, includes receiving a wind direction signal indicative of an instantaneous wind direction at the wind turbine and receiving a signal indicative of an instantaneous wind speed at the wind turbine. A rate of change of the wind direction at the wind turbine and a rate of change of wind speed at the wind turbine are determined. A control signal for a pitch system for blades of the wind turbine is determined based on the rate of change of the wind direction and the rate of change of wind speed. The pitch of the blades is then changed with the pitch system based on the control signal to reduce loads on the wind turbine from changes in the wind direction simultaneous with changes in the wind speed.

Abstract: The present disclosure is related to methods (400; 500; 600) configured for detecting the state of a wind turbine blade (22). The methods (400; 500; 600) comprising receiving (401; 501) load signals from a wind turbine blade (22), determining (402; 503) an energy of the load signal in a first and second frequency and comparing (403; 504) said energy to generate a flag signal if the energy in the first frequency is smaller than the energy in the second frequency. A control system (600) suitable to detect the state of a wind turbine blade (22) is also provided, as well as wind turbines (10) including such a control system (600).

Abstract: A method for operating a wind turbine determines reliability of an azimuth measurement system by measuring loads with load sensors during operation of the wind turbine. Based on the measured loads, in-plane moments generated on the blades at a rotational speed frequency of the rotor are determined. The azimuth measurement system has reduced reliability if the angular phase of the in-plane moments at the rotor rotational speed frequency of the rotor deviates from an angular phase measured by the azimuth measurement system by more than a first threshold value. The method generates a warning signal or changes operation of the wind turbine when it is determined that the azimuth measurement system has reduced reliability.

Abstract: The present disclosure relates to a method comprises receiving a wind direction signal and one or more signals indicative of an instantaneous wind speed at the wind turbine and determining a rate of change of the wind direction at the wind turbine and an indication of a rate of change of wind speed at the wind turbine. The method further comprises determining a control signal for a pitch system of the wind turbine at least partially based on the determined rate of change of the wind direction and the determined indication of the rate of change of wind speed. The present disclosure further relates to control systems for wind turbines which are configured to implement such methods. The present disclosure further relates to methods of operating wind turbines.

Abstract: The present disclosure relates to a method for determining reliability of one or more load sensors in a wind turbine. The method comprises measuring loads with the load sensors during operation of the wind turbine; determining in-plane moments based on the measured loads; selecting the in-plane moments with 1 p frequency; and comparing the selected in-plane moments with theoretical in-plane moments due to a mass of the blade. The method then comprises determining that the load sensors have reduced reliability if the selected in-plane moments deviate from the theoretical in-plane moments by more than a first threshold value. The present disclosure also relates to wind turbine systems incorporating load sensors and methods for on-line determination of correct functioning of load sensors mounted on a wind turbine blade.

Abstract: The present disclosure relates to methods which comprise receiving a wind direction signal indicative of an instantaneous wind direction at a wind turbine, filtering the wind direction signal to determine a filtered wind direction signal and determining a yaw error signal of the wind turbine indicating a difference between a yaw angle of the wind turbine and the instantaneous wind direction indicated by the filtered wind direction signal. The methods furthermore comprise determining a control signal for a yaw system of the wind turbine based on the yaw error signal. Filtering the wind direction signal comprises applying a low pass filter with a variable time constant, wherein the variable time constant is dependent on a wind condition. The present disclosure further relates to control systems for wind turbines which are configured to implement such methods. The present disclosure further relates to methods of operating wind turbines.

Abstract: Methods (200) for reducing vibrations in one or more rotor blades (120) of a wind turbine (160), when the wind turbine is in standstill conditions are provided. The method comprises measuring (201) one or more deformation parameters indicative of deformation of one or more blades (120), determining (202), at a dedicated controller (190) for an auxiliary drive system (20, 107), a vibration of one or more of the blades (120) based on the deformation parameters, wherein the dedicated controller (190) for the auxiliary drive system is separate from the wind turbine controller (180), and generating (203), at the dedicated controller (190), an output signal to operate the auxiliary drive system to reduce the vibration. Also disclosed are wind turbines (160) which comprise a dedicated controller (190) configured to determine a vibration and generating an output signal to reduce the vibration, when the wind turbine is in standstill conditions.

Abstract: The present disclosure relates to methods for determining reliability of an azimuth measurement system in a wind turbine. The methods comprise measuring loads with load sensors during operation and determining in-plane moments with rotor rotational speed frequency of one or more blades based on the measured loads. The methods further comprise measuring an azimuthal position of a wind turbine rotor. The method also comprises determining that the azimuth measurement system has reduced reliability if an angular phase of the in-plane moments deviates from the measured azimuthal position by more than a first threshold value. The present disclosure also relates to wind turbine systems incorporating azimuth measurements and methods for on-line determination of correct functioning of azimuth sensors.

Abstract: The present disclosure relates to methods which comprise receiving a wind direction signal indicative of an instantaneous wind direction at a wind turbine, filtering the wind direction signal to determine a filtered wind direction signal and determining a yaw error signal of the wind turbine indicating a difference between a yaw angle of the wind turbine and the instantaneous wind direction indicated by the filtered wind direction signal. The methods furthermore comprise determining a control signal for a yaw system of the wind turbine based on the yaw error signal. Filtering the wind direction signal comprises applying a low pass filter with a variable time constant, wherein the variable time constant is dependent on a wind condition. The present disclosure further relates to control systems for wind turbines which are configured to implement such methods. The present disclosure further relates to methods of operating wind turbines.

Abstract: The present disclosure relates to a method for determining reliability of one or more load sensors in a wind turbine. The method comprises measuring loads with the load sensors during operation of the wind turbine; determining in-plane moments based on the measured loads; selecting the in-plane moments with 1 p frequency; and comparing the selected in-plane moments with theoretical in-plane moments due to a mass of the blade. The method then comprises determining that the load sensors have reduced reliability if the selected in-plane moments deviate from the theoretical in-plane moments by more than a first threshold value. The present disclosure also relates to wind turbine systems incorporating load sensors and methods for on-line determination of correct functioning of load sensors mounted on a wind turbine blade.

Abstract: Methods (200) for reducing vibrations in one or more rotor blades (120) of a wind turbine (160), when the wind turbine is in standstill conditions are provided. The method comprises measuring (201) one or more deformation parameters indicative of deformation of one or more blades (120), determining (202), at a dedicated controller (190) for an auxiliary drive system (20, 107), a vibration of one or more of the blades (120) based on the deformation parameters, wherein the dedicated controller (190) for the auxiliary drive system is separate from the wind turbine controller (180), and generating (203), at the dedicated controller (190), an output signal to operate the auxiliary drive system to reduce the vibration. Also disclosed are wind turbines (160) which comprise a dedicated controller (190) configured to determine a vibration and generating an output signal to reduce the vibration, when the wind turbine is in standstill conditions.