Provided are a control method and apparatus for load reduction of a wind turbine. The control method for load reduction includes: determining a representative blade root load value of a wind turbine; determining an additional pitch rate value based on the representative blade root load value; determining a pitch rate control value based on a given pitch rate value and the additional pitch rate value: and applying the pitch rate control value to each blade of the wind turbine, to control each blade of the wind turbine to perform a pitch action.

A system and method are provided for reducing vibrations and loads in one or more rotor blades of a wind turbine when the rotor hub is locked against rotation, The method detects that the rotor blades are vibrating above a threshold limit, and determines one or more wind parameters for wind impacting the rotor blades. An initial orientation of the blades is also determined. Based on the wind parameters and initial blade orientation, a first angle of attack for the rotor blades is determined that will reduce the vibrations in the rotor blades. The method then determines if expected loads induced at one or more wind turbine components will exceed a threshold limit at the first angle of attack for the rotor blades. The first angle of attack is modified when the expected loads exceed the threshold limit to reduce the expected loads to below the threshold limit. A controller pitches the rotor blades to achieve the first angle of attack.

The invention relates to a method for limiting structural loads in a wind turbine in situations where the power produced by the wind turbine is increased or decreased. The limitation of structural loads is achieved by restricting the power ramp rate, i.e. the rate of change of increases or decreases in produced power. The restriction is only invoked if a maximum change of the produced power or the corresponding internal power reference within a time window exceeds a given threshold.

The present disclosure is directed to a method for responding to a friction coefficient signal of a pitch bearing of a pitch drive mechanism of a wind turbine and/or for controlling the pitch drive mechanism(s) and/or a bank of ultracapacitors. The method and system include: accessing high-frequency measurement data of the at least one pitch bearing; estimating, via a torque balance model implemented by a controller, a frictional torque of the at least one pitch bearing based, at least in part, on the high-frequency measurement data; estimating, via the controller, a friction coefficient signal of the at least one pitch bearing based, at least in part, on the frictional torque; comparing the friction coefficient signal with a friction threshold; determining whether the friction coefficient signal deviates from the friction threshold based, at least in part, on the comparison; and, if so, acting.

The present disclosure is directed to a method for estimating tower loads, such as tower deflection, of a wind turbine. The method includes receiving an estimate of slow variations in thrust of a tower of the wind turbine. The method also includes determining, via one or more sensors, tower accelerations of the tower of the wind turbine. Thus, the method also includes estimating the tower loads of the wind turbine as a function of the estimate of slow variations in thrust of the tower and the tower accelerations.

The invention relates to a method of identifying a wind distribution pattern over a rotor plane and a wind turbine thereof. At least one operating parameter of the wind turbine and a rotational position of the rotor are measured over a time period. A first wind turbine blade passing signal is extracted from the measured operating parameter and a second wind turbine blade passing signal is generated from the rotational position. The first and second wind turbine blade passing signals are then analysed to determine the characteristics of the actual wind turbine blade passing signal in the rotor plane. These characteristics are afterwards compared to the characteristics of a plurality of known wind distribution patterns, and a unique relationship between the characteristics of the wind turbine blade passing signal and the wind distribution pattern is used to identify a distinctive wind distribution pattern.

A method for adjusting a power parameter of a wind turbine is disclosed. The method includes determining a load parameter indicative of a mechanical load of the wind turbine; estimating a turbulence of a wind speed based on the determined load parameter; and adjusting the power parameter relating to a power of the wind turbine based on the estimated turbulence. A system for adjusting a power parameter of a wind turbine is also described.

The present subject matter is directed to a system and method for operating a wind turbine. The method includes determining an actual operating time for one or more wind turbine components at multiple power levels; determining a corresponding wind condition for each of the operating times at each power level; estimating a loading condition acting on the one or more wind turbine components at the multiple power levels and the corresponding wind conditions; estimating an accumulated fatigue life consumption of the one or more wind turbine components based at least partially on the operating times and the estimated loading conditions; and, operating the wind turbine based on the accumulated fatigue life consumption.

Provided is a method of controlling at least one wind turbine in case of a rotational overspeed situation, the method including: determining a current state related to the wind turbine; providing data related to the current state as input to a turbine model; predicting a load of at least one wind turbine component and power output of the wind turbine using the turbine model provided with the input for plural control strategies; comparing the predicted load and power output for the plural control strategies; and selecting that control strategy among the plural control strategies that satisfies a target criterion including the load and the power output.

A method of controlling a wind turbine comprising blades attached to a rotor hub for rotation in a rotor plane and a control system for individually pitching the blades relative to the hub. The method comprises dividing the rotor plane into a number of sectors, determining the individual sectors for each blade during the rotation by means of an azimuth angle sensor, and obtaining blade sensor data from a blade sensor on an individual blade relating to a sector, and comparing the obtained data with data relating to the same sector and representing blade sensor data on other blades. When an event is detected in a given sector, an individual pitch contribution is determined in the sector, and the blades are then pitched according to this individual pitch contribution for that given sector at least partly during passage of the sector.