A wind turbine drive system includes a plurality of drive devices, a state quantity detection unit, and a control unit. The plurality of drive devices are provided in a first structure (a nacelle), and a ring gear is provided in a second structure (a tower). Each of the drive devices includes a motor drive portion, a speed reducing portion, and a motor braking portion for braking the motor drive portion. The state quantity detection unit detects a load between a meshing portion of each of the drive devices and the ring gear. Based on the thus detected load for the each of the drive devices, the control unit controls at least one of the motor drive portion and the motor braking portion so as to reduce a degree of variation in the load among the drive devices.

There is provided a pitch control system (210) for controlling a pitch force system (220) for pitching a blade (103) of a wind turbine (100), the pitch control system (210) being arranged for activating (682) an auxiliary pitch force subsystem (224) at an initiation point in time where a main pitch force is sufficient to pitch the blade (103) into a target pitch value. An advantage thereof may be that tracking of a target pitch value may be improved and the impact on the pitch force system (220) may be reduced. In aspects, there is furthermore presented a hydraulic pitch system (206), a wind turbine (100), a method and a computer program product.

A method is provided of controlling a wind turbine. The method comprises over-rating the wind turbine above the wind turbine's rated power in response to a control signal and applying an over-rating control algorithm that restricts the amount of additional power produced by over-rating the wind turbine, due to the control signal, based upon one or more turbine parameters. The method further comprises receiving an over-ride signal; and in response to the over-ride signal, over-riding the over-rating control algorithm to temporarily increase the amount of power output by the wind turbine for a period of time.

A method for controlling a wind turbine is provided. The wind turbine is a turbine of the type that is operated to perform a control function that controls the amount of power produced based upon measures of fatigue life consumption of one or more turbine components. The method comprises initialising the control function by: over-riding or bypassing (405) the control function for a predetermined period of time, such that power produced by the wind turbine is not altered based upon the determined measures of fatigue life consumption; during the predetermined period of time, operating (407) one or more fatigue lifetime usage estimation algorithms, to determine a measure of the fatigue life consumed by each of the one or more turbine components; and after the predetermined period of time has elapsed, activating (409) the control function and using, in the control function, at least one of the measures of fatigue life consumption determined during the predetermined period of time. A corresponding wind turbine controller and wind power plant controller are also provided.

A method and control arrangement are disclosed for controlling power output of a wind power plant (WPP) including a plurality of wind turbine generators (WTGs). The method includes determining that overboosting is required for the WPP to meet a power demand at the WPP, and determining, for at least a first WTG of the plurality of WTGs, a corresponding amount of overboost capacity. The method further includes generating, based on the determined amount of overboost capacity, control signals causing the first WTG to increase its power output through overboosting to thereby fulfill at least a portion of the power demand.

A method is disclosed for controlling a wind turbine generator to provide power above a rated level based upon operational atonal constraints. The wind turbine includes an over-rating controller that calculates an over-rating power demand in response to the values of one or more operating parameters, and communicates this demand to the generator. An over- rating command value is calculated according to set points of the operating parameter(s), the calculation taking into account the extent to which the operating parameter differs from these set points. The over-rating command value may vary proportionately with the difference between the operating parameter and the associated set point. If multiple operating parameters are used then the over-rating power demand may correspond to the minimum over-rating command value. Furthermore, the power demand maybe communicated to wind turbine generators individually, or may be calculated for a wind turbine park.