There is presented a method for controlling a rotor on a wind turbine, wherein the rotor is comprising one or more blades, and wherein the wind turbine is comprising a pitch system, the method comprising: Operating the rotor in a standstill or idling operating state, determining or receiving one or more control parameters, where the control parameters enable determining one or more yawing parameters may be described as a function of the one or more control parameters, wherein the one or more yawing parameters comprises one or more of: An angular yawing velocity of the a yawing section, an angular yawing acceleration of the yawing section, and/or a yawing moment applied by the yawing section on a remainder of the wind turbine, and pitching based on the one or more control parameters one or more blades of the rotor with the pitch system.

A method for controlling a wind turbine during a safety operation is disclosed. A safety pitch control system is provided to pitch the blades individually at a number of pre-set approximately constant pitch rates including a first pitch rate and a second pitch rate lower than the first pitch rate. In response to a command for initiating the safety operation the blades are pitched towards a feathering position by the safety pitch control system including the blades being pitched according to a safety pitch strategy wherein for all the blades the pitch rate is changed between the first pitch rate and the second pitch rate according to a function of each blade azimuthal position. This is done such that each blade in turn is closer to the feathering position than the others.

A method of diagnosing a wind turbine power generating apparatus includes: an operation step of operating a pitch actuator corresponding to one of a plurality of wind turbine blades of the wind turbine power generating apparatus, without operating a pitch actuator corresponding to each of the wind turbine blades other than the one of the plurality of wind turbine blades; and a measurement step of measuring a response value indicating a response to operation of the pitch actuator corresponding to the one of the plurality of wind turbine blades. The operation step and the measurement step are performed repeatedly for each of the plurality of wind turbine blades, and the response value is obtained as data for health check of a blade pitch mechanism of the wind turbine power generating apparatus.

Method of reducing loads acting on a wind turbine yaw system in a wind turbine comprising a nacelle (2), a rotor which comprises at least one rotor blade (3) with a pitch control system and further comprising a yaw system that comprises the steps of detecting a yaw misalignment (), enabling a yaw maneuver and performing a pitch control in order to reduce a yaw moment (Mz) acting on the wind turbine once the yaw misalignment () is detected and prior to enabling the yaw maneuver. Thus, when a yaw movement to reduce the yaw misalignment is commanded, the yaw moment (Mz) due to aerodynamic forces has been reduced by means of the pitch control and undesired yaw movements are prevented.

In the case of wind turbines 10, deviations from the optimum operating state result in output losses. This applies, in particular, to angular deviations 62 in the alignment of the nacelle 14, and therefore of the rotor axis 28, relative to the wind direction 60. The invention relates to a wind turbine 10, and to a method for operating such a wind turbine, which wind turbine and method enable the nacelle 14 to be corrected, in respect of the wind direction, both on the basis of wind power and by motor.

The present disclosure is directed to a system for controlling a pitch angle of a rotor blade of a wind turbine. The system includes a pitch adjustment mechanism for adjusting the pitch angle of the rotor blade and a controller communicatively coupled to the pitch adjustment mechanism. The controller is configured to determine a wind asymmetry parameter based on an operating parameter of the wind turbine. The controller is also configured to determine first and second signal components of the wind asymmetry parameter, which are respectively indicative of a maximum load on a first wind turbine component and fatigue on a second wind turbine component. The controller is also configured to calculate a wear parameter based on the first and second signal components and initiate an adjustment of the pitch angle of the rotor blade based on the wear parameter.

A method of controlling pitch of individual blades in a wind turbine is described, together with a suitable controller. Wind speed is determined as a function of azimuthal angle. Wind speed is then predicted for individual blades over a prediction horizon using this determination of wind speed as a function of azimuthal angle. The predicted wind speed for each individual blade is used in a performance function, which is optimized to control individual blade pitches.

A wind turbine includes a plurality of wind turbine blades; a plurality of hydraulic actuators for controlling respective pitch angles of the wind turbine blades; a first tank storing control oil for the hydraulic actuators; a first hydraulic pump disposed between the plurality of hydraulic actuators and the first tank, for pumping the control oil; a plurality of valves each of which is provided for corresponding one of the hydraulic actuators, for controlling a supply state of the control oil to the hydraulic actuator; and a control part for controlling each of the valves. The control part is configured to, in warm-up of a pitch hydraulic system of the plurality of wind turbine blades, perform an oil transfer operation of changing the pitch angle of the wind turbine blade from a feather side toward a fine side and then returning the pitch angle to the feather side.

Systems, methods, and kits for reducing structural vibrations on wind turbine blades are provided. The actual dynamic structural conditions of a wind turbine blade can be used as a feedback mechanism. A flow control device and a sensor can be installed on a wind turbine blade, and a closed loop control system in operable communication with the flow control device and the sensor can be used to provide closed loop control.

The present invention refers to a method for operating a wind turbine, the wind turbine particularly comprising a tower and a rotor with rotor blades. The pitch angles of the rotor blades are adjusted to generate a force on the rotor and the tower. The force is adjusted to counteract and damp an oscillation. The adjustment is enabled by an activation decision unit, if the activation decision unit decides that certain parameters characterising the oscillation or loads of the tower indicate a requirement and/or if the activation decision unit determines that the generated force is sufficient to counteract an oscillation of the tower. In various embodiments the parameters characterising the oscillation or loads of the tower comprise current oscillations and their amplitude, an estimate of loads incurred in the turbine structure, an estimate whether damping in the near future might become necessary, an indication whether a different oscillation damping algorithm than individual blade pitch control is currently performing, and an indication whether a wind speed is above a certain portion of a rated wind speed.