A method for damping an oscillation of a tower of a wind turbine is disclosed, wherein a pitch angle of each of the one or more rotor blades is individually adjustable, the method comprising damping the oscillation of the tower by pitching each rotor blade individually according to tower damping pitch control signals, wherein each tower damping pitch control signal comprises a first periodic component, where a first frequency of the first periodic component corresponds to a frequency difference between a tower frequency of the oscillation of the tower and a rotor frequency of a rotation of the rotor, and where a second periodic component has been reduced or removed. A second frequency of the second periodic component corresponds to a frequency sum of the tower frequency and the rotor frequency.

The lengths and/or chords and/or pitches of wind turbine or propeller blades are individually established, so that a first blade can have a length/chord/pitch that is different at a given time to the length/chord/pitch of a second blade to optimize performance and/or to equalize stresses on the system.

A method of controlling a wind turbine having a nacelle, a rotor, a rotating hub, a first rotor blade and at least a second rotor blade, both rotor blades being mounted to the hub. The method includes measuring the strain in the first rotor blade by a strain measurement device attached to the first rotor blade; and choosing the operational parameters of the wind turbine based on the measured strain such that fatigue damage of the second rotor blade is reduced. A wind turbine is controlled by such a method.

There is provided a method for controlling a hydraulic pitch force system (220) so as to reduce or eliminate a decrease in hydraulic oil pressure (241) if a hydraulic system parameter value is outside a hydraulic system parameter range, the method comprising: Obtaining (690) the hydraulic system parameter value, and operating the hydraulic pitch force system (220) according to a reduced mode (692) if the hydraulic system parameter value is outside the hydraulic system parameter range, wherein in the reduced mode one or more pitch based activities are reduced (694) or suspended. An advantage thereof may be that it enables keeping the wind turbine in production in certain instances rather than shutting down the wind turbine. In aspects, there is furthermore presented a computer program product, a pitch control system (250) and a wind turbine (100).

An actuator device for a wind power installation, in particular for a rotor blade of a wind power installation, and also to an associated wind power installation and a method of assembly, with an actuator component and a control component, wherein the actuator component has at least one actuator layer with a preferential direction and, substantially parallel to the actuator layer, at least one exciting layer, wherein the actuator layer comprises a photoactuator, wherein the photoactuator is designed to change a strain and/or stress of the actuator layer in the preferential direction on the basis of excitation light, wherein the exciting layer is designed to guide excitation light into the actuator layer, wherein the control component comprises a light source and a light guide, wherein the light source is arranged away from the exciting layer and is connected to the exciting layer by means of the light guide. The actuator device makes it possible to ensure greater operational reliability.

An airfoil performance monitor comprising a housing mounted on a low pressure face of an airfoil, and defining pitot and static pressure orifices; an airspeed-dependent sensor that senses airflow impinging on the pitot orifices and generates a digital airflow signal indicative of turbulence of the airflow; and a controller that derives a turbulence intensity ratio by filtering turbulence values calculated from the digital airflow signal.

The present invention relates to a method of correcting rotor imbalance and a wind turbine thereof. The correction method comprises measuring the vibrations within at least one time window and determining an imbalance factor and an imbalance phase. The values of the parameters in the equation for calculating the correction action are then updated based on the imbalance factor and an imbalance phase. A correction angle for each of the wind turbine blades is calculated using these adjusted parameters. The correction angle is used to aerodynamically balance the rotor, and a model may be used to determine the initial values of the parameters. Another imbalance factor and imbalance phase is determined based on another set of measurements. This imbalance factor is then used to calculate a mass moment for correcting the mass imbalance in the wind turbine blades. The weight and location of a balancing mass is finally calculated based on this mass moment and installed in the respective wind turbine blades.

Provided is a pitch apparatus of a wind turbine. The wind turbine includes a wheel hub and multiple blades. The pitch apparatus includes a pitch bearing, a transmission element and a driving mechanism for driving the transmission element. The pitch bearing includes a bearing inner race and a bearing outer race. The bearing inner race is fixedly connected to the blade, the bearing outer race is fixedly connected to the wheel hub. The transmission element is driven by the driving mechanism, and drives the bade and the bearing inner race to rotate in relative to the wheel hub. A load level of ultimate bending moment for a blade root and a safety factor of the pitch apparatus increase, failure risks of the pitch bearing, bolts and the transmission belt are reduced. A wind turbine having pitch apparatus are provided.

A method for controlling a wind turbine having rotor blades with an adjustable blade angle, comprising the steps operating the wind turbine in a partial load mode for wind velocities up to a nominal wind velocity, wherein in the partial load mode, a fixed partial load angle is provided for the blade angle, operating the wind turbine in a full load mode for wind velocities above the nominal wind velocity, wherein in the full load mode the blade angle is enlarged with increasing wind velocity and has values above the partial load angle, and wherein in the partial load mode, starting from a predetermined operating state, the blade angle is reduced as compared with the partial load angle.

The invention provides a method for controlling a wind turbine. The method predicts behaviour of the wind turbine components for the time stages over a prediction horizon using a wind turbine model describing dynamics of the wind turbine, where the time stages include a first set of time stages from an initial time stage and a second set of time stages subsequent to the first set. The method determines control outputs, e.g. individual blade pitch, for time stages based on the predicted behaviour. The method then transmits a control signal to implement only the control outputs for each of the second set of time stages so as to control the wind turbine. Advantageously, the invention reduces both average and peak computational loads relative to standard predictive control algorithms.