Abstract: 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.

Abstract: A sensor system for a wind turbine blade, the system comprising: a blade load sensor providing a load measurement; a processing unit interfaced with the blade load sensor and configured to provide a corrected load parameter as an output. The processing unit includes: an axial force estimation module that determines an estimated axial force on the wind turbine blade in a direction along the length of the blade; and a load calculation module that 10 determines the corrected load parameter based on the estimated axial force and the load measurement of the blade load sensor.

Abstract: A method of measuring load on a wind turbine, and a wind turbine for such load measuring, are disclosed. The wind turbine comprises at least one rotor blade and at least one load sensor associated with the rotor blade. At least one load sensor is located at a position on the rotor blade remote from both a flap bending moment axis and an edge bending moment axis of the rotor blade. At the position, a flap bending moment component and an edge bending moment component of the load on the rotor blade are measurable. A load value is measured from the load sensor, and the measured load value is used to determine a flap bending moment component of the load and an edge bending moment component of the load, and optionally or additionally an axial force component of the load.

Abstract: A wind turbine comprising a tower, a nacelle, a rotor including a plurality of blades, an electrical generator operatively coupled to the rotor, and a control system. The control system comprises: a sensing system operable to output a signal indicative of the torsional oscillation frequency of the nacelle; a torsional damping module configured to monitor the torsional oscillation signal and to determine one or more blade pitch command signals for damping the torsional oscillation of the tower, and a filter module configured to receive the one or more blade pitch command signals as inputs and to output a respective one or more modified blade pitch command signals, wherein the filter module is configured to filter the one or more blade pitch command input signals to exclude frequency components greater than the torsional oscillation frequency. Aspects of the invention also relate to a method, a computer program software product and a controller for implementing the method.

Abstract: The invention presents a method for operating a horizontal axis wind turbine, the wind turbine comprising a tower and a rotor with at least one rotor blade, the rotor being connected to the tower, and being adapted to drive a generator connected to a utility grid, wherein a pitch angle of each rotor blade is adjustable, the method comprising detecting, when the wind turbine is in an idling power producing situation in relation to the utility grid, a tower oscillation, and controlling, when the wind turbine is in the idling power producing situation, the pitch angle of the at least one rotor blade so as to produce aerodynamic forces counteracting the detected tower oscillation.

Abstract: The present invention relates to control of a wind turbine where nacelle vibration is reduced by use of blade pitching. The nacelle vibrations are reduced based on a position signal of the nacelle. A pitch signal is determined based on the position signal and applied to the pitch-adjustable rotor blades in order to reduce nacelle vibration.

Abstract: The invention relates to a method for determining dynamic parameters associated with damping properties of a wind turbine. The method involves active excitation of tower oscillations by adjusting the pitch or rotor torque. After the active excitation, the parameters can be determined from the passive decay of the excited oscillations. Alternatively, the oscillations can be actively damped, so that the parameters can be determined from the active decay of the excited oscillations. The method for promoting oscillations may be triggered in response to different events or in response to predetermined times for determining the actual dynamic parameters.

Abstract: The invention relates to a method for controlling a wind turbine in partial and full load. In order to avoid disadvantages of switching between partial and full load controllers, the wind turbine control system is configured so that both the partial and full load controller provides control action during partial and full load. For that purpose, the partial and full load controllers are configured with variable gains, wherein gain scheduling is performed so that the gain of partial load controller is larger than the gain of the full load controller during partial load and vice verso so that the gain of the full load controller is larger than the gain of the partial load controller during full load.

Abstract: The invention relates to a method for wind turbine generators for reducing electrical disturbances in the form of power variations which are caused by damping controllers arranged the compensate structural oscillations by inducing shaft torque variations. The shaft torque variations are generated by imposing corresponding variations in a generator set-point, e.g. a power or torque set-point. Variations in the generator set-point cause undesired variations in the power injected to the grid by one or more wind turbine generators. According to an embodiment of the invention the electrical disturbances may be reduced by limiting a damping controller's control action. The amount of limitation or restriction of the damping controller may be determined on basis on electrical disturbance information determined from power measured e.g. at a location on the grid.

Abstract: A diagnostic system for use in a wind turbine yaw system, comprising: a tower motion sensor configured to output a signal indicative of tower oscillation, in particular though not exclusively side to side tower oscillation, and a diagnostic module configured to: analyse the tower motion sensor signal to identify frequency content of the signal that is not associated with the tower oscillation; and correlate the identified frequency content with the operation of the yaw system thereby to determine that the yaw system requires maintenance. Beneficially the invention provides that the health of the yaw system can be determined by analysing the oscillatory movement of the tower as measured by a tower motion sensor installed at a suitable location for example at the top of the tower or in the nacelle for example.

Abstract: A method of detecting a fault mode of a sensor is provided. The sensor may be, for example, a bending moment sensor and may sense a bending moment of a blade on a wind turbine generator (WTG). The method includes comparing data output by a first sensor with reference data indicating what is expected to be output by the first sensor to produce a first comparison result and comparing data output by the first sensor with data output by a second sensor to produce a second comparison result. A determination of whether the first sensor has entered a fault mode is made based at least in part on the first and second comparison results.

Abstract: A method is provided for controlling the shutdown of a wind turbine of the type having a rotor, the rotor comprising one or more wind turbine blades. The method comprises dynamically determining a rotor speed reference; obtaining a measure of the rotor speed of the rotor; determining an error between the rotor speed reference and the rotor speed of the rotor; and controlling a pitch of one or more of the wind turbine blades based on the determined error. A corresponding wind turbine controller and a wind turbine including such a controller are also provided.

Abstract: The invention relates to a controller configured to determine one or more future values of blade control references and/or a generator control references for a wind turbine generator. The first of the future values of the control references are used for control purposes. The future control references are determined from a physical model of a system of the wind turbine generator by solving an optimization problem which includes at least one cost function and at least one constraint.

Abstract: There is presented a method for damping an edgewise vibration of a rotor blade of a wind turbine, wherein the method comprises measuring at the rotor blade a motion parameter of the edgewise rotor blade vibration, generating based on said motion parameter a blade pitch angle control signal, and damping the edgewise vibration of the rotor blade by pitching the rotor blade according to the blade pitch angle control signal, wherein the blade pitch angle control signal is arranged so that a resulting force on a rotor blade pitched according to the blade pitch angle control signal, in a direction of the edgewise vibration of the rotor blade in a coordinate system, which rotates with a rotor of the wind turbine, is opposite and proportional to the edgewise rotor blade vibration velocity.

Abstract: 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).

Abstract: 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.

Abstract: A method of controlling a wind turbine is described. The method involves forecasting the temperature evolution of a component of the wind turbine based upon the current operating parameters of the wind turbine and upon a required power output; predicting from the temperature forecast a future alarm event caused by the temperature of the component exceeding a first threshold level or falling below a second threshold level; and adjusting the operating parameters of the wind turbine to control the temperature evolution of the component thereby to avoid or delay the predicted alarm event.

Abstract: Disclosed are a method and a control arrangement for frequency regulation of an electrical grid operatively coupled with at least one wind turbine generator. The method includes operating the wind turbine generator to consume electrical power from the electrical grid. Further disclosed is a method for increasing a ramp rate capacity of a wind power plant comprising a plurality of wind turbine generators. The method includes operating at least one of the plurality of wind turbine generators to consume electrical power.

Abstract: A sensor system for a wind turbine blade, the system comprising: a blade load sensor providing a load measurement; a processing unit interfaced with the blade load sensor and configured to provide a corrected load parameter as an output. The processing unit includes: an axial force estimation module that determines an estimated axial force on the wind turbine blade in a direction along the length of the blade; and a load calculation module that 10 determines the corrected load parameter based on the estimated axial force and the load measurement of the blade load sensor.

Abstract: A method of measuring load on a wind turbine, and a wind turbine for such load measuring, are disclosed. The wind turbine comprises at least one rotor blade and at least one load sensor associated with the rotor blade. At least one load sensor is located at a position on the rotor blade remote from both a flap bending moment axis and an edge bending moment axis of the rotor blade. At the position, a flap bending moment component and an edge bending moment component of the load on the rotor blade are measurable. A load value is measured from the load sensor, and the measured load value is used to determine a flap bending moment component of the load and an edge bending moment component of the load, and optionally or additionally an axial force component of the load.