Abstract: Operating a wind turbine generator (WTG) comprising a pitch control system, the operation comprising: a) operating the WTG in a normal mode while the WTG is connected to an external grid; b) controlling the pitch angle of the blades using a normal pitch control mode while the WTG is operating in the normal mode; c) detecting a grid loss; d) operating the WTG in a standby mode during the grid loss; and e) controlling the pitch angle of the blades in dependence on a monitored speed parameter of the WTG using a standby pitch control mode different to the normal pitch control mode while the WTG is operating in the standby mode, wherein the standby pitch control mode is less responsive than the normal pitch control mode such that the power consumption of the pitch control system is reduced when the WTG is operating in the standby mode.

Abstract: The present invention relates to control of a wind turbine where nacelle vibration is reduced by use of blade pitching or generator torque modulation. The nacelle vibrations are reduced based on a position signal of the nacelle. An actuator signal is determined based on the position signal and applied to the actuator capable of reducing nacelle vibration. The actuator signal is gain adjusted based on a separation between the rotor frequency and tower vibration frequency.

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: A plurality of wind turbine blades or blade portions have substantially the same size and outer geometrical shape, and corresponding plies of the blades or blade portions having the same position within the respective wind turbine blades or blade portions have different fibre orientation angles relative to a pitch axis of the respective wind turbine blade or blade portion. By changing the fibre orientation angles of the corresponding plies a bend-to-twist coupling of the blade or blade portions may be varied amongst the plurality of blades or blade portions. The blades may then be tailored according to their siting within or on a wind turbine park. A common mould shape may be used across the plurality of wind turbine blades or blade portions, together with a more streamlined blade design process.

Abstract: A method for determining the load on a wind turbine blade, comprising: measuring the blade load by way of a wind turbine blade load sensor; estimating the temperature of the blade; and determining, based on the estimated temperature and the measured load, a temperature-corrected value for the load on the wind turbine blade. The invention also relates to a sensor system for a wind turbine blade, the system comprising a load sensor; a processing unit interfaced with the load sensor and configured to provide a temperature-corrected load parameter as an output, wherein the processing unit includes: a temperature estimation module that determines an estimated temperature of the blade in the vicinity of the load sensor based on at least one wind turbine parameter; and a load compensation module that determines the temperature-corrected load parameter based on the estimated temperature and the measurement of the load sensor.

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: 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: Embodiments herein describe a hydraulic pitch system where a velocity (e.g., the velocity of a hydraulic cylinder or the piston rod in the cylinder) is fed forward and combined with a setting outputted by a pitch controller. The velocity of the hydraulic cylinder is derived from the reference pitch angle or a continuous pitch signal (e.g., a cyclic pitch or ramp rate) in the control system. In either case, the velocity can be determined by monitoring the change in the reference pitch angle or the continuous pitch signal. Using a gain control, the velocity is converted into a position setting of the hydraulic pitch system (e.g., a spool setting in a valve) which is combined with another position setting generated by the pitch controller.

Abstract: The invention provides a method for controlling a wind turbine, including predicting behaviour of one or more wind turbine components such as a wind turbine tower over a prediction horizon using a wind turbine model that describes dynamics of the one or more wind turbine components or states. The method includes determining behavioural constraints associated with operation of the wind turbine, wherein the behavioural constraints are based on operational parameters of the wind turbine such as operating conditions, e.g. wind speed. The method includes using the predicted behaviour of the one or more wind turbine components in a cost function, and optimising the cost function subject to the determined behavioural constraints to determine at least one control output, such as blade pitch control or generator speed control, for controlling operation of the wind turbine.

Abstract: A method for wind turbine tower damping is disclosed, as well as an associated controller and wind turbine. The method comprises determining, using one or more sensor signals, dynamic state information for a tower of a wind turbine during power production, wherein the dynamic state information comprises a tower frequency. The method further comprises determining at least one control loop gain value using the tower frequency, and generating, using the at least one control loop gain value, one or more control signals for controlling a rotational speed of a rotor of the wind turbine.

Abstract: A method for wind turbine tower damping is disclosed, as well as an associated controller and wind turbine. The method comprises generating, using at least a first sensor signal, a first pitch reference signal for one or more rotor blades of a wind turbine during partial load operation. The method further comprises determining, using at least a second sensor signal, dynamic state information for a tower of the wind turbine. The method further comprises generating a second pitch reference signal by adapting the first pitch reference signal using the dynamic state information. The method further comprises selecting a maximum pitch reference signal from the second pitch reference signal and a saturation pitch reference signal. The method further comprises communicating the maximum pitch reference signal to control a pitch of the one or more rotor blades.

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: 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 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 is provided for controlling the shutdown of a wind turbine of the type having a rotor, the rotor including one or more wind turbine blades. The method includes 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: This application describes a method of detecting an error in a rotor angle sensing system of a wind turbine, where the wind turbine comprises a rotor including a plurality of wind turbine blades, a blade load sensor associated with a respective one of the wind turbine blades, and a rotor angle sensing system configured to output a rotor angle signal. The blade load sensor is configured to output a measured blade load signal. The method comprises generating an estimated blade load signal based on at least the rotor angle signal; comparing the estimated blade load signal with the measured blade load signal to determine a phase difference between them; and identifying an error if the phase difference between the estimated blade load signal and the measured blade load signal exceeds a predetermined threshold.

Abstract: A method of calibrating load sensors of a wind turbine, and a wind turbine for such load sensor calibration, are disclosed. The wind turbine comprises a rotor, a plurality of rotor blades, and a plurality of load sensors associated with the rotor blades. While the rotor is rotating, at least one of the rotor blades is moved from a first calibration position to a second calibration position, and load values from the load sensors are measured. The number of rotor blades being moved is at least one fewer than the number of the plurality of rotor blades. The rotation of the rotor may be during idling of the wind turbine. The movement of the blade(s) may be to change the pitch angle of the blade(s). At least one of the rotor blades not being moved to a calibration position may also be moved, for example to control the rotational speed of the rotor.

Abstract: The invention relates to a control apparatus and method for controlling the rotor blades of a wind turbine, and in particular to controlling the rotor blades during an extreme wind event. An extended mode of operation of the wind turbine rotor beyond the cut-out wind speed is provided. In the extended mode of operation, the pitch of the wind turbine blades is actively controlled so that the rotor and the generator idle at a designated rotational speed. The rotational speed may be relatively high, say 15 to 20% of the nominal speed, compared with minimal speeds experienced by purely feathered wind turbine blades, and may be further controlled as a function of the incident wind speed. Output power control in the extended mode may be zero but is preferably a low, but non-zero value. The output power so produced may then be used as an auxiliary power source for controlling the wind turbine in situations where the utility grid fails.

Abstract: The present invention relates to control of a wind turbine where nacelle vibration is reduced by use of blade pitching or generator torque modulation. The nacelle vibrations are reduced based on a position signal of the nacelle. An actuator signal is determined based on the position signal and applied to the actuator capable of reducing nacelle vibration. The actuator signal is gain adjusted based on a separation between the rotor frequency and tower vibration frequency.

Abstract: A sensor system for a wind turbine, comprising: a blade load sensor; a blade temperature sensor configured to provide a temperature measurement of an associated blade; a load calculation module configured to output a temperature-corrected blade load value; and a processing unit interfaced with the temperature sensor. The processing unit includes a temperature estimator configured to determine an estimated temperature of the wind turbine blade based on at least one wind turbine parameter; and a comparator configured to generate a fault signal based on a comparison between the blade temperature measurement and the estimated blade temperature. The invention also resides in a corresponding method.