Abstract: Methods of measuring a stall condition of a rotor of a wind turbine are disclosed. In one aspect a stall parameter is obtained on the basis of the power parameter and a thrust parameter; and the stall parameter compared with a threshold to determine a stall condition of the rotor.

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 of operating a wind turbine generator comprising a plurality of blades, the method comprising iterating the following steps: comparing an indicated rotor speed with a rotor speed target to determine a rotor speed error; generating a modified rotor speed error by applying a control factor to the rotor speed error; controlling the pitch angle of the blades via a pitch control system in accordance with the modified speed error; and altering the control factor in dependence on a size of the indicated rotor speed.

Abstract: The invention relates to a method for controlling a wind turbine during start up, from a non-producing operation mode to a power producing operation mode when limit cycles occur during start-up. Limit cycles are detected when a number of cut-in transitions or a number of cut-out transitions are detected. A cut-in transition is when the wind turbine fails starting up despite having the wind speed or rotor speed normally required to enter a power producing operation mode. A cut-out transition is occurring when the wind turbine is falling out of power producing operation mode after having entered the power producing operation mode.

Abstract: Aspects of the present invention relate to controlling a wind turbine having a tower damping system actuable to control components of vibrational movement of the tower, a side-side component of a vibrational movement of the tower in a horizontal plane; and a fore-aft component of the vibrational movement of the tower in the horizontal plane are determined; and a control signal based on the side-side and fore-aft components is determined such that the tower damping system produces a force that increases or decreases the vibrational movement of the tower such that the side-side and fore-aft components are substantially equal.

Abstract: A method of controlling a wind turbine blade of a wind turbine comprising: providing data comprising a plurality of pitch angles of the wind turbine blade and corresponding expected power coefficients for the wind turbine, each pitch angle corresponding to a maximum expected power coefficient for a degradation state of the wind turbine blade; obtaining a current power coefficient of the wind turbine; determining a desired pitch angle for the wind turbine blade, the desired pitch angle being equal to a pitch angle from the dataset corresponding to an expected power coefficient equal to the current power coefficient; and changing a pitch angle of the wind turbine blade to the desired pitch angle.

Abstract: Methods of measuring a stall condition of a rotor of a wind turbine are disclosed. In one aspect a stall parameter is obtained on the basis of the power parameter and a thrust parameter; and the stall parameter compared with a threshold to determine a stall condition of the rotor.

Abstract: A first aspect of the invention provides a method of controlling a rotor of a wind turbine, the method comprising: obtaining a determination of whether there is ice on the rotor; obtaining one or more factors; generating an ice likelihood based on the obtained one or more factors, wherein the ice likelihood is indicative of whether it is likely that ice is building up on the rotor or thawing on the rotor; generating a confidence level based on the determination and the ice likelihood, wherein the confidence level provides an indication of the confidence that the determination is true; and controlling the wind turbine based on the confidence level.

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: The present invention relates to blade monitoring of a wind turbine by actively promoting blade vibrations by imposing a pitch actuation signal. A method of operating a wind turbine is disclosed where for each blade of a wind turbine, vibrations of the blade are actively promoted by imposing a pitch actuation signal to the pitch actuator, and at least one parameter relating to the blade vibration is determined.

Abstract: A method of operating a wind turbine generator comprising a plurality of blades, the method comprising iterating the following steps: comparing an indicated rotor speed with a rotor speed target to determine a rotor speed error; generating a modified rotor speed error by applying a control factor to the rotor speed error; controlling the pitch angle of the blades via a pitch control system in accordance with the modified speed error; and altering the control factor in dependence on a size of the indicated rotor speed.

Abstract: The invention relates to a method for controlling a wind turbine during start up, from a non-producing operation mode to a power producing operation mode when limit cycles occur during start-up. Limit cycles are detected when a number of cut-in transitions or a number of cut-out transitions are detected. A cut-in transition is when the wind turbine fails starting up despite having the wind speed or rotor speed normally required to enter a power producing operation mode. A cut-out transition is occurring when the wind turbine is falling out of power producing operation mode after having entered the power producing operation mode.

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: There is provided a method of controlling power output of a wind turbine at below-rated wind speed, the method comprising: determining an indication of blade torsion of one or more rotor blades of the wind turbine in dependence on wind speed and/or rotor speed; determining a torsion-corrected blade pitch based on the indication of blade torsion; and using the torsion-corrected blade pitch to control pitch the one or more rotor blades.

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: 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: 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 charging an energy storage system, such as a battery, a capacitor, or a super capacitor, using a wind turbine is described. The method comprises establishing if turbine power production can be increased and establishing if the energy storage system is capable of taking a charge. If both conditions are met, the power generated by the wind turbine is increased above a rated power of the wind turbine and the additional power is used to charge the energy storage systems. A method of control is also disclosed.