Abstract: A method for detecting a rotor blade pitch angle adjustment fault of a rotor blade of a wind turbine is provided, the method includes measuring a rotor blade pitch angle speed; predicting, based on an actual rotor speed, a rotor blade pitch angle speed; indicating a fault, if a first criterion is satisfied, wherein the first criterion is satisfied, if deviation between the measured rotor blade pitch angle speed and the predicted rotor blade pitch angle speed exceeds a speed threshold.

Abstract: A method and a control device for damping an oscillatory movement of the top of a tower of a wind turbine are provided. The described method includes (a) rotating a rotor being rotatably attached to a nacelle of the wind turbine with a rotational speed, and (b) yawing the nacelle of the wind turbine around an axis being aligned with the longitudinal axis of the tower with a yawing speed. Thereby, a yawing movement being associated with yawing the nacelle is coordinated with the oscillatory movement in such a manner that a gyroscopic torque resulting (i) from rotating the rotor and (ii) from yawing the rotor damps the oscillatory movement of the top of the tower. A wind turbine comprising such a control device and a computer program for controlling this method are also provided.

Abstract: A method for controlling a wind turbine with a rotor and at least one rotor blade, and a control unit are disclosed. The method is characterized in adjusting a pitch angle of the rotor blade and determining the limit of an input value based on the adjusted pitch angle, wherein the input value includes information about the turbine rotational speed.

Abstract: A method for detecting a rotor blade pitch angle adjustment fault of a rotor blade of a wind turbine is provided, the method includes measuring a rotor blade pitch angle speed; predicting, based on an actual rotor speed, a rotor blade pitch angle speed; indicating a fault, if a first criterion is satisfied, wherein the first criterion is satisfied, if deviation between the measured rotor blade pitch angle speed and the predicted rotor blade pitch angle speed exceeds a speed threshold.

Abstract: A method is provided for damping an oscillatory movement of a nacelle of a wind turbine. The nacelle is attached to a tower of the wind turbine. The method involves rotating the nacelle about a yawing axis with a yawing speed, the yawing axis being aligned with a longitudinal axis of the tower, changing the yawing speed, and coordinating the yawing speed with the oscillatory movement such that a torque resulting from the change of the yawing speed damps the oscillatory movement of the nacelle of the tower.

Abstract: A method for determining and applying a pitch angle offset signal for controlling a rotor frequency of a rotor of a wind turbine is disclosed. The method includes obtaining a motion quantity indicative of a motion of the rotor and determining the pitch angle offset signal based on the motion quantity such that the pitch angle offset signal is adapted to be used for adjusting a blade pitch angle of a rotor blade mounted at the rotor for controlling the rotor frequency in order to reduce a time span during which the rotor is in a critical motion region. A corresponding system and a method for controlling a rotor frequency are also disclosed.

Abstract: A method and a control device for damping an oscillatory movement of the top of a tower of a wind turbine are provided. The described method includes (a) rotating a rotor being rotatably attached to a nacelle of the wind turbine with a rotational speed, and (b) yawing the nacelle of the wind turbine around an axis being aligned with the longitudinal axis of the tower with a yawing speed. Thereby, a yawing movement being associated with yawing the nacelle is coordinated with the oscillatory movement in such a manner that a gyroscopic torque resulting (i) from rotating the rotor and (ii) from yawing the rotor damps the oscillatory movement of the top of the tower. A wind turbine comprising such a control device and a computer program for controlling this method are also provided.

Abstract: A method for controlling a generator having a rotor with a plurality of magnets and a first stator winding and a second stator winding, electrically separate from the first stator winding is provided. The rotor rotates around a rotation axis perpendicular to a radial direction relative to the stator windings. The method includes allowing flow of a first electric current through the first stator winding, thereby generating a first radial force having a first magnitude and acting between the first stator winding and the rotor, and allowing flow of a second electric current through the second stator winding, thereby generating a second radial force having a second magnitude and acting between the second stator winding and the rotor, wherein the first magnitude is different from the second magnitude resulting in a net generator generated radial force generated by the first stator winding and the second stator winding at the rotor.

Abstract: A method is provided for controlling the pitch systems of a plurality of pitch systems of a wind turbine. The method includes generating a main pitch control signal for the pitch systems on the basis of a performance parameter of the wind turbine and generating a distinct auxiliary pitch control signal for each individual pitch system of the plurality of pitch systems. The method further includes adding an auxiliary pitch control signal to the main pitch control signal to give a combined pitch control signal for a pitch system. The method then includes controlling that pitch system in response to that combined pitch control signal wherein an auxiliary pitch control signal is suppressed when a pitch activity value and/or a pitch variation value is below a predefined threshold.

Abstract: A stall sensor for a wind turbine is provided. A wind turbine including such a stall sensor and a method of operating such a wind turbine are also provided. The stall sensor includes detector means adapted to measure vibration of a rotor blade of the wind turbine and to output a vibration signal representative of the vibration of the rotor blade, conversion means connected to the detector means and adapted to determine a noise figure representative of a spectral signal content within a frequency band of the vibration signal received from the detector means and arbiter means connected to the conversion means and adapted to signal a presence or an absence of stall based on the noise figure received from the conversion means.

Abstract: A method for controlling a generator having a rotor with a plurality of magnets and a first stator winding and a second stator winding, electrically separate from the first stator winding is provided. The rotor rotates around a rotation axis perpendicular to a radial direction relative to the stator windings. The method includes allowing flow of a first electric current through the first stator winding, thereby generating a first radial force having a first magnitude and acting between the first stator winding and the rotor, and allowing flow of a second electric current through the second stator winding, thereby generating a second radial force having a second magnitude and acting between the second stator winding and the rotor, wherein the first magnitude is different from the second magnitude resulting in a net generator generated radial force generated by the first stator winding and the second stator winding at the rotor.

Abstract: A method for operating a wind turbine is proposed. The wind turbine has a rotor, a wind turbine converter and a wind turbine output terminal connected to a utility grid. The converter has a converter output terminal upstream of the wind turbine output terminal. An input signal related to an action output of the wind turbine is obtained at a location between the rotor and the wind turbine output terminal. A power difference is estimated between the power associated with the action output at the location and the output power at the converter output terminal. The converter is controlled based on the input signal and the estimated power difference.

Abstract: It is described an arrangement for determining a target value of an operational variable of a wind turbine, the arrangement comprising: at least one input terminal for receiving at least one operational parameter of the wind turbine; a determining unit adapted to determine a target value of an operational variable of the wind turbine based on the operational parameter. Further, a corresponding method and a wind turbine are described.

Abstract: A method for controlling a wind turbine with a rotor and at least one rotor blade, and a control unit are disclosed. The method is characterised in adjusting a pitch angle of the rotor blade and determining the limit of an input value based on the adjusted pitch angle, wherein the input value includes information about the turbine rotational speed.

Abstract: A method of controlling a wind turbine is provided. The method includes the steps of obtaining a number of operating values relevant to a wind turbine, calculating a thrust setpoint on the basis of the operating values, and controlling a wind turbine according to a thrust setpoint. A wind park controller, a wind turbine controller, and a wind park are also provided.

Abstract: A method and corresponding arrangement are provided for determining pitch angle adjustment signals for adjusting a pitch angle of a rotor blade connected to a rotation shaft of a wind turbine. The method includes obtaining a first maximal speed signal indicative of a first desired maximal rotational speed of the rotation shaft. The method also includes deriving a first pitch angle adjustment signal based on the first maximal speed signal. The method further includes obtaining a second maximal speed signal indicative of a second desired maximal rotational speed of the rotation shaft different from the first desired maximal rotational speed of the rotation shaft. Further, the method includes deriving a second pitch angle adjustment signal based on the second maximal speed signal. The second pitch angle adjustment signal is different from the first pitch angle adjustment signal.

Abstract: A method for determining and applying a pitch angle offset signal for controlling a rotor frequency of a rotor of a wind turbine is disclosed. The method includes obtaining a motion quantity indicative of a motion of the rotor and determining the pitch angle offset signal based on the motion quantity such that the pitch angle offset signal is adapted to be used for adjusting a blade pitch angle of a rotor blade mounted at the rotor for controlling the rotor frequency in order to reduce a time span during which the rotor is in a critical motion region. A corresponding system and a method for controlling a rotor frequency are also disclosed.

Abstract: A wind turbine includes a rotor, a permanent magnet generator and a generator converter, whereby an electric or electronic switch, which is arranged between the permanent magnet generator and the generator converter, is provided for selectively connecting the permanent magnet generator to at least one braking resistor.