The present disclosure relates to methods and systems for measuring deflection of blades of a wind turbine. Examples include a light emitting and collection device mounted to the nacelle and configured to emit light in a direction within a substantially vertical plane. Examples include a method for operating a wind turbine including emitting light above a hub, receiving the light when reflected by a blade of the wind turbine, and, if the level of blade deflection is above a threshold, reducing blade loading of the blade before the blade reaches a vertically downward position. Examples include a method for monitoring deflection of a rotor blade of a wind turbine comprising emitting a light sheet, collecting reflections of the emitted light, and determining deflection of the rotor blade by determining a time during which the blade reflects the emitted light sheet.

A rotor arresting device, a wind turbine and a method for arresting and/or rotating a rotor. The rotor arresting device comprises a rotor, a rotational assembly, and a static assembly fixed in position, comprising a toothed disk, which can be arranged on the rotational assembly, having a plurality of arresting recesses arranged along a circumference, wherein two adjacent arresting recesses form a tooth, a first arresting module having at least one first arresting element, a second arresting module having at least one second arresting element, wherein the first and the second arresting module can be arranged on the static assembly, wherein the first and the second arresting element are arranged and designed to engage in arresting recesses of the toothed disk, wherein the spacing of the first arresting element from the second arresting element in the circumferential direction of the toothed disk is a non-integral multiple of a tooth tip spacing of the toothed disk.

In a vertical rotor apparatus that rotates in response to a moving fluid, a shaft defines an axis of rotor rotation. Rotor blades are longitudinally aligned in parallel with the shaft and each rotor blade defines an axis of blade rotation. A sensor generates a signal when any of the rotor blades are within rotor azimuthal angles of blade stall regions. A controller generates blade pitch information for the blade stall regions and an actuator, which is mechanically coupled to each of the rotor blades, alters blade pitch about the axis of blade rotation in accordance with the blade pitch information.

The invention provides a method for determining angular position of a generator shaft of a wind turbine. The method includes receiving a position signal, from an encoder position sensor of the wind turbine, indicative of an angular position of the generator shaft. The method includes determining a compensation signal to compensate for a disturbance signal in the received position signal indicative of an imperfection associated with the encoder position sensor. The method includes modifying the position signal by applying the determined compensation signal to the received position signal to determine angular position.

In a vertical rotor apparatus that rotates in response to a moving fluid, a shaft defines an axis of rotor rotation. Rotor blades are longitudinally aligned in parallel with the shaft and each rotor blade defines an axis of blade rotation. A sensor generates a signal when any of the rotor blades are within rotor azimuthal angles of blade stall regions. A controller generates blade pitch information for the blade stall regions and an actuator, which is mechanically coupled to each of the rotor blades, alters blade pitch about the axis of blade rotation in accordance with the blade pitch information.

A turner gear assembly (52) for turning an unbalanced rotor of a wind turbine (10) having a drivetrain (30). The turner gear assembly (52) includes a turner gear (50) configured to couple to the drivetrain (30) and having at least two motors (58a, 58b), and a valve block (78) connectable to the turner gear (50) and having a first flow control valve (106) configured to be in fluid communication with a pump (80) and with the at least two motors (58a, 58b). The first flow control valve (106) is selectively moveable between a first fluid control position (106a) and a second fluid control position (106b). When the first flow control valve (106) is in the first fluid control position (106a), the at least two motors (58a, 58b) operate in parallel and when the first flow control valve (106) is in the second fluid control position (106b), the at least two motors (58a, 58b) operate in series. A method of operating the turner gear assembly is also disclosed.

In a vertical rotor apparatus that rotates in response to a moving fluid, a shaft defines an axis of rotor rotation. Rotor blades are longitudinally aligned in parallel with the shaft and each rotor blade defines an axis of blade rotation. A sensor generates a signal when any of the rotor blades are within rotor azimuthal angles of blade stall regions. A controller generates blade pitch information for the blade stall regions and an actuator, which is mechanically coupled to each of the rotor blades, alters blade pitch about the axis of blade rotation in accordance with the blade pitch information.

The invention relates to a method of identifying a wind distribution pattern over a rotor plane and a wind turbine thereof. At least one operating parameter of the wind turbine and a rotational position of the rotor are measured over a time period. A first wind turbine blade passing signal is extracted from the measured operating parameter and a second wind turbine blade passing signal is generated from the rotational position. The first and second wind turbine blade passing signals are then analysed to determine the characteristics of the actual wind turbine blade passing signal in the rotor plane. These characteristics are afterwards compared to the characteristics of a plurality of known wind distribution patterns, and a unique relationship between the characteristics of the wind turbine blade passing signal and the wind distribution pattern is used to identify a distinctive wind distribution pattern.

A wind turbine includes a rotor, a plurality of rotor blades coupled to the rotor, and a blade pitch control system coupled to each rotor blade. A computer-implemented method for controlling the wind turbine includes determining at least one pitch position for a first blade. The method also includes determining whether there is a malfunction of the blade pitch control system associated with the first blade. The method further includes predicting a rotor imbalance using a model of at least a portion of the wind turbine. The method also includes comparing the predicted rotor imbalance with a predetermined threshold value. The method further includes one of regulating the pitch position for the second blade such that the predicted rotor imbalance is restored to a value below the predetermined threshold and regulating a pitch position for a second blade such that the predicted rotor imbalance does not exceed the predetermined threshold.

A method of controlling a wind turbine comprising blades attached to a rotor hub for rotation in a rotor plane and a control system for individually pitching the blades relative to the hub. The method comprises dividing the rotor plane into a number of sectors, determining the individual sectors for each blade during the rotation by means of an azimuth angle sensor, and obtaining blade sensor data from a blade sensor on an individual blade relating to a sector, and comparing the obtained data with data relating to the same sector and representing blade sensor data on other blades. When an event is detected in a given sector, an individual pitch contribution is determined in the sector, and the blades are then pitched according to this individual pitch contribution for that given sector at least partly during passage of the sector.