A system for monitoring the axial position of a rotating shaft includes a phonic wheel mounted coaxially to the shaft for rotation with a circumferential row of teeth. The system includes a sensor configured to detect the passage of the teeth by generating an alternating measurement signal. First and second portions of the teeth alternate around the row and contribute respective first and second components to the alternating measurement signal. The first portion of teeth vary in height in an axial direction of the wheel such that the relative height of the first and second portions varies with axial distance across the phonic wheel, and the sensor is positioned relative to the phonic wheel such that axial displacement of the shaft causes the signal to vary the first component's amplitude relative to the second component's amplitude due to the height variation, to monitor the axial position of the shaft.

The present invention relates to a damper unit for damping oscillations of a tower structure when secured thereto, the damper unit comprising a damper unit structure adapted for attachment to the tower structure, a pendulum structure, a suspension arrangement for suspending the pendulum structure from the damper unit structure such that the pendulum structure is allowed to displace from a neutral position for the pendulum structure, the suspension arrangement comprising one or more wires for suspending the pendulum structure, a sensor adapted for measuring oscillations of the tower structure, and tuning means configured for adjusting the natural frequency of the suspended pendulum structure in response to measured oscillations of the tower structure. The present invention further relates to an associated method.

A method and associated system are provided for determining a yaw heading (θ.sub.heading) of a wind turbine, the wind turbine having a tower and a nacelle that includes a machine head and rotor at a top thereof. The method includes configuring a single rover receiver of a global navigation satellite system (GNSS) at a fixed position relative to the nacelle. A GNSS geographic location of a tower top pivot point (TPP) of the wind turbine is determined, as well as an angular offset of the rover receiver (β.sub.rover) relative to a centerline axis of the nacelle. Based on the GNSS geo-location of the TPP and a GNSS geo-location of the rover receiver, an angular vector () relative to North of a line between the TPP and the rover receiver is determined. The yaw heading (θ.sub.heading) is computed from a difference between the angle () and the angular offset (β.sub.rover) of the rover receiver.

The system and method of the present disclosure is configured to monitor changes associated with an air gap by: (1) receiving one or more sensor signals from one or more sensors that are indicative of changes associated with the air gap; and (2) comparing the changes associated with the air gap to certain thresholds to determine if the air gap is in need of attention. The system includes at least one proximity sensor arranged adjacent to the air gap, to monitor the air gap, and a controller. The controller is configured to receive the sensor signal(s) indicative of the changes associated with the air gap. The controller also is configured to compare the changes associated with the air gap to one or more air gap thresholds, and to implement a control action based on this comparison.

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 method of adjusting a drive mechanism includes measuring backlashes between the ring gear and the plurality of drive devices, and determining about positions of the plurality of drive devices with reference to the ring gear based on the backlashes measured in the measurement step. The measurement step includes: aligning the pinion of one of the plurality of drive devices to face a reference position in a circumferential direction of the ring gear and measuring a backlash between the ring gear and the said one drive device; and aligning the pinion of another one of the plurality of drive devices to face the reference position of the ring gear by revolving the plurality of the drive devices relative to the ring gear, and measuring a backlash between the ring gear and the said another drive device different from the said one drive device whose backlash has been measured.

A method and associated system are provided for determining a yaw heading (θ.sub.heading) of a wind turbine, the wind turbine having a tower and a nacelle that includes a machine head and rotor at a top thereof. The method includes configuring a single rover receiver of a global navigation satellite system (GNSS) at a fixed position relative to the nacelle. A GNSS geographic location of a tower top pivot point (TPP) of the wind turbine is determined, as well as an angular offset of the rover receiver (β.sub.rover) relative to a centerline axis of the nacelle. Based on the GNSS geo-location of the TPP and a GNSS geo-location of the rover receiver, an angular vector () relative to North of a line between the TPP and the rover receiver is determined. The yaw heading (θ.sub.heading) is computed from a difference between the angle () and the angular offset (β.sub.rover) of the rover receiver.

A monitoring system (100) monitors displacement of a wind turbine tower and includes at least one plumb bob with an upper part and a lower part, each plumb bob being configured to be pivotally suspended at its upper part, via a suspension device, from a point above so as to attain a rest position in a rest situation, and each said plumb bob has one or more sensing surfaces (12, 12′). One or more suspension devices means (10) suspend the at least one plumb bob. Two or more sensors (14, 14′, 14″), each being configured to sense, in a specific sensing direction (16, 16′, 16″), a distance to a plumb bob, provide displacement data. At least two of the two or more sensors (14, 14′, 14″) are arranged in a sensing vicinity of a plumb bob, with at least two of the specific sensing directions (16, 16′, 16″) not being parallel to each other. The monitoring system includes a control unit (18) configured to receive the displacement data from two or more of the sensors, and a device for reporting, to an external unit (20), parameter(s) representing displacement of a wind turbine tower.

A method of determining the shape of at least part of a wind turbine blade during operation of the wind turbine, the method comprising measuring first and second values of acceleration at one or more locations on the blade, the first and second values of acceleration being in substantially mutually perpendicular directions, and determining a shape parameter of the blade based upon the relative magnitudes of the measured first and second values of acceleration at the one or more locations.

A main shaft assembly of a wind turbine and method for manufacturing the same are provided. Accordingly, the main shaft assembly includes a structural/shaft body defining a cavity therein. The shaft body is configured to transmit a load of the wind turbine developed in response to the wind. An inner body is located within the cavity. The inner body is non-loadbearing with respect to the load. At least one sensor is coupled to the inner body and positioned within the cavity for detecting a deflection of the shaft body in response to the load.