Disclosed are a method and apparatus for detecting a yaw-to-wind abnormality. The method includes: acquiring a wind direction deviation angle within a specified time period; calculating a power performance index, wherein the power performance index is a dimensionless number used to characterize power generation performance of a wind turbine; determining an optimal wind direction deviation angle based on the power performance index; determining a current wind direction deviation angle according to probability distribution of the wind direction deviation angle; and if a difference between the optimal wind direction deviation angle and the current wind direction deviation angle is greater than a preset threshold, determining that a yaw-to-wind abnormality is detected. Compared with the related technology in which yaw-to-wind detection is performed through a power fitting curve, in the technical solution according to the embodiments of the present disclosure, a power index is directly used, which avoids the problem of poor power curve fitting effect and improves the accuracy of yaw-to-wind detection.

A method and a device for dampening movement in a multiple rotor (MR) wind turbine located at sea and comprising a tower (2) extending in an upwards direction, a load carrying structure (3, 4) forming a first section (3) and a second section (4), the first and second sections extending in different directions away from the tower (2). To provide efficient dampening of the movement, the method comprises tethering a first body (20) to the first section (3), the first body being at least partly submerged into the sea.

The invention provides a method for monitoring health state of blade root fastener, comprising the following steps: obtaining a sequence of acceleration signals representing the lateral vibration of the nacelle and a sequence of rotational speed signals representing the rotational speed of the rotor; analyzing the sequence of acceleration signals and the sequence of rotational speed signals to determine the amplitude of the nacelle at 2-time-frequncy of the rotational speed of the rotor; and determining the health state of the blade root fastener based on the amplitude. The invention also provides a system for monitoring the health state of the blade root fastener. Through the present invention, the health state of the blade root fastener can be determined with low cost and high precision, thereby improving the operation efficiency and operation safety of the wind turbine.

Provided herein are detection systems and related methods for detecting moving objects in an airspace surrounding the detection system. In an aspect, the moving object is a flying animal and the detection system comprises a first imager and a second imager that determines position of the moving object and for moving objects within a user selected distance from the system the system determines whether the moving object is a flying animal, such as a bird or bat. The systems and methods are compatible with wind turbines to identify avian(s) of interest in airspace around wind turbines and, if necessary, take action to minimize avian strike by a wind turbine blade.

Provided herein are detection systems and related methods for detecting moving objects in an airspace surrounding the detection system. In an aspect, the moving object is a flying animal and the detection system comprises a first imager and a second imager that determines position of the moving object and for moving objects within a user selected distance from the system the system determines whether the moving object is a flying animal, such as a bird or bat. The systems and methods are compatible with wind turbines to identify avian(s) of interest in airspace around wind turbines and, if necessary, take action to minimize avian strike by a wind turbine blade.

The method according to the invention for operating a wind turbine, comprising a tower and a rotor arranged at the top of the tower and having at least one rotor blade, which can be adjusted about a blade setting axis, has a first operating mode in which the at least one rotor blade has an operating angular position about the blade setting axis and a wind-force-dependent rotation of the rotor is converted into electrical power using a generator unit, which power is delivered from the wind turbine into an electrical network and/or stored, and a second operating mode in which the at least one rotor blade is adjusted by at least 60° and/or max. 110° about the blade setting axis relative to the operating angular position into a damping angular position, and a counter torque braking the rotor is controlled based on a vibration of the tower.

A method is provided for monitoring a pitch control system for a rotor blade of a wind turbine. The method comprises a step of receiving a blade pitch signal representative of a pitch position of the rotor blade, a step of determining a pitch deviation, based on the blade pitch signal and a blade pitch reference. If the determined pitch deviation exceeds a first pitch deviation threshold, a pitch deviation variable is increased by an amount that depends on the determined pitch deviation, the first pitch deviation threshold, and a duration of a time period during which the determined pitch deviation has been exceeding the first pitch deviation threshold. An error signal is provided when the increased pitch deviation variable exceeds a pitch deviation variable threshold.

A system and method are provided for reducing vibrations and loads in one or more rotor blades on a rotor hub of a wind turbine when the rotor hub is in a locked or idling condition. An electronically tunable mass damper is attached to a fixed location on one or more of the rotor blades. The mass damper is maintained on the rotor blades during the locked or idling condition of the rotor hub. The method includes sensing movement of a mass component of the mass damper from vibrations or oscillations induced in the rotor blade. The mass damper is automatically tuned based on the sensed movements of the mass component by automatically varying an electrical characteristic of the mass damper.

A method of determining an offset angle to the wind direction measured from a wind vane of a wind turbine includes the steps of: defining a plurality of power bins representing an interval of power which can be produced by the wind turbine, calculating an efficiency of the wind turbine for a plurality of time slots, determining a power output of the wind turbine for the plurality of time slots, comparing the efficiency of the wind turbine in two different time slots, and updating a value of the one of the power bins representing the interval of power determined for one of the compared time slots. The value of the power bin is updated with the result of the highest efficiency or a value derived from the highest efficiency multiplied with a constant.

A method of handling the pitch bearing unit of a rotor blade mounted to the hub of a wind turbine, the method including the steps of providing an extension assembly at the interface between the rotor blade and the hub, moving the rotor blade outward from the hub by means of the extension assembly to open a gap large enough to accommodate the pitch bearing unit while maintaining a connection between the rotor blade and the hub, and removing the pitch bearing unit through the gap.