The invention provides a method for stabilising a wind turbine blade (106), the method comprising, attaching (S2) an air blowing arrangement (201) to the blade, detecting (S4) an oscillation of the blade, and operating (S5) the attached air blowing arrangement to provide a thrust to counteract the oscillation.

Embodiments herein describe in-plane vibration damping techniques for MR turbines. The MR turbines can include arms that extend from a common tower and support multiple rotors. Because the rotors are disposed laterally away from the tower, side-to-side motion of the tower causes the rotors to have an angled trajectory that includes both lateral and vertical displacement. In addition, a rotor disposed on one side of the tower in MR turbine can have a very different trajectory than a rotor disposed on the opposite side of the tower. To account for the vertical displacement and the different trajectories, in one embodiment, a controller can use different phase offsets for each rotor when calculating pitch offsets for performing in-plane vibration damping. In another embodiment, the controller can use both the lateral and vertical accelerations of the rotors to identify the pitch offsets for the rotors to perform in-plane vibration damping.

A rotor blade with a leading edge and a trailing edge is provided, wherein the rotor blade is for being exposed to a fluid flowing substantially from the leading edge to the trailing edge, the rotor blade includes at least three sensors designed for detecting flow characteristics of the fluid and providing respective sensor signals, wherein the sensors are arranged with a non-uniform spacing, and the rotor blade further includes at least one actuator for producing an anti-noise signal based on a sensor signal, the sensors and the actuator are arranged at the surface of the rotor blade, and the actuator is arranged and prepared such that flow-induced edge noise of the rotor blade, which is generated by the fluid, is at least partly cancelled out by the anti-noise signal. A method for creating such rotor blade and a related wind turbine is also provided.

Methods (200) for reducing vibrations in one or more rotor blades (120) of a wind turbine (160), when the wind turbine is in standstill conditions are provided. The method comprises measuring (201) one or more deformation parameters indicative of deformation of one or more blades (120), determining (202), at a dedicated controller (190) for an auxiliary drive system (20, 107), a vibration of one or more of the blades (120) based on the deformation parameters, wherein the dedicated controller (190) for the auxiliary drive system is separate from the wind turbine controller (180), and generating (203), at the dedicated controller (190), an output signal to operate the auxiliary drive system to reduce the vibration. Also disclosed are wind turbines (160) which comprise a dedicated controller (190) configured to determine a vibration and generating an output signal to reduce the vibration, when the wind turbine is in standstill conditions.

A method of erecting a wind turbine on a wind turbine site, the wind turbine comprising a turbine tower and a nacelle. The method comprises the following steps: providing a plurality of tower sections being arrangeable upon each other in a vertical orientation in a tower structure to form the turbine tower; providing at least one damper unit configured to dampen oscillations of the turbine tower; attaching a damper unit to one of the plurality of the tower sections on an outside thereof, and subsequently arranging the tower section in the tower structure, and arranging the nacelle on top of the tower structure while the damper unit is attached to a tower section in the tower structure.

A damping device and a wind turbine generator system comprising the damping device. The damping device comprises: damping components; structural supports, the structural supports connecting the damping components to a mass block provided on an object to be damped, each structural support comprising a gear, and the gear being rotatably provided on the structural support; and guide rails, wherein each guide rail has a predetermined curvature, each guide rail has a first end used for being rotatably connected to the object to be damped and a second end supported on the corresponding structural support, a tooth portion engaged with a gear is formed on a side portion of each guide rail, and when the mass block swings, the swing of the mass block is converted into transmission by means of the engagement transmission between the guide rail and the gear for input into the corresponding damping component.

This invention relates to a noise reducing device, a wind turbine blade comprises such a noise reducing device, a method of retrofitted a noise reducing device, and a method of manufacturing such a noise reducing device. The noise reducing device comprises first noise reducing elements projecting from a base part having a third surface towards a second end. Second noise reducing elements are attached to the third surface and projects along the first noise reducing elements towards the second end. The first noise reducing elements are preferably serrations while the second noise reducing elements are bristles. The bristles projects at least into the gaps formed between adjacent serrations.

A method for operating a wind turbine, an associated wind turbine, and an associated wind park are provided. The wind turbine has a tower with tower loads acting thereon and an aerodynamic rotor which generates a rotor thrust. The method has a step of reducing the rotor thrust. The reduction of the rotor thrust is performed while considering the effect of the reduction of the rotor thrust on the tower loads. Thus, the reduction of the rotor thrust is avoided in cases which result in undesirable or even counter-productive effects on the tower loads.

An automated method to determine modal characteristics of a wind turbine tower at an offshore location in a continuous manner includes reading one or more sensor data signals, prefiltering the one or more sensor data signals to divide the signals into a plurality of time segments, obtaining a frequency domain representation of each of the plurality of time segments by computing a Power Spectral Density (PSD) of each of the time segments to identify one or more frequency peaks in each of the time segments, assigning a probability to each of the frequency peaks in the PSD of each of the time segments, combining all assigned probabilities and determining the likelihood of the one or more frequency peaks. Also disclosed is an offshore wind turbine tower having a turbine control system utilizing the automated method to determine modal characteristics of the wind turbine.

A method of mitigating a vibration of a wind turbine not receiving power from to a utility grid includes: receiving power from an energy storage system of the wind turbine; utilizing the power received from the energy storage system: to detect a wind direction and to adjust an orientation of the rotor axis of a rotor shaft, if a criterion is satisfied taking into account at least the relative orientation of the rotor axis and the detected wind direction and/or taking into account a level of the vibration.