Embodiments of the present invention provide methods and apparatus for increasing turbulent mixing in the wake of at least one wind turbine. Doing so, increases efficiency of a wind turbine located in the wake by transferring energy to the wake that was lost when the wind passed through the upwind turbine. Turbulent mixing may be increased by changing the induction factor for a rotor by, for example, altering the pitch of the blades, the RPMs of the rotor, or the yaw of the nacelle. These techniques may be static or dynamically changing. Further, the different induction factors for a plurality of wind turbines may be synchronized according to a predetermined pattern to further increase turbulent mixing.

A system and method are provided for controlling a wind turbine of a wind farm. Accordingly, a controller prepares a yaw bias correction function based, at least in part, on a yaw offset function, and on wind speed measurement data and wind direction reference data of a wind event acting on at least a portion of the wind farm. The controller also applies the yaw bias correction function based at least in part on position data of a nacelle of the wind turbine, to yaw the nacelle of the wind turbine.

A method of controlling a plurality of wind turbines of a wind park includes: determining an axial induction zone of at least a wind turbine of the wind park; and modifying the axial induction zone for controlling wind farm blockage by adjusting at least one of the following operational variables: a yaw angle of a blade rotor of the wind turbine, a pitch offset angle of at least one blade of the blade rotor, a rotor speed of the blade rotor.

A control arrangement for a variable-speed wind turbine includes a loading analysis module configured to analyse a number of environment values to establish whether the momentary wind turbine loading is lower than a loading threshold when the rotational speed of the aerodynamic rotor has reached its rated value; and a speed boost module configured to determine a speed increment for the rotational speed of the aerodynamic rotor if the wind turbine loading is lower than the loading threshold.

The present disclosure relates to methods which comprise receiving a wind direction signal indicative of an instantaneous wind direction at a wind turbine, filtering the wind direction signal to determine a filtered wind direction signal and determining a yaw error signal of the wind turbine indicating a difference between a yaw angle of the wind turbine and the instantaneous wind direction indicated by the filtered wind direction signal. The methods furthermore comprise determining a control signal for a yaw system of the wind turbine based on the yaw error signal. Filtering the wind direction signal comprises applying a low pass filter with a variable time constant, wherein the variable time constant is dependent on a wind condition. The present disclosure further relates to control systems for wind turbines which are configured to implement such methods. The present disclosure further relates to methods of operating wind turbines.

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.

An apparatus for a self-centering plunger for a hydraulic yaw brake having improved load distribution and ability to accommodate system forces, torques, stresses, etc. is disclosed. A lower section of the self-centering hydraulic plunger has a reduced diameter and does not include a bottom collar, which minimizes torque transfer from a brake piston. A brake piston seat washer is thicker, more robust and has increased surface area to better distribute the load onto the brake piston. The geometry of the piston seat washer also minimizes the torque transferred from the brake piston to the self-centering hydraulic plunger. A friction sleeve assembly improves load distribution at a plunger-housing interface by improving sliding contact surface area.

Provided is a wind park, a wind park controller, and a method for controlling a first wind turbine of a plurality of wind turbines of a wind park, wherein a second wind turbine of the plurality of wind turbines can be affected by a wake region caused by the first wind turbine which is positioned upstream of the second wind turbine. A current yaw state is determined and is selected from at least one of: a) an actual rotor yaw misalignment angle of the first wind turbine, wherein the actual rotor yaw misalignment angle is an angle between a rotating axis of a rotor of the first wind turbine and a current wind direction at the rotating axis upstream of the first wind turbine, b) an identifier representing whether the actual rotor yaw misalignment angle is either in a range of positive yaw misalignment angles or of negative yaw misalignment angles.

A method of adapting noise emission configurations of plural wind turbines, the method including: determining total wind turbine related noise levels at plural locations; determining, among the plural locations, a critical location having a most critical, in particular highest, total wind turbine related noise level; if the most critical total wind turbine related noise level is above a noise threshold: reducing the noise emission configuration of a wind turbine having the highest noise to power impact ratio, is provided.

The invention relates to techniques for verifying a nacelle yaw position sensor installed on a wind turbine and for taking restorative action to control the nacelle yaw position. The invention relates to a method performing the comprising determining a first absolute wind direction signal associated with the first wind turbine; determining a second absolute wind signal direction signal associated with the plurality of other wind turbines; comparing the two wind direction signals; and issuing a nacelle yaw position sensor fault signal if the first signal is beyond a predetermined error range of the second signal. A benefit of the invention is that it enables the detection of an inaccurate nacelle yaw sensor without direct measurement or inspection.