A device and a method of controlling blade instabilities of a wind turbine is provided. The method including the following steps: defining at least one preliminary overspeed threshold value; defining a fluttering rotor speed at and above which a predetermined fluttering of at least one of the blades occurs, the fluttering rotor speed is defined as a function of the pitch angle and/or as a function of the wind speed; setting a final overspeed threshold value to be equal to or smaller than a minimum rotor speed of the at least one preliminary overspeed threshold value and the fluttering rotor speed at the actual pitch angle and/or at the actual wind speed; and controlling the rotor speed to not exceed the final overspeed threshold value.

A self-inspection method for a hydraulic control turning system of a generator rotor includes: establishing a length dimension relationship table among a plurality of hydraulic cylinders of the hydraulic control turning system; selecting a reference hydraulic cylinder, and acquiring a reference length dimension when the reference hydraulic cylinder is located at a target working position, the target working position is a position at which a turning pin corresponding to the reference hydraulic cylinder is inserted into an adapted hole; and performing a function inspection of a motion execution module in sequence by the plurality of the hydraulic cylinders, based on the reference length dimension and the length dimension relationship table.

In a wind turbine comprising a tower supporting a nacelle, at least one blade rotationally attached to the nacelle and having a blade-tip section, a system for measuring the separation distance between the tower and the blade-tip-section of the wind turbine, comprising an indicator stripe on the surface of the blade-tip section, an indicator ring encircling the tower, a camera in the nacelle and positioned such that the blade-tip section and the indicator ring are within the camera's field of view when the blade-tip is at its closest approach position to the tower, the camera digitally recording an image of its field of view at this closest approach position, the distance between indicator ring and camera being essentially equal to the distance between the indicator stripe and the camera at this closest approach position, and an image processor and tip-tower clearance calculator unit receiving the digitally recorded image and calculating a physical separation distance between the indicator stripe and the indicator ring using the digitally recorded image information, the physical separation distance being indicative of the blade tip-tower clearance.

The present invention provides a method of operating a wind turbine. The wind turbine comprises at least one rotatable blade. The method comprises the steps of providing a load sensor configured to generate a load signal representing loading on the blade, generating a first load signal when the blade is in a first position, and generating a second load signal when the blade is in a second position. Additionally, the method comprises steps of detecting a rotational speed of the blade, calculating a weight force on the blade based on the first and the second load signal, and calculating a centrifugal force on the blade based on the first and the second load signal. Subsequently, the weight force is compared with a predetermined weight force, and the centrifugal force is compared with a predetermined centrifugal force at the detected rotational speed. Finally, a risk of ice throw is determined based on the comparisons of the weight force and the centrifugal force with the predetermined forces.

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.

The invention relates to a method for controlling a yaw offset of a plurality of wind turbines. The method uses a decision function which generates an activation parameter for determining if the yaw offset control of a specific wind turbine should be enabled or disabled. The decision function depends on two or more variables comprising a wind direction variable indicative of the wind direction of the specific wind turbine, and a wind variation variable defining at least a wind variation range where yaw offset control is disabled or enabled. Based on the decision function it is determined if a yaw offset should be added to the current yaw setting of the specific wind turbine.

A system and method are provided for reducing vibrations and loads in one or more rotor blades of a wind turbine when the rotor hub is locked against rotation, The method detects that the rotor blades are vibrating above a threshold limit, and determines one or more wind parameters for wind impacting the rotor blades. An initial orientation of the blades is also determined. Based on the wind parameters and initial blade orientation, a first angle of attack for the rotor blades is determined that will reduce the vibrations in the rotor blades. The method then determines if expected loads induced at one or more wind turbine components will exceed a threshold limit at the first angle of attack for the rotor blades. The first angle of attack is modified when the expected loads exceed the threshold limit to reduce the expected loads to below the threshold limit. A controller pitches the rotor blades to achieve the first angle of attack.

A method for iteratively estimating a wind speed at a wind turbine is disclosed, said wind turbine comprising a rotor carrying a set of wind turbine blades, each wind turbine blade having a variable pitch angle. A minimum tip speed ratio, λ.sub.min, is derived, based on an obtained pitch angle, θ. The minimum tip speed ratio, λ.sub.min, defines a limit between a stable and an unstable control region. An initial tip speed ratio, λ.sub.init>λ.sub.min, is selected, and an initial estimated wind speed, v.sub.init, is derived based on the initial tip speed ratio, λ.sub.int, and an obtained rotational speed, ω, of the rotor. An estimated wind speed, v.sub.est, is iteratively derived, based on the obtained rotational speed, ω, and the obtained pitch angle, ω, and using the derived initial estimated wind speed, v.sub.init, as a starting point. The iterative process converges fast and reliably.

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 method and apparatus for applying optimized yaw settings to wind turbines including receiving operating data from at least one wind turbine on a wind farm and sending the data to a supervisory control and data acquisition (SCADA) system on the at least one wind turbine to generate current SCADA data. The current SCADA data is sent a central processing center away from the wind farm. The central processing center includes an optimization system that can generate a new look up table (LUT) including at least one new wind turbine yaw setting calculated using information comprising wind direction, wind velocity, wind turbine location in the wind farm, information from a historic SCADA database, and yaw optimizing algorithms. The new LUT is then sent to a yaw setting selection engine (YSSE) where instructions regarding the use of the new LUT are generated.