A wind turbine is provided. The turbine includes a support having an axis of rotation, a generator, a plurality of blades rotatably mounted on the support about the axis of rotation, the blades being moveable between a retracted position generally parallel with the axis of rotation and a fully deployed position generally perpendicular with the axis of rotation, the blades being connected to the generator such that rotation of the blades in a direction induced by wind causes the generator to produce electricity, and the provision of electricity to the generator rotates the blades, and a controller connected to the generator and configured to deliver a flow of current to the generator that is sufficient to move the blades from the retracted position toward the fully deployed position and insufficient to move the blades all the way to the fully deployed position. The flow of current induces rotation of the blades in the direction induced by wind, which creates a centrifugal force that moves the blades from the retracted position toward the fully deployed position. As the blades move from the retracted position, the blades have increasing exposure to ambient wind to receive additional rotational force from ambient wind, and the additional rotational force being sufficient to, either alone or in combination with the flow of current, move the blades into the fully deployed position.

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 lock for preventing rotation of a rotor of a wind turbine has a rotatable lock pin, a pin support supportable in a nacelle of the wind turbine and a mechanism for rotating the lock pin. The pin support has a hub-facing face proximate a rotor hub. The rotatable lock pin is rotatably mounted on the pin support. The lock pin has a cammed portion extending away from the hub-facing face toward the hub. The lock pin inserted into a complementary rotor lock aperture on the rotor hub when the pin support is supported in the nacelle. Rotation of the lock pin causes engagement of an exterior surface of the cammed portion with an interior surface of the rotor lock aperture to immobilize the lock pin against the interior surface to prevent relative motion between the lock pin and the aperture to prevent rotation of the rotor.

The present invention relates to methods, apparatus and computer program products for controlling a wind turbine that comprises a nacelle and one or more turbine blades to reduce or prevent edgewise vibrations building up on the one or more turbine blades. It is identified 202 whether the nacelle is unable to yaw to an upwind position and initiating a corrective action 203 to prevent edgewise vibrations building up on the one or more turbine blades if the nacelle is unable to yaw to an upwind position.

The present disclosure is directed to a system and method for reducing vortex-induced vibrations of a tower of a wind turbine. The wind turbine has a nacelle mounted atop the tower. The nacelle has a rotor with a rotatable hub having at least one rotor blade mounted thereto. The rotor blade has a first pitch position. Thus, the method includes measuring, via one or more sensors, an acceleration of the nacelle. The method also includes determining a rotor speed of the rotor. Further, the method includes determining a second pitch position for the rotor blade based on the acceleration of the nacelle and the rotor speed and pitching the rotor blade to the second pitch position if the rotor speed is below a speed threshold and the acceleration of the nacelle is above an acceleration threshold. As such, the second pitch position disturbs vortices caused by interactions between the tower and the rotor blade as the rotor blade passes in front of the tower so as to reduce vortex-induced vibrations of the tower.

An apparatus and method is disclosed for over-rating a wind turbine using turbulence prediction. Weather forecast information is used to determine whether there is a risk of turbulent conditions occurring at the site of the wind turbine. The wind turbine is over-rated if turbulent conditions are not predicted, and conversely over-rating is cancelled or reduced if turbulent conditions are expected. This allows an increase in the annual energy production of the wind turbine to be realised. The weather forecast information may be combined with real time measurements of operating conditions to supplement the predictions.

An airborne wind turbine system is provided including an aerial vehicle having a fuselage, an electrically conductive tether having a first end secured to the aerial vehicle and a second end secured to a rotatable drum positioned on a tower onto which the tether is wrapped when the aerial vehicle is reeled in, a perch extending from the tower, one or more perch booms attached to the perch panel and pivotably mounted to the tower, wherein when the aerial vehicle is secured to the perch, the aerial vehicle is positionable in a lowered parked position, and wherein the aerial vehicle is movable to a raised parked position caused by rotation of the one or more perch booms with respect to the tower.

The invention relates to an assembly and a method of fixing a rotor blade of a wind power plant. The wind power plant comprises a rotor blade, a pitch adjustment means, a bearing for the rotor blade and a brake disk. There is an electro-mechanical brake configured to apply a controlled brake force to the brake disk that is a function of the pitch angle of the rotor blade.

A pitch control system for a wind turbine includes a backup battery bank assigned to each pitch drive motor, with each battery bank having a plurality of individual batteries connected in series. A battery charger is connected in parallel across each battery in the battery bank. A protective circuit is configured with each battery charger and includes a voltage comparator circuit that detects a reverse voltage applied to the battery charger above a threshold value to isolate the battery charger from the reverse voltage.

Systems and methods for increasing operational efficiency of wind turbines, especially offshore wind turbines. The invention discloses systems and methods for reducing the torque needed to rotate a rotor shaft axis with respect to the wind direction. Systems and methods for controlling the rotational speed of the rotor shaft axis are also disclosed.