There is provided a method for controlling a hydraulic pitch force system (220) so as to reduce or eliminate a decrease in hydraulic oil pressure (241) if a hydraulic system parameter value is outside a hydraulic system parameter range, the method comprising: Obtaining (690) the hydraulic system parameter value, and operating the hydraulic pitch force system (220) according to a reduced mode (692) if the hydraulic system parameter value is outside the hydraulic system parameter range, wherein in the reduced mode one or more pitch based activities are reduced (694) or suspended. An advantage thereof may be that it enables keeping the wind turbine in production in certain instances rather than shutting down the wind turbine. In aspects, there is furthermore presented a computer program product, a pitch control system (250) and a wind turbine (100).

A method of diagnosing a wind turbine power generating apparatus includes: an operation step of operating a pitch actuator corresponding to one of a plurality of wind turbine blades of the wind turbine power generating apparatus, without operating a pitch actuator corresponding to each of the wind turbine blades other than the one of the plurality of wind turbine blades; and a measurement step of measuring a response value indicating a response to operation of the pitch actuator corresponding to the one of the plurality of wind turbine blades. The operation step and the measurement step are performed repeatedly for each of the plurality of wind turbine blades, and the response value is obtained as data for health check of a blade pitch mechanism of the wind turbine power generating apparatus.

There is provided a pitch control system (210) for controlling a pitch force system (220) for pitching a blade (103) of a wind turbine (100), the pitch control system (210) being arranged for activating (682) an auxiliary pitch force subsystem (224) at an initiation point in time where a main pitch force is sufficient to pitch the blade (103) into a target pitch value. An advantage thereof may be that tracking of a target pitch value may be improved and the impact on the pitch force system (220) may be reduced. In aspects, there is furthermore presented a hydraulic pitch system (206), a wind turbine (100), a method and a computer program product.

A method for damping an oscillation of a tower of a wind turbine is disclosed, wherein a pitch angle of each of the one or more rotor blades is individually adjustable, the method comprising damping the oscillation of the tower by pitching each rotor blade individually according to tower damping pitch control signals, wherein each tower damping pitch control signal comprises a first periodic component, where a first frequency of the first periodic component corresponds to a frequency difference between a tower frequency of the oscillation of the tower and a rotor frequency of a rotation of the rotor, and where a second periodic component has been reduced or removed. A second frequency of the second periodic component corresponds to a frequency sum of the tower frequency and the rotor frequency.

A method for detaching or installing a rotor blade from or to a hub of a wind turbine includes positioning the rotor blade toward a ground location between a three o'clock position and a nine o'clock position. The method also includes mounting a mechanical arm to an uptower location of the wind turbine. Further, the mechanical arm includes a torqueing tool at a distal end thereof. Thus, the method also includes removing or installing, via the torqueing tool, each of the plurality of hub fasteners so as to detach or attach the rotor blade from or to the hub.

A clamping apparatus for positioning a main bearing of a wind turbine includes a push component arranged between a main flange of a main shaft of the wind turbine and a cover of the main bearing. Further, the clamping apparatus includes a spacer plate located within a gap between the cover and the main bearing. As such, the push component is configured to apply a force to the cover so as to push the spacer plate against the main bearing such that the main bearing is pushed into and secured in place.

A servo actuator is provided which may comprise a controller configured to control a plurality of solenoid valves based upon an output signal. The plurality of solenoid valves may be used to control the position of the object. For example, a set of solenoid valves, of the plurality of solenoid valves, may be configured to conduct fluid from a tank into a first chamber of the cylinder, conduct fluid from the tank into a second chamber of the cylinder, conduct fluid from the second chamber of the cylinder into a first solenoid valve and/or conduct fluid from the first chamber of the cylinder into the first solenoid valve. The first solenoid valve, of the plurality of solenoid valves, may be configured to conduct fluid from the set of solenoid valves into a vent valve based upon a pulse width modulation (PWM) signal received from the controller.

The present invention relates to a wind turbine comprising a nacelle (1) installed on a tower (2) supported by a floating support. The nacelle is articulated with respect to the tower in a vertical plane, and it comprises means (12, 16) for correcting the nacelle tilt, means for automatically adjusting the correction means in accordance with sensors detecting the correction values, the adjustment means being synchronous with the movements of the floating support. Figure 4 to be published.

A turbine comprises a shaft (20), a mass (10) eccentrically mounted for rotation about shaft (20), having its center of gravity at a distance from the shaft (20) and a motion base (15). Motion base (15)rigidly supports the shaft (20), and is configured for moving the shaft (20) in any direction of at least two degrees of movement freedom, except for heave.

A floating vessel-turbine (120),encloses entirely the eccentrically rotating mass (10) and the motion base (15). The turbine converts ocean wave energy into useful energy, very efficiently.

A movable-blade operation system for a hydraulic machine according to an embodiment includes an oil hydraulic cylinder installed within a rotational shaft, a bidirectional pump, a pump drive motor, a control unit, and an oil head installed in the hydraulic machine. The bidirectional pump selectively feeds pressurized hydraulic oil to one of a first cylinder chamber and a second cylinder chamber. The oil head couples the rotational shaft rotatably, and the hydraulic oil fed from the bidirectional pump to the first cylinder chamber and the second cylinder chamber flows through the oil head. The bidirectional pump, the pump drive motor, and the control unit are installed outside the hydraulic machine.