The invention relates to a wind turbine blade bearing removal apparatus and method for facilitating the change-over of the blade root bearing assembly (58) of a wind turbine blade (54). A plurality of support shoulders or yokes (60) are located on the hub (50) of the wind turbine rotor and provide attachment points for respective actuators (62). Corresponding attachment points (66) are provided in the wind turbine blade (54) via a blade support (section 64), which is constructed in the blade between the blade root bearing assembly (58) and the tip. The actuators (62) are mounted between the hub (50) and the blade root bearing assembly (58) and therefore support the blade (54) in a suspended position when the bearing is to be retained. The actuators (62) allow the blade to be easily reattached to the hub (50) when the blade root bearing replacement is completed.

A hydro turbine with a runner unit allows adjusting the gap clearance downstream and between the runner end tip portion and the inner edge of the blades. This gap clearance may depend on the angular position of the runner blades.

A yawing system (2) for a wind turbine and a method of operating the yawing system (2) are disclosed. The yawing system (2) comprises at least one yaw drive arranged to cause the yawing system (2) to perform yawing movements, a yaw bearing allowing mutual movement between two parts of the yawing system (2) during yawing movements, and a hydraulically driven preload mechanism (1) being adapted to provide an adjustable pre-load force to the yaw bearing. The preload mechanism (1) is automatically operated as a consequence of operating the yawing system (2). Thereby it can be ensured that the preload force is adjusted in accordance with whether yawing movements are being performed, or the position of the nacelle should be maintained. The preload mechanism (1) may be modular, in the sense that two or more preload mechanisms (1) operate independently of each other, thereby providing redundancy.

A hydraulic device for a pitch system of a wind turbine includes an air separation device which includes a fluid collector having an air accumulation portion, at least one fluid inlet and a fluid outlet portion, wherein a fluid emulsion of air and hydraulic fluid can be introduced into the fluid collector through the at least one fluid inlet. The fluid collector is labyrinth-shaped so that rotation of the air separation device about an axis of rotation causes the air in the fluid emulsion to move through the labyrinth-shaped fluid collector in a direction to the air accumulation portion and the hydraulic fluid in the fluid emulsion to move through the labyrinth-shaped fluid collector in a direction to the fluid outlet portion.

The disclosure relates to a piston accumulator comprising an accumulator housing and a separator piston which is longitudinally moveably arranged therein and separates two media chambers from one another within the accumulator housing, wherein the accumulator housing is elastically formed in a sandwich-type structure from individual, partially differing layers in such a way that, with the influence of at least one external force, it allows for a curvature as a whole, starting from a starting state, and it returns to the starting state with the removal of the respective force.

The present disclosure relates to methods (100, 200, 300) for controlling a wind turbine (10) during a yaw operation. The present disclosure further relates to control systems (92) for wind turbines and to wind turbines (10). A method for operating a wind turbine (10) during yaw operation comprises operating one or more yaw drives (35) to rotate the nacelle (16) with respect to the tower (15). In addition, the method comprises predicting an end of the yaw operation and, in response to predicting an end of the yaw operation, actuating a hydraulic brake (94) before the predicted end.

The invention relates to adjusting collective pitch of the wind turbine rotor blades. A sensor signal is received, from wind turbine sensors, indicative of wind turbine rotor loading in a fore-aft direction. A first component is determined, based on the received sensor signal, in the fore-aft direction, the first component including high frequency collective content, greater than 2P frequency content, from the received sensor signal. A second component that is orthogonal to the first component is generated. The first and second components are rotated about a phase angle to obtain first and second phase-shifted components. A collective pitch reference offset value is determined for the three rotor blades based on the first or the second phase-shifted component. A control signal is transmitted to adjust collective pitch of the rotor blades based on the determined collective pitch reference offset value.

The invention relates to adjusting collective pitch of the wind turbine rotor blades. A sensor signal is received, from wind turbine sensors, indicative of wind turbine rotor loading in a fore-aft direction. A first component is determined, based on the received sensor signal, in the fore-aft direction, the first component including high frequency collective content, greater than 2P frequency content, from the received sensor signal. A second component that is orthogonal to the first component is generated. The first and second components are rotated about a phase angle to obtain first and second phase-shifted components. A collective pitch reference offset value is determined for the three rotor blades based on the first or the second phase-shifted component. A control signal is transmitted to adjust collective pitch of the rotor blades based on the determined collective pitch reference offset value.

A hydraulic device for a pitch system of a wind turbine includes an air separation device which includes a fluid collector having an air accumulation portion, at least one fluid inlet and a fluid outlet portion, wherein a fluid emulsion of air and hydraulic fluid can be introduced into the fluid collector through the at least one fluid inlet. The fluid collector is labyrinth-shaped so that rotation of the air separation device about an axis of rotation causes the air in the fluid emulsion to move through the labyrinth-shaped fluid collector in a direction to the air accumulation portion and the hydraulic fluid in the fluid emulsion to move through the labyrinth-shaped fluid collector in a direction to the fluid outlet portion.