Abstract: Disclosed is a fluid control system for operation of a pitch control system for wind turbines of the type comprising a pitch system driving at least one rotor blade, by at least one hydraulic actuator (1, 41, 51, 61, 71, 91). A hydraulic pump(3, 43, 53, 63, 73, 93)of the fluid control system is supplied with hydraulic fluid from a hydraulic reservoir (5, 45, 55, 65, 75, 95) mounted on a rotating part of the wind turbine and the hydraulic reservoir is a pilot pressurized hydraulic reservoir (5, 45, 55, 65, 75, 95) being pressurized by the pitch system itself. The pilot pressurized hydraulic reservoir (5, 45, 55, 65, 75, 95) comprises a reservoir piston(101, 200)connected to a pilot piston (105, 202) through a rod (103), wherein the active reservoir piston area of the reservoir piston(101, 200) is larger than the active pilot piston area of the pilot piston (105, 202). A wind power generator is also disclosed.

Abstract: A wind turbine includes at least one wind turbine blade assembly. The blade assembly includes a blade and a pitch bearing arranged between the blade and a hub of the wind turbine, the blade assembly further including two or more hydraulic pitch cylinders for pitching the blade in relation to the hub. The two or more hydraulic pitch cylinders are arranged to expand in the same angular direction around the rotational axis of the pitch bearing. A method for pitching a blade of a wind turbine includes connecting a first end of the hydraulic pitch cylinders directly or indirectly to the hub; connecting a second end of the hydraulic pitch cylinders directly or indirectly to the blade; and expanding or contracting the hydraulic pitch cylinders in the same angular direction in relation to the rotational axis of the pitch bearing.

Abstract: A pilot circuitry is disclosed for controlling the activation of an emergency feathering system of a wind turbine by means of a pilot pressure, wherein the pilot circuitry comprises at least two parallel control circuits for providing a pilot pressure. Additionally, a selector may be provided for selectively preventing a control circuit from providing the pilot pressure to the emergency feathering system in case of malfunction of the control circuit.

Abstract: A wind turbine for producing power to a utility grid includes a rotor having one or more blades, wherein the rotor further includes one or more hydraulic pitch actuators for actively controlling the pitch angle of one or more of the blades. The wind turbine also includes one or more actuator hydraulic pumps adapted for powering the hydraulic pitch actuators, wherein the one or more actuator hydraulic pumps are powered by a normal operation energy source. The wind turbine further includes an emergency hydraulic pump also adapted for powering the hydraulic actuators, the emergency hydraulic pump being powered by an electrical energy storage. A method for powering one or more hydraulic pitch actuators for actively controlling the pitch angle of one or more blades of a wind turbine is also disclosed.

Abstract: A wind turbine for producing power to a utility grid includes a rotor having one or more blades, wherein the rotor further includes one or more hydraulic pitch actuators for actively controlling the pitch angle of one or more of the blades. The wind turbine also includes one or more actuator hydraulic pumps adapted for powering the hydraulic pitch actuators, wherein the one or more actuator hydraulic pumps are powered by a normal operation energy source. The wind turbine further includes an emergency hydraulic pump also adapted for powering the hydraulic actuators, the emergency hydraulic pump being powered by an electrical energy storage. A method for powering one or more hydraulic pitch actuators for actively controlling the pitch angle of one or more blades of a wind turbine is also disclosed.

Abstract: A wind turbine includes at least one wind turbine blade assembly. The blade assembly includes a blade and a pitch bearing arranged between the blade and a hub of the wind turbine, the blade assembly further including two or more hydraulic pitch cylinders for pitching the blade in relation to the hub. The two or more hydraulic pitch cylinders are arranged to expand in the same angular direction around the rotational axis of the pitch bearing. A method for pitching a blade of a wind turbine includes connecting a first end of the hydraulic pitch cylinders directly or indirectly to the hub; connecting a second end of the hydraulic pitch cylinders directly or indirectly to the blade; and expanding or contracting the hydraulic pitch cylinders in the same angular direction in relation to the rotational axis of the pitch bearing.

Abstract: A wind turbine is disclosed having a rotor with at least two blades and a blade pitch system for controlling the pitch angle of the blades. The blade pitch system comprises for each of the blades, a hydraulic blade pitch drive and at least two valves mutually connected in parallel for controlling a flow of liquid to the hydraulic blade pitch drive for that blade. The valves each comprises an arrangement for providing a variable flow of liquid.

Abstract: A pilot circuitry is disclosed for controlling the activation of an emergency feathering system of a wind turbine by means of a pilot pressure, wherein the pilot circuitry comprises at least two parallel control circuits for providing a pilot pressure. Additionally, a selector may provided for selectively preventing a control circuit from providing the pilot pressure to the emergency feathering system in case of malfunction of the control circuit.