A wind turbine includes a plurality of wind turbine blades; a plurality of hydraulic actuators for controlling respective pitch angles of the wind turbine blades; a first tank storing control oil for the hydraulic actuators; a first hydraulic pump disposed between the plurality of hydraulic actuators and the first tank, for pumping the control oil; a plurality of valves each of which is provided for corresponding one of the hydraulic actuators, for controlling a supply state of the control oil to the hydraulic actuator; and a control part for controlling each of the valves. The control part is configured to, in warm-up of a pitch hydraulic system of the plurality of wind turbine blades, perform an oil transfer operation of changing the pitch angle of the wind turbine blade from a feather side toward a fine side and then returning the pitch angle to the feather side.

Provided is a method for operating wind energy converters, in particular of a wind farm. The power limitation mode in this case comprises the steps of turning off at least one of the wind energy converters and operating at least one wind energy converter different to the turned-off wind energy converter, activating a generator heating of the turned-off wind energy converter, turning off the working wind energy converter at or after occurrence of a predefined event, in particular after a predefined time period has elapsed or when a predefined instant is reached, and activating the generator heating of the wind energy converter turned off at or after the occurrence of the predefined event. Provided is a wind farm and to a wind energy converter for carrying out such a method.

A method for initializing startup of a wind turbine includes measuring, via one or more sensors, a first wind condition at the wind turbine at a first moment in time. The method also includes measuring, via the one or more sensors, a second wind condition at the wind turbine at a subsequent, second moment in time. Further, the method includes estimating, via the processor(s), an acceleration parameter of the wind turbine as a function of the first wind condition and the second wind condition. Moreover, the method includes comparing, via the processor(s), the acceleration parameter to a predetermined threshold. As such, the method includes initializing, via the processor(s), a first startup process for the wind turbine when the acceleration parameter is at or below a predetermined threshold. Further, the method includes initializing, via the processor(s), a second startup process for the wind turbine when the acceleration parameter exceeds a predetermined threshold, the second startup process being faster than the first startup process.

A method of controlling a floating-body wind turbine power generating apparatus including a wind turbine generator disposed on a floating body includes a pitch-angle increasing step of increasing a pitch angle of a blade of the wind turbine generator when the wind turbine generator is stopped, so that an aerodynamic braking force is applied to a rotor of the wind turbine generator. In the pitch-angle increasing step, a first change rate of the pitch angle of the blade in a first period during which the wind turbine generator is in an inclining motion toward an upwind side from a vertical direction due to sway of the floating body, is smaller than a second change rate of the pitch angle of the blade in a second period during which the wind turbine generator is in an inclining motion toward a downwind side from the vertical direction due to the sway of the floating body.

A method for starting a wind turbine with hinged wind turbine blades, the wind turbine further comprising an adjustable biasing mechanism arranged to apply an adjustable biasing force to each wind turbine blade which biases the wind turbine blade towards a position defining a minimum pivot angle. The biasing mechanism is adjusted to apply a predefined biasing force to each wind turbine blade, and the pivot angle of each wind turbine blade is monitored. The wind turbine is started in the case that the pivot angle of at least one wind turbine blade exceeds a predefined pivot angle threshold.

A method of transitioning a wind turbine from a sleep state is provided in which a wind speed at the wind turbine is measured, and the measured wind speed is compared to a wake-up threshold. If the wind speed exceeds the wake-up threshold, the wind turbine is transitioned to an active state. Before comparing, either the measured wind speed or the wake-up threshold is adjusted based on an outcome of at least one previous transition from the sleep state of the wind turbine.

There is provided a method of controlling a wind turbine on starting or running up the wind turbine before the wind turbine is connected to an electrical supply grid or before the wind turbine is connected to the electrical energy supply grid again. The wind turbine has a rotor having a rotor arresting means, at least one rotor blade and at least one blade angle detection sensor for each rotor blade for detecting the blade angle of the rotor blade. The blade angle of the at least one rotor blade is detected by means of the blade angle detection sensor. Unlocking of the rotor arresting means is blocked until the detected at least one blade angle is within a predetermined angle range. In that way it is possible to ensure that the rotor arresting means is released only when the blades are for example in the feathered position.

A method for operating a wind turbine comprising an aerodynamic rotor with an approximately horizontal axis of rotation, an electrical generator and operating devices is disclosed, wherein the wind turbine is intended for feeding electrical energy into an electrical supply grid, and is kept in a starting state for starting the generator while the wind turbine cannot be completely put into operation, in particular the generator cannot be started.

A wind turbine power generating apparatus includes a wind turbine rotor including at least one blade; a pitch drive part for changing a pitch angle of the at least one blade; a generator configured to be driven by rotational energy of the wind turbine rotor; a circuit breaker for switching a connection state of the generator with respect to a utility grid; and a controller for controlling the wind turbine power generating apparatus. The controller includes a pitch control part configured to control the pitch drive part in a constant rotation-speed control mode for maintaining a rotation speed of the wind turbine rotor at a target rotation speed, before connection of the generator; a connection-condition determination part configured to determine whether a connection determination condition is satisfied; and a connection-command generation part configured to provide the circuit breaker with a connection command to connect the generator to the utility grid.

A method for operating a wind turbine, the method including, in response to receiving a request for a system start of the wind turbine, monitoring at least one measured value over a predetermined monitoring period; and effecting the system start in response to determining that the at least one measured value in the monitoring period corresponds to defined specifications, wherein: the at least one measured value is stored continuously in a data storage and a storage period in the data storage corresponds to at least the predetermined monitoring period, and monitoring the at least one measured value in response to receiving the request for the system start comprises checking, on the basis of the data storage, whether the at least one measured value in a storage period corresponding to the monitoring period before the request corresponds to the defined specifications.