Embodiments herein describe operating wind turbines in an offshore park to provide auxiliary power to a local AC grid or to an onshore grid during a grid malfunction. In one embodiment, the offshore park is coupled via a HVDC link to an onshore grid. When the HVDC link is down, a substation in the park includes a backup generator for creating a weak grid for powering auxiliary systems in a pilot turbine. The wind turbines in the park can switch to an auxiliary control system help power the auxiliary systems in the substation and in other turbines. In another embodiment, the offshore park is AC coupled to an onshore grid using a transformer in the substation. The wind turbines can participate in a brown or black start following a grid fault by switching to operating using the auxiliary control system.

Methods (200) for reducing vibrations in one or more rotor blades (120) of a wind turbine (160), when the wind turbine is in standstill conditions are provided. The method comprises measuring (201) one or more deformation parameters indicative of deformation of one or more blades (120), determining (202), at a dedicated controller (190) for an auxiliary drive system (20, 107), a vibration of one or more of the blades (120) based on the deformation parameters, wherein the dedicated controller (190) for the auxiliary drive system is separate from the wind turbine controller (180), and generating (203), at the dedicated controller (190), an output signal to operate the auxiliary drive system to reduce the vibration. Also disclosed are wind turbines (160) which comprise a dedicated controller (190) configured to determine a vibration and generating an output signal to reduce the vibration, when the wind turbine is in standstill conditions.

Provided is a safety stop valve arrangement of a hydraulic blade pitch system of a wind turbine, including an accumulator arrangement connected over a hydraulic line to a piston of the hydraulic blade pitch system; a redundant set of safety valves arranged between the accumulator arrangement and the piston; a small-orifice restriction nozzle arranged to determine a first rate of hydraulic fluid flow in response to a safety stop input; at least one speed-select valves arranged; and at least one large-orifice restriction nozzle arranged to determine a second rale of hydraulic fluid flow in response to a positive rotor acceleration input, wherein the second rate of fluid flow is faster than the first rate of fluid flow. A safety stop assembly of a wind turbine with hydraulic blade pitch systems and a method of performing a safety stop sequence is also provided.

A method of operating a wind energy installation having a rotor with at least one rotor blade that is angularly adjustable by an adjustment drive. In response to the occurrence of at least one special operating case, in particular at least one malfunction case, the rotor blade is adjusted in a direction of a shutdown position by the adjustment drive. In the shutdown position, a supply of energy from an energy storage device to the adjustment drive is switched off and/or a pitch brake for holding the rotor blade in its current position is closed. In response to at least one activation signal, the rotor blade is adjusted by the adjustment drive in an adjustment mode of operation while the special operating case is still ongoing, in particular while the malfunction case is still ongoing.

The present invention relates tocontrol of wind turbines based on predicted operational trajectories. A control system for a wind turbineis described wherea main controller calculating one or more predicted operational trajectories and a safety controller validates at least one of the one or more predicted operational trajectories. The control system controls the wind turbine with the predicted control trajectory if the validation is valid, and controls the wind turbine with a safe-mode control trajectory if the validation is invalid. In an embodiment, the main controller is implemented as a receding horizon controller, e.g. in the form of a model predictive controller (MPC).

A method for providing backup control for a supervisory controller of at least one wind turbine includes observing, via a learning-based backup controller of the at least one wind turbine, at least one operating parameter of the supervisory controller under normal operation. The method also includes learning, via the learning-based backup controller, one or more control actions of the at least one wind turbine based on the operating parameter(s). Further, the method includes receiving, via the learning-based backup controller, an indication that the supervisory controller is unavailable to continue the normal operation. Upon receipt of the indication, the method includes controlling, via the learning-based backup controller, the wind turbine(s) using the learned one or more control actions until the supervisory controller becomes available again. Moreover, the control action(s) defines a delta that one or more setpoints of the wind turbine(s) should be adjusted by to achieve a desired outcome.

A method of operating a wind energy installation having a rotor with at least one rotor blade that is angularly adjustable by an adjustment drive. In response to the occurrence of at least one special operating case, in particular at least one malfunction case, the rotor blade is adjusted in a direction of a shutdown position by the adjustment drive. In the shutdown position, a supply of energy from an energy storage device to the adjustment drive is switched off and/or a pitch brake for holding the rotor blade in its current position is closed. In response to at least one activation signal, the rotor blade is adjusted by the adjustment drive in an adjustment mode of operation while the special operating case is still ongoing, in particular while the malfunction case is still ongoing.

A wind energy installation includes a rotor with a first rotor blade that is angularly adjustable, a first adjustment drive for adjusting the first rotor blade, a safety control device/system, a first reversing device for supplying energy to the first adjustment drive from an energy source via the first reversing device to adjust the first rotor blade in a first direction and to adjust the first rotor blade in a second direction opposite to the first direction. A second reversing device can be switched over by the safety control device/system for supplying energy to the first adjustment drive from an energy storage device in a first special mode of operation via the second reversing device in a first switching position to adjust the first rotor blade in the first direction and in a second switching position to adjust the first rotor blade in the second direction.

A method of operating a wind energy installation wherein a rotor has a first rotor blade which can be angularly adjusted, a first adjustment drive for adjusting the rotor blade, and a safety control system. In a normal mode of operation, the first adjustment drive is supplied with energy from a source and is controlled by a first pitch control system. In a failure mode of operation, the supply of energy to the first adjustment drive is switched from the source to an energy storage device and the safety control system monitors a position and/or movement of the first rotor blade. The first rotor blade is adjusted by the first adjustment drive in a direction of a predetermined stopping position, while the safety control system, as a function of the monitored position and/or movement, enables or effects a deactivation of a first power supply shut-off device. In the failure mode of operation, the safety control system, as a function of the monitored position and/or movement, closes a first pitch brake and activates a first blocking mode in which the supply of energy to the first adjustment drive from the energy storage device and/or an opening of the first pitch brake is prevented.

The invention relates to a power management system for one or more wind turbines where the one or more wind turbines are connected to a power supply with a limited capacity for providing power to a number of power consuming units, such as to an emergency power supply arranged for providing power in a grid loss situation. The power management system comprises a dispatcher connected to the power supply to access an available capacity of the power supply, and a requester connected to at least one power consuming unit, the requester being arranged to control the power consumption of the power consuming unit by either allows or deny the power consuming unit to consume power.