A method for mitigating loads acting on a rotor blade of a wind turbine includes receiving a plurality of loading signals and determining at least one load acting on the rotor blade based on the loading signals. Further, the method includes determining a type of the load(s) acting on the rotor blade. Moreover, the method includes comparing the load(s) to a loading threshold, such as an extreme loading threshold. In addition, the method includes implementing a control scheme when the load(s) exceeds the loading threshold. More specifically, the control scheme includes providing a first pitching mode for reducing a first type of load, providing a different, second pitching mode for reducing a different, second type of load, and coordinating the first and second pitching modes based on the type of the at least one load to mitigate the loads acting on the rotor blade.

A method for adjusting a multi-dimensional operating space of a wind turbine includes receiving, via a central multi-dimensional operating space controller, a plurality of signals from a plurality of requestors of modified operating space. Each of the plurality of signals includes a data structure having requested set points for a plurality of dimensions in the operating space. The method also includes tracking, via the central multi-dimensional operating space controller, current set points for the plurality of dimensions in the operating space. Further, the method includes dynamically determining, via the central multi-dimensional operating space controller, an output signal based on the requested set points, the output signal comprising one or more changes for the current set points for the plurality of dimensions in the operating space. Moreover, the method includes controlling the wind turbine based on the output signal so as to provide a modified multi-dimensional operating space.

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.

The present invention relates to a method for stabilizing a rotor of a wind turbine during a time period following an abnormal grid event, the method comprising the steps of detecting an occurrence of the abnormal grid event, reducing an allowable rotor thrust from a first thrust limit to a second thrust limit, detecting that the abnormal grid event has ended, and maintaining the second thrust limit a selected time period after the abnormal grid event has ended. The present invention further relates to a wind turbine controller and a computer program product for performing this method.

A method for controlling a multirotor wind turbine is disclosed. A first operational state of each of the energy generating units of the wind turbine is obtained. A difference in thrust acting on at least two of the energy generating units is detected. At least one constraint parameter of the set of operational constraints is adjusted in accordance with prevailing operating conditions and in accordance with the detected difference in thrust, and a new operational state for at least one of the energy generating units is derived, based on the at least one adjusted constraint parameter, the new operational state(s) counteracting the detected difference in thrust. Finally, the wind turbine is controlled in accordance with the new operational states for the energy generating units.

A wind turbine and method are provided for defining a plurality of thrust limits for the wind turbine located at a site and having a rotor with rotor blades, wherein the thrust limits define values of aerodynamic thrust on the rotor not to be exceeded in operation. The method includes providing a wind speed distribution representative for the site and defining one or more isolines of constant turbulence probability representing a turbulence parameter as a function of wind speed. The isolines correspond to quantile levels of turbulence of the wind speed distribution and the turbulence parameter is indicative of wind speed variation. The turbulence parameter is determined by continuously measuring wind speed upstream of the rotor with an active sensing system and calculating the wind speed variations from the measured wind speed. Turbulence ranges are defined with respect to the isolines and thrust limits are defined for the turbulence ranges.

A wind turbine and method are provided for defining a plurality of thrust limits for the wind turbine located at a site and having a rotor with rotor blades, wherein the thrust limits define values of aerodynamic thrust on the rotor not to be exceeded in operation. The method includes providing a wind speed distribution representative for the site and defining one or more isolines of constant turbulence probability representing a turbulence parameter as a function of wind speed. The isolines correspond to quantile levels of turbulence of the wind speed distribution and the turbulence parameter is indicative of wind speed variation. The turbulence parameter is determined by continuously measuring wind speed upstream of the rotor with an active sensing system and calculating the wind speed variations from the measured wind speed. Turbulence ranges are defined with respect to the isolines and thrust limits are defined for the turbulence ranges.

A wind turbine controller includes a thrust limiter for controlling the thrust of the blades of wind turbine using an estimate of the air density at the wind turbine. In one embodiment, the controller receives the blade flap load indicating the current load on one of the blades which varies linearly to the air density experienced by the wind turbine. In one embodiment, the controller determines the mean of a plurality of the blade flap load values measured during a predefined time period. Using a transfer function, the controller converts the mean of the blade flap loads to an estimate of the air density at the turbine. Generally, higher air density results in greater loads on the blades while lower air density results in lower loads on the blades.

A method for mitigating loads acting on a rotor blade of a wind turbine includes receiving a plurality of loading signals and determining at least one load acting on the rotor blade based on the loading signals. Further, the method includes determining a type of the load(s) acting on the rotor blade. Moreover, the method includes comparing the load(s) to a loading threshold, such as an extreme loading threshold. In addition, the method includes implementing a control scheme when the load(s) exceeds the loading threshold. More specifically, the control scheme includes providing a first pitching mode for reducing a first type of load, providing a different, second pitching mode for reducing a different, second type of load, and coordinating the first and second pitching modes based on the type of the at least one load to mitigate the loads acting on the rotor blade.

A method of operating a wind turbine having a rotor. Sensor data is received from one or more sensors of the wind turbine and maximum load values are obtained on the basis of the sensor data. The maximum load values are indicative of maximum loads acting on a component of the wind turbine such as a rotor blade. An estimated extreme load value, such as a 50-year return load, is obtained on the basis of the maximum load values and compared with a reference value. A maximum thrust limit is set on the basis of the comparison, and the wind turbine is operated in accordance with the maximum thrust limit so that a wind thrust force acting on the rotor does not exceed the maximum thrust limit.