Abstract: Embodiments herein describe varying the rotor speed based on the current wind speed when operating in a low power mode. Generally, as the wind speed increases above the rated wind speed (i.e., the wind speed at which the turbine is capable of producing its rated or maximum output power), the rotor speed can be reduced thereby minimizing the risk that the turbine experiences smearing or torque reversals. In one embodiment, as the rotor speed decreases, the turbine maintains the ability to ramp to the rated power of the turbine only by pitching in the blades to an optimal blade pitch angle. Thus, upon receiving a request to cease operating in the low power mode, the turbine can increase the output power to the rated power without first increasing the rotor speed.

Abstract: The present disclosure relates to a control system for a wind turbine comprising more controllers and where at least some of the controllers operate at different sample frequencies. The control system comprises at least two controller units, a first controller (10) for determining an operational value (OV) of a sub-system and a second controller (20) for the sub-system. The second controller operates at a higher sample frequency than the first controller. It is disclosed that a faster reaction to a received demand value (V1), received for controlling the sub-system, can be obtained by setting the operational value (OV) of the sub-system as the sum of an internal operational value (V5) and a difference value (V4).

Abstract: The present invention relates to a method for controlling a wind turbine, the wind turbine comprises a rotor connected to a generator, and a rotational speed controller configured to control a speed of the rotor in response to a generator speed reference, and a power controller to control an electric power production, the method comprises the step for receiving a boost command to request a power boost event, so to increase the electrical power production, and imposing a dead band with a dead zone value limit to the rotational speed controller, and wherein the dead band imposes a zero signal to be send to the rotational speed controller, when a speed error is within the dead zone value limit and wherein the dead band imposes an error signal to be send to the rotational speed controller, when a speed error is greater than the dead zone value limit, the error signal being a function of the speed error and the dead zone value limit.

Abstract: The present invention relates to a method for operating a wind power plant in a wake situation, said wind power plant being connected to a power grid, the method comprising the steps of operating the wind power plant in a predetermined power mode of operation, terminating said predetermined power mode of operation, and increasing power generation of the wind power plant to a power level that exceeds an optimized wake power level of the wind power plant, and injecting the increased amount of power into the power grid as a power boost. Thus, the present invention is capable of generating a power boost to an associated power grid, said power boost exceeding the power level normally being available in a wake situation. The present invention further relates to a system for carrying out the method.

Abstract: To efficiently nm a wind turbine in varying wind speeds, the wind turbine may be configured to switch between two different electrical configurations that offer different efficiencies depending on wind speed. For example, a star configuration may be preferred during low wind speeds while a delta configuration is preferred for high wind speeds. Before switching, the power output by the turbine's generator may be driven to zero. Doing so, however, removes load from the rotor blades which cause the rotor speed to increase. Instead, the rotor speed may be controlled such that the speed stays at or above the speed of the rotor immediately before the generator power is ramped down. Maintaining rotor speed at or slightly above the current speed while switching between electrical configurations may mitigate the torque change experienced by the turbine and reduce the likelihood of structural failure.

Abstract: The invention relates to a method of controlling a wind turbine, the wind turbine comprising wind turbine blades attached to a rotor hub and a control system for pitching the blades relative to the hub. The method comprises providing wake sectors assigned to different wind directions and providing a normal pitch schedule to control an output parameter of the wind turbine (e.g. power, rotational speed), comprising pitch reference values as a function of the wind speed and at least one of the parameters of thrust coefficient Ct and axial induction factor a. Further, is provided a modified pitch schedule to control a modified output parameter of the wind turbine, comprising pitch reference values in dependence of the wind speed and at least one modified parameter of the thrust coefficient and/or the axial induction factor.

Abstract: The invention relates to a method for wind turbine generators for reducing electrical disturbances in the form of power variations which are caused by damping controllers arranged the compensate structural oscillations by inducing shaft torque variations. The shaft torque variations are generated by imposing corresponding variations in a generator set-point, e.g. a power or torque set-point. Variations in the generator set-point cause undesired variations in the power injected to the grid by one or more wind turbine generators. According to an embodiment of the invention the electrical disturbances may be reduced by limiting a damping controller's control action. The amount of limitation or restriction of the damping controller may be determined on basis on electrical disturbance information determined from power measured e.g. at a location on the grid.

Abstract: A method and associated control arrangement are disclosed for controlling a de-rated power output of a wind turbine generator, where the wind turbine generator is associated with a predetermined power ramp rate upper limit and operating with a de-rated rotor speed. The method includes ramping the power output from an initial power level to a target power level during a ramping interval. During a first portion of the ramping interval, the power output is ramped at a first power ramp rate less than the power ramp rate upper limit. The method further includes ramping the rotor speed to a predetermined rotor speed value contemporaneously with ramping the power output during the first portion of the ramping interval. The first power ramp rate is determined such that a difference between the power output and the target power level is monotonically decreasing during the entirety of the ramping interval.

Abstract: A diagnostic system for use in a wind turbine yaw system, comprising: a tower motion sensor configured to output a signal indicative of tower oscillation, in particular though not exclusively side to side tower oscillation, and a diagnostic module configured to: analyse the tower motion sensor signal to identify frequency content of the signal that is not associated with the tower oscillation; and correlate the identified frequency content with the operation of the yaw system thereby to determine that the yaw system requires maintenance. Beneficially the invention provides that the health of the yaw system can be determined by analysing the oscillatory movement of the tower as measured by a tower motion sensor installed at a suitable location for example at the top of the tower or in the nacelle for example.

Abstract: The invention relates to a control system for a wind turbine. The wind turbine comprises a power generator configured to generate power dependent on a power request. The control system comprises a ramp rate limiter configured to restrict a rate of change of the power request according to a rate of change limit and configured to determine the rate of change limit dependent on a power difference between the power request and an estimated available wind power.

Abstract: Controlling a wind turbine during a grid fault where the grid voltage drops below a nominal grid voltage. After detection of a grid fault, the total current limit for the power converter output is increased to a total maximum overload current limit. Depending on whether active or reactive current generation is prioritized, an active or reactive current reference is determined. The active current reference is determined in a way so that a reduction in active power production due to the grid voltage drop is minimized and based on the condition that the vector-sum of the active output current and the reactive output current is limited according to the total maximum overload current limit, and a maximum period of time is determined in which the power converter can be controlled based on the active/reactive current references. Afterwards the power converter is controlled based on the active and reactive current references.

Abstract: There is provided a method for controlling a hydraulic pitch force system (220) so as to reduce or eliminate a decrease in hydraulic oil pressure (241) if a hydraulic system parameter value is outside a hydraulic system parameter range, the method comprising: Obtaining (690) the hydraulic system parameter value, and operating the hydraulic pitch force system (220) according to a reduced mode (692) if the hydraulic system parameter value is outside the hydraulic system parameter range, wherein in the reduced mode one or more pitch based activities are reduced (694) or suspended. An advantage thereof may be that it enables keeping the wind turbine in production in certain instances rather than shutting down the wind turbine. In aspects, there is furthermore presented a computer program product, a pitch control system (250) and a wind turbine (100).

Abstract: A method and associated control arrangement are disclosed for controlling a de-rated power output of a wind turbine generator, where the wind turbine generator is associated with a predetermined power ramp rate upper limit and operating with a de-rated rotor speed. The method includes ramping the power output from an initial power level to a target power level during a ramping interval. During a first portion of the ramping interval, the power output is ramped at a first power ramp rate less than the power ramp rate upper limit. The method further includes ramping the rotor speed to a predetermined rotor speed value contemporaneously with ramping the power output during the first portion of the ramping interval. The first power ramp rate is determined such that a difference between the power output and the target power level is monotonically decreasing during the entirety of the ramping interval.

Abstract: A method, control arrangement, and wind power plant (WPP) comprising a plurality of wind turbine generators (WTGs) are disclosed. The method includes operating, responsive to a received power demand corresponding to the WPP, a boost group of one or more WTGs of the plurality of WTGs to begin producing a boosted power output, wherein the boosted power output of each of the one or more WTGs of the boost group is regulated independent of the power demand. The method further includes determining, based on a measured amount of boosted power production, power production set points for a regulation group of one or more different WTGs of the plurality of WTGs to thereby meet the power demand.

Abstract: A method and associated control arrangement are disclosed for controlling a power output of a wind power plant (WPP) according to a predetermined power ramp rate limit, the WPP comprising a plurality of wind turbine generators (WTGs). The method comprises receiving a first signal indicating that a first WTG is in a ready state to begin producing power. The method further comprises, upon determining that, responsive to the received first signal, beginning power production of the first WTG at a predetermined default power ramp rate would cause the power output of the WPP to exceed the power ramp rate limit, controlling power production of the first WTG using at least one of: a first delay, a power ramp rate reference less than the default power ramp rate, and a power reference less than a nominal power output of the first WTG.

Abstract: A method of controlling a wind turbine is described. The method involves forecasting the temperature evolution of a component of the wind turbine based upon the current operating parameters of the wind turbine and upon a required power output; predicting from the temperature forecast a future alarm event caused by the temperature of the component exceeding a first threshold level or falling below a second threshold level; and adjusting the operating parameters of the wind turbine to control the temperature evolution of the component thereby to avoid or delay the predicted alarm event.

Abstract: Embodiments of the present invention relate to control of a wind turbine during a recovery period after a grid fault. It is disclosed to operate a wind turbine during the recovery period to determine the actual pitch angle of the rotor blades and the actual wind speed, and based on that determining a desired pitch angle of the rotor blades, as well as a pitch ramp rate so that the actual pitch angle can be brought to match the desired pitch angle before the end of the recovery period. In embodiments, the steps performed in the recovery mode are repeated at intervals during the recovery period.

Abstract: The present disclosure relates to a control system for a wind turbine comprising more controllers and where at least some of the controllers operate at different sample frequencies. The control system comprises at least two controller units, a first controller (10) for determining an operational value (OV) of a sub-system and a second controller (20) for the sub-system. The second controller operates at a higher sample frequency than the first controller. It is disclosed that a faster reaction to a received demand value (V1), received for controlling the sub-system, can be obtained by setting the operational value (OV) of the sub-system as the sum of an internal operational value (V5) and a difference value (V4).

Abstract: Disclosed are a method and a control arrangement for frequency regulation of an electrical grid operatively coupled with at least one wind turbine generator. The method includes operating the wind turbine generator to consume electrical power from the electrical grid. Further disclosed is a method for increasing a ramp rate capacity of a wind power plant comprising a plurality of wind turbine generators. The method includes operating at least one of the plurality of wind turbine generators to consume electrical power.

Abstract: The present invention relates to a method for controlling a wind power plant, the wind power plant comprising a plurality of wind turbine generators, each wind turbine generator comprising at least one power converter for providing active power and/or reactive power to an electrical grid, wherein the method is determining a required amount of reactive power provided by the plurality of wind turbine generators, and grouping the plurality of wind turbine generators into a first set of wind turbine generators and a second set of wind turbine generators based on a demand for reactive power; and supplying reactive power to the grid (20) from the first set of wind turbine generators and disconnecting the second set of wind turbine generators from the electrical grid (20) in response to a control demand, in order to minimize active power losses. The present invention also relates to a wind power plant arranged to perform the method.