Abstract: A method for estimating an achievable power production of a wind turbine, which is operated with a reduced power set point is provided. The method includes determining the values of at least two parameters, inputting the values of the at least two parameters into a neural network, and outputting an output value from the neural network. The at least two parameters are indicative of an operating condition of the wind turbine. Thereby, the output value is an estimate of the achievable power production of the wind turbine. A control system which is adapted to carry out the described power estimation method is also provided. Furthermore, a wind turbine which uses the control system adapted to carry out the described power estimation method is provided.

Abstract: A method for damping an oscillation of a rotational speed of a shaft of a wind turbine is described. A converter is connected between a generator and a wind turbine output terminal. The rotational speed of the shaft or the generator is measured. A DC-link voltage reference varying in dependence with the rotational speed is determined. A DC-link voltage of a DC-link of the converter according to the DC-link voltage reference is controlled.

Abstract: Disclosed is a method of reducing a structural unbalance in a wind turbine rotor with pitch control and a control device for performing. A frequency component is detected resulting from the structural unbalance in the wind turbine rotor on the basis of the rotor speed signal. The multiplying the frequency component signal is multiplied by a complex correction factor. Individual pitch angle offsets are establishing for each blade of the rotor based on the magnitude and the phase and complex correction factor. Individual pitch angle offset are added to the respective pitch angles of the blades of the rotor.

Abstract: In one aspect, a hydraulic system including a reservoir, a hydraulic device, a first sensor, a second sensor and a controller is described. The reservoir is connected to the hydraulic device for supplying hydraulic fluid to and from the hydraulic device. The first sensor is adapted for measuring a first volume of the hydraulic fluid in the reservoir. The second sensor is connected to the hydraulic device such that at least one parameter being indicative for a second volume of the hydraulic fluid in the hydraulic device is measurable. The controller is adapted for calculating the second volume of the hydraulic fluid based on the at least one parameter. The controller is adapted for determining a leakage of hydraulic fluid in the hydraulic system based on the first volume and the second volume.

Abstract: The disclosure concerns a method for operating a wind farm, the wind farm includes a wind turbine, and an energy storage device, the wind farm being connected to an external grid, the method comprising determining a demanded active power, determining a demanded reactive power, determining power production of the wind turbine, and charging the energy storage device, when the power production is above the demanded active power, the demanded reactive power, or the vector sum of demanded active power and demanded reactive power. Furthermore, corresponding wind farm controllers, wind farms, program elements, and computer readable media are subject of the current disclosure.

Abstract: A method for determining a total mechanical load of a wind turbine is provided. A present load signal indicative of a present load of a wind turbine base structure is obtained, wherein the present load acts in a present angular direction. A first present load and a second present load are derived based upon the present load signal and the present angular direction, wherein the first present load is associated with a first angular sector of the turbine and the second present load is associated with a second angular sector of the turbine. Further, a total mechanical load is derived based upon the first present load and the second present load.

Abstract: A method for monitoring blade frequencies of a wind turbine and a monitoring system for performing the method are provided. An accelerometer or G-sensor is placed into a nacelle of a wind turbine and thereby measuring the vibrations of the nacelle. To extract the vibration signals originating from each blade, the vibration signals are combined with the measuring signals from the azimuth angle sensor (rotating angle), which is normally used for pitch control. To further extract each blade frequency a Fast Fourier Transformation is used on the modulated G-sensor signals. To further monitor a severe and alarming change in each blade frequency, each blade frequency is compared to the other blade frequencies and an alarm is set when a given level is reached.

Abstract: Disclosed is a method of reducing a structural unbalance in a wind turbine rotor with pitch control and a control device for performing the method are provided. The method comprises the steps of: detecting a magnitude of the structural unbalance and its phase in relation the rotor's azimuth (?) on the basis of a measurement of the rotor's azimuth (?) and a measurement of the rotor speed or the generator speed (?), establishing individual pitch angle offsets for each blade of the rotor on the basis of the magnitude and the phase, and adding the individual pitch angle offsets to the respective pitch angles of the blades of the rotor.

Abstract: A method of controlling the load of a wind turbine is provided. A rate of wear experienced by the wind turbine as a result of the current operating conditions of the wind turbine is determined. A control vector for controlling the wind turbine is determined based on the determined rate of wear. The load of the wind turbine is controlled in accordance with the determined control vector. Determining the control vector includes weighting the determined rate of wear by a cost of electricity value and determining the control vector based on the weighted rate of wear.

Abstract: The disclosure relates to a method for controlling a wind farm, the wind farm includes at least two wind turbines, the method includes determining the required power, determining fatigue load versus power curves for each wind turbine, and based on the determined fatigue load versus power curves attributing different power settings to the wind turbines such that sum of the power settings of all wind turbines is equal to the required power. Furthermore, the invention concerns a park controller for controlling a wind farm and a program element for controlling a wind farm.

Abstract: A method for controlling a wind turbine with a rotor and at least one rotor blade, and a control unit are disclosed. The method is characterised in adjusting a pitch angle of the rotor blade and determining the limit of an input value based on the adjusted pitch angle, wherein the input value includes information about the turbine rotational speed.

Abstract: An asynchronous power generator for a wind turbine is provided. The asynchronous power generator includes a voltage supply and a stator with stator coils supplied with an alternating voltage by the voltage supply. The voltage supply is configured to adjust the voltage supplied to the stator coils based upon an output power generated by the wind turbine. Further, a method of voltage control is provided.

Abstract: A method for determining a total mechanical load of a wind turbine is provided. A present load signal indicative of a present load of a wind turbine base structure is obtained, wherein the present load acts in a present angular direction. A first present load and a second present load are derived based upon the present load signal and the present angular direction, wherein the first present load is associated with a first angular sector of the turbine and the second present load is associated with a second angular sector of the turbine. Further, a total mechanical load is derived based upon the first present load and the second present load.

Abstract: An arrangement for generating a control signal for controlling a power output of a power generation system is described. The power output is to be supplied to a utility grid, the arrangement includes an input terminal for receiving an input signal indicative of an actual grid frequency of the utility grid; a control circuit for generating the control signal wherein the control circuit comprises a first circuit for generating a time derivative value of the input signal; and an output terminal to which the control signal is supplied, wherein the control signal depends on the generated time derivative value of the input signal. Further a power generation system is described.

Abstract: A wind turbine control master unit has a communication interface and a signal processing unit. The communication interface is configured to receive a rotor rotational speed of at least a first and a second wind turbine over a communication link. The signal processing unit is configured to determine a synchronized rotor speed value based on a mean value of the rotor rotational speeds. The signal processing unit is configured to calculate a synchronized azimuth angle value based on integrating the synchronized rotor speed value. Further, the communication interface is configured to send the synchronized rotor speed value and the synchronized azimuth angle value over a communication link. Also, a signal light control module and a wind turbine in connection with the control master unit are provided.

Abstract: A method for determining a mass change at a rotating blade of a wind turbine is provided. The method includes measuring a vibration quantity representative of a vibration of the wind turbine, measuring an azimuthal quantity representative of a rotation angle of the blade, determining a frequency quantity representative of a vibration frequency of the blade from the vibration quantity and the azimuthal quantity, and determining the mass change at the blade based on the frequency quantity.

Abstract: A wind turbine rotor blade is equipped with an air chamber and equipped via the air chamber to route a modulation beam out of the rotor blade such that the air current along the rotor blade is changed. Thereby the laminar current is changed into a turbulent current on the one hand and its detachment and on the other hand its recreation is achieved in order to produce the laminar current. The control may occur via electrostatic actuators via a learnable control strategy based on neural forecasts, which take the complexity of the non-linear system into account and allow for the plurality of influencing factors. The stress on the rotor blades may be reduced, resulting in longer service life and reduced maintenance costs, a higher level of efficiency or quieter operation.

Abstract: Described is a controller, wherein the controller is adapted: to control a transformation ratio of a park transformer of a wind turbine park including wind turbines connected to a first node. The park transformer is connected between a first node and a second node which is connected to a utility grid to which electric energy produced by the wind turbines is to be delivered. Further a wind park and a control method are described.

Abstract: The invention concerns a method for controlling of at least one element of a first component of a wind turbine and a control device not permanently belonging to the wind turbine wherein the control device is connected to a communication interface of the first component for supporting the mounting of the first component and a second component of the wind turbine with each other and/or for the purpose of service of the wind turbine. Moreover the invention concerns the use of the control device for controlling of at least one element of a first component of a wind turbine during the mounting of the first component and a second component of the wind turbine with each other and/or during a service procedure of the wind turbine.

Abstract: A method for acoustically monitoring a wind turbine, in particular for monitoring the existence of loose objects inside the wind turbine is provided. A sound generated in a rotating part of the wind turbine is monitored during operation of the wind turbine which sound is analyzed with respect to specific parameter values of the sound within at least one specific frequency range and if such specific parameter values are detected, a signal for possible further actions is generated. An acoustic monitoring system for a wind turbine and a re-equipment kit are also disclosed.