Abstract: A power oscillation damping controller is provided for a power generation device such as a wind turbine device. The power oscillation damping controller receives an oscillation indicating signal indicative of a power oscillation in an electricity network and provides an oscillation damping control signal in response to the oscillation indicating signal, by processing the oscillation damping control signal in a signal processing chain. The signal processing chain includes a filter configured for passing only signals within a predetermined frequency range.

Abstract: A wind turbine device having in one embodiment a diesel generator to initialize a black start in case of a blackout of an electricity network is disclosed. For performing the black start, the diesel generator provides a predetermined voltage to a power output of the wind turbine device in order to imitate the electricity network in its running state. A wind park is also disclosed, the wind park having in one embodiment at least two wind turbine devices. In one embodiment a wind park controller provides the same reference value for the phase angle ? for the at least two turbines.

Abstract: A method of controlling a wind turbine in response to an overvoltage event in an electricity grid to which the wind turbine is connected is provided, which method includes the steps of controlling at least one auxiliary device to increase its consumption of reactive power, wherein an auxiliary device is a device used during normal operation of the wind turbine; and/or controlling at least one reactive power generating device to decrease its generation of reactive power, wherein a reactive power generating device is a device that generates reactive power during normal operation of the wind turbine. An overvoltage response arrangement adapted for controlling a wind turbine in response to an overvoltage event in an electricity grid to which the wind turbine is connected is also provided. A wind turbine having an overvoltage response arrangement and a wind park are also provided.

Abstract: An arrangement for generating a control signal for controlling a power output of a power generation system, such as a wind turbine, is provided. The power output is supplied to a utility grid. The arrangement includes a first input terminal for receiving a first input signal indicative of an actual grid frequency of the utility grid, a control circuit for generating the control signal, and an output terminal to which the control signal is supplied. The control circuit includes a bang-bang controller for generating a first power signal being indicative of a predefined amount of power to be added to the power output of the power generation system. The bang-bang controller is adapted to be activated when the first input signal falls below a first predefined threshold. The control signal depends on the first power signal.

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: An arrangement for generating a control signal for controlling a power output of a power generation system, such as a wind turbine, is provided. The power output is supplied to a utility grid. The arrangement includes a first input terminal for receiving a first input signal indicative of an actual grid frequency of the utility grid, a control circuit for generating the control signal, and an output terminal to which the control signal is supplied. The control circuit includes a bang-bang controller for generating a first power signal being indicative of a predefined amount of power to be added to the power output of the power generation system. The bang-bang controller is adapted to be activated when the first input signal falls below a first predefined threshold. The control signal depends on the first power signal.

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 power distribution system for distributing electric power generated by a wind farm between an AC power transmission link and a DC power transmission link is provided. Both power transmission links connect the wind farm to a substation of a power grid. The power distribution system includes a central wind farm controller and a distribution device. In response to a control signal from the central wind farm controller, the distribution device distributes the generated electrical power between the two power transmission links. It is further described a power transmission system with the above described power distribution system and a method for distributing electric power between an AC power transmission link and a DC power transmission link.

Abstract: A method of controlling a wind turbine in response to an overvoltage event in an electricity grid to which the wind turbine is connected is provided, which method includes the steps of controlling at least one auxiliary device to increase its consumption of reactive power, wherein an auxiliary device is a device used during normal operation of the wind turbine; and/or controlling at least one reactive power generating device to decrease its generation of reactive power, wherein a reactive power generating device is a device that generates reactive power during normal operation of the wind turbine. An overvoltage response arrangement adapted for controlling a wind turbine in response to an overvoltage event in an electricity grid to which the wind turbine is connected is also provided. A wind turbine having an overvoltage response arrangement and a wind park are also provided.

Abstract: A system is provided for mitigating an electric unbalance of a three-phase current at a Point of Common Coupling being located between a wind farm having a plurality of wind turbines and a power grid. The system includes a measurement device and a central wind farm controller. The measurement device measures the electric unbalance at the Point of Common Coupling and provides a measurement signal being indicative for the measured electric unbalance. The central wind farm controller is coupled to the measurement device and controls the operation of the plurality of wind turbines. In response to the measurement signal the central wind farm provides a control signal for mitigating the electric unbalance at the Point of Common Coupling. Also provided is a corresponding method for mitigating an electric unbalance of a three-phase current and a computer program for controlling and/or for carrying out the mentioned method.

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: 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 power oscillation damping controller is provided for a power generation device such as a wind turbine device. The power oscillation damping controller receives an oscillation indicating signal indicative of a power oscillation in an electricity network and provides an oscillation damping control signal in response to the oscillation indicating signal, by processing the oscillation damping control signal in a signal processing chain. The signal processing chain includes a filter configured for passing only signals within a predetermined frequency range.

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: An arrangement is provided for controlling a power output of a power generation system by controlling an acceleration of a generator of a power generation system. The arrangement includes an input terminal for receiving an input signal indicative of an actual grid frequency of a utility grid, a control circuit for generating a control signal, and an output terminal to which the control signal is supplied. The control circuit is adapted for receiving the input signal, for determining whether the actual grid frequency is above a predefined threshold, and, if the input signal indicates that the actual grid frequency is above the predefined threshold, for generating the control signal based on the input signal. The control signal is indicative of an acceleration of the generator. The power output of the power generation system is controlled by controlling the acceleration of the generator. Further a power generation system is described.

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: An arrangement for generating a control signal for controlling a power output of a power generation system, such as a wind turbine, is provided. The power output is supplied to a utility grid. The arrangement includes a first input terminal for receiving a first input signal indicative of an actual grid frequency of the utility grid, a control circuit for generating the control signal, and an output terminal to which the control signal is supplied. The control circuit includes a bang-bang controller for generating a first power signal being indicative of a predefined amount of power to be added to the power output of the power generation system. The bang-bang controller is adapted to be activated when the first input signal falls below a first predefined threshold. The control signal depends on the first power signal.

Abstract: A wind turbine device having in one embodiment a diesel generator to initialize a black start in case of a blackout of an electricity network is disclosed. For performing the black start, the diesel generator provides a predetermined voltage to a power output of the wind turbine device in order to imitate the electricity network in its running state. A wind park is also disclosed, the wind park having in one embodiment at least two wind turbine devices. In one embodiment a wind park controller provides the same reference value for the phase angle ? for the at least two turbines.

Abstract: A wind farm capacitance determination device for receiving a wind farm layout information of a wind farm and at least one optimization constraint is provided. An optimization unit optimizes a cost by providing an optimized capacitance related parameter value set, the cost being determined by a cost function which associates to each capacitance related parameter value set a cost value, the cost function being based on the wind farm layout information and the optimization taking the at least one optimization constraint into account. In an embodiment the optimized capacitance related parameter value set includes a location, a number and a size of capacitor banks to be electrically connected to the wind farm.

Abstract: A system is provided for mitigating an electric unbalance of a three-phase current at a Point of Common Coupling being located between a wind farm having a plurality of wind turbines and a power grid. The system includes a measurement device and a central wind farm controller. The measurement device measures the electric unbalance at the Point of Common Coupling and provides a measurement signal being indicative for the measured electric unbalance. The central wind farm controller is coupled to the measurement device and controls the operation of the plurality of wind turbines. In response to the measurement signal the central wind farm provides a control signal for mitigating the electric unbalance at the Point of Common Coupling. Also provided is a corresponding method for mitigating an electric unbalance of a three-phase current and a computer program for controlling and/or for carrying out the mentioned method.