Abstract: The present invention relates to a control system and an associated method for controlling an amount of reactive power delivered from a wind power plant to an associated power supply grid, the control system comprising a wind power plant controller and a number of wind turbine controllers each being in communication with said wind power plant controller, wherein the wind power plant controller is adapted to provide a grid voltage reference in response to a required total amount of reactive power to at least one wind turbine controller, said wind turbine controller comprising a voltage control loop comprising means for cancellation of a steady-state local voltage error.

Abstract: The present invention relates to a method for controlling a reactive power source in a wind power plant, the method comprising the steps of providing a wind turbine reactive power control signal and providing an active power reference signal, said active power reference signal being a measure of an active power production of the wind power plant. A control signal for the reactive power source is generated by combining the wind turbine reactive power control signal and the active power reference signal in such a way that the control signal for the reactive power source becomes a weighted signal of the wind turbine reactive power control signal. Moreover, the present invention relates to control units and wind power plants suitable for carrying out the present invention.

Abstract: The present invention relates to a method for controlling a fundamental frequency of power supply grid being operatively connected to a power supply grid, the method comprising the steps of determining a steady-state and/or a dynamic-state related parameter of the associated power supply grid, and applying said determined parameter(s) in a frequency 5 controller of the wind turbine facility in order to improve frequency control of the fundamental frequency of the power supply grid.

Abstract: The present invention relates to a method and a system for on-site and full-scale testing of wind turbine plants. In particular, the present invention relates to a method and a system applying resonance circuits tuned with the fundamental frequency, or harmonics thereof, of a power supply grid connected to a wind turbine plant to be tested. The wind turbine plant to be tested may remain connected to the power supply grid during on-site and full-scale testing.

Abstract: The present invention addresses the problem of avoiding that wind turbine voltage levels within a wind power plant do not exceed predetermined overvoltage and/or undervoltage protection levels. In particular, the present invention relates to shifting of an output voltage level of a wind power plant in order to protect an internal power plant grid against overvoltages.

Abstract: This invention relates to a method and a system (10) for controlling a wind power plant (20) comprising at least one wind turbine generator (21 a-n), the wind power plant being connected to a power network (30) for delivering power to the power network. The method comprises: detecting (201) a frequency of the power network; calculating (202) a variation rate in the detected frequency of the power network; calculating (203) a requested variation of delivered power for the wind power plant based on a value of the inertia of the wind power plant and the calculated frequency variation rate; calculating (204) a requested variation of delivered power for each wind turbine generator of the wind power plant based on the calculated requested variation of delivered power for the wind power plant and a current power level of each wind turbine generator. The resulting calculated re-quested power variation is then used for controlling (205) each wind turbine generator to deliver power to the network.

Abstract: This invention relates to a method and a system for operating a wind power plant (1) connected to a power grid (2), the wind power plant comprising a number of wind turbine generators.

Abstract: The present invention relates to a method for determining location of faults in a wind power plant comprising a first plurality of wind turbines arranged in n groups, each group comprising mn wind turbines electrically arranged in series, each of the wind turbines having a fault detector and a timing device for recording a time of fault occurrence, all groups electrically connected via a bus bar. The method may comprise the steps of detecting a fault, obtaining a status indicator from each of the fault detectors and timing devices, evaluating time of fault occurrence for two wind turbines in each of the n groups to determine if the fault have occurred inside a group, evaluating if a fault is registered in the wind turbine closest to the bus bar in each group. Further the present invention relates to a wind park.

Abstract: The present invention relates to a control system comprising a control interface between one or more wind turbine generators and a power grid, where the wind turbine generators are coupled to the power grid and contribute to the power production of the grid. The control interface is arranged to receive a set of event data. In embodiments, the set of event data may be any data available to a SCADA system. The set of event data is analysed in terms of predetermined event rules comprising at least one predefined event condition and a set of adaptive event conditions. Based on the analysis an event output is provided in order to control a parameter of the one or more wind turbine generators. In embodiments, the control system may be implemented in, or in connection with a SCADA system, moreover, the event output may be based on fuzzy logic, a neural network or statistical analysis.

Abstract: A method for controlling a current in a wind park is provided. The wind park includes at least one wind turbine and at least one current generator. The method includes detecting a grid irregularity, determining an optimal current to be provided at a predetermined location in the wind park during the grid irregularity and determining a corresponding current to be generated from the at least one current generator so as to provide the optimal current at the predetermined location. The corresponding current is determined based on at least an impedance value between the at least one current generator and the predetermined location.

Abstract: The invention relates a method for controlling a common output from at least two wind turbines comprising the steps of receiving at a central wind turbine control system at least one set point value of a set point parameter from a utility grid operator, and at least one operational value of a operational parameter from at least one of said wind turbines Furthermore the method comprises the steps of stablishing a cost function equation comprising at least one function variable reflecting an operational parameter of said wind turbines and said received set point parameter, solving the cost function equation with respect to said at least one function variable to find an extremum for said cost function, calculating weighted operational parameter set points for each of said wind turbines from the obtained solution, and controlling at least one of said wind turbines in relation to said weighted operational parameter set points.

Abstract: The present invention relates to a method for determining location of faults in a wind power plant comprising a first plurality of wind turbines arranged in n groups, each group comprising mn wind turbines electrically arranged in series, each of the wind turbines having a fault detector and a timing device for recording a time of fault occurrence, all groups electrically connected via a bus bar. The method may comprise the steps of detecting a fault, obtaining a status indicator from each of the fault detectors and timing devices, evaluating time of fault occurrence for two wind turbines in each of the n groups to determine if the fault have occurred inside a group, evaluating if a fault is registered in the wind turbine closest to the bus bar in each group. Further the present invention relates to a wind park.

Abstract: A method and a controller for controlling a wind power generation system is disclosed. The system is connected to a grid at a point of connection, and is devised to feed reactive power to the grid in order to improve grid stability. A Q-V characteristic is determined for the grid at the point of connection as well as a nose point for the Q-V characteristic. A minimum reactive current, IQmin, which is safe from the nose point, is determined, and the feeding of reactive power is controlled such that the reactive current is kept higher than the minimum reactive current. This ensures that the reactive current does not make the Q-V characteristic reverse, and thereby the stability of the system is improved.