Abstract: A method for controlling a wind turbine is provided. The method includes monitoring an electrical quantity at an output terminal of the wind turbine. The electric quantity has an amplitude and periodically varying with a grid frequency. The method further includes detecting an oscillation of the amplitude and decreasing active power output from the wind turbine at the output terminal depending on the detected oscillation.

Abstract: A method of operating a converter of a wind turbine for providing electric energy to a utility grid includes determining a grid voltage. If the grid voltage is between a nominal voltage and a first voltage threshold, i.e. higher than the nominal voltage, a normal procedure for lowering the grid voltage is performed. If the grid voltage is above the first voltage threshold, another procedure for keeping the wind turbine connected is performed, wherein the other procedure is different from the normal procedure. Further a corresponding arrangement is described.

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: A method for determining a limit value of a wind turbine reference operational variable is described The wind turbine being connected to a connection node to which a utility grid is connected. The method includes: obtaining a first input signal indicative of a connection node limit voltage; obtaining a second input signal indicative of a connection node voltage; and determining the limit value of the wind turbine reference operational variable based on the first signal and the second signal. Further a corresponding arrangement is described.

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 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: The wind power installation comprises a rotor with at least one rotor blade, a generator, and a pitch control system for controlling the pitch of the rotor blades, said pitch control system comprising at least one AC motor (100) arranged to be fed by a converter (101). The pitch control system further comprises means (102) for bypassing said converter (101) so as to connect the AC motor (100) to receive power from an emergency AC power supply source.

Abstract: A method for controlling a power production entity is provided. The method includes generating a plurality of electric power signals by a plurality of power production entities, measuring a plurality of power levels of the plurality of power signals, modifying the plurality of power signals, supplying the plurality of modified power signals at a common node, and adjusting an operation voltage of at least one power production entity of the plurality of power production entities based on the plurality of measured power levels such that a power loss of the power signals caused by the modifying and/or supplying is minimized. Also a system for controlling a power production entity is described.

Abstract: A converter device for power conversion in e.g. a power plant such as a wind turbine is disclose. The converter device is configured for converting an electrical input power to an electrical output power. The converter device may be configured for receiving mechanical input power or, according to another embodiment, may be configured for receiving electrical input power. The converter device includes a voltage input for receiving a voltage signal, which is indicative of a voltage in a electricity network to which the converter device is coupled during operation in order to provide the electrical output power to the electricity network The converter device includes a controller being configured for setting a reactive component of the electrical output power depending on the voltage signal according to a out-of-band reactive current gradient if the voltage indicated by the voltage signal is outside a predetermined voltage band.

Abstract: The wind power system comprises an installation (1) for generating electrical power from wind by means of at least one power generating turbine arranged to be rotated by wind, and a control system (2) including a power controller (22). The power controller (22) is configured to keep the magnitude of the total current below a pre-set maximum magnitude (Imax).

Abstract: A converter device (for power conversion in e.g. a power plant such as a wind turbine is disclosed. An individual controller is provided for each phase of an electrical output power of the converter. If a voltage of one phase is indicated as being out of a predetermined voltage band, an active current of this phase is set to zero and optionally a reactive component of this phase is set to a value that depends on the indicated voltage.

Abstract: A converter device for power conversion in e.g. a power plant such as a wind turbine is disclosed. The converter device is configured for converting an input power to an electrical output power. The converter device may be configured for receiving mechanical input power or, according to another embodiment, may be configured for receiving electrical input power. The converter device includes a controller which is configured for setting a phase angle between a voltage and a total current of the electrical output power to a predetermined value if the voltage indicated by the voltage signal is outside a predetermined voltage band.

Abstract: The wind power installation comprises a rotor with at least one rotor blade, a generator, and a pitch control system for controlling the pitch of the rotor blades, said pitch control system comprising at least one AC motor (100) arranged to be fed by a converter (101). The pitch control system further comprises means (102) for bypassing said converter (101) so as to connect the AC motor (100) to receive power from an emergency AC power supply source.

Abstract: The present invention relates to a method for operating a converter system of a wind turbine, wherein the converter system includes converter modules capable of converting electric power produced by a generator to electric power applicable to a utility grid. The converter modules include generator inverters and grid inverters. The method determines the enabling/disabling of the converter modules in response to a parameter related to the variable amount of electric power being produced by the generator. Advantages of the present invention are optimisation of power efficiency of the converter modules and improved reliability of the converter modules. Another advantage is the capability of fast enabling and disabling of the converter modules.

Abstract: The present invention relates to an Uninterruptible Power Supply and a method for operating an Uninterruptible Power Supply, where the UPS is connected between a grid and a consumer, where the UPS is rectifying the power from the grid for generating DC, which DC is used as source for an inverter, which inverter generates power for the consumer. The main object of the invention is to achieve UPS to bridge the grid voltage drops by supplying power for one-phase or multi-phase consumer in a short period after a grid failure. The object can be achieved if the preamble to claim 1 is modified so that the DC link comprises a boost device, which boost device has at least one an input line, which input line is connected through rectifier means to the grid, which boost device has at least one output line, which output line is connected to the power conversion means.

Abstract: The wind power system comprises an installation (1) for generating electrical power from wind by means of at least one power generating turbine arranged to be rotated by wind, and a control system (2) including a power controller (22). The power controller (22) is configured to keep the magnitude of the total current below a pre-set maximum magnitude (Imax).

Abstract: The invention relates to a variable speed drive system of a wind turbine, which comprises: an asynchronous generator (10) with wound rotor (11), together with a synchronous generator (20) connected on its stator side to a frequency converter (30), the converter being connected on its other end through a slip ring unit (3) to the rotor windings of the asynchronous generator, both the asynchronous and synchronous generators being mounted on a same single shaft (2) and constituting a single generator system (1) under a single stator housing (5).

Abstract: The present invention relates to a method for operating a converter system of a wind turbine, wherein the converter system includes converter modules capable of converting electric power produced by a generator to electric power applicable to a utility grid. The converter modules include generator inverters and grid inverters. The method determines the enabling/disabling of the converter modules in response to a parameter related to the variable amount of electric power being produced by the generator. Advantages of the present invention are optimisation of power efficiency of the converter modules and improved reliability of the converter modules. Another advantage is the capability of fast enabling and disabling of the converter modules.

Abstract: The present invention relates to a method for operating a converter system of a wind turbine, wherein the converter system includes converter modules capable of converting electric power produced by a generator to electric power applicable to a utility grid. The converter modules include generator inverters and grid inverters. The method determines the enabling/disabling of the converter modules in response to a parameter related to the variable amount of electric power being produced by the generator. Advantages of the present invention are optimisation of power efficiency of the converter modules and improved reliability of the converter modules. Another advantage is the capability of fast enabling and disabling of the converter modules.