Abstract: A power conversion system is provided, which system includes a first power converter including power electronic switches of a first type that are switchable to provide electric power conversion; and a second power converter connected in parallel to the first power converter. The second power converter includes power electronic switches of a second type that are switchable to provide electric power conversion. The second type is different from the first type. The second type of power electronic switches includes wide bandgap semiconductor switches. The system further includes a controller configured to operate the power conversion system in a first operating mode in which the second power converter is operated at a first switching frequency, and in a second operating mode in which the second power converter is operated at a second switching frequency of the power electronic switches and the first power converter is operated to provide power conversion.

Abstract: A wind power plant for providing electrical power to a utility grid is provided, the wind power plant including: at least one wind turbine having a wind turbine generator coupled to a wind turbine rotation shaft to which plural rotor blades are mounted, the wind turbine providing electric power at an output terminal; at least one power conversion system, each including: a plant motor electrically coupled and configured to receive the electric power from the output terminal of the at least one wind turbine and convert it into rotational power of a plant motor shaft; a plant generator mechanically coupled to the plant motor shaft and electrically coupleable to the electric utility grid.

Abstract: A wind turbine electrical power generating system includes a first generator configured to be mechanically coupled to a rotor, a second generator configured to be mechanically coupled to the rotor; and an electrical power conversion system including at least a first and a second power converter section. The first power converter section is electrically coupled between a rotor winding of the first generator and a coupling point and a stator winding of the first generator is electrically coupled to the coupling point such that only a fraction of electrical power generated by the first generator passes through the power conversion system. The second power converter section is electrically coupled between an electrical power output of the second generator and the coupling point such that the electrical power provided by the second generator to the coupling point passes through the power conversion system.

Abstract: A method for controlling the reactive power exchange of a DFIG wind facility with the grid is provided. The method includes determining a grid side converter reactive power thermal limit value and determining the value of the required DFIG magnetizing reactive power to be consumed by the stator. Then setting dynamically the sharing of the reactive power between the stator and the GSC such that the GSC reactive power value is the difference between the reactive power demand of the DFIG wind facility and the magnetizing reactive power consumed by the stator. Afterwards operating the DFIG wind turbine facility such that the absolute value of GSC reactive power is adjusted to be below the grid side converter reactive power thermal limit value value. An arrangement and a wind turbine are also provided.

Abstract: A method for computer-implemented controlling a doubly-fed electric machine, where stator windings are directly connected to an electrical grid and where rotor windings of a rotor are connected to the electrical grid via a power conversion system, includes an AC-to-DC converter and a DC-to-AC converter and being adapted to control a rotor current, the method including obtaining a rotational speed of the machine; determining, whether the obtained rotational speed is within a predetermined operational speed range around the synchronous speed; and if it is determined that the obtained rotational speed is within the predetermined operational speed range, controlling the AC-to-DC converter of the power conversion system to force injection of a stator reactive power to create a harmonic at a frequency different than a rated frequency of the machine; and controlling the DC-to-AC converter of the power conversion system to compensate the created stator reactive power and the harmonic.

Abstract: A method of controlling the operation of a doubly fed induction machine is provided. The DFIM includes a stator electrically coupled to a power grid and a rotor rotating with a rotational speed. The DFIM has a synchronous rotational speed of the rotor and a rated rotational speed of the rotor. Rotation of the rotor at the synchronous rotational speed generates one or more slot harmonic distortions having a harmonic order. The method comprises operating the DFIM at the rated rotational speed of the rotor, wherein the rated rotational speed of the rotor is set to a value selected such that a shift of the harmonic order of one or more of the slot harmonic distortions at the rated rotational speed of the rotor is an integer number or is within a predefined limit of an integer number.

Abstract: A DFIG wind power facility configured to be operated during grid faults is provided. The wind power facility includes a Doubly-Fed Induction Generator, a control system, an electric converter, a short-circuit controlled switch to selectively short-circuit the stator and a Stator Neutral Brake Chopper coupled to the stator. The DFIG includes a rotor and a stator, the stator including at least one three-phase winding. The electric converter includes a Machine Side Converter, a Grid Side Converter and a DC link connected therebetween. The SNBC includes a three-phase rectifier including three inputs, an impedance and an active high-frequency switch configured to vary the average value of the impedance by adjusting its duty cycle; wherein each of the three inputs of the rectifier is connected to a phase of the at least one three-phase winding of the stator. Methods for operating a DFIG wind power facility during grid faults are also provided.

Abstract: A control method of a hybrid power switch having at least a first switching device connected in parallel with a second switching device is provided. A first gate signal is provided to the first switching device for turning on and turning off the first switching device. A second gate signal is provided to the second switching device for turning on and turning off the second switching device. A first delay time is stablished between the turning on of the first switching device and the turning on of the second switching device, and a second delay time is established between the turning off of the first switching device and the turning off of the second switching device. The temperature of the first switching device is determined, and at least one of the first and second delay times is modified depending on such temperature.

Abstract: A slip ring unit for an electric generator is provided. The slip ring unit includes a slip ring attachable to a rotor shaft of the electric generator, a plurality of sliding contacts arranged along a circumference of the slip ring, to provide an electrical connection with the slip ring, at least one temperature sensor for measuring a temperature inside the slip ring unit, a fan for providing a cooling flow in the slip ring unit, and a controller connected to the fan for controlling the cooling flow rate generated by the fan, the controller being connected to the at least one temperature sensor. The at least one temperature sensor is attached to at least a holder for supporting the sliding contacts. The controller is configured in such a way that the cooling flow rate is generated depending on the temperature measured by the at least one temperature sensor.

Abstract: A method for controlling the reactive power exchange of a DFIG wind facility with the grid is provided. The method includes determining a grid side converter reactive power thermal limit value and determining the value of the required DFIG magnetizing reactive power to be consumed by the stator. Then setting dynamically the sharing of the reactive power between the stator and the GSC such that the GSC reactive power value is the difference between the reactive power demand of the DFIG wind facility and the magnetizing reactive power consumed by the stator. Afterwards operating the DFIG wind turbine facility such that the absolute value of GSC reactive power is adjusted to be below the grid side converter reactive power thermal limit value value. An arrangement and a wind turbine are also provided.

Abstract: A wind power plant for providing electrical power to a utility grid is provided, the wind power plant including: at least one wind turbine having a wind turbine generator coupled to a wind turbine rotation shaft to which plural rotor blades are mounted, the wind turbine providing electric power at an output terminal; at least one power conversion system, each including: a plant motor electrically coupled and configured to receive the electric power from the output terminal of the at least one wind turbine and convert it into rotational power of a plant motor shaft; a plant generator mechanically coupled to the plant motor shaft and electrically coupleable to the electric utility grid.

Abstract: A wind turbine electrical power generating system includes a first generator configured to be mechanically coupled to a rotor, a second generator configured to be mechanically coupled to the rotor; and an electrical power conversion system including at least a first and a second power converter section. The first power converter section is electrically coupled between a rotor winding of the first generator and a coupling point and a stator winding of the first generator is electrically coupled to the coupling point such that only a fraction of electrical power generated by the first generator passes through the power conversion system. The second power converter section is electrically coupled between an electrical power output of the second generator and the coupling point such that the electrical power provided by the second generator to the coupling point passes through the power conversion system.

Abstract: The invention provides methods and systems for real-time monitoring of the insulation state of wind-powered generator windings comprising the following steps: a) capturing in real-time, during a predetermined time period (in situations where the generator is synchronized to the electrical network but is not yet couplet thereto as well as in situations where the generator is producing energy) the values of one or more electrical and vibration variables of the generator; b) obtaining in real-time, the temporal evolution of the vibration and of the inverse components of electrical variables at one or more predetermined frequencies; c) identifying a possible generator insulation fault when the inverse component of at least one electrical variable and/or one vibration at a predetermined frequency exceeds an absolute threshold or a temporal increase threshold pre-sets.

Abstract: This invention relates to a synchronous generator for wind turbines comprising a rotor (20) and a stator (10), wherein the stator (10) comprises a plurality of induction coils (11) of a high-temperature superconducting material arranged to generate a magnetic field. The use of the superconducting stator, instead of a superconducting rotor, allows simplifying the refrigeration system, thus eliminating, for example, the rotating joints for cryogenic gas and the rotating joints for high-purity helium gas.

Abstract: The invention provides methods and systems for real-time monitoring of the insulation state of wind-powered generator windings comprising the following steps: a) capturing in real-time, during a predetermined time period (in situations where the generator is synchronized to the electrical network but is not yet couplet thereto as well as in situations where the generator is producing energy) the values of one or more electrical and vibration variables of the generator; b) obtaining in real-time, the temporal evolution of the vibration and of the inverse components of electrical variables at one or more predetermined frequencies; c) identifying a possible generator insulation fault when the inverse component of at least one electrical variable and/or one vibration at a predetermined frequency exceeds an absolute threshold or a temporal increase threshold pre-sets.