Abstract: A method for controlling a variable speed wind turbine generator is disclosed. The generator is connected to a power converter comprising switches. The generator comprises a stator and a set of terminals connected to the stator and to the switches of the power converter. The method comprises: determining a stator flux reference value corresponding to a generator power of a desired magnitude, determining an estimated stator flux value corresponding to an actual generator power, determining a difference between the determined stator flux reference value and the estimated stator flux value, and operating said switches in correspondence to the determined stator flux reference value and the estimated stator flux value to adapt at least one stator electrical quantity to obtain said desired generator power magnitude.

Abstract: A controller arrangement of an electrical power transfer system (1) of a wind turbine is described. The wind turbine has an electrical generator and is connected to an electrical power grid, wherein the power transfer system (1) is arranged to transfer electrical power from the generator to the grid. The power transfer system (1) has at least two electrical elements (2-6), e.g. converters, and at least two controllers (15-17) each arranged to control at least one element (2-6).

Abstract: According to a method of the present invention, a method of operating a wind turbine comprising a power generator, a generator side converter connected to the power generator, a line side converter connected to a power grid through power components, and a DC-link connected between the generator side converter and the line side converter is provided, the method comprising: monitoring the grid voltages on the power grid for overvoltage events; if an overvoltage event is detected, operating the line side converter in an overmodulation range for at least a part of the duration of the overvoltage event.

Abstract: A power conversion system for converting electrical power from at least one power source includes a plurality of converter chains which couple the at least one power source to at least one load. At least two of the converter chains comprise an associated dissipating unit. The dissipating units are coupled via at least one switch. A controller is arranged to control the at least one switch to route power to be dissipated from one of the converter chains to the converter chain's associated dissipating unit, or to at least one of the other dissipating units, or to the converter chain's associated dissipating unit and to at least one of the other dissipating units, to cause corresponding dissipation of the power to be dissipated.

Abstract: According to an embodiment of the present invention, a method of operating a wind turbine including a power generator, a generator/machine side converter connected to the power generator, a grid/line side converter connected to a power grid through power components, and a DC-link connected between the machine side converter and the line side converter, comprises: Monitoring the power grid for overvoltage events; if an overvoltage event is detected disabling active operation of the machine side converter and of the line side converter, enabling an AC-load dump connected between the machine side converter and the power generator in order to dissipate active power output by the power generator into the AC-load dump, waiting for a waiting period, and enabling active operation of the line side converter and the machine side converter if the overvoltage ends within the waiting period.

Abstract: A system for a wind turbine generator comprising: a set of voltage limiting elements, and a controller configured to bypass the voltage limiting elements when a line voltage is below a predetermined threshold, and configured to connect each voltage limiting element in series between a grid side converter and a turbine transformer of the wind turbine generator, and to determine a current control reference signal for controlling the grid side converter (to generate a determined current) when the line voltage is above the predetermined threshold.

Abstract: A method for operating an electromechanical generator is provided, the method comprising: determining a magnetic field reference parameter based on an electromagnetic power reference representing a desired output of the electromechanical generator, determining a scaling factor for adjusting an air-gap magnetization level of the electromechanical generator to reduce loss in operating the electromechanical generator, modifying the magnetic field reference parameter with the scaling factor; and operating the electromechanical generator based on at least the modified magnetic field reference parameter.

Abstract: Parameters of PM machines, especially for IPM machine, are known to vary by significant amounts. This affects the controllability of such machines, which may lead to reduced power loading capability and increased losses. The present invention relates to a method for PM machine inductance profile identification based on voltage mode stator flux observation which could be easily integrated to the generator start-up process in wind turbine application for both stator flux vector feedback control system and current vector feedback control system.

Abstract: According to an embodiment, a method of operating a wind turbine comprising a DC-to-AC voltage converter is provided, the wind turbine being connectable to a grid via the DC-to-AC voltage converter, the method comprising: determining a line voltage of a power line connecting the DC-to-AC voltage converter to the grid; if the determined line voltage exceeds a predefined voltage threshold value, injecting reactive current into the power line, wherein the amount of reactive current injected is chosen such that an output voltage of the DC-to-AC voltage converter is kept within a predetermined voltage range.

Abstract: A wind farm is provided that is capable of quickly starting up without delay after an electrical grid becomes available after an outage. According to one embodiment, the wind farm comprises one or more main WTGs and an auxiliary WTG having a substantially lower start-up energy requirement than the one or more main WTGs. The auxiliary WTG is coupled to supply power to the one or more main WTGs to prepare the one or more main WTGs for start-up.

Abstract: A method for controlling a variable speed wind turbine generator is disclosed. The generator is connected to a power converter comprising switches. The generator comprises a stator and a set of terminals connected to the stator and to the switches of the power converter. The method comprises: determining a stator flux reference value corresponding to a generator power of a desired magnitude, determining an estimated stator flux value corresponding to an actual generator power, determining a difference between the determined stator flux reference value and the estimated stator flux value, and operating said switches in correspondence to the determined stator flux reference value and the estimated stator flux value to adapt at least one stator electrical quantity to obtain said desired generator power magnitude.

Abstract: A position sensorless control methodology for electrical machines using high frequency flux vector signal injection in the estimated rotor flux rotational reference frame is provided. In one aspect, the estimated position error function is derived directly from the stator flux equation without any simplification. The method is applicable for electrical generator motoring mode operation from standstill and power generation mode operation.

Abstract: A method for controlling a variable speed wind turbine generator is disclosed. The generator is connected to a power converter comprising switches. The generator comprises a stator and a set of terminals connected to the stator and to the switches of the power converter. The method comprises: determining a stator flux reference value corresponding to a generator power of a desired magnitude, determining an estimated stator flux value corresponding to an actual generator power, determining a difference between the determined stator flux reference value and the estimated stator flux value, and operating said switches in correspondence to the determined stator flux reference value and the estimated stator flux value to adapt at least one stator electrical quantity to obtain said desired generator power magnitude.

Abstract: A position sensorless control methodology for an electrical machine is provided. In particular, one aspect provides a method for position sensorless operation of an electrical machine using direct position error computation from stator flux observation results and stator current measurement.

Abstract: A method for controlling a variable speed wind turbine generator is disclosed. The generator is connected to a power converter comprising switches. The generator comprises a stator and a set of terminals connected to the stator and to the switches of the power converter. The method comprises: determining a stator flux reference value corresponding to a generator power of a desired magnitude, determining an estimated stator flux value corresponding to an actual generator power, determining a difference between the determined stator flux reference value and the estimated stator flux value, and operating said switches in correspondence to the determined stator flux reference value and the estimated stator flux value to adapt at least one stator electrical quantity to obtain said desired generator power magnitude.

Abstract: A method for controlling a variable speed wind turbine generator is disclosed. The generator is connected to a power converter comprising switches. The generator comprises a stator and a set of terminals connected to the stator and to the switches of the power converter. The method comprises: determining a stator flux reference value corresponding to a generator power of a desired magnitude, determining an estimated stator flux value corresponding to an actual generator power, determining a difference between the determined stator flux reference value and the estimated stator flux value, and operating said switches in correspondence to the determined stator flux reference value and the estimated stator flux value to adapt at least one stator electrical quantity to obtain said desired generator power magnitude.

Abstract: A variable speed wind turbine is provided. The wind turbine comprises a generator, a power converter for converting at least a portion of electrical power generated by the generator, an energy management arrangement coupled to the power converter, the energy management arrangement comprises an energy storage unit, and a controller. The controller is adapted to detect a power imbalance event and to transfer at least a portion of excess electrical energy generated by the generator to the energy storage unit to be stored therein when the power imbalance event is detected.

Abstract: A method of controlling a wind turbine generator is provided, the wind turbine generator converting mechanical energy to electrical. The method comprises: determining an electromagnetic power reference representing the electromagnetic power generated by the wind turbine generator, wherein the electromagnetic power reference is determined based on a desired output of the wind turbine generator; controlling the electrical power generated by the wind turbine generator using a control signal, wherein the control signal is derived from the electromagnetic power reference and is modified in dependence on an inverse power function of the wind turbine generator by incorporating minimal copper loss constraint and stator voltage limiting constraint such that non-linearity of the wind turbine generator plant is compensated in the control loop and it operates at its maximum efficiency. One effect of the method is that classical linear control loop design can be employed in spite of the plant being a non-linear identity.

Abstract: A method for operating an electromechanical generator is provided, the method comprising: determining a magnetic field reference parameter based on an electromagnetic power reference representing a desired output of the electromechanical generator, determining a scaling factor for adjusting an air-gap magnetization level of the electromechanical generator to reduce loss in operating the electromechanical generator, modifying the magnetic field reference parameter with the scaling factor; and operating the electromechanical generator based on at least the modified magnetic field reference parameter.

Abstract: A method for validating and initializing a control system for an electrical generator connected to a power converter in a wind turbine. The method may include generating a first parameter value representing control signal for controlling the stator flux of a stator of the electrical generator, measuring a second parameter value specifying an electrical operational characteristic of the electrical generator, and determining an accuracy level of the control signal based on the first parameter value and the second parameter value, wherein the accuracy level of the control signal has to fall within a predefined threshold for the control system to be validated.