Abstract: The invention relates to monitoring a wind turbine having an electrical component. An exterior temperature and power loss associated with the electrical component is obtained, and a thermal model describing the electrical component is executed, based on the exterior temperature and power loss, to determine an internal temperature of the electrical component. A further thermal model describing the electrical component is executed, based on the internal temperature and an exterior component temperature, to predict a future thermal condition of the electrical component in order to monitor operation of the wind turbine.

Abstract: A method of operating a power generating system for a wind turbine connected to an electrical grid, the power generating system comprising a power generator, a converter, a transformer and a tap changer, the method comprising; when operating the power generating system in a grid-forming configuration, monitoring a signal for detecting a voltage of the electrical grid which requires an increase in output voltage from the power generating system in order to maintain the grid voltage within a predetermined voltage range; and operating the tap changer to tap-up the transformer to provide at least part of the voltage increase required to maintain the grid voltage within the predetermined voltage range.

Abstract: A method of operating a power generating system for a wind turbine connected to an electrical grid, the power generating system comprising a power generator, a converter, a transformer and a tap changer, the method comprising; monitoring a signal for detecting an over-voltage condition in the electrical grid which requires a reduction in the output voltage from the power generating system; initiating a convertor response mode configured to provide at least part of the required voltage reduction; and initiating a transformer response mode configured to provide at least part of the required voltage reduction; wherein the transformer response mode comprises operating the tap changer to adjust the output voltage from the power generating system.

Abstract: This disclosure proposes procedures and systems for discharging system capacitors and de-energizing power transmission systems having Modular Multilevel Converter (MMC) topologies by intelligent control of MMC cell components including configuration of bypass and insert switches using integrated DC choppers to effectively de-energize MMC cell capacitors and/or DC-link capacitors under operating conditions such as after a normal stop, for protection against over-voltages, dumping turbine energy, and under certain hardware fault conditions.

Abstract: This disclosure proposes a topology that integrates a DC chopper into the Modular Multilevel Converter (MMC) cells of a power converter. The integrated DC chopper may include chopper resistors that may also be advantageously integrated into a heat sink for a power module comprising at least the power transistors of the MMC cell. Embodiments herein also describe a method for using an MMC cell's IGBTs and chopper resistors for providing a safe discharge of both cell capacitors and DC-link capacitors in different operating conditions.

Abstract: This invention concerns a method of controlling a line side converter of a power converter system operating in an over-modulation range. The line side converter comprises a controller comprising a feedback control module configured to output a feedback control signal for modifying a drive signal received by a modulator. The method comprises determining a modulation index within the over-modulation range; and, controlling the feedback control module to adjust the feedback control signal based on the modulation index.

Abstract: This invention concerns a method of controlling a power converter system 26 operating in an overmodulation region. The power converter system 26 comprises more than two current controllers 71, 73, 77, 79 a modulator 76 and a power converter 78, and the modulator 76 is configured to provide at least one modulated drive signal 87 to the power converter 78 based on voltage reference vector signals 82a, 82b, 82c, 82d from the more than two current controllers 71, 73, 77, 79. The method comprises determining the voltage reference vector signals 82a, 82b, 82c, 82d; determining compensated voltage reference vector signals 84a, 84b, 84c, 84d indicative of a fundamental frequency of a respective voltage reference vector signal 82a, 82b, 82c, 82d; and, determining the at least one modulated drive signal 87 based on a combination of the compensated voltage reference vector signals 84a, 84b, 84c, 84d.

Abstract: A method of operating a power generating system for a wind turbine connected to an electrical grid, the power generating system comprising a power generator, a converter, a transformer and a tap changer, the method comprising; monitoring a signal for detecting a voltage in the electrical grid which requires an increase in output voltage from the power generating system; determining a partial-load condition of the converter, which corresponds to the converter being configured to output a voltage which is substantially below its maximum output voltage; and upon determining the partial-load condition, operating the tap changer to tap down the transformer, and operating the converter to provide the required increase in output voltage from the power generating system.

Abstract: This disclosure proposes a topology that integrates a DC chopper into the Modular Multilevel Converter (MMC) cells of a power converter. The integrated DC chopper may include chopper resistors that may also be advantageously integrated into a heat sink for a power module comprising at least the power transistors of the MMC cell. Embodiments herein also describe a method for using an MMC cell's IGBTs and chopper resistors for providing a safe discharge of both cell capacitors and DC-link capacitors in different operating conditions.

Abstract: The invention relates to a method for operating a wind turbine which comprises a power generator, a generator side converter, a grid side converter, a DC link electrically connected to an output of the generator side converter and an input of the grid side converter. The method comprises monitoring a wind turbine signal for detection of an operational condition which requires an increase of an output voltage of the grid side converter, upon detection of the operational condition, initiate an over-modulation mode wherein the grid side converter is operated with a modulation index in an over-modulation range, and upon the detection of the operational condition, initiate a DC-voltage adjustment mode wherein the a DC-voltage of the DC link is increased from a first voltage level towards a second voltage level.

Abstract: Aspects of the present invention relate to a method for controlling an amount of reactive current provided from a wind turbine generator to a power grid during an abnormal power grid event, said wind turbine generator comprising a doubly-fed induction generator having a rotor and a stator, and a power converter coupling the rotor to the power grid, the power converter comprising a grid-side inverter, wherein the method comprises the step of balancing the reactive current provided to the power grid between a reactive stator current and a reactive grid-side inverter current, wherein the reactive grid-side inverter current is controlled in accordance with a reactive current capacity of a grid breaker receiving the reactive current provided by the grid-side inverter. Aspects of the present invention also relate to a wind turbine generator being capable of performing the method.

Abstract: A wind power plant system comprising: a plurality of wind turbine generators each having a corresponding generator controller, and a power plant controller for controlling the power generated by the wind power plant system; wherein at least some of the plurality of generator controllers are each configured to: generate a model that indicates the thermal capacity of one or more components of the wind turbine generator, determine power capacity data from the model, said data relating to: at least one reactive power supply level and a corresponding time limit for which that reactive power supply level may be maintained, and transmit to the power plant controller the determined power capacity data, wherein the power plant controller is operable to receive the power capacity data from the plurality of generator controllers and to transmit respective power references to the plurality of generator controllers to control the power generated by the wind power plant system.

Abstract: A power conversion system for a wind turbine generator, comprising a machine-side converter having an AC voltage input from a generator and a DC voltage output to a DC link, wherein the machine-side converter is a modular multi-level converter comprising one or more converter legs corresponding to a respective one or more electrical phases of the generator, each of the converter legs comprising a plurality of converter cells, the system further comprising: a converter control module which provides the machine-side converter with a gate signal, and an electrical frequency estimation module configured to estimate the mean electrical frequency of the generator; wherein the gate signal has at least one mean switching frequency corresponding to at least one electrical phase of the generator; wherein the converter control module is configured to modulate the mean switching frequency of the gate signal in dependence on the mean electrical frequency of the generator.

Abstract: Controlling a power converters during over voltage condition. A wind turbine signal is monitored for detection of an over voltage of the grid and upon detection of the over voltage, an over-modulation mode is initiated wherein the grid side converter is operated with a modulation index being increased in an over-modulation range at least during a sub-period of the over-modulation mode, and upon the detection of the operational condition, a DC-voltage adjustment mode is initiated wherein the DC voltage of the DC link is decreased from a second voltage level towards a first voltage level at least during a sub-period of the DC-voltage adjustment mode.

Abstract: Aspects of the present invention relate to a method for controlling an amount of power to be delivered from a wind turbine generator to a power grid during an abnormal power grid event, the method comprising the steps of detecting an abnormal power grid event; controlling an active current delivered to the power grid in response to a measured or determined total active current; and controlling a reactive current delivered to the power grid in response to a measured or determined total reactive current. Aspects of the present invention further relate to a computer program product for carrying out the method as well as a wind turbine generator being capable of carrying out embodiments of the invention.

Abstract: Controlling a wind turbine during a grid fault where the grid voltage drops below a nominal grid voltage. After detection of a grid fault, the total current limit for the power converter output is increased to a total maximum overload current limit. Depending on whether active or reactive current generation is prioritized, an active or reactive current reference is determined. The active current reference is determined in a way so that a reduction in active power production due to the grid voltage drop is minimized and based on the condition that the vector-sum of the active output current and the reactive output current is limited according to the total maximum overload current limit, and a maximum period of time is determined in which the power converter can be controlled based on the active/reactive current references. Afterwards the power converter is controlled based on the active and reactive current references.

Abstract: A method is provided of protecting a wind turbine with a doubly-fed induction generator (DFIG) against a sub-synchronous resonance (SSR) event acting on the wind turbine. A plurality of power-output values or current-output values is measured over a given period of time that corresponds to a measurement cycle. It is determined whether power-output values or current-output-values measured in the at-least-one measurement cycle are indicative of an SSR-event critical for further operation of the wind turbine. The wind turbine is shut down if the measured power-output values or current-output values are indeed indicative of an SSR-event critical for operation of the wind turbine.

Abstract: A method is provided of controlling a doubly fed induction generator—(DFIG) wind turbine converter system if a sub-synchronous resonance event acts on the wind turbine. According to the method a sub-synchronous resonance event is detected. Thereupon, a switch from a non-SSR-current/voltage control mode to a SSR-control mode is performed. At least one of the following activities is performed in the SSR-control mode, namely: (i) freezing rotor AC voltages in magnitude and phase, (ii) altering at least one rotor-current-controller gain (iii) altering at least one rotor-current-controller time constant, to dampen the effect of the SSR-event on the wind turbine.

Abstract: The present invention relates to a method for operating a doubly fed induction generator wind power facility during an OVRT event, said the wind turbine facility being adapted to inject active and/or reactive current into an associated grid, the method comprising the steps of determining the occurrence of an over voltage grid event, and maintaining a grid-side inverter of the doubly fed induction generator wind power facility fully operable during the over voltage ride though event so as to maintain a controllable active and/or reactive current capability during the over voltage grid event,?