Abstract: A wind turbine system with a medium voltage (MV) converter system for converting electric power by the wind turbine generator. A housing, e.g. a placed on the ground near the wind turbine tower, encloses the MV converter to block access. An access door with a controllable locking mechanism is controlled by an access control system which unlocks the access door after execution of a safety access algorithm. This allows a person to provide service to the potentially dangerous MV equipment in a safe an automated way after request. The housing preferably has a control compartment where a person can request access and await opening of the access door for safe access to the MV converter.

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: According to embodiments described herein a Modular Multilevel Converter (MMC) is pre-charged by: driving a bypass current from an auxiliary power source through a plurality of bypass switches included in a corresponding plurality of cells; in response to a summed voltage across a plurality of cell capacitors included in the plurality of cells satisfying a drive threshold, driving an insert current through a plurality of insert switches included in the plurality of cells; and in response to a voltage across a Direct Current (DC) link capacitor satisfying a pre-charge threshold when driving the insert current, opening a circuit breaker connecting the auxiliary power source with the plurality of cells and connecting a generator with external power line rails between which the DC link capacitor is connected.

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 including 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 present invention relates to wind energy park connected to an electrical grid, having airborne wind energy systems (AWES), e.g. with kites. The wind energy park has an electrical DC network connecting the plurality of AWES and a grid converter unit for converting DC to AC, and transmit AC to the electrical grid. The wind energy park control unit controls the AWES to produce electrical power to the electrical grid by alternating between a power production phase, and a recovery phase so to balance the supply of power to the electrical grid according a demanded setpoint. An advantage is that the grid converter may be smaller, as compared to an AC network, because the power is evened out with the negative power from the AWES being in recovery phase. In this way, the invention stabilizes the grid and has a grid forming capability.

Abstract: A method for use in controlling a wind turbine generator of a wind power plant based on a condition of a power converter or a component forming part of a power converter in the wind power plant. The method comprises determining the initial condition of the power converter or a component forming part of a power converter and determining the evolution of the condition from the initial condition based on notional power reference values of the wind turbine generator. The method further comprises comparing the evolution of the condition to a predetermined threshold and determining, from the comparison, a time period by which the condition of the power converter or a component forming part of a power converter will substantially equal the predetermined threshold.

Abstract: The present invention relates to a method for simultaneous operation of a plurality of chopper circuits of a wind turbine power converter, the method comprising the steps of operating a controllable switching member of a first chopper circuit in accordance with a first switching pattern, and operating a controllable switching member of a second chopper circuit in accordance with a second switching pattern, wherein the first switching pattern is different from the second switching pattern during a first time period. In order to reduce switching losses the first switching pattern may involve that the controllable switching member of the first chopper circuit is clamped during the first time period. Additional chopper circuits may be provided in parallel to the first and second chopper circuits. The present invention further relates to a power dissipation chopper being operated in accordance with the before mentioned method.

Abstract: A Direct Current (DC) chopper may be integrated 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 including at least the power transistors of the MMC cell. The safe discharge of both cell capacitors and DC-link capacitors in different operating conditions is performed using Insulated-Gate Bipolar Transistors (IGBTs) and chopper resistors of an MMC cell.

Abstract: The present invention relates to operation of a wind turbine using a power storage unit, such as a rechargeable battery, to power a group of power consuming units during grid loss. The wind turbine comprises a number of power consuming units being grouped into at least a first group and a second group, a first electrical converter for connecting the generator to the electrical grid, and a second electrical converter for connecting the electrical generator to the power storage unit. Upon detecting an occurrence of the grid loss, the generator is operated to ensure sufficient power of the power storage unit to operate the first group of power consuming units.

Abstract: A method for use in controlling a wind turbine generator based on a condition of a power converter or a component forming part of a power converter in the wind turbine generator. The method comprises determining a condition of the power converter or the component forming part of a power converter, then comparing the condition to a predetermined threshold and modifying an operational parameter of the wind turbine generator if the condition substantially equals or exceeds the predetermined threshold. In particular, the invention proposes the wind turbine generator is derated if the condition of the power converter or the component forming part of a power converter substantially equals or exceeds the predetermined threshold.

Abstract: Aspects of the present disclosure are generally directed to configurations of power conversion systems for wind turbine generators. For example, certain aspects are directed to a multi-rotor wind turbine. The multi-rotor wind turbine generally includes a plurality of rotors, each coupled to a plurality of electrical generators, one or more machine-side converters, MSCs, coupled to the electrical generators of each of the plurality of rotors and configured to generate at least one direct-current, DC, signal, and one or more line-side converters, LSCs, coupled to the MSCs and configured to generate at least one AC signal based on the at least one DC signal.

Abstract: Aspects of the present disclosure are generally directed to using a rotary transformer to transfer power for a wind turbine generator. Certain aspects of the present disclosure are directed to a multi-rotor wind turbine. The multi-rotor wind turbine generally includes a plurality of rotors, a plurality of electrical generators, each coupled to one of the plurality of rotors, and one or more rotary transformers configured to transfer power between the electrical generators and a power grid. In some aspects, each rotary transformer comprises a first winding coupled to one or more electrical generators of the plurality of electrical generators, and a second winding magnetically coupled to the first winding and coupled to the power grid, wherein the first winding is rotatable with respect to the second winding.

Abstract: A method of controlling a wind turbine generator (1) comprising an electrical generator (10) and a power converter (12), the power converter (12) comprising an electrical switch (14a, 14b) that is configured to process electrical power produced by the electrical generator (10), the method comprising: controlling an output from the electrical switch (14a, 14b) using a variable pulse-width modulated control signal, thereby to control characteristics of output power from the power converter (12); acquiring sample data (26) relating to an electronic signal within the wind turbine generator (1), wherein the sample data (26) is used for controlling the wind turbine generator (1); and dynamically adjusting a frequency (30) at which the sample data is acquired to synchronise data acquisition with a carrier frequency (24) of the control signal.

Abstract: A method, converter arrangement, and controller are disclosed for connecting an output of a converter with an electrical grid to control inrush currents into a grid filter assembly connected with the output of the converter, the electrical grid carrying an alternating current (AC) signal having one or more phases. The method includes determining a voltage of the AC signal and operating, after pre-charging a direct current (DC) link of the converter to a predetermined voltage, the converter using open-loop voltage control to produce an AC output signal that substantially matches the AC signal of the electrical grid. The open-loop voltage control is based on the determined voltage of the AC signal. The method further includes closing, after a predetermined amount of time of operating the converter using the open-loop voltage control, a switching device to thereby connect the output of the converter with the electrical grid.

Abstract: A wind turbine generator 1 supplies three-phase a.c. current of variable voltage and variable frequency to two pairs of rectifiers 4a, 4b and 4c, 4d which generate respective d.c. outputs connected to positive, negative and neutral d.c. conductors 6, 7, 8. The outputs from each pair of rectifiers are connected together, and the outputs from the two pairs are connected in series to create a high-voltage d.c. output. Inverters 10a, 10b, 10c, 10d then convert the d.c. power to a.c. at a fixed frequency and voltage suitable for connection to the mains grid. To reduce the effect of common-mode noise, a capacitor is connected between the 1 neutral conductor 7 and earth, and a respective filter circuit 30 is connected between each of the a.c. outputs of the inverters 10a, 10b, 10c, 10d and earth. To reduce the effect of voltage surges during lightning, a surge protection device is also connected between the neutral d.c. conductor 7 and earth.

Abstract: A method of controlling a full-scale converter system in which both the grid-side inverter unit and the generator-side inverter unit have a series-connection of parallel inverters and form a generator-side and grid-side voltage-center-point at a voltage level between the inverters connected in series. The voltage-center-points are electrically connected by a center-line conductor. Conversion operation with a de-rated maximum active power-output is performed in response to at least one of (i) the grid-side inverter and (ii) the generator-side inverter of the first converter-string being disabled, by disabling active power production of at least one of (i) the grid-side inverter and (ii) the generator-side inverter of the second converter-string, or correspondingly reducing active power production of the second converter-string, thereby preventing a compensation current along the center-line conductor.

Abstract: A wind turbine converter system with a rectifier and an inverter and a converter controller has at least first and second converter strings. The converter system is controlled by a master-converter controller and a slave-converter controller. The master-converter controller controls the first converter string and the slave-converter controller controls the second converter string. The master-converter controller receives commands from a superordinate wind turbine controller, provides the slave-converter controller with string-control commands on the basis of the superordinate control commands, and controls the conversion operation of the first converter string on the basis of the superordinate control command. The slave-converter controller receives the string-control commands from the master-converter controller and controls the conversion operation of the second converter string on the basis of the string-control commands received.

Abstract: Techniques are described for operating a wind power facility in order to provide reactive power support to a power grid. The wind power facility may be a wind turbine or a wind power plant. An exemplary method includes increasing an amount of reactive power injected into the power grid, decreasing an amount of active power injected into the power grid by a certain amount, and dissipating and/or storing substantially the certain amount of active power.

Abstract: In a full-scale converter system both the grid-side inverter unit and the generator-side inverter unit have a series convection of parallel inverters and form a generator-side and grid-side voltage-center-point at a voltage level between those of the inverters connected in series. The voltage-center-points are electrically connected by a center-line conductor that has a cross-section between 30% and 70% of that of a positive or negative potential conductor. The converter system continues conversion operation in the event of a fault in an inverter of a first converter-string, with non-faulty inverters of the converter system, as the center-line conductor is dimensioned by said cross-section to carry a compensation current resulting from an unbalanced active power-output.

Abstract: The present invention relates to a connection system for connecting a power generator to a DC electrical power system, with a controllable voltage source unit functionally connected in series with the power generator to receive AC electrical power from the power generator, and to generate an AC electrical power output accordingly, and a rectifier arranged to receive AC electrical power output from said voltage source unit and to rectify the AC electrical power output to a DC electrical power to be provided to the DC electrical power system. The invention also relates to method for connecting a power generator to a DC electrical power system.