Abstract: The present invention discloses a Bipolar VSC-HVDC and UPFC Hybrid Topology and its operation method. The first control circuit includes a positive and a negative circuit at the series side, in which the VSC converter can operate in bipolar mode; the second control circuit includes a positive and a negative circuit, in which the VSC converter can operate in bipolar mode; the third control circuit is the same as the second control circuit in terms of structure; the positive electrode and negative electrode of the second control circuit are connected to the DC bus via a DC breaker respectively; the other end of the DC transmission line is connected to the third control circuit via a DC breaker.

Abstract: Some embodiments include a high voltage direct current (HVDC) power generator system for information technology (IT) racks. The HVDC power generator system can include a three-phase alternating current (AC) transformer having a primary winding and a plurality of secondary windings. A plurality of three-phase bridge rectifier circuits can be electrically coupled respectively to the plurality of secondary windings. The HVDC power generator system can include output terminals for powering its load. A first string of bridge rectifier circuits can be in series with each other and a first inductor. A second string of bridge rectifier circuits can be in series with each other and a second inductor. The first and second strings can be electrically coupled in parallel to the output terminals.

Abstract: A bus conditioner for an electrical power system having at least one bus couplable to an electric power generation device driven by a prime mover includes a first energy storage device, a bi-directional power converter including a first converter input electrically connected to the first energy storage device and a converter output for connection to the bus, and a controller operatively coupled to the bi-directional power converter. The controller is configured to maintain a substantially constant load on the power generation device by commanding the power converter to divert excess power into the first energy storage device or use energy from the first storage device to provide power to the bus.

Abstract: The multilevel cascade hexagonal voltage source converter with isolated DC sources has a plurality of polyphase stages, each stage having AC inputs corresponding to a number of phases, and a numerically identical plurality of n outputs, cascaded by connection of the outputs of one stage to the inputs of a next stage. Each stage has plural DC-to-AC converters corresponding to the number of phases, and connected to one of the AC inputs, each having a connection for receiving DC power, and amplifying its AC outputs with the received DC power. The DC-to-AC converters are connected by split inductors, with each split inductor providing an output at a center tap terminal. The inductor half-segments are cross-connected with inductive cross-coupling links inductively connected to the inductor half-segments at opposite sides of the polyphase ring connection. The middle terminals of the n split inductors provide n AC outputs for its respective polyphase stage.

Abstract: Embodiments are generally based on employing a power transmission line in a HVDC link to provide auxiliary power to one of the ends of the HVDC link for facilitating a black start thereof when the HVDC link is de-energized, i.e. when at least one of the HVDC converter stations is de-energized and there is no transmission of power between inverter and rectifier HVDC converter stations on each side of the HVDC link. A relatively small amount of power can be conveyed towards one of the HVDC converter stations via the power transmission line so as to provide power to any auxiliary system(s) of the converter station, for example prior to a black start of the converter station being carried out.

Abstract: The present invention discloses an LCC and MMC series-connected HVDC system with DC fault ride-through capacity, comprising rectifier and inverter linked by DC transmission line; Both the positive pole and the negative pole of the rectifier and the inverter consist of line-commutated converter and modular converter in series-connection; the modular converter adopts one MMC or several parallel-connected MMCs. The present invention has the advantage of low cost, low power loss and high reliability of the LCC, as well as flexible control, low harmonics and AC voltage support of the MMC. Further, the present invention is able to deal with DC fault by itself, hence additional DC fault clearing equipment is not needed. As a result, the present invention is suitable for the field of long-distance large-capacity power transmission and has broad development potential.

Abstract: A system includes a current source rectifier which has a plurality of switches configured to receive an input current from an AC voltage source and to receive a plurality of control signals. The switches are configured to produce a rectified output current based on the input current and the control signals. The system also includes a rectifier controller configured to receive a current sense signal indicative of the rectified output current and to generate the control signals based at least in part on the current sense signal, where the control signals cause the current source rectifier to attenuate at least one of a plurality of harmonic frequencies in the rectified output current.

Abstract: A voltage at a point of common coupling (PCC) between a photovoltaic (PV) system and a power grid is regulated by a controller having a gain determined according to a gain function that is a function of a time. The gain function is determined based on an error between the voltage measured at the PCC and the reference voltage, and the gain is updated according to the updated gain function and a current instance of time. The controller generates a modulating signal using the updated gain and the voltage at the PCC is regulated according to the modulating signal.

Abstract: An apparatus for operating a distributed generator in connection with a power system includes an input unit which receives a parameter calculated using power system information and a voltage and a current at a point of common coupling with the distributed generator, with which the distributed generator is connected, a calculation unit which calculates an operating power factor instruction value and an active output instruction value using the parameter and the voltage and current at the point of common coupling with the distributed generator input to the input unit, and a control communication unit which determines and transmits the operating power factor instruction value and the active output instruction value according to the voltage at the point of common coupling with the distributed generator input to the input unit and an admissible voltage upper limit at the point of common coupling with the distributed generator to the distributed generator.

Abstract: A multi-terminal DC power system includes: a DC network connecting together multiple terminals. Each terminal is represented by one of: a voltage source converter having a capacitor at an interface to the DC network, wherein a difference between a converter-side current and a network-side current charges the capacitor, and a current source converter having an inductor at an interface to the DC network, wherein a difference between a converter-side voltage and a network-side voltage drives current through the inductor. A local controller for each terminal directly controls the converter-side current of each voltage source controller and the converter-side voltage of each current source converter, independent of the terminals, leaving network-side currents and voltages to be determined by the network, resulting in simplified terminal control and avoidance of the need for high-speed communication among all terminals at all times.

Abstract: A modular multilevel converter for hybrid energy storage includes a battery. Three phases are connected in serial to the battery and in parallel to one another, each phase having two arms of sub-modules and buffer inductors. Each of the sub-modules includes a half-bridge and an ultracapacitor. A control module is configured to control the battery output power and ultracapacitor output power independently.

Abstract: A thyristor controlled LC (TCLC) compensator for compensating dynamic reactive power in a power grid system, with an advantage of mitigating harmonic current injection from solid-state switches during switching on or off is provided. Exemplarily, the TCLC compensator is shunt-connected to the three-phase power grid and comprises an electronic controller, a coupling inductor (Lc), a first branch of circuit with a parallel inductor (LPF) and a solid-state switch, and a second branch of circuit with a parallel capacitor (CPF), wherein the coupling inductor (Lc) is connected in series with a parallel combination of the first and second branch of circuit. The electronic controller for the TCLC compensator is configured in accordance to the generalized instantaneous reactive power theory for improving the response speed instead of using traditional average reactive power concept.

Abstract: The present invention provides a marine propulsion system that is suitable for any civilian and military marine vessels and which offers operational flexibility. The marine propulsion system includes a pair of ac busbars, each in parallel connection with a power converter. The respective power converters each connected in parallel to a propulsion motor.

Abstract: The battery charger comprises: two output terminals (BS1, BS2) between which a battery (102) is designed to be connected; two input terminals (BE1, BE2) designed to be connected to an electrical network (110); two inductors (L.A, L.C) respectively connected to the first input terminal (BE1) and to the second input terminal (BE2); two switching arms (BA, BC) for respectively connecting the inductors (LA, LC) selectively to the first output terminal (BS1) and to the second output terminal (BS2); a control device (120) designed for controlling the switching arms (BA, BC) so as to draw from the electrical network (110) a mains current (iR) in phase with the mains voltage (uR). The battery charger further comprises: a smoothing capacitor (C) connected to the second output terminal (BS2); and a connection device (112) for connecting the smoothing capacitor (C) to the second input terminal (BE2). The control device (120) is further designed to control at least the second switching arm (B.sub.

Abstract: Provided herein is a fusion energy extraction circuit (FEEC) device having a grid-tied bidirectional converter and a resonant converter. The resonant converter can include an inverse cyclotron converter with two or more or quadruple plates and a plurality of circuit switches. The bidirectional converter can include a three-phase grid-tied converter. The FEEC device is capable of decelerating plasma particle beams, thereby extracting the energy from the deceleration, converting the extracted energy to electric energy, and sending the electric energy to a power grid.

Abstract: The present invention discloses a direct current (DC) voltage control method. The present invention further discloses an apparatus for implementing the method. With the present invention, DC voltage oscillation of a system, which is caused when a DC voltage primary control station stops running, may be reduced.

Abstract: A system, method and controller for managing and controlling a micro-grid network. The system includes a plurality of energy resources including at least one dispatchable energy resource and at least one intermittent energy resource, wherein the at least one of the energy resources is an energy storage element and at least one of the intermittent energy resources is responsive to environmental conditions to generate power, a controller configured to record operational constraints of the energy resources, obtain an environmental condition prediction and generate a component control signal based on the environmental condition prediction and the operational constraints corresponding to the energy resources. The controller is further configured to receive a network disturbance signal and generate a dynamic control signal based on such disturbances.

Abstract: A voltage source converter comprises first and second DC terminals for connection to a DC network, and at least one limb connected between the first and second DC terminals. The or each limb includes: a phase element including two parallel-connected sets of series-connected switching elements connected in an H-bridge to define first and second diagonal switching pairs, a respective junction between each set of series-connected switching elements defining an AC terminal for connection to an AC network; and a sub-converter configured to be controllable to act as a voltage waveform synthesizer. The voltage source converter further includes a controller to operate the sub-converter to selectively synthesize a driving commutation voltage to modify a DC side current at a DC side of the H-bridge to minimize any differences in magnitude and direction between the DC side current and an AC side current at an AC side of the H-bridge.

Abstract: A power supply device for HVDC controller is provided. The power supply device comprises: a first High Voltage Direct Current (HVDC) converter unit connected to an active power grid; a second HVDC converter unit connected to a passive power grid, the second HVDC converter unit being capable of receiving first DC power from the first HVDC converter unit by being connected to the first HVDC converter unit via a Direct Current (DC) transmission line; and an HVDC controller, arranged in the second HVDC converter unit, for receiving the first DC power, applied from the first HVDC converter unit to the second HVDC converter unit, by being connected to the DC transmission line that connects the first HVDC converter unit with the second HVDC converter unit.

Abstract: An intermediate voltage circuit current converter having two current converter sections arranged in series on the direct voltage side is disclosed. The current converter section has a capacitor connected in parallel with two bridge modules that are connected in series with each other. The output of the current converter section is located on the series connection between the two bridge modules and the outputs of the two current converter sections are connected to a further bridge module. Each bridge modules comprises a series connection of two power semiconductor units. The intermediate potentials on the connection between the two power semiconductor units in each of the bridge modules are electrically connected to one another by a further capacitor, and the intermediate potential of the further bridge module provides the phase connection of the intermediate voltage circuit current converter for a given phase of the intermediate voltage circuit current converter.

Abstract: A high voltage direct current (HVDC) transmission system is provided. The high voltage direct current (HVDC) transmission system includes a rectifier converting alternating current (AC) power into DC power; an inverter converting the DC power into the AC power; DC transmission lines W1 and W2 transmitting the DC power obtained from the rectifier through conversion to the inverter; a first active power measurement unit measuring first active power input to the rectifier; a second active power measurement unit measuring second active power output from the inverter; and a first control unit controlling the operations of the rectifier and the inverter based on the first active power measured and the second active power measured, wherein the first control unit senses oscillation generated in the HVDC transmission system and generates a control signal for damping the sensed oscillation to control one or more of the rectifier and the inverter.

Abstract: A converter performs full-wave rectification on a single-phase voltage, thus outputting a rectified voltage across DC power supply lines. An inverter receives the rectified voltage and then supplies a three-phase AC current to an inductive load. Between the DC power supply lines is connected a charge and discharge circuit. The charge and discharge circuit includes a buffer circuit and a boost circuit. The buffer circuit includes a series connection between a capacitor and a switch. The boost circuit, which may be configured by a boost chopper, includes a switch, a reactor and a diode. The charge and discharge circuit provides and receives part of pulsations of the power input to the converter between the DC power supply lines.

Abstract: In a method of operating a dual mode DC-DC converter having first and second bridge converters connected via a transformer, a capacitor in series with each winding of the transformer, and an inductance, wherein each bridge converter includes a number of switches operating under the control of a controller, in a first mode of operation, the switching of the number of switches is controlled in a manner to transfer DC electrical power from the first bridge converter to the second bridge converter, or vice versa. In a second mode of operation, one switch of each bridge converter is maintained in a closed state and one switch of each bridge converter is maintained in an open state while the switching of the other of the number of switches of the first and second bridge converters is controlled in a manner to transfer DC electrical power from the first bridge converter to the second bridge converter, or vice versa.

Abstract: A high voltage direct current (HVDC) transmission system is provided. The high voltage direct current (HVDC) transmission system includes: a rectifier converting alternating current (AC) power into DC power; an inverter converting the DC power into the AC power; a DC transmission line transmitting, to the inverter, the DC power obtained through conversion by the rectifier; a first active power measurement unit measuring first active power input to the rectifier; a second active power measurement unit measuring second active power output from the inverter; and a first control unit detecting an abnormal voltage state on the DC transmission line based on the first and second active power measured.

Abstract: A resonance suppression device, in which power loss and apparatus capacitance are reduced by outputting a compensating current only while a voltage resonance is being generated, and which suppresses resonance generated by connection of a power apparatus to a power system. In one embodiment, the device includes a capacitance change detector that detects a change of an electrostatic capacitance (impedance) connected to the power system. When the resonance detector detects the resonance, a current command value generator generates the current command value on the basis of harmonic components included in a current supplied from the power apparatus to the power system. When the impedance change detector detects a change of the impedance, the current command value generator generates the current command value so as to reduce the compensating current.

Abstract: We describe a photovoltaic power conditioning unit comprising: both dc and ac power inputs; a dc link; at least one dc-to-dc converter coupled between dc input and dc link; and a dc-to-ac converter coupled between dc link and ac output. The dc-to-dc converter comprises: a transformer having input and output windings; an input dc-to-ac converter coupled between dc input and input winding; and an ac-to-dc converter coupled between output winding the dc link. The output winding has a winding tap between the first and second portions. The ac-to-dc converter comprises: first and second rectifiers, each connected to a respective first and second portion of the output winding, to the dc link and winding tap; and a series inductor connected to the winding tap. Rectifiers are connected to the winding tap of the output winding via the series inductor wherein the series inductor is shared between the first and second rectifiers.

Abstract: In a converter for converting energy from a generator to a power network, wherein the converter comprises multiple power modules, wherein each power module includes at least two power cells and a transformer for connecting the power cells to the power network, wherein each power cell includes a phase input, a phase output, a transformer output connected to the transformer, a rectifier circuit and an inverter, the transformer (T) of a power module (4.1, . . . , 4.n) includes one generator-side winding (10) for each of the power cells (5) and exactly one common grid-side winding for balancing an energy flow through the power cells (5) of a power module (4.1, . . . , 4.n).

Abstract: A controller of a power conversion apparatus according to an embodiment causes a chopper and an inverter to generate an alternating-current (AC) voltage including first and second parts of an AC voltage waveform and causes the inverter to output the AC voltage. The chopper generates the first part having an absolute value higher than a voltage of a DC power supply, and the inverter generates the second part having an absolute value lower than the voltage of the DC power supply. The controller is configured to alternately turn on the first and second switching elements in a period during which the controller controls the chopper to generate the first part of the AC voltage waveform.

Abstract: Provided is a synthetic test circuit for synthetic-testing a thyristor valve in high voltage direct current (HVDC). A resonant circuit applies forward DC current, a reverse DC voltage, and a forward DC voltage to synthetic-test the thyristor valve. A current generation unit generates DC current that is above a reference current value to supply the generated DC current into the resonant circuit. A voltage generates unit generating a DC voltage that is above a reference voltage value to supply the generated DC voltage into the resonant circuit. The resonant circuit includes a charging auxiliary valve for charging a gate driver of the thyristor valve.

Abstract: Example energy management systems and methods are described. In one implementation, a system includes an inverter and a combiner module coupled to the inverter. The combiner module receives DC signals from multiple DC sources and delivers a DC output signal. A control module manages a voltage and a current associated with the DC output signal delivered by the combiner module.

Abstract: The present invention discloses a hybrid converter and a wind power generating system, the hybrid converter including a voltage source converter, a line commutated converter and a line commutated converter, a positive DC terminal of the voltage source converter is connected to a negative DC terminal of the line commutated converter, a positive DC terminal of the line commutated converter is connected to a positive DC transmission line, a negative DC terminal of the voltage source converter is connected to a positive DC terminal of the line commutated converter, and a negative DC terminal of the line commutated converter is connected to a negative DC transmission line. The present invention features a self-commutating capability, can be directly connected to a wind farm to convert wind power to DC power, and is able to improve rated voltage and rated power of the hybrid converter, technology of each component thereof is mature, and system reliability thereof is high.

Abstract: A power electronic converter for use in high voltage direct current power transmission and reactive power compensation comprises a plurality of switching elements interconnecting in use a DC network and one or more AC networks, the plurality of switching elements being controllable in use to facilitate power conversion between the AC and DC networks, wherein in use, the plurality of switching elements are controllable to form one or more short circuits within the power electronic converter so as to define one or more primary current flow paths, the or each primary current flow path including a respective one of the AC networks and the power electronic converter and bypassing the DC network.

Abstract: A method to control a voltage source converter (CON1; CON2) in a HVDC system comprises the step of controlling a frequency and a voltage amplitude of an AC voltage (UV1; UV2) generated by the voltage source converter (CON1; CON2) independently of the conditions in an AC network (N1; N2) connected to the voltage source converter (CON1; CON2). This method is performed by a control unit of a HVDC system. In a special embodiment, the method forms the basis of a method to black start an AC network, where the AC network comprises transmission lines and is connected to at least two AC power stations, where one of the at least two AC power stations is connected via a HVDC system to the AC network.

Abstract: A power transmission system is provided. The power transmission system includes at least one power substation for receiving power from a power source, and a Direct Current (DC) cable for transferring the power from the power source to the power substation. The DC cable includes a plurality of segments individually or in combination forming a path to route the power to the power substation. The system further includes at least one segment switch unit electrically coupled to each segment. At least one of the segment switch units includes a shorting switch element for providing a short circuit path to prevent the power from the power source to be routed to a respective segment in response to a shorting command, and a disconnect switch element for disconnecting the respective segment in response to a disconnect command.

Abstract: A system for delivering power to an offshore load is disclosed. The system may include an on-land source of three-phase power, an on-land AC-to-DC power conversion module, a DC transmission line, and an offshore DC-to-AC power inverter. The on-land AC-to-DC power conversion module may be configured to convert the three-phase power to DC power. The DC transmission line may have a source end and a load end, where the source end is configured to receive DC power from the on-land AC-to-DC power conversion module. The offshore DC-to-AC power inverter may be configured to receive DC power from the DC transmission line, convert the DC power to three-phase AC power, and deliver the three-phase AC power to an offshore load.

Abstract: A power generation system includes at least one generator having at least two sets of stator windings, an active rectifier comprising power cell based modular converters associated with each set of generator windings. Each set of windings is connected to an AC voltage side of the associated active rectifier, with each active rectifier having a positive DC voltage output and a negative DC voltage output. The DC voltage outputs of active rectifiers are connected to each other in series. A medium voltage DC (MVDC) collection network comprises positive pole cables and negative pole cables, wherein each positive pole cable is connected to the positive DC voltage output of a first active rectifier and each negative pole cable is connected to the negative DC voltage output of a last active rectifier. A substation receives the negative and positive pole cables of the MVDC collection network for further transformation and transmission.

Abstract: An uninterruptible power supply device including a rectifier circuit rectifying output power of an inverter. At a first startup of the inverter, output power of the rectifier circuit is supplied to an electric double-layer capacitor. At second and subsequent startups of the inverter, output power of one of a converter and the rectifier circuit is selectively supplied to the electric double-layer capacitor. Therefore, by controlling the inverter, the electric double-layer capacitor can be precharged easily with a simple configuration.

Abstract: A power electronic converter for use in high voltage direct current power transmission and reactive power compensation comprises a plurality of switching elements interconnecting in use a DC network and one or more AC networks, the plurality of switching elements being controllable in use to facilitate power conversion between the AC and DC networks, wherein in use, the plurality of switching elements are controllable to form one or more short circuits within the power electronic converter so as to define one or more primary current flow paths, the or each primary current flow path including a respective one of the AC networks and the power electronic converter and bypassing the DC network.

Abstract: Connection schemes for offshore power generation with an internal collection grid include a power generation system which includes a plurality of generator-rectifier subsystems. The scheme further includes a medium voltage DC (MVDC) collection network with positive pole cables and negative pole cables connected to the DC outputs of the generator-rectifier subsystems. At least one offshore substation includes a positive bus bar and a negative bus bar correspondingly connected to the positive pole cables and negative pole cables of the MVDC collection network and a plurality of main DC-DC converters. Each main DC-DC converter includes multiple modules connected to the MVDC bus bars and each module has a positive and a negative output such that the modules' outputs are serially connected to one another. The schemes may also include a high voltage DC (HVDC) transmission system connected to the modules' outputs and at least one DC/AC converter at an onshore substation.

Abstract: The present invention discloses a hybrid converter and a wind power generating system, the hybrid converter comprising a voltage source converter, a line commutated converter and a line commutated converter, a positive DC terminal of the voltage source converter is connected to a negative DC terminal of the line commutated converter, a positive DC terminal of the line commutated converter is connected to a positive DC transmission line, a negative DC terminal of the voltage source converter is connected to a positive DC terminal of the line commutated converter, and a negative DC terminal of the line commutated converter is connected to a negative DC transmission line. The present invention features a self-commutating capability, can be directly connected to a wind farm to convert wind power to DC power, and is able to improve rated voltage and rated power of the hybrid converter, technology of each component thereof is mature, and system reliability thereof is high.

Abstract: An integrated power quality control system includes a transformer with a primary winding, a secondary winding and a compensation winding wound on a magnetic core. A power electronic converter in the system provides a reference voltage to the compensation winding for injecting a series voltage in the secondary winding of the transformer. A controller is utilized to generate a reference control voltage for the power electronic converter based on a power quality control requirement.

Abstract: An exemplary Multi-Terminal High Voltage Direct Current (MTDC) system includes at least three terminals, where each terminal including a Voltage Source Converter (VSC) controlled by a VSC controller. A method for controlling the MTDC system includes providing a converter schedule including at least one of a desired power flow value and a DC voltage; determining, by a MTDC master controller, a present state of the MTDC system including a dynamic topology of the MTDC system; determining, by the MTDC master controller, based on the present state of the MTDC system, based on the schedule and based on MTDC system constraints, VSC controller parameters including droop settings for local control by the VSC controllers; and transmitting the VSC controller parameters to the VSC controllers.

Abstract: A minimalized power converter has a square-wave voltage source operating at 100 percent duty-ratio, a series inductance and a rectifier. A high frequency square-wave power distribution system comprises a plurality of minimalized power converters connected by a common ac power distribution link. Because the ac power distribution link carries current at a high frequency, the square-wave may be degraded by the stray inductance with distance. Re-squaring circuits along the length of the ac power distribution link operating synchronously restore and preserve the integrity of the square-wave. The minimalized power converter is very flexible and has very fast dynamic response, being able to make very fast controlled current transitions from any current to any other current, including zero or current reversal (same voltage, opposite current flow).

Abstract: The present invention relates to a method for charging a DC link of a power converter included in a wind turbine generator, the wind turbine generator comprising a generator side converter connected to an electrical generator and a grid side converter connectable, or connected, to an electrical grid through a grid circuit breaker, and a converter controller arranged to control at least the DC link, the DC link having a DC voltage level, the wind turbine generator comprising a wind turbine rotor arranged to rotate the electrical generator, wherein the method comprises rotating the wind turbine rotor whereby the electrical generator generates electrical power, rectifying the electrical power through at least one diode of the generator side converter in order to pre-charge the DC link to a DC voltage level, closing the grid circuit breaker when the DC voltage level is greater than a threshold level.

Abstract: The present invention provides a multi-terminal power conversion device, a multi-terminal power transfer device, and a power network system which allows an existing power grid to be divided into a plurality of power grids that can be interconnected together and operated stably via existing or new transmission lines. An inter-power grid asynchronous interconnection network system includes a multi-terminal power conversion device characterized by connecting together a plurality of asynchronous power grids including a bulk power grid and controlling power so that the sum of inflow power and outflow power is zero. An intra-power grid synchronous network system includes a power apparatus control terminal device with means for controlling power for a power apparatus installed in an autonomous power grid. A plurality of inter-power grid asynchronous interconnection network systems are connected to an intra-power grid synchronous network system to integrate the power control with communication control.

Abstract: A power electronic converter for high/medium voltage direct current power transmission and reactive power compensation comprises a primary converter unit and an auxiliary converter unit, the primary converter unit including at least one primary converter limb including first and second DC terminals for connection in use to a DC network and an AC terminal, the or each primary converter limb defining first and second limb portions, each limb portion including at least one primary module, the or each primary module including at least one primary switching element connected to an energy storage device, the auxiliary converter unit including at least one auxiliary converter limb including at least one auxiliary module including a plurality of auxiliary switching elements connected to the energy storage device of a corresponding primary module in the first limb portion of a respective primary converter limb, the primary switching elements of the primary modules being controllable in use to switch the respective ene

Abstract: A system for providing, from a direct current (DC) voltage source, an alternating current (AC) to an electrical grid outputting a grid voltage, the system including: a transformer for coupling to the DC voltage source through a first switch controlled by a first control signal, and configured to provide a converted voltage based on a DC voltage; a rectifier coupled to the transformer, and configured to generate an envelope voltage of the converted voltage; a plurality of switches coupled to the rectifier to receive the generated envelope voltage of the converted voltage, the plurality of switches being controlled by a plurality of control signals, respectively, and configured to generate the AC from the generated envelope voltage of the converted voltage; and control apparatus coupled to the first switch and the plurality of switches, and configured to provide, based on the grid voltage, the first control signal and the plurality of control signals.

Abstract: A power conversion system eliminates output transformers and replaces them with a zig-zag transformer and a filter that provides a 3-phase 5-wire system with significantly reduced weight and size as compared with conventional systems. The zig-zag transformer may have a low zero sequence impedance. The power conversion system also ensures operational safety by detecting various types of ground faults.

Abstract: An exemplary power conversion system includes a first power conversion module, a second power conversion module, and a controller. The first power conversion module includes a first source side converter, a first load side converter, and a first DC link coupled between the first source side converter and the second load side converter. The second power conversion module includes a second source side converter, a second load side converter, and a second DC link coupled between the second source side converter and the second load side converter. The controller is configured to generate a number of switching signals according to a circuit structure of the power source module or a circuit structure of the load module. The switching signals are provided to the first power conversion module and the second power conversion module to balance a first DC link voltage and a second DC link voltage.

Abstract: A regenerative variable frequency drive includes an active converter connected to an inverter. The converter has a filter capacitor, an inductor, two half bridges, bus bars that connect to the inverter and bus capacitors. The converter converts single phase AC power to DC power and DC power to single phase AC power, boosts the AC power, reduces input line harmonics, maintains input current in phase with utility voltage in order to achieve near unity power factor, and maintains constant DC voltage between the bus bars.