99 results about "HVDC converter" patented technology

A modular HVDC converter system including a high voltage direct current network, and at least two DC/AC converters being connected in series to the HVDC network. Each of the DC/AC converters is arranged to provide AC to a separate AC load.

A high voltage direct current (HVDC) converter system includes a line commutated converter (LCC) configured to convert a plurality of AC voltages and currents to a regulated DC voltage of one of positive and negative polarity and a DC current transmitted in only one direction. The HVDC converter system also includes a buck converter configured to convert a plurality of AC voltages and currents to a regulated DC voltage of one of positive and negative polarity and a DC current transmitted in one of two directions. The LCC and the buck converter are coupled in parallel to an AC conduit and are coupled in series to a DC conduit. The HVDC converter system further includes a filtering device coupled in parallel to the buck converter through the AC conduit. The filtering device is configured to inject AC current having at least one harmonic frequency into the AC conduit.

A circuit and method of providing three dc voltage buses and transforming power between a low voltage dc converter and a high voltage dc converter, by coupling a primary dc power circuit and a secondary dc power circuit through an isolation transformer; providing the gating signals to power semiconductor switches in the primary and secondary circuits to control power flow between the primary and secondary circuits and by controlling a phase shift between the primary voltage and the secondary voltage. The primary dc power circuit and the secondary dc power circuit each further comprising at least two tank capacitances arranged in series as a tank leg, at least two resonant switching devices arranged in series with each other and arranged in parallel with the tank leg, and at least one voltage source arranged in parallel with the tank leg and the resonant switching devices, said resonant switching devices including power semiconductor switches that are operated by gating signals. Additional embodiments having a center-tapped battery on the low voltage side and a plurality of modules on both the low voltage side and the high voltage side are also disclosed for the purpose of reducing ripple current and for reducing the size of the components.

The invention provides a dual feed-in DC transmission method, belonging to the distribution technical field. The invention is used for solving the operation reliability of the high-voltage DC transmission. The technical proposal is that an HVDC subsystem and a VSC-HVDC subsystem are connected on the same generatrix of a transmission AC system in parallel or respectively connected with two substations which are very closely connected with each other electrically; the HVDC subsystem consists of an AC system S1 at a sending end, a system resistance Zs1, a converter transformer Ts1, an HVDC converter and a transmission line DC1, and a converter transformer (Tr1); the VSC-HVDC subsystem consists of an AC system S2 at the sending end, a system resistance Zs2, a converter transformer Ts, a VSC-HVDC converter and a transmission line DC2, and a converter transformer (Tr2). Compared with the existing HVDC system, the invention can effectively reduce the possibility that steering failure occurs to the HVDC sub-system inverter, and improves the operation reliability of the HVDC subsystem.

The invention relates to a power electronic converter (20a) for use in high voltage direct current power transmission and reactive power compensation which comprises at least one converter limb (22) including first and second DC terminals (24a, 24b) for connection in use to a DC network (26), the or each converter limb (22) including at least one first converter block (32) and at least one second converter block (34) connected between the first and second DC terminals (24a, 24b); the or each first converter block (32) including a plurality of line-commutated thyristors (36) and at least one first AC terminal (28) for connection in use to an AC network (30), the or each second converter block (34) including at least one auxiliary converter including a plurality of self-commutated switching elements; wherein the self-commutated switching elements are controllable in use to inject a voltage to modify a DC voltage presented to the DC side of the converter limb (22) and/or modify an AC voltage and an AC current on the AC side of the power electronic converter (20a).

A voltage source converter (10a) is used in high voltage direct current power transmission and reactive power compensation. The voltage source converter (10a) comprises first and second DC terminals (12, 14) for connection in use to a DC network (20), three phase elements (16) and at least one auxiliary converter (18) connected between the first and second DC terminals (12, 14), each phase element (16) including a plurality of primary switching elements (22) and at least one AC terminal (24) for connection in use to a respective phase of a multiphase AC network (26), the plurality of primary switching elements (22) being controllable in use to facilitate power conversion between the AC and DC networks (26, 20), the or each auxiliary converter (18) being operable in use to act as a waveform synthesizer to modify a first DC voltage presented to the DC network (20); so as to minimise ripple in the DC voltage.

A meshed HVDC power transmission network (10) comprises at least three HVDC converter stations (1, 2, 3) interconnected in a first closed path by at least three transmission lines (16, 18, 20). A first DC power flow control device (30) is series connected to a first (20) of the at least three transmission lines. That first DC power flow control device (30) takes its power from the first transmission line (20) and balances the DC current distribution in the first closed path.

A method and apparatus for start-up of a voltage source converter (VSC) which is connected to an energized DC link (DC+, DC−). The VSC is connected to a first AC network via a first transformer and an AC isolation switch, the AC isolation switch being coupled between the first transformer and the AC network. The method involves using an auxiliary AC power supply to generate an AC supply to energize the first transformer with the AC isolation switch open. The VSC is then started, with a VSC controller using the AC supply generated by the auxiliary AC power supply as a reference for controlling the VSC. The auxiliary AC power supply may also be used to supply power to at least one VSC load, such as the controller and/or an auxiliary load such as a cooling system. Once the VSC is started the isolation switch 204 can be closed.

A hybrid HVDC converter system includes at least one alternating current (AC) conduit, at least one transformer coupled to said at least one AC conduit, and at least one direct current (DC) conduit. The hybrid HVDC converter system also includes at least one capacitor commutated converter (CCC) configured to convert AC voltages and AC currents to a DC voltage and DC current. The at least one CCC is coupled to the at least one AC conduit through the at least one transformer. The hybrid HVDC converter system further includes at least one self-commutated converter (SCC) configured to convert AC voltages and AC currents to a regulated DC voltage and DC current. The at least one SCC includes at least one AC/DC stage and at least one DC/DC stage coupled to the at least one AC/DC stage.

The direct current (DC) side fault isolator for high voltage direct current (HVDC) converters (10) includes a first set of double thyristor switches (12) connected across the line-to-line voltage terminals between first and second phases of alternating current (AC) terminals of a HVDC converter (14), and a second set of double thyristor switches (12) connected across the line-to-line voltage between the second phase and a third phase of the AC terminals of the HVDC converter (14). In use, the first and second sets of double thyristor switches (12) separate the HVDC converter (10) from an external power grid (18) during direct current (DC) side faults by turning on these thyristors (12).

The invention discloses a series voltage compensator and a system for inhibiting commutation failure of a conventional DC converter station. The compensator comprises a first to a third converter chain, wherein each converter chain of the first to the third converter chain comprises a plurality of fully controlled voltage source sub-modules and is connected in series with an LCC- Between the HVDCconverter transformer and the AC port of the converter to control the series voltage to assist the valve bank commutation and increase the LCC- The commutation voltage area of the HVDC converter. Thecompensator adopts the converter chain composed of controllable full-bridge submodules connected in series between the converter AC port of conventional DC system and the converter transformer, and does not need to modify the internal structure of the original converter bridge arm, which is conductive to LCC- HVDC has good commutation failure suppression and fast recovery ability, which can significantly improve the performance of LCC The ability of HVDC to resist commutation failure and the recovery speed after commutation failure have the advantages of high control flexibility, low cost andgood engineering practicability.

A power electronic converter (40) for use in high voltage direct current power transmission and reactive power compensation comprises three converter limbs (42), each converter limb (42) including first and second DC terminals (46,48) for connection in use to a DC network (52) and an AC terminal (50) for connection in use to a respective phase of a three- phase AC network (54), each converter limb (42) defining first and second limb portions (56,58) being connected in series between the respective AC terminal (60) and a respective one of the first and second DC terminals (46,48), each limb portion (56,58) including at least one switching element (62,66) being controllable in use to facilitate power conversion between the AC and DC networks (52,54), the power electronic converter (40) further including a plurality of auxiliary units (44), each auxiliary unit (44); being operably associated with the respective phase of the AC network (54), each auxiliary unit (44) including at least one module (60) including a voltage source, the limb portions (56,58) being controllable in use to define at least one three-phase static synchronous compensator including at least one of the plurality of auxiliary units (44) in each branch of a star configuration, each of the first and/or second DC terminals (46,48) defining the neutral point of the respective star configuration.

A power electronic converter(30)is for use in high voltage direct current power transmission and reactive power compensation, the power electronic converter (30) including three phase elements (32) defining a star connection (36) and a converter unit (34) including first and second DC terminals (50,52) for connection in use to a DC network (56) and three AC terminals (54), the converter unit (34) including a plurality of switching elements (70,74) controllable in use to facilitate power conversion between the AC and DC networks (44,56), the power electronic converter (30) further including a third DC terminal(78) connected between the first and second DC terminals (50,52), the third DC terminal (78) being connected to a common junction (40) of the star connection (36) to define an auxiliary connection (82), the auxiliary connection (82)including at least one dump resistor (84); connected between the common junction (40) and the third DC terminal (78), wherein the switching elements (70,74) of the converter unit (34) are controllable in use to modify a phase voltage at each AC terminal (54) to include a triplen harmonic voltage component so as to dissipate real power in the or each dump resistor (84) at a triplen harmonic frequency.

The present disclosure provides a method for controlling a direct current, DC, current in a voltage source converter (VSC) station, wherein the VSC station includes at least on modular multi-level converter (MMC), including for example a full-bridge MMC (FB-MMC) submodule. The method includes determining a DC current reference (212), and determining, using a DC current controller (200), a DC voltage correction (222) based on the DC current reference (212). The method also includes generating a DC voltage reference based on a sum of the DC voltage correction (222) and at least one of an actualDC voltage and an ordered DC voltage. The method includes switching the at least one MMC based on the DC voltage reference. The method includes determining whether a DC fault has occurred in the powertransmission system, and controlling, on a basis that it is determined that the DC fault has occurred, a DC fault current to zero or close to zero by said switching. The present disclosure also provides a VSC station (700) including a controller (740) for performing the method, and a high-voltage power transmission system (800) including at least one such VSC station (810).

The invention discloses a delay compensation system of an MMC valve-controlled pulse distribution screen. The delay compensation system comprises a valve-controlled main control screen, a pulse distribution screen realizing power module pulse distribution, a pulse interface screen, a protocol conversion interface screen, an FPGA used for simulating a power module, an upper-layer direct-current control protection device used for generating modulated waves and issuing the modulated waves to a valve-controlled device, an external circuit real-time simulator used for simulating an MMC-HVDC converter valve external circuit, a delay timer and a real-time simulation interface used for being connected with the upper-layer direct-current control protection device and the external circuit real-timesimulator, wherein the delay timer measures delay time. According to the scheme, control link delay compensation of the MMC valve-controlled pulse distribution screen connected into a real-time simulation system can be flexibly realized, and simulation system delay and field delay can be maintained consistent according to an actual demand.

It provides an HVDC converter system, a method therefor and an HVDC system using the same. The HVDC converter system includes a plurality of VSCs (110,111,120,121) being coupled at their DC sides in series, wherein two terminals of the series connection are configured to be coupled with HVDC network; a plurality of by-pass breakers (112,113,122,123), each being in parallel coupled with the DC sideof the corresponding one of the plurality of VSCs (110,111,120,121) and being closed where its corresponding VSC is blocked; and a controller (15), being adapted to control current following throughthe closed by-pass breaker to reach zero and subsequently control the closed by-pass breaker to open. By controlling the by-pass breaker associated with the VSC to be taken in to reach zero current inthe first place and then opening the by-pass breaker and deblocking the VSC, the by-pass breaker can be opened in a reliable way independent of zero-crossing of the by-pass breaker naturally would have generated, otherwise, by using converter system built up of LCCs. Therefore, a blocked VSC of converter system of a converter station for HVDC transmission system can be reliably taken into operation, while the other VSC is still operating.

The invention discloses a high-voltage electrostatic field floating air removing device and relates to the technical field of designing of devices for removing floating air on pile fabric. The high-voltage electrostatic field floating air removing device comprises a fabric transfer guide belt, a conductive metal plate, a metal screen, a floating air receiving cover, a dust collection air compressor, a floating hair receiving pipe and a hair storage device, wherein the metal screen is arranged at a hair inlet of the floating hair receiving cover; a hair outlet of the floating air receiving cover is connected with the dust collection air compressor; an output end of the dust collection air compressor is connected with the hair storage device through the floating air receiving pipe; the conductive metal plate is arranged at the upper part of the fabric transfer guide belt through a bracket; the conductive metal plate is correspondingly arranged below the metal screen; the pile fabric is transferred between the metal screen and the conductive metal plate through the fabric transfer guide belt in use; the metal screen is connected with a ground wire; the conductive metal plate is connected with a high-voltage DC converter through a wire; and the high-voltage DC converter is electrically connected with AC. The high-voltage electrostatic field floating air removing device is low in energy consumption, free of noise pollution and good in floating air removal effect.

The invention discloses a novel three-phase serial modular multilevel converter HVDC converter, comprising a DC output end, a three-phase AC input end, a first transformer, a second transformer, a third transformer, a first single-phase converter, a second single-phase converter and a third single-phase converter. The novel three-phase serial modular multilevel converter HVDC converter disclosed by the invention has a low cost and can block the DC short circuit current.