WO2022160929A1 - Unité de commutation active, structure topologique de convertisseur hybride à commutation forcée et procédé - Google Patents

Unité de commutation active, structure topologique de convertisseur hybride à commutation forcée et procédé Download PDF

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Publication number
WO2022160929A1
WO2022160929A1 PCT/CN2021/135027 CN2021135027W WO2022160929A1 WO 2022160929 A1 WO2022160929 A1 WO 2022160929A1 CN 2021135027 W CN2021135027 W CN 2021135027W WO 2022160929 A1 WO2022160929 A1 WO 2022160929A1
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Prior art keywords
branch
commutation
bridge arm
control valve
power
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PCT/CN2021/135027
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English (en)
Chinese (zh)
Inventor
高冲
贺之渊
张娟娟
王治翔
李婷婷
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全球能源互联网研究院有限公司
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Publication of WO2022160929A1 publication Critical patent/WO2022160929A1/fr

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/145—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means
    • H02M7/155—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only
    • H02M7/1552—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only in a biphase or polyphase arrangement
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/145—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means
    • H02M7/155—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only
    • H02M7/162—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only in a bridge configuration
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/505—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means
    • H02M7/515—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only
    • H02M7/521—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only in a bridge configuration
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

Definitions

  • the present invention is based on a Chinese patent application with an application number of 202110137729.3 and an application date of February 1, 2021, and claims the priority of the Chinese patent application.
  • the entire content of the Chinese patent application is incorporated herein by reference.
  • the invention relates to the technical field of commutation in power electronics, in particular to an active commutation unit, a hybrid converter topology structure and a forced commutation method.
  • the traditional line commutated converter high voltage direct current (LCC-HVDC) transmission system has the advantages of long-distance large-capacity power transmission and controllable active power, and is widely used in the world.
  • the converter is the core functional unit to realize the conversion of AC and DC power, and its operational reliability largely determines the operational reliability of the UHV DC power grid.
  • each bridge arm is composed of multi-stage thyristors and their buffer components in series. Commutation failure is prone to occur in the case of faults, resulting in a surge of DC current and a rapid and large loss of DC transmission power, which affects the stable and safe operation of the power grid.
  • the embodiments of the present invention provide an active commutation unit and a forced commutation hybrid converter topology structure and method, so as to solve the problem that commutation failure affects the stable and safe operation of the power grid.
  • an embodiment of the present invention provides an active commutation unit, which is arranged in a bridge arm circuit of a converter, one end of which is connected to a converter transformer, and the other end is connected to a DC bus, including: a main branch, the A thyristor valve is arranged on the main branch; an auxiliary branch is arranged in parallel with the main branch, and a first control valve and a second control valve are sequentially arranged on the auxiliary branch along the direction from the converter transformer to the DC bus.
  • the first control valve has a unidirectional voltage output controllable shutdown function
  • the second control valve has a forward current controllable shutdown function and a forward and reverse voltage blocking function.
  • the thyristor valve includes: at least one thyristor, the at least one thyristor is arranged in series; at least one first buffer component, connected in parallel or in series with the at least one thyristor .
  • the first control valve includes: at least one first power unit, the at least one first power unit is arranged in series; at least one second buffer component, connected to The at least one first power unit is connected in parallel.
  • the first power unit includes: a first branch, a first power device and a diode are arranged on the first branch, and the first branch is provided with a first power device and a diode.
  • the first power device is a fully-controlled power electronic device; the second branch is connected in parallel with the first branch, and the second branch is provided with a first capacitive element and the first power device, and the first A power device is connected in series with the first capacitive element.
  • the first power unit includes: a third branch, and the third branch is a full circuit formed by connecting four second power devices. a bridge circuit; the second power device is a fully-controlled power electronic device; a fourth branch, a second capacitive element is arranged on the fourth branch, and the second capacitive element is connected in parallel with the full-bridge circuit between the half bridge and the lower half bridge.
  • the second control valve includes: at least one second power unit, the at least one second power unit is arranged in series; at least one third buffer component, connected to The at least one second power unit is connected in parallel.
  • the second power unit includes: a fifth branch, and the fifth branch is provided with a third power device and a first diode tube, the third power device is connected in series with the first diode; or, a sixth branch, at least one third power device is arranged on the sixth branch, and the at least one third power device is arranged in series the third power device is a power electronic device without reverse blocking function; the seventh branch is connected in series with the sixth branch; the seventh branch is provided with at least one second diode, The at least one second diode is arranged in series.
  • the second power unit includes: an eighth branch, and the eighth branch is a full circuit formed by connecting a plurality of fourth power devices.
  • a bridge circuit; the fourth power device is a fully-controlled power electronic device.
  • the second power unit includes: at least one ninth branch, the ninth branch includes a first sub-branch, a second branch sub-branch and third sub-branch; the first sub-branch, the second sub-branch, the third sub-branch and the third buffer component constitute an H-bridge circuit; the first sub-branch The branch is provided with a plurality of third diodes connected in series; the second sub-branch is connected in parallel between the first sub-branch and the third sub-branch, and the second sub-branch is connected in parallel A plurality of fifth power devices connected in series are provided, and the fifth power devices are fully-controlled power electronic devices; the third sub-branch is provided with a plurality of fourth diodes connected in series.
  • the first buffer part, the second buffer part and the third buffer part all include: composed of capacitors The first buffer branch; or, the second buffer branch of the resistor and the capacitor in series; or, the third buffer branch of the capacitor and the resistor in parallel; or, the resistor and the fifth diode connected in parallel, and then connected in series with the capacitor to form a fourth buffer branch; or, the resistor and the capacitor connected in parallel, and then connected in series with the fifth buffer to form a fifth buffer branch; or, a lightning arrester formed by the sixth buffer branch; or, the first buffer branch, the second buffer branch, the third buffer branch, the fourth buffer branch, the fifth buffer branch and the A seventh buffer branch formed by a plurality of parallel connection in the sixth buffer branch.
  • an embodiment of the present invention provides a forced commutation hybrid converter topology structure, the topology structure is connected to an AC power grid through a converter transformer, and the topology structure includes a three-phase six-arm circuit, Each phase bridge arm includes an upper bridge arm and a lower bridge arm respectively, and at least one of the upper bridge arm or the lower bridge arm is provided with the active commutation unit according to the first aspect or any embodiment of the first aspect.
  • an embodiment of the present invention provides a control method for forced commutation, which is used for the forced commutation hybrid converter topology structure described in the second aspect, including the following steps: turning on the forced commutation The thyristor valve of the main branch of the ith bridge arm of the hybrid converter topology structure; the first auxiliary branch of the ith bridge arm of the forced commutation hybrid converter topology is turned on a control valve and a second control valve; the first control valve and the second control valve of the auxiliary branch of the ith bridge arm of the forced commutation hybrid converter topology structure are turned off; after one control cycle, The thyristor valve that turns on the main branch of the ith bridge arm of the forced commutation hybrid converter topology structure is returned, where i ⁇ [1,6].
  • the method further includes: when it is detected that a commutation failure or a short-circuit fault occurs in the i-th bridge arm of the hybrid converter topology, acquiring the commutation failure or the duration of the short-circuit fault; when the duration reaches the first preset duration, the second control valve of the auxiliary branch of the ith bridge arm is turned on, and when the duration reaches the second preset duration, the second control valve is turned on
  • the first control valve of the auxiliary branch of the i-th bridge arm performs commutation from the main branch to the auxiliary branch, wherein the second preset duration is greater than or equal to the first preset duration; when the hybrid commutation is performed When the current of the main branch of the ith bridge arm of the ith bridge arm is reduced to zero, and the duration reaches the third preset time length, the second control valve of the auxiliary branch of the ith bridge arm is turned off, The third preset duration is longer than the second preset duration;
  • the method further includes: the main branch and the auxiliary circuit of the ith bridge arm of the forced commutation hybrid converter topology structure The branches run alternately periodically.
  • the active commutation unit provided by the embodiment of the present invention includes a main branch and an auxiliary branch connected in parallel, and the main branch is provided with a thyristor valve, which has a large current capacity and carries a normal operating current; the first branch of the auxiliary branch is The control valve has a forward current controllable shutdown function, and the second control valve has forward and reverse voltage blocking capabilities.
  • the active commutation unit takes advantage of the thyristor and the advantages that the first control valve can be turned off and the second control valve can be turned off, adopts two branches in parallel, and realizes current transfer through the first control valve in the auxiliary branch.
  • the second control valve is used to withstand a large turn-off voltage stress in the event of a fault, and does not need to withstand the current stress for a long time, thereby avoiding the increase of device loss and improving the utilization rate of the first control valve and the second control valve.
  • the auxiliary branch with reverse voltage and self-shutoff capability can be provided in parallel, so as to realize the reliable shutdown of the main branch and the active commutation of the entire bridge arm.
  • the auxiliary branch When the active commutation unit is in normal operation, the auxiliary branch can be kept off and only needs to bear the voltage stress; when the active commutation unit fails to commutate, the auxiliary branch is immediately turned on, and the first control valve can transfer the current to the auxiliary branch The second control valve can replace the main branch to complete the commutation, so as to realize the auxiliary commutation function in a short time and avoid the occurrence of commutation failure.
  • the forced commutation hybrid converter topology structure includes a three-phase six-arm circuit, and each phase arm includes an upper arm and a lower arm respectively, and at least one upper arm or a lower arm.
  • the arm is provided with an active commutation unit.
  • the first control valve of the auxiliary branch of the active commutation unit can cut off the current of the main branch in advance, and at the same time provide a reverse voltage, which increases the commutation voltage-time area of the thyristor valve of the main branch, ensures its reliable shutdown, and avoids The problem of commutation failure occurs, so as to ensure the stable and safe operation of the power grid.
  • the forced commutation hybrid converter topology provided by the embodiment of the present invention includes a three-phase six-arm circuit, and each phase arm includes an upper arm and a lower arm respectively, and at least one upper arm or a lower arm.
  • the arm is provided with an active commutation unit.
  • the second control valve of the auxiliary branch of the active commutation unit can quickly transfer the commutation current and flexibly control the commutation time. When the commutation fails, the current of the main branch is transferred to the auxiliary branch, and the commutation between the two bridge arms is completed through the second control valve, which speeds up the recovery time of the converter after the commutation failure.
  • the forced commutation hybrid converter topology structure provided by the embodiment of the present invention includes a three-phase six-arm circuit, and each phase arm includes an upper arm and a lower arm respectively, and at least one upper arm or a lower arm.
  • the arm is provided with an active commutation unit.
  • the forced commutation hybrid converter topology structure can turn on the auxiliary branch at any time, effectively reducing the loss of the main branch, and at the same time, it can realize low voltage and low turn-off angle operation, thereby reducing the reactive power on the inverter side .
  • the first control valve and the second control valve of the auxiliary branch of the i-th bridge arm of the hybrid converter topology are kept in a closed state and turned on.
  • the thyristor valve of the main branch of the ith bridge arm of the hybrid converter topology structure thus realizing the forced commutation hybrid converter topology structure can work in the normal commutation operation mode, that is, in the temporary commutation
  • the auxiliary branch is in the off state and only bears the voltage stress, which reduces the increase of the converter loss under long-term operation.
  • the first control valve and the second control valve of the auxiliary branch of the ith bridge arm of the hybrid converter topology are turned on; the current of the main branch is forcibly transferred to The auxiliary branch, when the current transfer is completed, closes the first control valve and the second control valve of the auxiliary branch of the ith bridge arm of the hybrid converter topology to realize the forced commutation of the hybrid converter .
  • the step of turning on the thyristor valve of the main branch of the i-th bridge arm of the hybrid converter topology structure is returned, and the main branch continues to operate independently and normally, so as to ensure that the auxiliary branch is only Turn-off voltage stress during faults reduces device losses, thereby extending device life.
  • the control method for forced commutation controls the hybrid converter topology to turn on the forced commutation operation mode when commutation fails or a short-circuit fault occurs, so as to avoid the occurrence of commutation failure, and in the event of a commutation failure.
  • the operation mode of forced commutation is exited, and the auxiliary branch continues to remain in the off state, and the main branch operates independently and normally, thus ensuring that the auxiliary branch can only be turned off in the event of a fault.
  • the voltage stress reduces the loss of the device, thereby extending the service life of the device.
  • the control method for forced commutation provided by the embodiment of the present invention can not only resist the commutation failure, but also does not need to predict the commutation failure through the periodic alternate operation of the main branch and the auxiliary branch. At the same time, it is ensured that the hybrid inverter works in an operation mode with a small turn-off angle, and the reactive power consumption of the hybrid inverter is reduced.
  • FIG. 1 is a structural block diagram of an active commutation unit according to an embodiment of the present invention.
  • FIG. 2 is a structural block diagram of a thyristor valve according to an embodiment of the present invention.
  • FIG. 3 is a structural block diagram of a first control valve according to an embodiment of the present invention.
  • FIG. 4 is another structural block diagram of the first control valve according to an embodiment of the present invention.
  • FIG. 5 is a structural block diagram of a second control valve according to an embodiment of the present invention.
  • FIG. 6 is a structural block diagram of a second power unit according to an embodiment of the present invention.
  • FIG. 7 is another structural block diagram of the second control valve according to an embodiment of the present invention.
  • FIG. 8 is another structural block diagram of a second control valve according to an embodiment of the present invention.
  • FIG. 9 is a structural block diagram of a buffer component according to an embodiment of the present invention.
  • FIG. 10 is a block diagram of a forced commutation hybrid converter topology according to an embodiment of the present invention.
  • FIG. 11 is a flowchart of a control method for forced commutation according to an embodiment of the present invention.
  • 13a is a trigger control sequence of a normal operation state according to an embodiment of the present invention.
  • 13b is a trigger control sequence of a commutation failure or a short-circuit fault according to an embodiment of the present invention
  • Fig. 14a is a current flow path for commutation from the main branch to the auxiliary branch according to an embodiment of the present invention
  • FIG. 14b is a current flow path of an auxiliary branch flow stage according to an embodiment of the present invention.
  • FIG. 14c is a current flow path in an auxiliary branch off stage according to an embodiment of the present invention.
  • FIG. 15 is the periodic triggering control sequence of the main branch and the auxiliary branch according to an embodiment of the present invention.
  • the converter As the core equipment of DC transmission, the converter is the core functional unit to realize the conversion of AC and DC power, and its operational reliability largely determines the operational reliability of the UHV DC power grid.
  • traditional converters mostly use half-controlled thyristors as the core components to form a six-pulse bridge commutation topology, each bridge arm is composed of multi-stage thyristors and their buffer components in series.
  • commutation failure is prone to occur, resulting in a surge in DC current and a rapid and large loss of DC transmission power, which affects the stable and safe operation of the power grid.
  • the technical solution of the present invention utilizes the advantages of a thyristor and a control valve that can be turned off, and by shutting off the control valve in advance to ensure that the thyristor valve has a sufficient turn-off time to restore the turn-off capability, and realize the reliable turn-off of the converter. , to avoid commutation failure and affect the stable and safe operation of the power grid.
  • an embodiment of an active commutation unit is provided, and the active commutation unit is provided in a bridge arm circuit of a converter.
  • One end of the active commutation unit is connected to the output end of the converter transformer, and the other end is connected to the DC bus.
  • the active commutation unit includes: a main branch 1 and an auxiliary branch 2 .
  • the main branch 1 is provided with a thyristor valve 11;
  • the auxiliary branch 2 is arranged in parallel with the main branch 1, and a first control valve 21 and a first control valve 21 and a second control valve are arranged on the auxiliary branch 2 in sequence along the direction from the converter transformer to the DC bus.
  • the second control valve 22 is not specifically limited here for the arrangement sequence of the first control valve 21 and the second control valve 22 .
  • the first control valve 21 has a unidirectional voltage output controllable shutdown function
  • the second control valve 22 has a forward current controllable shutdown function and a forward and reverse voltage blocking function.
  • the active commutation unit utilizes the advantages of a thyristor and that the first control valve can be turned off and the second control valve can be turned off, adopts two branches in parallel, and realizes the current through the first control valve in the auxiliary branch.
  • the transfer of the second control valve is used to withstand a large turn-off voltage stress in the event of a fault, and it does not need to withstand the current stress for a long time, which avoids the increase of device loss and improves the utilization rate of the first control valve and the second control valve.
  • the auxiliary branch with reverse voltage and self-shutoff capability can be provided in parallel, so as to realize the reliable shutdown of the main branch and the active commutation of the entire bridge arm.
  • the auxiliary branch can be kept off and only needs to bear the voltage stress; when the active commutation unit fails to commutate, the auxiliary branch is immediately turned on, and the first control valve can transfer the current to the auxiliary branch
  • the second control valve can replace the main branch to complete the commutation, so as to realize the auxiliary commutation function in a short time and avoid the occurrence of commutation failure.
  • the thyristor valve 11 includes at least one thyristor 111 and a first buffer part 112 respectively connected in parallel or in series with the thyristor 111, wherein the at least one thyristor is arranged in series, and the first buffer part 112 is used for the thyristor device to avoid suffering Damaged by high voltage and high current.
  • the thyristor valve 11 includes at least one thyristor 111 and first buffer members 112 connected in parallel with the thyristors 111 respectively.
  • the first control valve 21 includes at least one first power unit 211 and a second buffer component respectively connected in parallel with the first power unit 211 (those skilled in the art can know the parallel connection method, not shown in the figure). shown), wherein at least one first power unit is arranged in series, and a second buffer component is used to limit the voltage and current stress.
  • the first power unit 211 may be a power electronic unit composed of a first branch circuit and a second branch circuit.
  • a first power device is arranged on the first branch; the second branch is connected in parallel with the first branch, a first capacitive element and a first power device are arranged on the second branch, and the first power device and the first capacitive element are connected in series.
  • the first power device is a fully-controlled power electronic device, and the fully-controlled power electronic device is one or more of IGBT, IGCT, IEGT, GTO, or MOSFET that can be turned off.
  • the first power unit 211 may also be a power electronic unit composed of a third branch and a fourth branch.
  • the third branch is a full-bridge circuit formed by connecting four second power devices; the fourth branch is provided with a second capacitive element, and the second capacitive element is connected in parallel between the upper half-bridge and the lower half-bridge of the full-bridge circuit.
  • the second power device is a fully-controlled power electronic device, and the fully-controlled power electronic device is one or more of IGBT, IGCT, IEGT, GTO, or MOSFET, which is not limited in the embodiment of the present invention.
  • the above-mentioned first control valve 21 is a low-pressure shut-off valve with a one-way voltage controllable output capability. It is mainly used to shut off the current of the main branch and provide it with a reverse voltage, so as to ensure that the thyristor valve of the main branch has sufficient capacity. The turn-off time can be reliably turned off, and the number of series stages of the first control valve 21 is required to be less, resulting in a lower total loss.
  • the embodiment of the present invention does not limit the topological form of the first control valve 21, as long as it is a topological form with the function of unidirectional voltage controllable output.
  • the second control valve 22 includes at least one second power unit 221 and third buffer components 222 connected in parallel with the second power units 221 respectively, wherein the at least one second power unit 221 is arranged in series, the third The buffer member 222 is used to limit the voltage and current stress.
  • the second power unit 221 may be a power electronic unit composed of a fifth branch.
  • a third power device and a first diode are arranged on the fifth branch, and the third power device and the first diode are arranged in series.
  • the third power device is a power electronic device without reverse blocking function
  • the power electronic device without reverse blocking function is one or more of IGBT, IGCT, IEGT, GTO or MOSFET.
  • the embodiment is not limited.
  • the power electronic device without reverse blocking function is combined with the first diode in series to form a power electronic unit with reverse blocking and forward turn-off capabilities.
  • the second power unit 221 may also be a power electronic unit composed of a sixth branch and a seventh branch.
  • At least one third power device is arranged on the sixth branch, and at least one third power device is arranged in series; the seventh branch is connected in series with the sixth branch, and at least one second diode is arranged on the seventh branch, and at least one second diode is arranged on the seventh branch. A second diode is placed in series.
  • the third power device is a power electronic device without reverse blocking function, and the power electronic device without reverse blocking function is one or more of IGBT, IGCT, IEGT, GTO or MOSFET. The embodiment is not limited.
  • the topological form of the above-mentioned second power unit is that a power electronic device without a reverse blocking function cooperates with the first diode, and a single-stage power electronic device without a reverse blocking function can be matched with a single-stage diode and a buffer component.
  • a multi-stage series structure is formed, which can be composed of multi-stage power electronic devices without reverse blocking function and their buffer components in series with multi-stage diodes and their buffer components, or multi-stage power electronics without reverse blocking function.
  • the electronic devices and the multi-stage diodes are alternately connected in series, and of course other topological forms are also possible, which are not specifically limited here, and can be determined by those skilled in the art according to actual needs.
  • the second power unit 221 may also be a power electronic unit composed of an eighth branch.
  • the eighth branch is a full-bridge circuit formed by connecting a plurality of fourth power devices, wherein the fourth power device is a fully-controlled power electronic device, and the fully-controlled power electronic device is one of IGBT, IGCT, IEGT, GTO or MOSFET.
  • the fourth power device is a fully-controlled power electronic device
  • the fully-controlled power electronic device is one of IGBT, IGCT, IEGT, GTO or MOSFET.
  • the full-bridge circuits can be connected in series to realize the forward and reverse current control, and the transfer of the current from the main branch to the auxiliary branch can be completed at any time, and at the same time, it can withstand the forward and reverse voltages.
  • the single-stage structure or multi-stage series structure composed of diodes can also be other topological forms, which are not specifically limited here, and can be determined by those skilled in the art according to actual needs.
  • the second power unit 221 may also be a power electronic unit composed of a ninth branch, and the nine branches include a first sub-branch, a second sub-branch and a third sub-branch.
  • the first sub-branch, the second sub-branch, the third sub-branch and the third buffer part constitute an H-bridge circuit.
  • the first sub-branch is provided with a plurality of third diodes connected in series; the second sub-branch is connected in parallel between the first sub-branch and the third sub-branch, and a plurality of series-connected diodes are arranged on the second sub-branch
  • the fifth power device wherein the fifth power device is a fully-controlled power electronic device, and the fully-controlled power electronic device is one or more of IGBT, IGCT, IEGT, GTO or MOSFET. Definition; a plurality of fourth diodes connected in series are arranged on the third sub-branch.
  • the fully-controlled power electronic devices and diodes in the H-bridge circuit can be either a single-stage structure or a multi-stage series structure, and the H-bridge circuit can be connected in series to realize bidirectional current flow and bidirectional shutdown functions.
  • the above-mentioned second control valve 22 is a high-pressure shut-off valve, with forward current controllable shut-off and forward and reverse voltage blocking capabilities.
  • the application does not limit the topology of the second control valve 212, as long as it has a forward current control valve 212. Topological forms of the function of current-controlled turn-off and forward and reverse voltage blocking are sufficient.
  • the auxiliary branch may be constituted by the first control valve 21 and the second control valve 22 in series, or may be constituted by the units in the first control valve 21 and the second control valve 22 in alternate series.
  • the first buffer component 112 , the second buffer component 212 , and the third buffer component 222 are all composed of one or more forms of components such as capacitors, RC loops, diodes, inductors, or arresters.
  • the first buffer component 112 , the second buffer component and the third buffer component 222 may be a first buffer branch composed of capacitors; may be a second buffer branch composed of a resistor and a capacitor in series. It can be a third buffering branch consisting of a capacitor and a resistor in parallel; it can be a fourth buffering branch RCD1 consisting of a resistor and a fifth diode in parallel, and then a capacitor in series; it can be a resistor and a capacitor in parallel, and then The fifth buffer branch RCD2 formed in series with the fifth diode; it can also be the sixth buffer branch formed by the arrester; it can also be the above-mentioned first buffer branch, second buffer branch, and third buffer branch , a seventh buffer branch formed in parallel among the fourth buffer branch, the fifth buffer branch and the sixth buffer branch.
  • a forced commutation hybrid converter topology structure is provided, and the topology structure is connected to an AC power grid through a converter transformer.
  • the forced commutation hybrid converter topology includes a three-phase six-arm circuit, each phase arm includes an upper arm and a lower arm, and at least one upper arm or lower arm thereof The arm is provided with the active commutation unit described in the above embodiment.
  • the forced commutation hybrid converter topology shown in FIG. 10 includes 3 upper bridge arms and 3 lower bridge arms.
  • Each active commutation unit is used as a converter valve
  • the topology of the hybrid converter with forced commutation described in FIG. 10 includes a converter valve V1, a converter valve V2, a converter valve V3, and a converter valve.
  • V4 converter valve V5 and converter valve V6.
  • the main branches of the three upper arms respectively include thyristor valves V11, V31 and V51; the auxiliary branches of the three upper arms respectively include the first control valves V13, V33 and V53; the auxiliary branches of the 3 upper bridge arms respectively include the second control valves V12, V32 and V52, the main branches of the 3 lower bridge arms respectively include the thyristor valves V21, V41 and V6; the auxiliary branches of the 3 lower bridge arms
  • the auxiliary branches of the three lower bridge arms respectively include the second control valves V22, V42 and V62, and the thyristor valve, the first control valve and the second control valve are controlled by the control trigger control system. Control valve off and on.
  • the above-mentioned forced commutation hybrid converter topology can provide reverse voltage and auxiliary branches with self-shut-off capability by connecting thyristor valves in parallel, so as to achieve reliable shutdown of the main branch and active active switching of the entire bridge arm. commutation.
  • the auxiliary branch is composed of a first control valve capable of providing reverse voltage and a second control valve having bidirectional pressure bearing capability in series, that is, a shut-off valve is introduced for each bridge arm.
  • the forced commutation hybrid converter topology provided by the embodiment of the present invention includes a three-phase six-arm circuit, and each phase arm includes an upper arm and a lower arm respectively, and at least one upper arm or a lower arm An active commutation unit is provided.
  • the first control valve of the auxiliary branch of the active commutation unit can cut off the current of the main branch in advance, and at the same time provide a reverse voltage to realize the active commutation of the entire bridge arm.
  • the forced commutation hybrid converter topology increases the commutation voltage-time area of the thyristor valve of the main branch to ensure its reliable shutdown, avoid the problem of commutation failure, and ensure the stable and safe operation of the power grid.
  • an embodiment of a control method for forced commutation is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings may be executed in a computer system such as a set of computer-executable instructions, Also, although a logical order is shown in the flowcharts, in some cases the steps shown or described may be performed in an order different from that herein.
  • FIG. 11 is a flow chart of a control method for forced commutation according to an embodiment of the present invention. Figure, as shown in Figure 11, the process includes the following steps:
  • Figure 12 shows the valve current flow path of the hybrid converter topology under normal operating conditions.
  • the main branch is periodically subjected to voltage and current stress, and the auxiliary branch is always in the off state.
  • the thyristor valve of the main branch is subjected to voltage stress when it is turned off.
  • the first control valve and the second control valve of the auxiliary branch of the ith bridge arm of the hybrid converter topology are kept in a closed state, and the hybrid converter is turned on.
  • the thyristor valve of the main branch of the i-th bridge arm of the converter topology thereby realizing the forced commutation hybrid converter topology can work in the normal commutation operation mode, that is, in the temporary commutation operation mode
  • the auxiliary branch is in the off state and only bears the voltage stress, which reduces the increase of the converter loss under long-term operation.
  • the first control valve and the second control valve of the auxiliary branch of the ith bridge arm of the hybrid converter topology are turned on; the current of the main branch is forcibly transferred to The auxiliary branch, when the current transfer is completed, closes the first control valve and the second control valve of the auxiliary branch of the ith bridge arm of the hybrid converter topology to realize the forced commutation of the hybrid converter .
  • the step of turning on the thyristor valve of the main branch of the i-th bridge arm of the hybrid converter topology structure is returned, and the main branch continues to operate independently and normally, so as to ensure that the auxiliary branch is only Turn-off voltage stress during faults reduces device losses, thereby extending device life.
  • Figure 13a shows the trigger control sequence in the normal operation mode, and t0 in the figure represents the initial trigger moment.
  • Figure 14a, Figure 14b and Figure 14c close the V1 valve when the main branch is commutating to the auxiliary branch, and the auxiliary branch begins to bear the voltage stress.
  • Figure 14a converts the main branch to the auxiliary branch.
  • the auxiliary branch receives the trigger signal and turns on, and then the auxiliary branch V12 valve and V13 valve receive the conduction signal, transfer the current of the main branch to the auxiliary branch, and apply a reverse voltage to the main branch.
  • Figure 14b is the auxiliary branch flow-through stage, the main branch has been completely turned off at this stage, and the main branch current has been fully transferred to the auxiliary branch
  • Figure 14c is the auxiliary branch off stage, this stage receives the turn-off signal
  • the V13 valve of the auxiliary branch is closed first, and the V1 valve is in the closed state to withstand the forward voltage, and then the V12 valve is closed before the V11 valve of the main branch is opened or at the same time in the next control cycle.
  • the above operation process can be put into operation when a commutation failure or a commutation failure is predicted.
  • Fig. 13b is the trigger control sequence of the forced commutation hybrid converter topology when commutation failure or AC short circuit fault occurs.
  • the auxiliary branch V13 valve is turned on when the first preset time period ⁇ t1 passes, and the auxiliary branch V12 valve is turned on when the second preset time period ⁇ t2 passes.
  • the commutation process from the main branch to the auxiliary branch is performed, and ⁇ t2 ⁇ t1 ⁇ 0.
  • the main branch current I11 gradually decreases to zero, and the auxiliary branch current I12 gradually increases.
  • the auxiliary branch V13 valve is turned off, and the time between the main branch current zero crossing and the V13 valve turning off is the turn-off time toff of the thyristor valve, and the toff here is greater than the minimum turn-off time of the thyristor valve to ensure that the thyristor valve V11 has enough time to turn off.
  • the auxiliary branch current will commutate to the V3 valve until it reaches the DC current Id. At this point, the commutation of the V1 valve to the V3 valve is completed, successfully resisting the commutation failure fault, and then in the next control cycle. Close the auxiliary branch V12 valve before opening the V11 valve.
  • This operation mode is started when commutation failure is predicted or detected, which can successfully avoid commutation failure.
  • the operation mode is exited, and the auxiliary branch keeps In the off state, the main branch operates independently and normally.
  • the control method for forced commutation controls the hybrid converter topology to enable the forced commutation operation mode when commutation fails or a short-circuit fault occurs, so as to avoid the occurrence of commutation failure, and in the hybrid converter
  • the operation mode of forced commutation is exited, and the auxiliary branch continues to be turned off. , reducing the loss of the device, thereby extending the service life of the device.
  • FIG 15 shows the control trigger sequence when the forced commutation hybrid converter topology structure detects commutation failure or short-circuit fault in advance, and the control of each valve when the main branch and auxiliary branch of the V1 valve operate alternately periodically
  • the trigger sequence the specific operation process is shown in Figure 14a, Figure 14b and Figure 14c.
  • the trigger pulse Sg1 of the V1 valve is delayed by 120°, or the auxiliary branch V13 valve is triggered near this moment, and the auxiliary branch V12 is opened after a short time (such as 1s, 5s, etc.)
  • the valve realizes the commutation from the main branch to the auxiliary branch.
  • the main branch V11 valve After the main branch current crosses zero, the main branch V11 valve is turned off and bears the reverse voltage, and the time from the main branch current zero crossing to the auxiliary branch V13 valve turning off is the turn-off time toff of the thyristor valve, and toff
  • the minimum turn-off time of the thyristor valve is greater than the minimum turn-off time of the thyristor valve to ensure its reliable turn-off.
  • the V1 valve current is all transferred to the auxiliary branch.
  • the auxiliary branch V13 valve After ⁇ t, the auxiliary branch V13 valve starts to turn off, and the V1 valve begins to bear the forward voltage, and then the next work
  • the auxiliary branch V12 valve is closed before or at the same time as the period V11 valve is opened.
  • the main branch and the auxiliary branch in the bridge arm of the forced commutation hybrid converter topology operate alternately periodically.
  • the hybrid inverter can be in a small turn-off angle operation mode, and the reactive power consumption of the hybrid inverter can be reduced.
  • the control method for forced commutation provided by the embodiment of the present invention can not only resist the commutation failure, but also does not need to predict the commutation failure through the periodic alternate operation of the main branch and the auxiliary branch. At the same time, it is ensured that the hybrid inverter works in an operation mode with a small turn-off angle, and the reactive power consumption of the hybrid inverter is reduced.
  • the invention discloses an active commutation unit and a forced commutation hybrid converter topology structure and method, wherein the active commutation unit is arranged in the bridge arm circuit of the converter, one end of which is connected to the converter transformer, and the other is connected to the converter transformer. One end is connected to the DC bus, including: a main branch, which is provided with a thyristor valve; an auxiliary branch, which is arranged in parallel with the main branch, and a first control valve and a second control valve are arranged on the auxiliary branch in sequence, and the first control valve has a one-way voltage Output controllable shutdown function, the second control valve has forward current controllable shutdown function and forward and reverse voltage blocking function.
  • the forced commutation hybrid converter topology structure is connected to the AC power grid through the converter transformer.
  • the topology structure includes a three-phase six-bridge circuit, and each phase bridge includes an upper bridge arm and a lower bridge arm, and at least one upper bridge arm. Or an active commutation unit is arranged on the lower bridge arm.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Rectifiers (AREA)
  • Inverter Devices (AREA)

Abstract

Sont divulgués dans la présente invention une unité de commutation active, une structure topologique de convertisseur hybride à commutation forcée et un procédé. L'unité de commutation active est disposée dans un circuit de branche de pont d'un convertisseur, a une extrémité connectée à un transformateur convertisseur et l'autre extrémité connectée à un bus à courant continu, et comprend : une ramification principale munie d'une vanne à thyristor, et une ramification auxiliaire disposée en parallèle de la ramification principale ; une première vanne de commande et une seconde vanne de commande sont disposées successivement sur la ramification auxiliaire, la première vanne de commande a une fonction de désactivation commandable de sortie de tension unidirectionnelle, et la seconde vanne de commande a une fonction de mise hors tension pouvant être commandée par courant vers l'avant et une fonction de blocage de tension directe/inverse. La structure topologique de convertisseur hybride à commutation forcée est connectée à un réseau d'alimentation à courant alternatif au moyen du transformateur convertisseur ; la structure topologique comprend un circuit de branche à six ponts triphasés, chaque branche de pont de phase comprend une branche de pont supérieure et une branche de pont inférieure, et au moins une branche de pont supérieure ou une branche de pont inférieure est pourvue de l'unité de commutation active.
PCT/CN2021/135027 2021-02-01 2021-12-02 Unité de commutation active, structure topologique de convertisseur hybride à commutation forcée et procédé WO2022160929A1 (fr)

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