WO2022160791A1 - 一种混合式换流器拓扑结构及其控制方法 - Google Patents

一种混合式换流器拓扑结构及其控制方法 Download PDF

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Publication number
WO2022160791A1
WO2022160791A1 PCT/CN2021/124770 CN2021124770W WO2022160791A1 WO 2022160791 A1 WO2022160791 A1 WO 2022160791A1 CN 2021124770 W CN2021124770 W CN 2021124770W WO 2022160791 A1 WO2022160791 A1 WO 2022160791A1
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Prior art keywords
branch
bridge arm
auxiliary
valve
main
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PCT/CN2021/124770
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English (en)
French (fr)
Inventor
高冲
贺之渊
汤广福
杨俊�
盛财旺
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全球能源互联网研究院有限公司
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Publication of WO2022160791A1 publication Critical patent/WO2022160791A1/zh

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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
    • H02M7/42—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
    • 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
    • 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 application relates to the technical field of commutation in power electronics, in particular to a hybrid converter topology and a control method thereof.
  • the traditional power grid commutated high voltage direct current (Line Commutated Converter High Voltage Direct Current, LCC-HVDC) transmission system has the advantages of long-distance large-capacity 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 application provide a hybrid converter topology structure and a control method thereof, so as to solve the problem that the commutation failure affects the stable and safe operation of the power grid.
  • an embodiment of the present application provides a hybrid converter topology structure, the topology structure is connected to an AC power grid through a converter transformer, and the topology structure includes: at least one phase main branch, each phase main branch The road includes the main branch of the upper bridge arm and the main branch of the lower bridge arm, the first thyristor valve is arranged on the main branch of the upper bridge arm, and the second thyristor valve is arranged on the main branch of the lower bridge arm; One end of the circuit is connected to the DC bus, and the other end is connected to the output end of the converter transformer; at least one phase auxiliary branch, each phase auxiliary branch includes an upper bridge arm auxiliary branch and a lower bridge arm auxiliary branch.
  • a first auxiliary commutation valve is arranged on the auxiliary branch of the upper bridge arm, and a second auxiliary commutation valve is arranged on the auxiliary branch of the lower bridge arm;
  • a shut-off valve can be set on the main branch or the auxiliary branch, and is used to force the commutation of the main branch when the commutation is forced. Current is diverted to the auxiliary branch.
  • the auxiliary branch of the upper bridge arm is connected in parallel with the main branch of the upper bridge arm, and the auxiliary branch of the lower bridge arm is connected to the main branch of the lower bridge arm in parallel.
  • the branches are connected in parallel;
  • the shut-off valve is arranged on the main branch of the upper bridge arm of each phase and the main branch of the lower bridge arm of each phase; wherein, one end of the shut-off valve arranged on the main branch of the upper bridge arm is connected to The other end of the first thyristor valve is connected to the output end of the converter transformer; one end of the shut-off valve disposed on the main branch of the lower bridge arm is connected to the second thyristor valve, and the other end is connected to the negative electrode of the DC bus.
  • the auxiliary branch of the upper bridge arm is connected in parallel with the main branch of the upper bridge arm, and the auxiliary branch of the lower bridge arm is connected to the main branch of the lower bridge arm in parallel.
  • the branches are connected in parallel;
  • the shut-off valve is respectively arranged on the auxiliary branch of the upper bridge arm and the auxiliary branch of the lower bridge arm; wherein, the shut-off valve arranged on the auxiliary branch of the upper bridge arm One end of the valve is connected to the first auxiliary commutation valve, and the other end is connected to the output end of the converter transformer; one end of the shut-off valve arranged on the auxiliary branch of the lower bridge arm is connected to the second auxiliary commutator Phase valve, and the other end is connected to the negative pole of the DC bus.
  • the main branch of the upper bridge arm and the main branch of the lower bridge arm are connected in series; the auxiliary branch of the upper bridge arm and the auxiliary branch of the lower bridge arm connected in series; one end of the shut-off valve is connected to the connection end of the main branch of the upper bridge arm and the main branch of the lower bridge arm, and the other end is connected to the output end of the converter transformer; the upper bridge arm auxiliary The connection end of the branch and the auxiliary branch of the lower bridge arm is connected to the output end of the converter transformer.
  • the main branch of the upper bridge arm and the main branch of the lower bridge arm are connected in series; the auxiliary branch of the upper bridge arm and the auxiliary branch of the lower bridge arm connected in series; one end of the shut-off valve is connected to the connection end of the upper bridge arm auxiliary branch and the lower bridge arm auxiliary branch, and the other end is connected to the output end of the converter transformer; the upper bridge arm main The connecting end of the branch and the main branch of the lower bridge arm is connected to the output end of the converter transformer.
  • the topology structure includes two shut-off valves, the upper bridge arm main branch and the lower bridge arm main branch are connected in series; the upper bridge arm The auxiliary branch is connected in series with the auxiliary branch of the lower bridge arm; wherein, one end of the first shut-off valve is connected to the main branch of the upper bridge arm of each phase, and the other end is connected to the auxiliary branch of the upper bridge arm of each phase; the second One end of the shut-off valve is connected with the main branch of the lower bridge arm of each phase, and the other end is connected with the auxiliary branch of the lower bridge arm of each phase.
  • the topology structure further includes: at least one isolation valve, disposed on the AC bus, for isolating between the main branch and the auxiliary branch voltage.
  • the first end of the at least one isolation valve is respectively connected to the main branch of the upper bridge arm of each phase and the main branch of the lower bridge arm of each phase. a connection end, the second end is connected to the connection end of the upper bridge arm auxiliary branch and the lower bridge arm auxiliary branch;
  • the topology structure includes two shut-off valves, the upper bridge arm main branch and the lower bridge arm auxiliary branch
  • the main branch of the bridge arm is connected in series; the auxiliary branch of the upper bridge arm and the auxiliary branch of the lower bridge arm are connected in series; wherein, one end of the first shut-off valve is connected to the main branch of the upper bridge arm of each phase, and the other end is connected to the main branch of the upper bridge arm of each phase.
  • Each phase upper bridge arm auxiliary branch is connected; one end of the second shut-off valve is connected with the lower bridge arm main branch, and the other end is connected with the lower bridge arm auxiliary branch.
  • the main branch of the upper bridge arm and the main branch of the lower bridge arm are connected in series; the auxiliary branch of the upper bridge arm and the lower bridge
  • the arm auxiliary branch is connected in series; the upper arm main branch and the lower arm main branch are provided with the shut-off valve; the shut-off valve of the upper arm main branch of each phase is connected to the lower arm of each phase.
  • the connection end between the shut-off valves of the main branch is connected with the first end of the isolation valve.
  • the main branch of the upper bridge arm and the main branch of the lower bridge arm are connected in series; the auxiliary branch of the upper bridge arm and the lower bridge
  • the arm auxiliary branch is connected in series; both the upper bridge arm auxiliary branch and the lower bridge arm auxiliary branch are provided with the shut-off valve, and the shut-off valve of the upper bridge arm auxiliary branch is connected to the lower arm auxiliary branch.
  • the connection end between the shut-off valves of the bridge arm auxiliary branch is connected with the second end of the at least one isolation valve.
  • the main branch of the upper bridge arm and the main branch of the lower bridge arm are connected in series; the auxiliary branch of the upper bridge arm and the lower bridge
  • the arm auxiliary branches are connected in series; one end of the shut-off valve is connected to the first end of the at least one isolation valve, and the other end is connected to the connection ends of the upper bridge arm auxiliary branch and the lower bridge arm auxiliary branch .
  • the first thyristor valve and the second thyristor valve each include: at least one controllable device for reverse voltage blocking , the at least one controllable device is arranged in series; at least one first auxiliary component is arranged in parallel with the at least one controllable device; the controllable device includes a thyristor, a gate-turn-off thyristor (GTO, Gate-Turn- One or more of Integrated Gate-Commutated Thyristor (Off Thyristor) and reverse resistance integrated gate commutated thyristor (IGCT).
  • GTO gate-turn-off thyristor
  • IGCT reverse resistance integrated gate commutated thyristor
  • the shut-off valve includes: at least one first power unit for conducting and shutting off control of the transfer branch; a second The auxiliary component is arranged in parallel with the first power unit.
  • the first power unit includes: a first branch, and the first branch is provided with a first power device; or, A second branch and a third branch; wherein, at least one of the first power devices is arranged on the second branch, and the at least one first power device is arranged in series; the third branch is connected to all The structure of the second branch is the same, and the third branch and the second branch are arranged in parallel; or, the fourth branch and the fifth branch; wherein, the fourth branch is provided with at least one a first diode, the at least one first diode is arranged in series; the structure of the fifth branch is the same as that of the fourth branch, and the fourth branch and the fifth branch are connected in parallel or, a sixth branch and a seventh branch; wherein the sixth branch is provided with the first power device; the seventh branch is provided with the first power device and the second An auxiliary component, the first power device and the second auxiliary component are connected in parallel;
  • the first auxiliary phase-change valve and the second auxiliary phase-change valve include: at least one second power unit, the at least one second power The units are connected in series; at least one third auxiliary component is connected in parallel with the at least one second power unit.
  • the second power unit includes: a first connection branch, and a second power device is disposed on the first connection branch; Or, a second connection branch; at least one of the second power devices is provided on the second connection branch, and the at least one of the second power devices is connected in reverse series; or, at least one of the third connection branches and at least one fourth connection branch; wherein, the third connection branch has the same structure as the first connection branch, and the fourth connection branch is provided with a second diode or a first thyristor; the At least one third connection branch and the at least one fourth connection branch are alternately arranged in series; or, a fifth connection branch and a sixth connection branch; wherein, at least one of the a second power device, the at least one second power device is arranged in series; the sixth connection branch has the same structure as the fifth connection branch, and the fifth connection branch and the sixth connection branch have the same structure
  • the connection branches are arranged in parallel; the fifth connection branch, the
  • the first auxiliary component, the second auxiliary component and the third auxiliary component include: A first buffer branch composed of a capacitor; or, a second buffer branch in which a resistor and the capacitor are connected in series; or, a third buffer branch in which the capacitor and the resistor are connected in parallel; or, the resistor and the fifth buffer branch
  • the diode is connected in parallel
  • the fourth buffer branch is formed by connecting with the capacitor in series; or, the resistor and the capacitor are connected in parallel
  • the fifth buffer branch is formed by connecting with the fifth diode in series; or,
  • the sixth buffer branch composed of arresters; or, the first buffer branch, the second buffer branch, the third buffer branch, the fourth buffer branch, and the fifth buffer branch and a seventh buffer branch formed in parallel with a plurality of the sixth buffer branches.
  • an embodiment of the present application provides a method for controlling a hybrid inverter topology, which is used in the hybrid inverter topology in the first aspect or any embodiment of the first aspect, including the following steps : turn off the auxiliary branch and/or the shut-off valve of the hybrid converter topology; turn on the main branch and/or the shut-off valve of the hybrid converter topology; turn on the hybrid converter Auxiliary branch and/or shut-off valve of the topology; turn off the auxiliary branch and/or shut-off valve of the hybrid converter topology; turn on the hybrid converter topology after one control cycle
  • the thyristor valve of the main branch where, i ⁇ [1,6].
  • the method further includes: the main branch and the auxiliary branch of the hybrid converter topology are operated alternately periodically.
  • the hybrid converter topology provided by the embodiment of the present application includes at least one phase main branch, at least one phase auxiliary branch, and a shut-off valve, and the main branch and the auxiliary branch are arranged in parallel, and the shut-off valve is arranged On the main branch or auxiliary branch.
  • the auxiliary branch can remain in the off state, and only needs to bear the voltage stress, and the main branch carries the normal operating current; when the main branch fails commutation or AC short-circuit fault, the auxiliary branch is turned on, and the combination can be turned off
  • the closing or opening of the valve diverts the current from the main branch to the auxiliary branch.
  • the reverse voltage and the auxiliary branch with self-shutoff capability can be provided in parallel, so as to realize the reliable turn-off of the main branch and the active commutation of the bridge arm of each phase, so as to realize the realization in a relatively short time.
  • the auxiliary commutation function avoids the occurrence of commutation failure, thereby ensuring the stable and safe operation of the power grid.
  • Fig. 1a is a schematic block diagram of a hybrid converter topology structure according to an embodiment of the present application
  • Fig. 1b is another principle block diagram of a hybrid converter topology structure according to an embodiment of the present application.
  • FIG. 2 is a structural block diagram of an optional hybrid converter topology according to an embodiment of the present application.
  • FIG. 3 is another structural block diagram of an optional hybrid converter topology according to an embodiment of the present application.
  • FIG. 4 is another structural block diagram of an optional hybrid converter topology according to an embodiment of the present application.
  • FIG. 5 is another structural block diagram of an optional hybrid converter topology according to an embodiment of the present application.
  • FIG. 6 is another structural block diagram of an optional hybrid converter topology according to an embodiment of the present application.
  • FIG. 7 is another schematic block diagram of a hybrid converter topology according to an embodiment of the present application.
  • FIG 8 is another structural block diagram of an optional hybrid converter topology according to an embodiment of the present application.
  • FIG. 9 is another structural block diagram of an optional hybrid converter topology according to an embodiment of the present application.
  • FIG. 10 is another structural block diagram of an optional hybrid converter topology according to an embodiment of the present application.
  • FIG. 11 is another structural block diagram of an optional hybrid converter topology according to an embodiment of the present application.
  • FIG. 12 is a structural block diagram of a main branch according to an embodiment of the present application.
  • FIG. 13 is a structural block diagram of a shut-off valve according to an embodiment of the present application.
  • FIG. 14 is a structural block diagram of an auxiliary phase changing valve according to an embodiment of the present application.
  • 15 is a structural block diagram of a buffer component according to an embodiment of the present application.
  • 16 is a flowchart of a control method for a hybrid converter topology according to an embodiment of the present application.
  • 17 is a current flow path of a bridge arm in a normal operating state according to an embodiment of the present application.
  • FIG. 18 is a current flow process of commutating from a main branch to an auxiliary branch according to an embodiment of the present application
  • FIG. 19 is a periodic trigger control sequence of a main branch and an auxiliary branch according to an embodiment of the present application.
  • FIG. 20 is the normal trigger control sequence of the main branch according to the embodiment of the present application.
  • 21 is a current flow path of a bridge arm in a normal operating state according to an embodiment of the present application.
  • FIG. 22 is a trigger control sequence of a main branch commutation failure or a short-circuit fault according to an embodiment of the present application
  • Fig. 24 is the trigger control sequence of the main branch and auxiliary branch periodic according to the embodiment of the present application.
  • FIG. 25 is a current flow path of a bridge arm in a normal operating state according to an embodiment of the present application.
  • Fig. 26 is the triggering control sequence of each valve according to the embodiment of the present application.
  • FIG. 28 is a periodic trigger control sequence of a main branch and an auxiliary branch according to an embodiment of the present application.
  • FIG. 29 is the triggering control sequence of each valve according to the embodiment of the present application.
  • FIG. 30 is a current flow process of commutating from a main branch to an auxiliary branch according to an embodiment of the present application
  • FIG. 31 is a periodic trigger control sequence of a main branch and an auxiliary branch according to an embodiment of the present application.
  • Fig. 32 is the triggering control sequence of each valve according to the embodiment of the present application.
  • FIG. 34 is a periodic trigger control sequence of a main branch and an auxiliary branch according to an embodiment of the present application.
  • Fig. 35 is the triggering control sequence of each valve according to the embodiment of the present application.
  • FIG. 36 is a current flow process of commutation from the main branch to the auxiliary branch according to an embodiment of the present application.
  • FIG. 37 is the periodic triggering control sequence of the main branch and the auxiliary branch according to an embodiment of the present application.
  • 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.
  • an auxiliary branch is set on the basis of the main branch, and the shut-off capability of the shut-off valve is used to realize the reliable shut-off of the main branch, avoid commutation failure, and ensure the operation of the power grid. stability and security.
  • the hybrid converter topology structure is connected to an AC power grid through a converter transformer.
  • the hybrid converter topology includes: at least one phase main branch 1 , at least one phase auxiliary branch 2 and a shut-off valve 3 .
  • one end of the main branch 1 is connected to the DC bus, and the other end is connected to the output end of the converter transformer.
  • the main branch 1 of each phase includes the main branch of the upper bridge arm and the main branch of the lower bridge arm.
  • a first thyristor valve 11 is arranged on the branch, and a second thyristor valve 12 is arranged on the main branch of the lower bridge arm.
  • the first thyristor valve 11 and the second thyristor valve 12 are mainly used for flow; the auxiliary branch 2 and the main branch 1 Parallel connection is used for forced commutation of auxiliary main branch 1 when the commutation of main branch 1 fails.
  • Each auxiliary branch includes an auxiliary branch of the upper bridge arm and an auxiliary branch of the lower bridge arm.
  • a first auxiliary commutation valve 21 is provided, and a second auxiliary commutation valve 22 is provided on the auxiliary branch of the lower arm.
  • the shut-off valve 3 can be set on the main branch 1, as shown in Figure 1a; the shut-off valve 3 can also be set on the auxiliary branch 2, as shown in Figure 1b. It should be noted that the dotted frame in the figure represents a plurality of identical units.
  • the auxiliary branch 2 can keep the off state, and only needs to bear the voltage stress, and the main branch 1 carries the normal operating current; when the main branch 1 fails commutation or AC short circuit fault The auxiliary branch is connected, and the current of the main branch 1 is transferred to the auxiliary branch 2 in combination with the closing or opening of the shut-off valve 3 .
  • the hybrid converter topology provided in this embodiment can provide reverse voltage and an auxiliary branch with self-shutoff capability in parallel on the basis of the main branch, so as to realize reliable turn-off of the main branch and Active commutation, so as to realize the auxiliary commutation function in a short time, avoid the occurrence of commutation failure, and ensure the stable and safe operation of the power grid.
  • the topology may be a three-phase six-arm circuit
  • the auxiliary branch of the upper arm corresponding to each phase arm is connected in parallel with the main arm of the upper arm
  • the lower arm is connected in parallel.
  • the auxiliary arm branch is arranged in parallel with the main branch of the lower arm
  • the shut-off valve 3 is arranged on the main branch of the upper arm of each phase and the main branch of the lower arm of each phase.
  • shut-off valve 3 arranged on the main branch of the upper bridge arm is connected to the first thyristor valve 11, and the other end is connected to the output end of the converter transformer; the shut-off valve 3 arranged on the main branch of the lower bridge arm One end is connected to the second thyristor valve 12, and the other end is connected to the negative pole of the DC bus.
  • the auxiliary branch When the hybrid converter is in normal operation, the auxiliary branch can be kept in the off state, and the thyristor valve and the shut-off valve of the main branch of the i-th bridge arm can be turned on. At this time, the auxiliary branch only needs to bear the voltage stress , the main branch carries the normal operating current; when the main branch fails commutation or AC short-circuit fault, the valve can be turned off, the auxiliary branch is turned on, and the current of the main branch is transferred to the auxiliary branch. When the current is completely transferred to the auxiliary branch, the auxiliary branch is turned off to realize the forced commutation of the main branch.
  • the topology is a three-phase six-arm circuit
  • the auxiliary branch of the upper arm is connected in parallel with the main branch of the upper arm
  • the auxiliary branch of the lower arm is connected to the lower arm in parallel.
  • the main arm branches are connected in parallel
  • the shut-off valve 3 is respectively arranged on the auxiliary branch of the upper bridge arm and the auxiliary branch of the lower bridge arm.
  • shut-off valve 3 arranged on the auxiliary branch of the upper bridge arm is connected to the first auxiliary commutation valve 21, and the other end is connected to the output end of the converter transformer, and the shut-off valve arranged on the auxiliary branch of the lower bridge arm One end of 3 is connected to the second auxiliary commutation valve 22, and the other end is connected to the negative electrode of the DC bus.
  • the auxiliary branch When the hybrid converter is in normal operation, the auxiliary branch can be kept off, and the thyristor valve of the main branch of the i-th bridge arm can be turned on. At this time, the auxiliary branch only needs to bear the voltage stress, and the main branch will be Carry the normal operating current; when the main branch fails to commutate or the AC short circuit fails, the turn-off valve of the auxiliary branch and the auxiliary commutation valve of the upper bridge arm are turned on to transfer the current of the main branch to the auxiliary branch. When the current on the road is completely transferred to the auxiliary branch, the auxiliary commutation valve and the shut-off valve of the upper bridge arm are closed to realize the forced commutation of the main branch.
  • the topology includes a three-phase six-arm circuit, the main branch of the upper arm and the main branch of the lower arm are connected in series, and the auxiliary arm of the upper arm and the lower arm are connected in series
  • the auxiliary branch of the arm is connected in series, and one end of the shut-off valve 3 is connected to the connection end between the main branch of the upper bridge arm and the main branch of the lower bridge arm, and the other end is connected to the output end of the converter transformer.
  • the connection end of the auxiliary branch of the lower bridge arm is connected with the output end of the converter transformer. Similar to the concept in FIG.
  • shut-off valve 3 on the main branch 1, by connecting the main branch of the upper arm and the main branch of the lower arm in series, and connecting one end of the shut-off valve 3.
  • the connection end between the main branch of the upper bridge arm and the main branch of the lower bridge arm, and the other end is connected to the output end of the converter transformer, so that the main branch of the upper bridge arm and the main branch of the lower bridge arm can share one and can be turned off valve, reducing the number of series stages of shut-off valves.
  • the auxiliary branch When the hybrid converter is in normal operation, the auxiliary branch can be kept in the off state, and the thyristor valve and the shut-off valve of the main branch of the i-th bridge arm can be turned on. At this time, the auxiliary branch only needs to bear the voltage stress , the main branch carries the normal operating current; when the main branch fails commutation or AC short-circuit fault, the valve can be turned off, the auxiliary branch is turned on, and the current of the main branch is transferred to the auxiliary branch. When the current is completely transferred to the auxiliary branch, the auxiliary branch is turned off to realize the forced commutation of the main branch.
  • the topology includes a three-phase six-arm circuit, the main branch of the upper arm and the main branch of the lower arm are connected in series, and the auxiliary branch of the upper arm and the lower arm are connected in series
  • the arm auxiliary branch is connected in series, and one end of the shut-off valve 3 is connected to the connection end of the upper bridge arm auxiliary branch and the lower bridge arm auxiliary branch, and the other end is connected to the output end of the converter transformer, the upper bridge arm main branch and the lower bridge arm.
  • the connection end of the arm main branch is connected with the output end of the converter transformer. Similar to the concept in Fig.
  • shut-off valve 3 it is equivalent to disposing the shut-off valve 3 on the auxiliary branch 2, by connecting the auxiliary branch of the upper bridge arm and the auxiliary branch of the lower bridge arm in series, and connecting one end of the shut-off valve to the auxiliary branch.
  • the connection end of the auxiliary branch of the bridge arm and the auxiliary branch of the lower bridge arm, and the other end is connected to the output end of the converter transformer, so that the auxiliary branch of the upper bridge arm and the auxiliary branch of the lower bridge arm can share a shut-off valve, reducing the The number of series stages of shut-off valves.
  • the auxiliary branch When the hybrid converter is in normal operation, the auxiliary branch can be kept off, and the thyristor valve of the main branch of the i-th bridge arm can be turned on. At this time, the auxiliary branch only needs to bear the voltage stress, and the main branch will be Carry the normal operating current; when the main branch fails to commutate or the AC short circuit fails, the turn-off valve of the auxiliary branch and the auxiliary commutation valve of the upper bridge arm are turned on to transfer the current of the main branch to the auxiliary branch. When the current on the road is completely transferred to the auxiliary branch, the auxiliary commutation valve and the shut-off valve of the upper bridge arm are closed to realize the forced commutation of the main branch.
  • the topology structure includes a three-phase main branch and a three-phase auxiliary branch, and both the three-phase main branch and the three-phase auxiliary branch are three-phase six-bridge Arm structure, the main branch of the upper bridge arm and the main branch of the lower bridge arm are connected in series; the auxiliary branch of the upper bridge arm and the auxiliary branch of the lower bridge arm are connected in series; at this time, two shut-off valves can be set in this topology structure 3.
  • One end of the first shut-off valve is connected to the main branch of the upper bridge arm of each phase, and the other end is connected to the auxiliary branch of the upper bridge arm of each phase; one end of the second shut-off valve is connected to the main branch of the lower bridge arm of each phase. The other end is connected with the auxiliary branch of the lower bridge arm of each phase.
  • the auxiliary branch When the hybrid converter is in normal operation, the auxiliary branch can be kept in the off state, and the thyristor valve and the shut-off valve of the main branch of the i-th bridge arm can be turned on. At this time, the auxiliary branch only needs to bear the voltage stress , the normal operating current is carried by the main branch; when the commutation of the main branch fails or the AC short circuit fails, the shut-off valve is turned off, and the auxiliary commutation valve of the upper arm of the auxiliary branch is turned on to transfer the current of the main branch. To the auxiliary branch, when the current on the main branch is completely transferred to the auxiliary branch, the auxiliary commutation valve of the upper bridge arm of the auxiliary branch is turned off to realize the forced commutation of the main branch.
  • the three-phase upper arm main branch can share one shut-off valve and the three-phase lower arm main branch.
  • a shut-off valve can be shared, reducing the number of series stages of shut-off valves.
  • the topology may further include at least one isolation valve 4 .
  • the isolation valve 4 is arranged on the AC bus, and the AC bus is connected to the output end of the converter transformer. Among them, the isolation valve is used to isolate the high voltage generated between the main branch and the auxiliary branch.
  • the topology structure includes a three-phase main branch and a one-phase auxiliary branch
  • the three-phase main branch is a three-phase six-arm structure
  • the upper arm is the main branch.
  • the branch is connected in series with the main branch of the lower bridge arm, and the auxiliary branch of the upper bridge arm and the auxiliary branch of the lower bridge arm are connected in series.
  • One end of the first shut-off valve is connected to the main branch of the upper bridge arm of each phase, and the other end is connected to the auxiliary branch of the upper bridge arm; one end of the second shut-off valve is connected to the main branch of the lower bridge arm of each phase , and the other end is connected to the auxiliary branch of the lower bridge arm.
  • the first ends of the three isolation valves 4 are respectively connected to the connection ends of the main branch of the upper bridge arm of each phase and the main branch of the lower bridge arm of each phase, and the second ends of the three isolation valves 4 are connected to the auxiliary branch of the upper bridge arm and the main branch of the lower bridge arm of each phase.
  • the connection ends between the auxiliary branches of the lower bridge arm are connected.
  • the isolation valve When the hybrid converter is in normal operation, the isolation valve is closed, the auxiliary branch is kept in the closed state, and the thyristor valve and the shut-off valve of the main branch of the i-th bridge arm are turned on.
  • the auxiliary branch is only It needs to bear the voltage stress, and the main branch carries the normal operating current; when the main branch fails to commutate or the AC short circuit fails, the shut-off valve is turned off, the isolation valve and the auxiliary commutation valve of the upper arm of the auxiliary branch are turned on.
  • the current of the main branch is transferred to the auxiliary branch.
  • the auxiliary commutation valve of the upper arm of the auxiliary branch is turned off to realize the forced commutation of the main branch.
  • the topology structure includes a three-phase main branch and a one-phase auxiliary branch, and the three-phase main branch is a three-phase six-arm structure, and the upper arm is the main branch.
  • the branch is connected in series with the main branch of the lower bridge arm, and the auxiliary branch of the upper bridge arm and the auxiliary branch of the lower bridge arm are connected in series.
  • a shut-off valve 3 is provided on both the road and the main branch of the lower bridge arm.
  • connection ends between the shut-off valve 3 of the main branch of the upper bridge arm of each phase and the shut-off valve 3 of the main branch of the lower bridge arm of each phase are respectively connected with the first ends of the three isolation valves 4;
  • the connection end between the auxiliary branch and the auxiliary branch of the lower bridge arm is connected with the second end of each isolation valve 4 .
  • FIG. 9 The concept of FIG. 9 is similar to that of FIG. 8 , in order to precisely control the operation of each main branch, a shut-off valve is provided in the main branch of the upper bridge arm and the main branch of the lower bridge arm of each phase.
  • the isolation valve is closed, the auxiliary branch is kept in the closed state, and the thyristor valve and the shut-off valve of the main branch of the i-th bridge arm are turned on.
  • the auxiliary branch is only It needs to bear the voltage stress, and the main branch carries the normal operating current; when the main branch fails to commutate or the AC short circuit fails, the shut-off valve is turned off, the isolation valve and the auxiliary commutation valve of the upper arm of the auxiliary branch are turned on.
  • the current of the main branch is transferred to the auxiliary branch.
  • the auxiliary commutation valve of the upper arm of the auxiliary branch is turned off to realize the forced commutation of the main branch.
  • the isolation valve is turned off before or at the same time when the thyristor valve that turns on the main branch of the i-th bridge arm is started in the next control cycle, and the main branch operates independently.
  • the topology structure includes a three-phase main branch and a one-phase auxiliary branch
  • the three-phase main branch is a three-phase six-arm structure
  • the upper arm is the main branch.
  • the branch is connected in series with the main branch of the lower bridge arm, and the auxiliary branch of the upper bridge arm and the auxiliary branch of the lower bridge arm are connected in series.
  • a shut-off valve 3 is provided on both the road and the auxiliary branch of the lower bridge arm.
  • connection ends between the main branch of the upper bridge arm of each phase and the main branch of the lower bridge arm of each phase are respectively connected to the first ends of the three isolation valves 4; the second ends of each isolation valve 4 are connected to the auxiliary branch of the upper bridge arm.
  • the topology in Figure 10 is equivalent to setting the shut-off valve on the auxiliary branch.
  • the isolation valve is closed, the auxiliary branch is kept in the off state, and the ith bridge arm is turned on.
  • the auxiliary branch only needs to bear the voltage stress, and the main branch carries the normal operating current; when the main branch fails commutation or AC short-circuit fault, the isolation valve, shut-off valve and auxiliary
  • the auxiliary commutation valve of the upper bridge arm of the branch transfers the current of the main branch to the auxiliary branch.
  • the shut-off valve and the upper bridge arm of the auxiliary branch are turned off.
  • Auxiliary commutation valve to realize forced commutation of the main branch.
  • the isolation valve is turned off before or at the same time when the thyristor valve that turns on the main branch of the i-th bridge arm is started in the next control cycle, and the main branch operates independently.
  • the topology structure includes a three-phase main branch and a one-phase auxiliary branch
  • the three-phase main branch is a three-phase six-arm structure
  • the upper arm is the main branch.
  • the branch is connected in series with the main branch of the lower bridge arm
  • the auxiliary branch of the upper bridge arm and the auxiliary branch of the lower bridge arm are connected in series.
  • a shut-off valve 3 can be set in this topology, and one end of the valve 3 can be shut off. They are respectively connected to the first ends of the three isolation valves 4, and the other end of the shut-off valve 3 is connected to the connection ends of the auxiliary branch of the upper bridge arm and the auxiliary branch of the lower bridge arm.
  • the connection ends between the main branches of the lower bridge arm are respectively connected with the second ends of the three isolation valves 4 .
  • the isolation valve and the shut-off valve are closed, the auxiliary branch is kept in the closed state, and the thyristor valve of the main branch of the i-th bridge arm is turned on. It needs to bear the voltage stress, and the main branch carries the normal operating current; when the main branch fails to commutate or the AC short circuit fails, the isolation valve, the shut-off valve and the auxiliary commutation valve of the upper bridge arm of the auxiliary branch are turned on, and the main branch is turned on. The current of the branch is transferred to the auxiliary branch.
  • the shut-off valve and the auxiliary commutation valve of the upper arm of the auxiliary branch are turned off to realize the forced commutation of the main branch.
  • the isolation valve is turned off before or at the same time when the thyristor valve that turns on the main branch of the i-th bridge arm is started in the next control cycle, and the main branch operates independently.
  • both the first thyristor valve and the second thyristor valve may include: at least one controllable device and at least one first auxiliary component, wherein at least one controllable device is arranged in series, and at least one first The auxiliary components are respectively arranged in parallel with at least one controllable device, that is, the number of the first auxiliary components is equal to the number of the controllable components.
  • the controllable device is mainly used for reverse voltage blocking, and may include one or more of thyristor, GTO, and reverse resistance IGCT, which is not specifically limited here.
  • the shut-off valve 3 in FIG. 1 to FIG. 11 may include: at least one first power unit and a second auxiliary component, wherein the first power unit is used for on- and off-control of the transfer branch , the second auxiliary component is arranged in parallel with the first power unit.
  • the first power unit may be a power electronic unit composed of a first branch circuit, wherein the first branch circuit is provided with a first power device.
  • the first power unit may be a power electronic unit composed of the second branch and the third branch. Wherein, at least one first power device is arranged on the second branch, and at least one first power device is arranged in series; the structure of the third branch is the same as that of the second branch, and the third branch and the second branch are arranged in parallel .
  • the first power unit may be a power electronic unit composed of the fourth branch and the fifth branch.
  • the first power unit may also be a power electronic unit composed of a sixth branch and a seventh branch.
  • the sixth branch is provided with a first power device;
  • the seventh branch is arranged in parallel with the sixth branch,
  • the seventh branch is provided with a first power device and a second auxiliary component, and the first power device and the second auxiliary Components are connected in parallel.
  • the first power unit may also be a power electronic unit composed of an eighth branch, a ninth branch, a tenth branch and an eleventh branch; wherein the eighth branch and the The ninth branch is connected in series, the first power device and the first diode are arranged on the eighth branch, the first power device and the first diode are connected in parallel, and the ninth branch is connected at least one first diode is provided; the tenth branch and the eleventh branch are connected in series, at least one first diode is arranged on the tenth branch, and the eleventh branch is The first power device and the first diode are provided, and the first power device and the first diode are connected in parallel; the eighth branch and the ninth branch connected in series are connected in series The tenth branch and the eleventh branch are arranged in parallel.
  • the first power unit may also be a power electronic unit composed of the twelfth branch, the thirteenth branch, the fourteenth branch and the fifteenth branch; wherein the twelfth branch The thirteenth branch is connected in series, the twelfth branch is provided with the first power device and the first diode, the first power device and the first diode are respectively connected with The second auxiliary component is connected in parallel, the thirteenth branch is provided with at least one first diode, and the at least one first diode is connected in parallel with the second auxiliary component; the fourteenth branch is connected at least one first diode is provided, the at least one first diode is connected in parallel with the second auxiliary component, the first power device and the first diode are provided on the fifteenth branch, The first power device and the first diode are respectively connected in parallel with the second auxiliary component; the twelfth branch and the thirteenth branch connected in series are connected with the tenth branch connected in series The four branches and the fifteenth branch are
  • the first power device is a fully-controlled power electronic device
  • the fully-controlled power electronic device may be an insulated gate bipolar transistor (IGBT, Insulated Gate Bipolar Transistor), IGCT, GTO, and a metal-oxide semiconductor field effect transistor (MOSFET, one or more of Metal-Oxide-Semiconductor Field-Effect Transistor), which is not limited here.
  • IGBT Insulated Gate Bipolar Transistor
  • IGCT Insulated Gate Bipolar Transistor
  • GTO GTO
  • MOSFET metal-oxide semiconductor field effect transistor
  • the upper bridge arm auxiliary branch in FIG. 1 to FIG. 11 is provided with a first auxiliary phase change valve 21
  • the lower bridge arm auxiliary branch is provided with a second auxiliary phase change valve 22
  • Both the first auxiliary commutating valve 21 and the second auxiliary commutating valve 22 may include: at least one second power unit and at least one third auxiliary component, and at least one second power unit is connected in series, and at least one third auxiliary component is connected with at least one third auxiliary component.
  • a second power unit is connected in parallel, that is, the number of third auxiliary components is the same as the number of second power devices.
  • the second power unit may be a power electronic unit composed of a first connection branch, wherein the first connection branch is provided with a second power device.
  • the second power unit may be a power electronic unit composed of a second connection branch, wherein at least one of the second power devices is provided on the second connection branch, and at least one second power device is reversed concatenate.
  • the second power unit may be a power electronic unit composed of at least one third connection branch and at least one fourth connection branch, wherein the third connection branch and the first connection branch are The structure is the same, the fourth connection branch is provided with a second diode (as shown in Figure 14c) or a first thyristor (as shown in Figure 14d), and at least one third connection branch is interlaced with at least one fourth connection branch Concatenated settings.
  • the second power unit may be a power electronic unit composed of a fifth connection branch and a sixth connection branch, wherein at least one second power device is provided on the fifth connection branch, and at least one second power device is provided on the fifth connection branch.
  • the power devices are arranged in series, the sixth connection branch and the fifth connection branch have the same structure, and the fifth connection branch and the sixth connection branch are arranged in parallel, the fifth connection branch, the sixth connection branch and the third auxiliary
  • the components form a full bridge structure. As shown in FIG.
  • the second power unit may be a power electronic unit composed of a seventh connection branch, an eighth connection branch and a ninth connection branch, wherein at least one third dipole is arranged on the seventh connection branch tube, and at least one third diode is arranged in series, at least one of the second power devices is arranged on the eighth connection branch, and at least one second power device is arranged in series, the ninth connection branch and the seventh connection branch
  • the structure is the same, the ninth connecting branch, the eighth connecting branch and the seventh connecting branch are connected in parallel, and the seventh connecting branch, the eighth connecting branch, the ninth connecting branch and the third auxiliary component constitute an H-bridge structure.
  • the second power device is a fully-controlled power electronic device, and the fully-controlled power electronic device may be one or more of IGBT, IGCT, GTO, and MOSFET, which is not limited here.
  • the first auxiliary component, the second auxiliary component and the third auxiliary component may be a first buffer branch composed of a capacitor; it may be a second buffer circuit composed of a resistor and a capacitor in series Buffer branch; it can be a third buffer branch connected in parallel with a capacitor and a resistor; it can be a fourth buffer branch RCD1 formed by 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 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 first buffer branch, the second buffer branch, the third buffer A plurality of seventh buffer branches formed in parallel among the branch, the fourth buffer branch, the fifth buffer branch and the sixth buffer branch.
  • the beneficial effects of the embodiments of the present application are as follows: 1.
  • the auxiliary branch can be kept in an off state, and only needs to bear the voltage stress, and the main branch can carry the normal operating current; when the main branch fails commutation or an AC short-circuit fault
  • the auxiliary branch is turned on, the current of the main branch is transferred to the auxiliary branch in combination with the closing or conduction of the shut-off valve.
  • the reverse voltage and the auxiliary branch with self-shutoff capability can be provided in parallel, so as to realize the reliable turn-off of the main branch and the active commutation of the bridge arm of each phase, so as to realize the realization in a relatively short time.
  • the auxiliary commutation function avoids the occurrence of commutation failure, thereby ensuring the stable and safe operation of the power grid.
  • the auxiliary branch can turn off the current of the main branch in advance, and at the same time provide a reverse voltage to the main branch to ensure its reliable turn-off and avoid commutation failure The problem.
  • the hybrid converter topology provided in the embodiment of the present application 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 inverter power consumption. side reactive power.
  • the auxiliary branch of the i-th bridge arm of the hybrid inverter topology is kept in an off state, and the hybrid inverter topology is turned on.
  • the auxiliary branch and/or the shut-off valve of the i-th bridge arm of the hybrid converter topology When a commutation failure or an AC short-circuit fault occurs, the auxiliary branch and/or the shut-off valve of the i-th bridge arm of the hybrid converter topology is turned on, and the current of the main branch is forcibly transferred to the auxiliary branch , when the current transfer is completed, the auxiliary branch and/or the shut-off valve of the ith bridge arm of the hybrid converter topology is turned off to realize forced commutation of the hybrid converter.
  • the step of returning to the main branch and/or the shut-off valve of the i-th bridge arm of the hybrid converter topology continues to operate independently and normally by the main branch, thereby ensuring the auxiliary The branch is only subjected to turn-off voltage stress during faults, reducing device losses and extending device life.
  • the control method for forced commutation provided by the embodiment of the present application, through the periodic alternate operation of the main branch and the auxiliary branch, not only can resist commutation failure, but also does not need to predict commutation failure. 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.
  • an embodiment of a control method for a hybrid converter topology is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer such as a set of computer-executable instructions. system, and, 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. 16 shows the control of the topology of the hybrid inverter according to an embodiment of the present application.
  • the flow chart of the method, as shown in Figure 16, includes the following steps:
  • the main branch of the hybrid converter topology is periodically subjected to voltage and current stress, and the auxiliary branch is always in an off state, and is only subjected to voltage stress when the main branch is turned off.
  • the auxiliary branch of the i-th bridge arm of the hybrid converter topology is kept in an off state, and the main branch and/or the shut-off valve of the i-th bridge arm of the hybrid converter topology structure is turned on.
  • the hybrid converter topology that realizes forced commutation can work in the normal commutation operation mode, that is, in the temporary commutation operation mode, the auxiliary branch is in the off state when the hybrid converter is in normal operation, Only withstand voltage stress, reducing the increase in converter losses under long-term operation.
  • the auxiliary branch and/or the shut-off valve of the i-th bridge arm of the hybrid converter topology When a commutation failure or an AC short-circuit fault occurs, the auxiliary branch and/or the shut-off valve of the i-th bridge arm of the hybrid converter topology is turned on, and the current of the main branch is forcibly transferred to the auxiliary branch , when the current transfer is completed, the auxiliary branch and/or the shut-off valve of the ith bridge arm of the hybrid converter topology is turned off to realize forced commutation of the hybrid converter. After a control cycle, the step of returning to the main branch and/or the shut-off valve of the i-th bridge arm of the hybrid converter topology continues to operate independently and normally by the main branch.
  • the control method of the hybrid converter topology provided by the embodiment of the present application ensures that the auxiliary branch only bears the turn-off voltage stress in the event of a fault, reduces the loss of the device, and further prolongs the service life of the device.
  • control method mainly includes the following steps:
  • Figure 17 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 off.
  • the thyristor valve is subjected to voltage stress when it is turned off.
  • Figure 18a, Figure 18b and Figure 18c turn off the main branch when the main branch is commutating to the auxiliary branch, and the auxiliary branch begins to bear the voltage stress. This process is divided into three stages.
  • Figure 18a changes from the main branch to the auxiliary branch In the flow stage, the auxiliary branch receives the trigger signal and turns on, and then the auxiliary branch receives the turn-on signal.
  • the shut-off valve of the main branch receives the turn-off signal, and sends the current of the main branch to the auxiliary branch.
  • Figure 18b shows the auxiliary branch current flow 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 18c is the auxiliary branch off In the off stage, when a shutdown signal is received in this stage, the auxiliary branch is turned off, and the main branch at this time is in the off state and bears the voltage.
  • the valve can be turned off before or at the same time when the thyristor valve of the main branch is turned on 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. 19 is the triggering control sequence of the hybrid converter topology when commutation failure or AC short-circuit failure occurs.
  • the valve V13 of the auxiliary branch is turned on when the first preset time period ⁇ t 1 passes, and the valve of the auxiliary branch circuit is turned off when the second preset time period ⁇ t 2 passes. Shut off the valve, perform the commutation process from the main branch to the auxiliary branch, and ⁇ t 2 ⁇ t 1 ⁇ 0.
  • the main branch current I11 gradually decreases to zero, the auxiliary branch current I12 gradually increases, and then the auxiliary branch is turned off after a third preset time period ⁇ t3, and the main branch current I11 crosses zero until the auxiliary branch is turned off.
  • the period of time is the turn-off time t off of the thyristor valve, where t off is greater than the minimum turn-off time of the thyristor valve to ensure that the thyristor valve of the main branch has enough time to turn off.
  • the auxiliary branch current will commutate to the adjacent main branch until it reaches the DC current I12. At this point, the commutation of the main branch is completed, and the commutation failure fault is successfully resisted.
  • a shut-off valve that conducts the main branch before or at the same time as the thyristor valve opens.
  • start this operation mode which can successfully avoid the occurrence of commutation failure.
  • the operation mode is exited, and the auxiliary branch keeps In the off state, the main branch operates independently and normally.
  • the hybrid converter topology is controlled to enable the forced commutation operation mode, thereby avoiding the occurrence of commutation failure, and in the hybrid converter
  • the forced commutation operation mode is exited, and the auxiliary branch continues to be turned off. The device loss is reduced, thereby extending the service life of the device.
  • Figure 20 shows the control triggering sequence when the hybrid converter topology structure detects a commutation failure or a short-circuit fault in advance, wherein the main branch and the auxiliary branch run alternately periodically.
  • the specific operation process is shown in Figure 18a, Figure 18b and Figure 18c.
  • the trigger pulse Sg1 of the thyristor valve of the main branch is delayed by 120°, or the auxiliary branch is triggered near this moment, and the main branch is turned off after a short time (for example, 1s, 5s, etc.).
  • the shut-off valve realizes the commutation from the main branch to the auxiliary branch.
  • the main branch After the current of the main branch crosses zero, the main branch is turned off and bears the reverse voltage, and the time from the current of the main branch to the turn off of the auxiliary branch is the turn-off time t off of the thyristor valve, and t off is greater than the thyristor
  • the minimum turn-off time of the valve ensures its reliable turn-off.
  • the V1 valve current is all transferred to the auxiliary branch.
  • the auxiliary branch valve After ⁇ t, the auxiliary branch valve starts to turn off, and the main branch begins to bear the forward voltage.
  • the thyristor valve of the branch conducts the shut-off valve of the main branch before opening. In this operating mode, the main branch and auxiliary branch in the bridge arm of the hybrid converter topology operate alternately periodically.
  • the hybrid inverter is in a small turn-off angle operation mode, which reduces the reactive power consumption of the hybrid inverter.
  • control method mainly includes the following steps:
  • the current flow path of the hybrid converter topology under normal operating conditions the main branch is periodically subjected to voltage and current stress, the auxiliary branch is always off, and only in the main branch.
  • the thyristor valve of the branch is subjected to voltage stress when it is closed.
  • FIG. 22 is the trigger control sequence of the hybrid converter topology, and t0 in the figure represents the initial trigger time.
  • Fig. 23a, Fig. 23b and Fig. 23c When the main branch commutates to the auxiliary branch, the auxiliary branch begins to bear the voltage stress. The process is divided into three stages. Fig. 23a is the stage of commutation from the main branch to the auxiliary branch.
  • the auxiliary branch receives the trigger signal and turns on, and then the shut-off valve set in the auxiliary branch receives the opening signal, applies a reverse voltage to the main branch, and transfers the current of the main branch to the auxiliary branch;
  • Figure 23b It is the auxiliary branch flow-through stage, in which the main branch has been completely turned off, and the main branch current is all transferred to the auxiliary branch;
  • Figure 23c is the auxiliary branch off stage, when a shutdown signal is received at this stage, it is turned off first.
  • the auxiliary commutation valve of the upper bridge arm of the auxiliary branch is turned off.
  • the main branch is in the off state to withstand the forward voltage, and then the valve can be turned off before the thyristor valve of the main branch is turned on in the next control cycle.
  • the above operation process can be put into operation at the time of commutation failure or predicted commutation failure.
  • Figure 24 shows the control triggering sequence when the forced commutation hybrid converter topology structure detects commutation failure or short-circuit fault in advance, and each valve control triggering sequence when the main branch and the auxiliary branch run alternately periodically,
  • the specific operation process is shown in Figure 23a, Figure 23b and Figure 23c.
  • 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.
  • Fig. 26 is the trigger control sequence of the hybrid converter topology, and t 0 in the figure represents the initial trigger time.
  • Fig. 27a, Fig. 27b and Fig. 27c commutation process from the main branch to the auxiliary branch.
  • Fig. 28 shows the triggering sequence of each valve when the main branch and the auxiliary branch run alternately periodically, and the specific operation process is shown in Fig. 27a, Fig. 27b and Fig. 27c.
  • control method of the topology shown in FIG. 4 is similar to the control method of the topology shown in FIG. 5 , and will not be repeated here.
  • FIG. 29 shows the trigger control sequence of the hybrid converter topology, and t 0 in the figure represents the initial trigger time.
  • Fig. 30a, Fig. 30b and Fig. 30c commutation process from the main branch to the auxiliary branch.
  • Fig. 31 shows the triggering sequence of each valve when the main branch and the auxiliary branch run alternately periodically, and the specific operation process is shown in Fig. 30a, Fig. 30b and Fig. 30c.
  • FIG. 32 shows the trigger control sequence of the hybrid converter topology, and t 0 in the figure represents the initial trigger time.
  • Fig. 33a, Fig. 33b and Fig. 33c commutation process from the main branch to the auxiliary branch.
  • Fig. 34 shows the triggering sequence of each valve when the main branch and the auxiliary branch operate alternately periodically, and the specific operation process is shown in Fig. 33a, Fig. 33b and Fig. 33c.
  • FIG. 35 shows the trigger control sequence of the hybrid converter topology, and t 0 in the figure represents the initial trigger time.
  • Fig. 36a, Fig. 36b and Fig. 36c commutation process from the main branch to the auxiliary branch.
  • Fig. 37 shows the triggering sequence of each valve when the main branch and the auxiliary branch run alternately periodically, and the specific operation process is shown in Fig. 36a, Fig. 36b and Fig. 36c.
  • the control methods of the above-mentioned hybrid topology structure are of the same conception, all of which are to keep the auxiliary branch in the off state in the normal operation state, and the main branch to work independently.
  • the auxiliary branch is started, and the auxiliary main branch is used for commutation to avoid commutation failure.

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Abstract

本申请实施例公开了一种混合式换流器拓扑结构及其控制方法，其中，该拓扑结构包括：至少一相主支路，每相主支路包括上桥臂主支路和下桥臂主支路，上桥臂主支路上设置有第一晶闸管阀，下桥臂主支路上设置有第二晶闸管阀；至少一相辅助支路，每相辅助支路包括上桥臂辅助支路和下桥臂辅助支路，上桥臂辅助支路上设置有第一辅助换相阀，下桥臂辅助支路上设置有第二辅助换相阀；辅助支路与主支路并联，用于在主支路换相失败时，辅助主支路进行强迫换相；可关断阀设置在主支路或者辅助支路上，用于强迫换相时，将主支路的电流转移至辅助支路。

Description

一种混合式换流器拓扑结构及其控制方法
相关申请的交叉引用
本申请基于申请号为202110139638.3、申请日为2021年02月01日的中国专利申请提出，并要求该中国专利申请的优先权，该中国专利申请的全部内容在此以引入方式并入本申请。
技术领域
本申请涉及电力电子中的换流技术领域，具体涉及一种混合式换流器拓扑结构及其控制方法。
背景技术
传统的电网换相高压直流(Line Commutated Converter High Voltage Direct Current，LCC-HVDC)输电系统具有远距离大容量输电、有功功率可控等优势，在世界范围内广泛应用。换流器作为直流输电的核心装备，是实现交、直流电能转换的核心功能单元，其运行可靠性很大程度上决定了特高压直流电网的运行可靠性。
由于传统换流器多采用半控型器件晶闸管作为核心部件构成六脉动桥换流拓扑，每个桥臂由多级晶闸管及其缓冲部件串联组成，由于晶闸管不具备自关断能力，在交流系统故障等情况下容易发生换相失败，导致直流电流激增和直流传输功率迅速大量损失，影响电网的稳定安全运行。
发明内容
有鉴于此，本申请实施例提供了一种混合式换流器拓扑结构及其控制方法，以解决换相失败影响电网稳定安全运行的问题。
第一方面，本申请实施例提供了一种混合式换流器拓扑结构，所述拓扑结构通过换流变压器接入交流电网，所述拓扑结构包括：至少一相主支路，每相主支路包括上桥臂主支路和下桥臂主支路，所述上桥臂主支路上设置有第一晶闸管阀，所述下桥臂主支路上设置有第二晶闸管阀；所述主支路的一端接入直流母线，另一端接入所述换流变压器的输出端；至少一相辅助支路，每相辅助支路包括上桥臂辅助支路和下桥臂辅助支路，所述上桥臂辅助支路上设置有第一辅助换相阀，所述下桥臂辅助支路上设置有第二辅助换相阀；所述辅助支路与所述主支路并联，用于在所述主支路换相失败时，辅助所述主支路进行强迫换相；可关断阀，设置在所述主支路或者辅助支路上，用于强迫换相时，将所述主支路的电流转移至所述辅助支路。
结合第一方面，在第一方面的第一实施方式中，所述上桥臂辅助支路与所述上桥臂主支路并联，所述下桥臂辅助支路与所述下桥臂主支路并联；所述可关断阀设置在每相上桥臂主支路和每相下桥臂主支路上；其中，设置在上桥臂主支路上的所述可关断阀的一端连接所述第一晶闸管阀，另一端连接所述换流变压器的输出端；设置在下桥臂主支路上的所述可关断阀的一端连接所述第二晶闸管阀，另一端连接直流母线负极。
结合第一方面，在第一方面的第二实施方式中，所述上桥臂辅助支路与所述上桥臂主支路并联，所述下桥臂辅助支路与所述下桥臂主支路并联；所述可关断阀分别设置在所述上桥臂辅助支路和所述下桥臂辅助支路上；其中，设置在所述上桥臂辅助支路上的所述可关断阀的一端连接所述第一辅助换相阀，另一端连接所述换流变压器的输出端；设置在所述下桥臂辅助支路上的所述可关断阀的一端连接所述第二辅助换相阀，另一端连接直流母线负极。
结合第一方面，在第一方面的第三实施方式中，所述上桥臂主支路和 下桥臂主支路串联；所述上桥臂辅助支路和所述下桥臂辅助支路串联；所述可关断阀的一端连接所述上桥臂主支路和所述下桥臂主支路的连接端，另一端连接所述换流变压器的输出端；所述上桥臂辅助支路和所述下桥臂辅助支路的连接端与所述换流变压器的输出端连接。
结合第一方面，在第一方面的第四实施方式中，所述上桥臂主支路和下桥臂主支路串联；所述上桥臂辅助支路和所述下桥臂辅助支路串联；所述可关断阀的一端连接所述上桥臂辅助支路和所述下桥臂辅助支路的连接端，另一端连接所述换流变压器的输出端；所述上桥臂主支路和所述下桥臂主支路的连接端与所述换流变压器的输出端连接。
结合第一方面，在第一方面的第五实施方式中，所述拓扑结构包括两个可关断阀，所述上桥臂主支路和下桥臂主支路串联；所述上桥臂辅助支路和所述下桥臂辅助支路串联；其中，第一可关断阀的一端与每相上桥臂主支路连接，另一端与每相上桥臂辅助支路连接；第二可关断阀的一端与每相下桥臂主支路连接，另一端与每相下桥臂辅助支路连接。
结合第一方面，在第一方面的第六实施方式中，所述拓扑结构还包括：至少一个隔离阀，设置在交流母线上，用于隔离所述主支路和所述辅助支路之间的电压。
结合第一方面第六实施方式，在第一方面的第七实施方式中，所述至少一个隔离阀的第一端分别连接每相上桥臂主支路和每相下桥臂主支路的连接端，第二端连接所述上桥臂辅助支路和所述下桥臂辅助支路的连接端；所述拓扑结构包括两个可关断阀，所述上桥臂主支路和下桥臂主支路串联；所述上桥臂辅助支路和所述下桥臂辅助支路串联；其中，第一可关断阀的一端与每相上桥臂主支路连接，另一端与每相上桥臂辅助支路连接；第二可关断阀的一端与下桥臂主支路连接，另一端与下桥臂辅助支路连接。
结合第一方面第六实施方式，在第一方面的第八实施方式中，所述上 桥臂主支路和下桥臂主支路串联；所述上桥臂辅助支路和所述下桥臂辅助支路串联；所述上桥臂主支路和下桥臂主支路均设置有所述可关断阀；每相上桥臂主支路的可关断阀与每相下桥臂主支路的可关断阀之间的连接端与所述隔离阀的第一端连接。
结合第一方面第六实施方式，在第一方面的第九实施方式中，所述上桥臂主支路和下桥臂主支路串联；所述上桥臂辅助支路和所述下桥臂辅助支路串联；所述上桥臂辅助支路和所述下桥臂辅助支路均设置有所述可关断阀，所述上桥臂辅助支路的可关断阀与所述下桥臂辅助支路的可关断阀之间的连接端与所述至少一个隔离阀的第二端连接。
结合第一方面第六实施方式，在第一方面的第十实施方式中，所述上桥臂主支路和下桥臂主支路串联；所述上桥臂辅助支路和所述下桥臂辅助支路串联；所述可关断阀的一端与所述至少一个隔离阀的第一端连接，另一端连接所述上桥臂辅助支路和所述下桥臂辅助支路的连接端。
结合第一方面第六实施方式，在第一方面的第十一实施方式中，所述第一晶闸管阀和所述第二晶闸管阀均包括：至少一个可控器件，用于反向电压阻断，所述至少一个可控器件串联设置；至少一个第一辅助部件，与所述至少一个可控器件并联设置；所述可控器件包括晶闸管、门极可关断晶闸管(GTO，Gate-Turn-Off Thyristor)、逆阻型集成门极换流晶闸管(IGCT，Integrated Gate-Commutated Thyristor)中的一种或多种。
结合第一方面，在第一方面的第十二实施方式中，所述可关断阀包括：至少一个第一功率单元，用于所述转移支路的导通控制和关断控制；第二辅助部件，与所述第一功率单元并联设置。
结合第一方面第十二实施方式，在第一方面的第十三实施方式中，所述第一功率单元包括：第一支路，所述第一支路上设置有第一功率器件；或，第二支路和第三支路；其中，所述第二支路上设置有至少一个所述第 一功率器件，所述至少一个所述第一功率器件串联设置；所述第三支路与所述第二支路的结构相同，且所述第三支路与所述第二支路并联设置；或，第四支路和第五支路；其中，所述第四支路上设置有至少一个第一二极管，所述至少一个第一二极管串联设置；所述第五支路与所述第四支路的结构相同，且所述第四支路与所述第五支路并联设置；或，第六支路和第七支路；其中，所述第六支路上设置有所述第一功率器件；所述第七支路上设置有所述第一功率器件和所述第二辅助部件，所述第一功率器件和所述第二辅助部件并联；所述第六支路与所述第七支路并联设置。
结合第一方面，在第一方面的第十四实施方式中，所述第一辅助换相阀和所述第二辅助换相阀包括：至少一个第二功率单元，所述至少一个第二功率单元串联；至少一个第三辅助部件，与所述至少一个第二功率单元并联。
结合第一方面第十四实施方式，在第一方面的第十五实施方式中，所述第二功率单元包括：第一连接支路，所述第一连接支路上设置有第二功率器件；或，第二连接支路；所述第二连接支路上设置有至少一个所述第二功率器件，所述至少一个所述第二功率器件反向串联；或，至少一个第三连接支路和至少一个第四连接支路；其中，所述第三连接支路与所述第一连接支路的结构相同，所述第四连接支路上设置有第二二极管或第一晶闸管；所述至少一个第三连接支路与所述至少一个第四连接支路交错串联设置；或，第五连接支路和第六连接支路；其中，所述第五连接支路上设置有至少一个所述第二功率器件，所述至少一个所述第二功率器件串联设置；所述第六连接支路与所述第五连接支路的结构相同，且所述第五连接支路与所述第六连接支路并联设置；所述第五连接支路、所述第六连接支路和所述第三辅助部件构成全桥结构；或，第七连接支路、第八连接支路和第九连接支路；其中，第七连接支路上设置有至少一个第三二极管，所 述至少一个第三二极管串联设置；第八连接支路上设置有至少一个所述第二功率器件，所述至少一个所述第二功率器件串联设置；所述第九连接支路和所述第七连接支路的结构相同，所述第九连接支路和所述第八连接支路及所述第七连接支路并联；所述第七连接支路、第八连接支路、第九连接支路和所述第三辅助部件构成H桥结构。
结合第一方面第十一实施方式或第十二实施方式或第十四实施方式，在第一方面的第十六实施方式中，第一辅助部件、第二辅助部件和第三辅助部件包括：由电容组成的第一缓冲支路；或，电阻和所述电容串联的第二缓冲支路；或，所述电容和所述电阻并联的第三缓冲支路；或，所述电阻和第五二极管并联，再与所述电容串联构成的第四缓冲支路；或，所述电阻和所述电容并联，再与所述第五二极管串联构成的第五缓冲支路；或，避雷器组成的第六缓冲支路；或，所述第一缓冲支路、所述第二缓冲支路、所述第三缓冲支路、所述第四缓冲支路、所述第五缓冲支路和所述第六缓冲支路中的多种并联构成的第七缓冲支路。
第二方面，本申请实施例提供了一种混合式换流器拓扑结构的控制方法，用于第一方面或第一方面任一实施方式所述的混合式换流器拓扑结构，包括如下步骤：关断混合式换流器拓扑结构的辅助支路和/或可关断阀；导通混合式换流器拓扑结构的主支路和/或可关断阀；导通混合式换流器拓扑结构的辅助支路和/或可关断阀；关断混合式换流器拓扑结构的辅助支路和/或可关断阀；经过一个控制周期后，导通混合式换流器拓扑结构的主支路的晶闸管阀，其中，i∈[1,6]。
结合第二方面，在第二方面的第一实施方式中，所述方法还包括：所述混合式换流器拓扑结构的主支路与辅助支路周期性交替运行。
本申请实施例的技术方案，具有如下优点：
本申请实施例提供的混合式换流器拓扑结构，包括至少一相主支路、 至少一相辅助支路以及可关断阀，且主支路与辅助支路并联设置，可关断阀设置在主支路或辅助支路上。在正常运行时，辅助支路可保持关断状态，只需承担电压应力，由主支路承载正常运行电流；当主支路换相失败或交流短路故障时导通辅助支路，结合可关断阀的关断或导通将主支路的电流转移至辅助支路。通过在主支路的基础上并联可提供反向电压和具备自关断能力的辅助支路，实现主支路的可靠关断和每相桥臂的主动换相，从而在较短时间内实现辅助换相功能，避免换相失败的发生，从而保证电网的稳定安全运行。
附图说明
为了更清楚地说明本申请具体实施方式或现有技术中的技术方案，下面将对具体实施方式或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图是本申请的一些实施方式，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1a是根据本申请实施例的混合式换流器拓扑结构的原理框图；
图1b是根据本申请实施例的混合式换流器拓扑结构的另一原理框图；
图2是根据本申请实施例可选的混合式换流器拓扑结构的结构框图；
图3是根据本申请实施例可选的混合式换流器拓扑结构的另一结构框图；
图4是根据本申请实施例可选的混合式换流器拓扑结构的另一结构框图；
图5是根据本申请实施例可选的混合式换流器拓扑结构的另一结构框图；
图6是根据本申请实施例可选的混合式换流器拓扑结构的另一结构框图；
图7是根据本申请实施例的混合式换流器拓扑结构的另一原理框图；
图8是根据本申请实施例可选的混合式换流器拓扑结构的另一结构框图；
图9是根据本申请实施例可选的混合式换流器拓扑结构的另一结构框图；
图10是根据本申请实施例可选的混合式换流器拓扑结构的另一结构框图；
图11是根据本申请实施例可选的混合式换流器拓扑结构的另一结构框图；
图12是根据本申请实施例的主支路的结构框图；
图13是根据本申请实施例的可关断阀的结构框图；
图14是根据本申请实施例的辅助换相阀的结构框图；
图15是根据本申请实施例的缓冲部件的结构框图；
图16是根据本申请实施例的混合式换流器拓扑结构的控制方法的流程图；
图17是根据本申请实施例的正常运行状态的桥臂电流流通路径；
图18是根据本申请实施例的主支路向辅助支路换流的电流流通过程；
图19是根据本申请实施例的主支路和辅助支路周期性的触发控制时序；
图20是根据本申请实施例的主支路的正常触发控制时序；
图21是根据本申请实施例的正常运行状态的桥臂电流流通路径；
图22是根据本申请实施例的主支路换相失败或短路故障的触发控制时序；
图23是根据本申请实施例的主支路向辅助支路换流的电流流通过程；
图24是根据本申请实施例的主支路和辅助支路周期性的触发控制时 序；
图25是根据本申请实施例的正常运行状态的桥臂电流流通路径；
图26是根据本申请实施例的各阀触发控制时序；
图27是根据本申请实施例的主支路向辅助支路换流的电流流通过程；
图28是根据本申请实施例的主支路和辅助支路周期性的触发控制时序；
图29是根据本申请实施例的各阀触发控制时序；
图30是根据本申请实施例的主支路向辅助支路换流的电流流通过程；
图31是根据本申请实施例的主支路和辅助支路周期性的触发控制时序；
图32是根据本申请实施例的各阀触发控制时序；
图33是根据本申请实施例的主支路向辅助支路换流的电流流通过程；
图34是根据本申请实施例的主支路和辅助支路周期性的触发控制时序；
图35是根据本申请实施例的各阀触发控制时序；
图36是根据本申请实施例的主支路向辅助支路换流的电流流通过程；
图37是根据本申请实施例的主支路和辅助支路周期性的触发控制时序。
附图说明，1-主支路，2-辅助支路，3-可关断阀，4-隔离阀，11-第一晶闸管阀，12-第二晶闸管阀，21-第一辅助换相阀，22-第二辅助换相阀。
具体实施方式
为使本申请实施例的目的、技术方案和优点更加清楚，下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域技术人员在没有做出创造性劳动前提下所 获得的所有其他实施例，都属于本申请实施例保护的范围。
换流器作为直流输电的核心装备，是实现交、直流电能转换的核心功能单元，其运行可靠性很大程度上决定了特高压直流电网的运行可靠性。然而，由于传统换流器多采用半控型器件晶闸管作为核心部件构成六脉动桥换流拓扑，每个桥臂由多级晶闸管及其缓冲部件串联组成，由于晶闸管不具备自关断能力，在交流系统故障等情况下容易发生换相失败，导致直流电流激增和直流传输功率迅速大量损失，影响电网的稳定安全运行。
基于此，本申请实施例在主支路的基础上设置辅助支路，并利用可关断阀的可关断能力，实现主支路的可靠关断，避免出现换相失败，保证了电网运行的稳定性和安全性。
根据本申请实施例，提供了一种混合式换流器拓扑结构的实施例，该混合式换流器拓扑结构通过换流变压器接入交流电网。具体地，如图1a和图1b所示，该混合式换流器拓扑结构包括：至少一相主支路1、至少一相辅助支路2和可关断阀3。其中，主支路1的一端接入直流母线，另一端接入换流变压器的输出端，每相主支路1包括上桥臂主支路和下桥臂主支路，在上桥臂主支路上设置有第一晶闸管阀11，下桥臂主支路上设置有第二晶闸管阀12，第一晶闸管阀11和第二晶闸管阀12主要用于通流；辅助支路2与主支路1并联，用于在主支路1换相失败时，辅助主支路1进行强迫换相，每相辅助支路包括上桥臂辅助支路和下桥臂辅助支路，上桥臂辅助支路上设置有第一辅助换相阀21，下桥臂辅助支路上设置有第二辅助换相阀22，第一辅助换相阀21和第二辅助换相阀22具备正向电流可控关断和正反向电压阻断功能；可关断阀3可以设置在主支路1上，如图1a所示；可关断阀3也可以设置在辅助支路2上，如图1b所示。需要说明的是，图中的虚线框表示为多个同样的单元。
当混合式换流器在正常运行时，辅助支路2可保持关断状态，只需承 担电压应力，由主支路1承载正常运行电流；当主支路1换相失败或交流短路故障时导通辅助支路，结合可关断阀3的关断或导通将主支路1的电流转移至辅助支路2。
本实施例提供的混合式换流器拓扑结构在主支路的基础上并联可提供反向电压和具备自关断能力的辅助支路，实现主支路的可靠关断和每相桥臂的主动换相，从而在较短时间内实现辅助换相功能，避免换相失败的发生，从而保证电网的稳定安全运行。
在一些可选实施例中，如图2所示，所述拓扑结构可以为三相六桥臂电路，每相桥臂对应的上桥臂辅助支路与上桥臂主支路并联，下桥臂辅助支路与下桥臂主支路并联设置，可关断阀3设置在每相上桥臂主支路和每相下桥臂主支路上。其中，设置在上桥臂主支路上的所述可关断阀3的一端连接第一晶闸管阀11，另一端连接换流变压器的输出端；设置在下桥臂主支路上的可关断阀3的一端连接第二晶闸管阀12，另一端连接直流母线负极。
当混合式换流器在正常运行时，辅助支路可保持关断状态，导通第i个桥臂的主支路的晶闸管阀和可关断阀，此时辅助支路只需承担电压应力，由主支路承载正常运行电流；当主支路换相失败或交流短路故障时，关断可关断阀，导通辅助支路，将主支路的电流转移至辅助支路，当主支路上的电流完全转移至辅助支路时，关断辅助支路，实现主支路的强迫换相。
在一些可选实施例中，如图3所示，所述拓扑结构为三相六桥臂电路，上桥臂辅助支路与上桥臂主支路并联，下桥臂辅助支路与下桥臂主支路并联，可关断阀3分别设置在上桥臂辅助支路和下桥臂辅助支路上。其中，设置在上桥臂辅助支路上的可关断阀3的一端连接第一辅助换相阀21，另一端连接换流变压器的输出端，且设置在下桥臂辅助支路上的可关断阀3的一端连接第二辅助换相阀22，另一端连接直流母线负极。
当混合式换流器在正常运行时，辅助支路可保持关断状态，导通第i个桥臂的主支路的晶闸管阀，此时辅助支路只需承担电压应力，由主支路承载正常运行电流；当主支路换相失败或交流短路故障时，导通辅助支路的可关断阀以及上桥臂辅助换相阀，将主支路的电流转移至辅助支路，当主支路上的电流完全转移至辅助支路时，关断上桥臂辅助换相阀以及可关断阀，实现主支路的强迫换相。
在一些可选实施例中，如图4所示，所述拓扑结构包括三相六桥臂电路，上桥臂主支路和下桥臂主支路串联，上桥臂辅助支路和下桥臂辅助支路串联，可关断阀3的一端连接上桥臂主支路和下桥臂主支路之间的连接端，另一端连接换流变压器的输出端，上桥臂辅助支路和下桥臂辅助支路的连接端与换流变压器的输出端连接。与图2的构思类似，相当于将可关断阀3设置在主支路1上，通过将上桥臂主支路和下桥臂主支路串联，并将可关断阀3的一端连接上桥臂主支路和下桥臂主支路之间的连接端，另一端连接换流变压器的输出端，实现了上桥臂主支路和下桥臂主支路可以共用一个可关断阀，减少了可关断阀的串联级数。
当混合式换流器在正常运行时，辅助支路可保持关断状态，导通第i个桥臂的主支路的晶闸管阀和可关断阀，此时辅助支路只需承担电压应力，由主支路承载正常运行电流；当主支路换相失败或交流短路故障时，关断可关断阀，导通辅助支路，将主支路的电流转移至辅助支路，当主支路上的电流完全转移至辅助支路时，关断辅助支路，实现主支路的强迫换相。
在一些可选实施例中，如图5所示，所述拓扑结构包括三相六桥臂电路，上桥臂主支路和下桥臂主支路串联，上桥臂辅助支路和下桥臂辅助支路串联，可关断阀3的一端连接上桥臂辅助支路和下桥臂辅助支路的连接端，另一端连接换流变压器的输出端，上桥臂主支路和下桥臂主支路的连接端与换流变压器的输出端连接。与图3的构思类似，相当于将可关断阀3 设置在辅助支路2上，通过将上桥臂辅助支路和下桥臂辅助支路串联，并将可关断阀的一端连接上桥臂辅助支路和下桥臂辅助支路的连接端，另一端连接换流变压器的输出端，实现了上桥臂辅助支路和下桥臂辅助支路可以共用一个可关断阀，减少了可关断阀的串联级数。
当混合式换流器在正常运行时，辅助支路可保持关断状态，导通第i个桥臂的主支路的晶闸管阀，此时辅助支路只需承担电压应力，由主支路承载正常运行电流；当主支路换相失败或交流短路故障时，导通辅助支路的可关断阀以及上桥臂辅助换相阀，将主支路的电流转移至辅助支路，当主支路上的电流完全转移至辅助支路时，关断上桥臂辅助换相阀以及可关断阀，实现主支路的强迫换相。
在一些可选实施例中，如图6所示，所述拓扑结构中包括三相主支路和三相辅助支路，且三相主支路以及三相辅助支路均为三相六桥臂结构，上桥臂主支路和下桥臂主支路串联；上桥臂辅助支路和所述下桥臂辅助支路串联；此时可以在该拓扑结构中设置两个可关断阀3。其中，第一可关断阀的一端与每相上桥臂主支路连接，另一端与每相上桥臂辅助支路连接；第二可关断阀的一端与每相下桥臂主支路连接，另一端与每相下桥臂辅助支路连接。
当混合式换流器在正常运行时，辅助支路可保持关断状态，导通第i个桥臂的主支路的晶闸管阀和可关断阀，此时辅助支路只需承担电压应力，由主支路承载正常运行电流；当主支路换相失败或交流短路故障时，关断可关断阀，导通辅助支路的上桥臂辅助换相阀，将主支路的电流转移至辅助支路，当主支路上的电流完全转移至辅助支路时，关断辅助支路的上桥臂辅助换相阀，实现主支路的强迫换相。
通过将两个可关断阀分别设置在主支路与辅助支路连接的直流母线上，实现了三相上桥臂主支路可以共用一个可关断阀以及三相下桥臂主支 路可以共用一个可关断阀，减少了可关断阀的串联级数。
在一些可选实施例中，如图7所示，所述拓扑结构还可以包括至少一个隔离阀4。该隔离阀4设置在交流母线上，该交流母线与换流变压器的输出端连接。其中，隔离阀用于隔离主支路和辅助支路之间产生的高电压。
在一些可选实施例中，如图8所示，所述拓扑结构中包括三相主支路和一相辅助支路，且三相主支路为三相六桥臂结构，上桥臂主支路和下桥臂主支路串联，上桥臂辅助支路和下桥臂辅助支路串联，此时可以在该拓扑结构中设置两个可关断阀3。其中，第一可关断阀的一端与每相上桥臂主支路连接，另一端与上桥臂辅助支路连接；第二可关断阀的一端与每相下桥臂主支路连接，另一端与下桥臂辅助支路连接。三个隔离阀4的第一端分别连接每相上桥臂主支路和每相下桥臂主支路的连接端，三个隔离阀4的第二端均与上桥臂辅助支路和下桥臂辅助支路之间的连接端连接。
当混合式换流器在正常运行时，关断隔离阀，辅助支路保持关断状态，导通第i个桥臂的主支路的晶闸管阀和可关断阀，此时辅助支路只需承担电压应力，由主支路承载正常运行电流；当主支路换相失败或交流短路故障时，关断可关断阀，导通隔离阀以及辅助支路的上桥臂辅助换相阀，将主支路的电流转移至辅助支路，当主支路上的电流完全转移至辅助支路时，关断辅助支路的上桥臂辅助换相阀，实现主支路的强迫换相。
在一些可选实施例中，如图9所示，所述拓扑结构中包括三相主支路和一相辅助支路，且三相主支路为三相六桥臂结构，上桥臂主支路和下桥臂主支路串联，上桥臂辅助支路和下桥臂辅助支路串联，此时可以在该拓扑结构中设置六个可关断阀3，即在上桥臂主支路和下桥臂主支路均设置有一可关断阀3。每相上桥臂主支路的可关断阀3与每相下桥臂主支路的可关断阀3之间的连接端分别与三个隔离阀4的第一端连接；上桥臂辅助支路和下桥臂辅助支路之间的连接端与各个隔离阀4的第二端连接。
图9与图8的构思类似，为了精准控制每个主支路的运行，在各相的上桥臂主支路和下桥臂主支路均设置可关断阀。当混合式换流器在正常运行时，关断隔离阀，辅助支路保持关断状态，导通第i个桥臂的主支路的晶闸管阀和可关断阀，此时辅助支路只需承担电压应力，由主支路承载正常运行电流；当主支路换相失败或交流短路故障时，关断可关断阀，导通隔离阀以及辅助支路的上桥臂辅助换相阀，将主支路的电流转移至辅助支路，当主支路上的电流完全转移至辅助支路时，关断辅助支路的上桥臂辅助换相阀，实现主支路的强迫换相。在下个控制周期启动导通第i个桥臂的主支路的晶闸管阀之前或同时关断隔离阀，由主支路独立运行。
在一些可选实施例中，如图10所示，所述拓扑结构中包括三相主支路和一相辅助支路，且三相主支路为三相六桥臂结构，上桥臂主支路和下桥臂主支路串联，上桥臂辅助支路和下桥臂辅助支路串联，此时可以在该拓扑结构中设置两个可关断阀3，即在上桥臂辅助支路和下桥臂辅助支路上均设置有一可关断阀3。每相上桥臂主支路与每相下桥臂主支路的之间的连接端分别与三个隔离阀4的第一端连接；各个隔离阀4的第二端连接上桥臂辅助支路的可关断阀3与下桥臂辅助支路的可关断阀3之间的连接端。
图10的拓扑结构相当于将可关断阀设置在辅助支路上，当混合式换流器在正常运行时，关断隔离阀，辅助支路保持关断状态，导通第i个桥臂的主支路的晶闸管阀，此时辅助支路只需承担电压应力，由主支路承载正常运行电流；当主支路换相失败或交流短路故障时，导通隔离阀、可关断阀以及辅助支路的上桥臂辅助换相阀，将主支路的电流转移至辅助支路，当主支路上的电流完全转移至辅助支路时，关断可关断阀以及助支路的上桥臂辅助换相阀，实现主支路的强迫换相。在下个控制周期启动导通第i个桥臂的主支路的晶闸管阀之前或同时关断隔离阀，由主支路独立运行。
在一些可选实施例中，如图11所示，所述拓扑结构中包括三相主支路 和一相辅助支路，且三相主支路为三相六桥臂结构，上桥臂主支路和下桥臂主支路串联，上桥臂辅助支路和下桥臂辅助支路串联，此时可以在该拓扑结构中设置一个可关断阀3，即可关断阀3的一端分别与三个隔离阀4的第一端连接，可关断阀3的另一端连接上桥臂辅助支路和下桥臂辅助支路的连接端，每相上桥臂主支路与每相下桥臂主支路的之间的连接端分别与三个隔离阀4的第二端连接。
当混合式换流器在正常运行时，关断隔离阀和可关断阀，辅助支路保持关断状态，导通第i个桥臂的主支路的晶闸管阀，此时辅助支路只需承担电压应力，由主支路承载正常运行电流；当主支路换相失败或交流短路故障时，导通隔离阀、可关断阀以及辅助支路的上桥臂辅助换相阀，将主支路的电流转移至辅助支路，当主支路上的电流完全转移至辅助支路时，关断可关断阀以及助支路的上桥臂辅助换相阀，实现主支路的强迫换相。在下个控制周期启动导通第i个桥臂的主支路的晶闸管阀之前或同时关断隔离阀，由主支路独立运行。
可选地，图1至图11中的上桥臂主支路设置有第一晶闸管阀11，下桥臂主支路设置有第二晶闸管阀12。可选地，如图12所示，第一晶闸管阀以及第二晶闸管阀均可以包括：至少一个可控器件以及至少一个第一辅助部件，其中，至少一个可控器件串联设置，至少一个第一辅助部件分别与至少一个可控器件并联设置，即第一辅助部件的数目与可控器件的数目相等。可控器件主要用于反向电压阻断，可以包括晶闸管、GTO、逆阻型IGCT中的一种或多种，此处不作具体限定。
可选地，图1至图11中的可关断阀3可以包括：至少一个第一功率单元以及第二辅助部件，其中，第一功率单元用于转移支路的导通控制和关断控制，第二辅助部件与第一功率单元并联设置。
示例性的，如图13a所示，第一功率单元可以为第一支路组成的电力 电子单元，其中，第一支路上设置有第一功率器件。如图13b所示，第一功率单元可以为第二支路和第三支路组成的电力电子单元。其中，第二支路上设置有至少一个第一功率器件，且至少一个第一功率器件串联设置；第三支路与第二支路的结构相同，且第三支路与第二支路并联设置。如图13c所示，第一功率单元可以为第四支路和第五支路组成的电力电子单元。其中，第四支路上设置有至少一个第一二极管，且至少一个第一二极管串联设置；第五支路与第四支路的结构相同，且第四支路与第五支路并联设置。如图13d所示，第一功率单元还可以为第六支路和第七支路组成的电力电子单元。其中，第六支路上设置有第一功率器件；第七支路上与第六支路并联设置，第七支路上设置有第一功率器件和第二辅助部件，且第一功率器件和第二辅助部件并联。如图13e所示，第一功率单元还可以为第八支路、第九支路、第十支路和第十一支路组成的电力电子单元；其中，所述第八支路和所述第九支路串联连接，所述第八支路上设置有所述第一功率器件和第一二极管，所述第一功率器件和所述第一二极管并联，所述第九支路上设置有至少一个第一二极管；所述第十支路和所述第十一支路串联连接，所述第十支路上设置有至少一个第一二极管，所述第十一支路上设置有所述第一功率器件和第一二极管，所述第一功率器件和所述第一二极管并联；串联连接的所述第八支路和所述第九支路与串联连接的所述第十支路和所述第十一支路并联设置。如图13f所示，第一功率单元还可以为第十二支路、第十三支路、第十四支路和第十五支路组成的电力电子单元；其中，所述第十二支路和所述第十三支路串联连接，所述第十二支路上设置有所述第一功率器件和第一二极管，所述第一功率器件和所述第一二极管分别与所述第二辅助部件并联，所述第十三支路上设置有至少一个第一二极管，所述至少一个第一二极管与所述第二辅助部件并联；所述第十四支路上设置有至少一个第一二极管，所述至少一个第一二极管与所述 第二辅助部件并联，所述第十五支路上设置有所述第一功率器件和第一二极管，所述第一功率器件和所述第一二极管分别与所述第二辅助部件并联；串联连接的所述第十二支路和所述第十三支路与串联连接的所述第十四支路和所述第十五支路并联设置。其中，第一功率器件为全控型电力电子器件，全控型电力电子器件可以为绝缘栅双极型晶体管(IGBT，Insulated Gate Bipolar Transistor)、IGCT、GTO以及金属-氧化物半导体场效应晶体管(MOSFET，Metal-Oxide-Semiconductor Field-Effect Transistor)中的一种或多种，此处不作限定。
可选地，图1至图11中的上桥臂辅助支路设置有第一辅助换相阀21，下桥臂辅助支路设置有第二辅助换相阀22。第一辅助换相阀21和第二辅助换相阀22均可以包括：至少一个第二功率单元和至少一个第三辅助部件，且至少一个第二功率单元串联，至少一个第三辅助部件与至少一个第二功率单元并联，即第三辅助部件的数目与第二功率器件的数目相同。
示例性的，如图14a所示，第二功率单元可以为第一连接支路组成的电力电子单元，其中，第一连接支路上设置有第二功率器件。如图14b所示，第二功率单元可以为第二连接支路组成的电力电子单元，其中，第二连接支路上设置有至少一个所述第二功率器件，且至少一个第二功率器件反向串联。如图14c和图14d所示，第二功率单元可以为至少一个第三连接支路和至少一个第四连接支路组成的电力电子单元，其中，第三连接支路与第一连接支路的结构相同，第四连接支路上设置有第二二极管(如图14c所示)或第一晶闸管(如图14d所示)，至少一个第三连接支路与至少一个第四连接支路交错串联设置。如图14e所示，第二功率单元可以为第五连接支路和第六连接支路组成的电力电子单元，其中，第五连接支路上设置有至少一个第二功率器件，且至少一个第二功率器件串联设置，第六连接支路与第五连接支路的结构相同，且第五连接支路与第六连接支路并 联设置，第五连接支路、第六连接支路和第三辅助部件构成全桥结构。如图14f所示，第二功率单元可以为第七连接支路、第八连接支路和第九连接支路组成的电力电子单元，其中，第七连接支路上设置有至少一个第三二极管，且至少一个第三二极管串联设置，第八连接支路上设置有至少一个所述第二功率器件，且至少一个第二功率器件串联设置，第九连接支路和第七连接支路的结构相同，第九连接支路和第八连接支路及第七连接支路并联，第七连接支路、第八连接支路、第九连接支路和第三辅助部件构成H桥结构。其中，第二功率器件为全控型电力电子器件，全控型电力电子器件可以为IGBT、IGCT、GTO以及MOSFET中的一种或多种，此处不作限定。
在一些可选实施例中，如图15所示，第一辅助部件、第二辅助部件和第三辅助部件可以是由电容组成的第一缓冲支路；可以是由电阻和电容串联的第二缓冲支路；可以是由电容和电阻并联的第三缓冲支路；可以是由电阻和第五二极管并联，再与电容串联构成的第四缓冲支路RCD1；可以是由电阻和电容并联，再与第五二极管串联构成的第五缓冲支路RCD2；也可以是由避雷器组成的第六缓冲支路；还可以是上述第一缓冲支路、第二缓冲支路、第三缓冲支路、第四缓冲支路、第五缓冲支路和第六缓冲支路中多个并联构成的第七缓冲支路。
本申请实施例的有益效果在于：1.在正常运行时，辅助支路可保持关断状态，只需承担电压应力，由主支路承载正常运行电流；当主支路换相失败或交流短路故障时导通辅助支路，结合可关断阀的关断或导通将主支路的电流转移至辅助支路。通过在主支路的基础上并联可提供反向电压和具备自关断能力的辅助支路，实现主支路的可靠关断和每相桥臂的主动换相，从而在较短时间内实现辅助换相功能，避免换相失败的发生，从而保证电网的稳定安全运行。
2.本申请实施例提供的混合式换流器拓扑结构，辅助支路可提前关断主支路电流，同时为主支路提供反向电压，保证其可靠关断，以避免出现换相失败的问题。
3.本申请实施例提供的混合式换流器拓扑结构，可随时导通辅助支路，有效降低了主支路的损耗，同时可实现低电压和低关断角运行，从而降低了逆变侧无功功率。
4.本申请实施例提供的混合式换流器拓扑结构的控制方法，混合式换流器拓扑结构的第i个桥臂的辅助支路保持关断状态，导通混合式换流器拓扑结构的第i个桥臂的主支路和/或可关断阀，由此实现了强迫换相的混合式换流器拓扑结构能够工作于正常换相运行模式，即在暂时换相的运行模式下，辅助支路在混合式换流器正常运行时处于关断状态，只承受电压应力，减少了长期运行下的换流器损耗的增加量。当出现换相失败或交流短路故障时，导通混合式换流器拓扑结构的第i个桥臂的辅助支路和/或可关断阀，将主支路的电流强迫转移至辅助支路，当电流转移完成时，关断混合式换流器拓扑结构的第i个桥臂的辅助支路和/或可关断阀，实现混合式换流器的强迫换相。经过一个控制周期后，返回导通混合式换流器拓扑结构的第i个桥臂的主支路和/或可关断阀的步骤，继续由主支路独立正常运行，从而实现保证了辅助支路仅在故障时承受关断电压应力，降低了器件损耗，进而延长了器件的使用寿命。
5.本申请实施例提供的强迫换相的控制方法，通过主支路与辅助支路的周期性交替运行，不仅能够抵御换相失败，而且无需对换相失败进行预测。同时保证了混合式换流器工作于小关断角的运行模式，降低了混合式换流器的无功消耗。
根据本申请实施例，提供了一种混合式换流器拓扑结构的控制方法的实施例，需要说明的是，在附图的流程图示出的步骤可以在诸如一组计算 机可执行指令的计算机系统中执行，并且，虽然在流程图中示出了逻辑顺序，但是在某些情况下，可以以不同于此处的顺序执行所示出或描述的步骤。
在本实施例中提供了一种混合式换流器拓扑结构的控制方法，可用于上述的混合式换流器拓扑结构，图16是根据本申请实施例的混合式换流器拓扑结构的控制方法流程图，如图16所示，该流程包括如下步骤：
S11，导通混合式换流器拓扑结构的第i个桥臂的主支路和/或可关断阀；
S12，导通混合式换流器拓扑结构的第i个桥臂的辅助支路和/或可关断阀；
S13，关断混合式换流器拓扑结构的第i个桥臂的辅助支路和/或可关断阀；
S14，经过一个控制周期后，导通混合式换流器拓扑结构的第i个桥臂的主支路和/或可关断阀，其中，i∈[1,6]。
可选地，混合式换流器拓扑结构在正常运行条件下主支路周期性承受电压和电流应力，辅助支路一直处于关断状态，只在主支路关断时承受电压应力。混合式换流器拓扑结构的第i个桥臂的辅助支路保持关断状态，导通混合式换流器拓扑结构的第i个桥臂的主支路和/或可关断阀，由此实现了强迫换相的混合式换流器拓扑结构能够工作于正常换相运行模式，即在暂时换相的运行模式下，辅助支路在混合式换流器正常运行时处于关断状态，只承受电压应力，减少了长期运行下的换流器损耗的增加量。当出现换相失败或交流短路故障时，导通混合式换流器拓扑结构的第i个桥臂的辅助支路和/或可关断阀，将主支路的电流强迫转移至辅助支路，当电流转移完成时，关断混合式换流器拓扑结构的第i个桥臂的辅助支路和/或可关断阀，实现混合式换流器的强迫换相。经过一个控制周期后，返回导通混合式换流器拓扑结构的第i个桥臂的主支路和/或可关断阀的步骤，继续由主 支路独立正常运行。
本申请实施例提供的混合式换流器拓扑结构的控制方法，实现保证了辅助支路仅在故障时承受关断电压应力，降低了器件损耗，进而延长了器件的使用寿命。
对于如图2所示的拓扑结构，该控制方法主要包括如下步骤：
S21，导通混合式换流器拓扑结构的第i个桥臂的主支路的晶闸管阀和可关断阀。
S22，导通混合式换流器拓扑结构的第i个桥臂的辅助支路。
S23，关断混合式换流器拓扑结构的第i个桥臂的主支路的可关断阀。
S24，关断混合式换流器拓扑结构的第i个桥臂的辅助支路。
S25，经过一个控制周期后，导通混合式换流器拓扑结构的第i个桥臂的主支路的晶闸管阀和可关断阀，其中，i∈[1,6]。
如图17所示为混合式换流器拓扑结构在正常运行条件下的阀电流流通路径，主支路周期性承受电压和电流应力，辅助支路一直处于关断状态，只在主支路的晶闸管阀关断时承受电压应力。
图18a、图18b和图18c为主支路向辅助支路换流时关断主支路，辅助支路开始承受电压应力，该过程分为三个阶段，图18a为主支路向辅助支路换流阶段，该阶段辅助支路接收到触发信号导通，紧接着辅助支路接收到导通信号，主支路的可关断阀接收到关断信号，将主支路的电流向辅助支路转移，向主支路施加反向电压；图18b为辅助支路通流阶段，该阶段主支路已完全关断，主支路电流已全部转移至辅助支路；图18c为辅助支路关断阶段，该阶段接收到关断信号时，关断辅助支路，此时的主支路处于关断状态并承受电压。在下个控制周期主支路的晶闸管阀导通之前或同时导通可关断阀。上述运行过程可以在换相故障或预测到换相故障时投入运行。
图19为混合式换流器拓扑结构在换相失败或交流短路故障时的触发控制时序。图19中在t f时刻监测到主支路换相失败后，经过第一预设时长Δt 1时导通辅助支路V13阀，经过第二预设时长Δt 2时关断主支路的可关断阀，执行主支路向辅助支路的换流过程，且Δt 2≥Δt 1≥0。主支路电流I11逐渐减小至零，辅助支路电流I12逐渐增大，再经过第三预设时长Δt 3关断辅助支路，且主支路电流I11过零至辅助支路关断这段时间为晶闸管阀的关断时间t off，此处的t off大于晶闸管阀的最小关断时间以保证主支路的晶闸管阀拥有足够的时间进行关断。辅助支路关断后，辅助支路电流将向相邻主支路进行换流直至达到直流电流I12，至此完成主支路的换相，成功抵御了换相失败故障，此后在下一个控制周期的晶闸管阀开通之前或同时导通主支路的可关断阀。在预测到换相失败将要发生或检测到换相失败发生时启动此种运行模式，可成功避免换相失败发生，待换流器换相过程恢复正常时即退出该运行模式，辅助支路保持关断状态，由主支路独立正常运行。
本实施例提供的强迫换相的控制方法，在换相失败或短路故障时，控制混合式换流器拓扑结构开启强迫换相的运行模式，避免了换相失败的发生，并在混合式换流器换相过程恢复正常时退出强迫换相的运行模式，辅助支路继续保持关断状态，由主支路独立正常运行，从而实现保证了辅助支路仅在故障时承受关断电压应力，降低了器件损耗，进而延长了器件的使用寿命。
图20所示为混合式换流器拓扑结构预先检测到换相失败或短路故障时的控制触发时序，其中，主支路与辅助支路周期性交替运行。具体运行过程如图18a、图18b和图18c所示。在主支路换相开始时刻，即主支路的晶闸管阀触发脉冲Sg1延时120°，或者在此刻附近触发辅助支路，并经过较短时间(例如1s、5s等)关断主支路的可关断阀，实现主支路向辅助支路的换流。主支路电流过零之后，主支路关断并承受反向电压，且主支路电 流过零至辅助支路关断这段时间为晶闸管阀的关断时间t off，且t off大于晶闸管阀的最小关断时间保证其可靠关断，至此，V1阀电流全部转移至辅助支路，经过Δt后辅助支路阀开始关断，主支路开始承受正向电压，然后在下一个工作周期主支路的晶闸管阀开通之前导通主支路的可关断阀。该种运行模式下，混合式换流器拓扑结构的桥臂中的主支路与辅助支路周期性交替运行，在具备抵御换相失败能力的基础上，无需预测换相失败，同时可以使混合式换流器处于小关断角运行模式，减少混合式换流器的无功消耗。
对于如图3所示的拓扑结构，该控制方法主要包括如下步骤：
S31，导通混合式换流器拓扑结构的第i个桥臂的主支路。
S32，导通混合式换流器拓扑结构的第i个桥臂的辅助支路和可关断阀。
S33，关断混合式换流器拓扑结构的第i个桥臂的辅助支路和可关断阀。
S34，经过一个控制周期后，导通混合式换流器拓扑结构的第i个桥臂的主支路，其中，i∈[1,6]。
示例性的，如图21所示为混合式换流器拓扑结构在正常运行条件下的电流流通路径，主支路周期性承受电压和电流应力，辅助支路一直处于关断状态，只在主支路的晶闸管阀关断时承受电压应力。
图22为混合换流器拓扑结构的触发控制时序，图中t0表示初始触发时刻。
图23a、图23b和图23c为主支路向辅助支路换流时，辅助支路开始承受电压应力，该过程分为三个阶段，图23a为主支路向辅助支路换流阶段，该阶段辅助支路接收到触发信号导通，紧接着设置在辅助支路的可关断阀接收到开通信号，向主支路施加反向电压，将主支路的电流向辅助支路转移；图23b为辅助支路通流阶段，该阶段主支路已完全关断，主支路电流全部转移至辅助支路；图23c为辅助支路关断阶段，该阶段接收到关断信号时，先关断辅助支路的上桥臂辅助换相阀，此时的主支路处于关断状态 用于承受正向电压，随后在下个控制周期主支路的晶闸管阀开通之前关断可关断阀。上述运行过程可以在换相故障或预测换相故障时投入运行。
图24所示为强迫换相的混合式换流器拓扑结构预先检测到换相失败或短路故障时的控制触发时序，主支路与辅助支路周期性交替运行时的各阀控制触发时序，具体运行过程如图23a、图23b和图23c所示。该种运行模式下，强迫换相的混合式换流器拓扑结构的桥臂中的主支路与辅助支路周期性交替运行，在具备抵御换相失败能力的基础上，无需预测换相失败，同时可以使混合式换流器处于小关断角运行模式，减少混合式换流器的无功消耗。
基于上述的控制方法，对于如图5所示的拓扑结构，其正常运行模式如图25所示。图26为混合换流器拓扑结构的触发控制时序，图中t 0表示初始触发时刻。图27a、图27b和图27c为主支路向辅助支路换流过程。图28为主支路与辅助支路周期性交替运行时的各阀控制触发时序，具体运行过程如图27a、图27b和图27c。
图4所示的拓扑结构，其控制方法与图5所示的拓扑结构的控制方法类似，此次不再赘述。
基于上述的控制方法，对于如图6所示的拓扑结构，图29为混合换流器拓扑结构的触发控制时序，图中t 0表示初始触发时刻。图30a、图30b和图30c为主支路向辅助支路换流过程。图31为主支路与辅助支路周期性交替运行时的各阀控制触发时序，具体运行过程如图30a、图30b和图30c。
基于上述的控制方法，对于如图8所示的拓扑结构，图32为混合换流器拓扑结构的触发控制时序，图中t 0表示初始触发时刻。图33a、图33b和图33c为主支路向辅助支路换流过程。图34为主支路与辅助支路周期性交替运行时的各阀控制触发时序，具体运行过程如图33a、图33b和图33c。
图9和图10所示的拓扑结构，其控制方法与图8所示的拓扑结构的控 制方法类似，此次不再赘述。
基于上述的控制方法，对于如图11所示的拓扑结构，图35为混合换流器拓扑结构的触发控制时序，图中t 0表示初始触发时刻。图36a、图36b和图36c为主支路向辅助支路换流过程。图37为主支路与辅助支路周期性交替运行时的各阀控制触发时序，具体运行过程如图36a、图36b和图36c。
上述混合式拓扑结构的控制方法构思相同，均是在正常运行状态时保持辅助支路处于关断状态，由主支路进行独立工作。当主支路换相失败或交流短路故障时启动辅助支路，以辅助主支路进行换相，避免换相失败。
虽然结合附图描述了本申请的实施例，但是本领域技术人员可以在不脱离本申请的精神和范围的情况下做出各种修改和变型，这样的修改和变型均落入由所附权利要求所限定的范围之内。

Claims (19)

  1. 一种混合式换流器拓扑结构，所述拓扑结构通过换流变压器接入交流电网，所述拓扑结构包括：
    至少一相主支路，每相主支路包括上桥臂主支路和下桥臂主支路，所述上桥臂主支路上设置有第一晶闸管阀，所述下桥臂主支路上设置有第二晶闸管阀；所述主支路的一端接入直流母线，另一端接入所述换流变压器的输出端；
    至少一相辅助支路，每相辅助支路包括上桥臂辅助支路和下桥臂辅助支路，所述上桥臂辅助支路上设置有第一辅助换相阀，所述下桥臂辅助支路上设置有第二辅助换相阀；所述辅助支路与所述主支路并联，用于在所述主支路换相失败时，辅助所述主支路进行强迫换相；
    可关断阀，设置在所述主支路或者辅助支路上，用于强迫换相时，将所述主支路的电流转移至所述辅助支路。
  2. 根据权利要求1所述的拓扑结构，其中，所述上桥臂辅助支路与所述上桥臂主支路并联，所述下桥臂辅助支路与所述下桥臂主支路并联；
    所述可关断阀设置在每相上桥臂主支路和每相下桥臂主支路上；其中，设置在上桥臂主支路上的所述可关断阀的一端连接所述第一晶闸管阀，另一端连接所述换流变压器的输出端；设置在下桥臂主支路上的所述可关断阀的一端连接所述第二晶闸管阀，另一端连接直流母线负极。
  3. 根据权利要求1所述的拓扑结构，其中，所述上桥臂辅助支路与所述上桥臂主支路并联，所述下桥臂辅助支路与所述下桥臂主支路并联；
    所述可关断阀分别设置在所述上桥臂辅助支路和所述下桥臂辅助支路上；其中，设置在所述上桥臂辅助支路上的所述可关断阀的一端连接所述第一辅助换相阀，另一端连接所述换流变压器的输出端；设置在所述下桥臂辅助支路上的所述可关断阀的一端连接所述第二辅助换相阀，另一端连 接直流母线负极。
  4. 根据权利要求1所述的拓扑结构，其中，所述上桥臂主支路和下桥臂主支路串联；所述上桥臂辅助支路和所述下桥臂辅助支路串联；
    所述可关断阀的一端连接所述上桥臂主支路和所述下桥臂主支路的连接端，另一端连接所述换流变压器的输出端；所述上桥臂辅助支路和所述下桥臂辅助支路的连接端与所述换流变压器的输出端连接。
  5. 根据权利要求1所述的拓扑结构，其中，所述上桥臂主支路和下桥臂主支路串联；所述上桥臂辅助支路和所述下桥臂辅助支路串联；
    所述可关断阀的一端连接所述上桥臂辅助支路和所述下桥臂辅助支路的连接端，另一端连接所述换流变压器的输出端；所述上桥臂主支路和所述下桥臂主支路的连接端与所述换流变压器的输出端连接。
  6. 根据权利要求1所述的拓扑结构，其中，所述拓扑结构包括两个可关断阀，所述上桥臂主支路和下桥臂主支路串联；所述上桥臂辅助支路和所述下桥臂辅助支路串联；
    其中，第一可关断阀的一端与每相上桥臂主支路连接，另一端与每相上桥臂辅助支路连接；
    第二可关断阀的一端与每相下桥臂主支路连接，另一端与每相下桥臂辅助支路连接。
  7. 根据权利要求1所述的拓扑结构，其中，所述拓扑结构还包括：
    至少一个隔离阀，设置在交流母线上，用于隔离所述主支路和所述辅助支路之间的电压。
  8. 根据权利要求7所述拓扑结构，其中，所述至少一个隔离阀的第一端分别连接每相上桥臂主支路和每相下桥臂主支路的连接端，第二端连接所述上桥臂辅助支路和所述下桥臂辅助支路的连接端；
    所述拓扑结构包括两个可关断阀，所述上桥臂主支路和下桥臂主支路 串联；所述上桥臂辅助支路和所述下桥臂辅助支路串联；
    其中，第一可关断阀的一端与每相上桥臂主支路连接，另一端与每相上桥臂辅助支路连接；
    第二可关断阀的一端与下桥臂主支路连接，另一端与下桥臂辅助支路连接。
  9. 根据权利要求7所述拓扑结构，其中，所述上桥臂主支路和下桥臂主支路串联；所述上桥臂辅助支路和所述下桥臂辅助支路串联；
    所述上桥臂主支路和下桥臂主支路均设置有所述可关断阀；每相上桥臂主支路的可关断阀与每相下桥臂主支路的可关断阀之间的连接端与所述隔离阀的第一端连接；所述上桥臂辅助支路和所述下桥臂辅助支路之间的连接端与各个所述隔离阀的第二端连接。
  10. 根据权利要求7所述拓扑结构，其中，所述上桥臂主支路和下桥臂主支路串联；所述上桥臂辅助支路和所述下桥臂辅助支路串联；
    所述上桥臂辅助支路和所述下桥臂辅助支路均设置有所述可关断阀，所述上桥臂辅助支路的可关断阀与所述下桥臂辅助支路的可关断阀之间的连接端与所述至少一个隔离阀的第二端连接。
  11. 根据权利要求7所述拓扑结构，其中，所述上桥臂主支路和下桥臂主支路串联；所述上桥臂辅助支路和所述下桥臂辅助支路串联；
    所述可关断阀的一端与所述至少一个隔离阀的第一端连接，另一端连接所述上桥臂辅助支路和所述下桥臂辅助支路的连接端。
  12. 根据权利要求1所述的拓扑结构，其中，所述第一晶闸管阀和所述第二晶闸管阀均包括：
    至少一个可控器件，用于反向电压阻断，所述至少一个可控器件串联设置；
    至少一个第一辅助部件，与所述至少一个可控器件并联设置；
    所述可控器件包括晶闸管、门极可关断晶闸管GTO、逆阻型集成门极换流晶闸管IGCT中的一种或多种。
  13. 根据权利要求1所述的拓扑结构，其中，所述可关断阀包括：
    至少一个第一功率单元，用于所述转移支路的导通控制和关断控制；
    第二辅助部件，与所述第一功率单元并联设置。
  14. 根据权利要求13所述的拓扑结构，其中，所述第一功率单元包括：
    第一支路，所述第一支路上设置有第一功率器件；
    或，第二支路和第三支路；其中，所述第二支路上设置有至少一个所述第一功率器件，所述至少一个所述第一功率器件串联设置；所述第三支路与所述第二支路的结构相同，且所述第三支路与所述第二支路并联设置；
    或，第四支路和第五支路；其中，所述第四支路上设置有至少一个第一二极管，所述至少一个第一二极管串联设置；所述第五支路与所述第四支路的结构相同，且所述第四支路与所述第五支路并联设置；
    或，第六支路和第七支路；其中，所述第六支路上设置有所述第一功率器件；所述第七支路上设置有所述第一功率器件和所述第二辅助部件，所述第一功率器件和所述第二辅助部件并联；所述第六支路与所述第七支路并联设置；
    或，第八支路、第九支路、第十支路和第十一支路；串联连接的所述第八支路和所述第九支路与串联连接的所述第十支路和所述第十一支路并联设置；其中，所述第八支路上设置有所述第一功率器件和第一二极管，所述第一功率器件和所述第一二极管并联，所述第九支路上设置有至少一个第一二极管；所述第十支路上设置有至少一个第一二极管，所述第十一支路上设置有所述第一功率器件和第一二极管，所述第一功率器件和所述第一二极管并联；
    或，第十二支路、第十三支路、第十四支路和第十五支路；串联连接 的所述第十二支路和所述第十三支路与串联连接的所述第十四支路和所述第十五支路并联设置；其中，所述第十二支路上设置有所述第一功率器件和第一二极管，所述第一功率器件和所述第一二极管分别与所述第二辅助部件并联，所述第十三支路上设置有至少一个第一二极管，所述至少一个第一二极管与所述第二辅助部件并联；所述第十四支路上设置有至少一个第一二极管，所述至少一个第一二极管与所述第二辅助部件并联，所述第十五支路上设置有所述第一功率器件和第一二极管，所述第一功率器件和所述第一二极管分别与所述第二辅助部件并联。
  15. 根据权利要求1所述的拓扑结构，其中，所述第一辅助换相阀和所述第二辅助换相阀包括：
    至少一个第二功率单元，所述至少一个第二功率单元串联；
    至少一个第三辅助部件，与所述至少一个第二功率单元并联。
  16. 根据权利要求15所述的拓扑结构，其中，所述第二功率单元包括：
    第一连接支路，所述第一连接支路上设置有第二功率器件；
    或，第二连接支路；所述第二连接支路上设置有至少一个所述第二功率器件，所述至少一个所述第二功率器件反向串联；
    或，至少一个第三连接支路和至少一个第四连接支路；其中，所述第三连接支路与所述第一连接支路的结构相同，所述第四连接支路上设置有第二二极管或第一晶闸管；所述至少一个第三连接支路与所述至少一个第四连接支路交错串联设置；
    或，第五连接支路和第六连接支路；其中，所述第五连接支路上设置有至少一个所述第二功率器件，所述至少一个所述第二功率器件串联设置；所述第六连接支路与所述第五连接支路的结构相同，且所述第五连接支路与所述第六连接支路并联设置；所述第五连接支路、所述第六连接支路和所述第三辅助部件构成全桥结构；
    或，第七连接支路、第八连接支路和第九连接支路；其中，第七连接支路上设置有至少一个第三二极管，所述至少一个第三二极管串联设置；第八连接支路上设置有至少一个所述第二功率器件，所述至少一个所述第二功率器件串联设置；所述第九连接支路和所述第七连接支路的结构相同，所述第九连接支路和所述第八连接支路及所述第七连接支路并联；所述第七连接支路、第八连接支路、第九连接支路和所述第三辅助部件构成H桥结构。
  17. 根据权利要求12或13或15所述的拓扑结构，其中，第一辅助部件、第二辅助部件和第三辅助部件包括：
    由电容组成的第一缓冲支路；
    或，电阻和所述电容串联的第二缓冲支路；
    或，所述电容和所述电阻并联的第三缓冲支路；
    或，所述电阻和第五二极管并联，再与所述电容串联构成的第四缓冲支路；
    或，所述电阻和所述电容并联，再与所述第五二极管串联构成的第五缓冲支路；
    或，避雷器组成的第六缓冲支路；
    或，所述第一缓冲支路、所述第二缓冲支路、所述第三缓冲支路、所述第四缓冲支路、所述第五缓冲支路和所述第六缓冲支路中的多种并联构成的第七缓冲支路。
  18. 一种混合式换流器拓扑结构的控制方法，用于如权利要求1-17任一项所述的混合式换流器拓扑结构，包括如下步骤：
    导通混合式换流器拓扑结构的第i个桥臂的主支路和/或可关断阀；
    导通混合式换流器拓扑结构的第i个桥臂的辅助支路和/或可关断阀；
    关断混合式换流器拓扑结构的第i个桥臂的辅助支路和/或可关断阀；
    经过一个控制周期后，导通混合式换流器拓扑结构的第i个桥臂的主支路和/或可关断阀，其中，i∈[1,6]。
  19. 根据权利要求18所述的方法，其中，所述方法还包括：
    混合式换流器拓扑结构的主支路与辅助支路周期性交替运行。
PCT/CN2021/124770 2021-02-01 2021-10-19 一种混合式换流器拓扑结构及其控制方法 WO2022160791A1 (zh)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2852040A1 (en) * 2013-09-20 2015-03-25 Alstom Technology Ltd Module
CN108712090A (zh) * 2018-07-03 2018-10-26 清华大学 一种高压直流输电混合换流器
CN112311274A (zh) * 2019-08-02 2021-02-02 全球能源互联网研究院有限公司 一种基于可控关断的混合式换流器拓扑结构及其控制方法
CN112311273A (zh) * 2019-08-02 2021-02-02 全球能源互联网研究院有限公司 一种基于谐振回路的混合式换流器拓扑结构及其控制方法
CN112803815A (zh) * 2021-02-01 2021-05-14 全球能源互联网研究院有限公司 一种混合式换流器拓扑结构及其控制方法
CN214380688U (zh) * 2021-02-01 2021-10-08 全球能源互联网研究院有限公司 一种混合式换流器拓扑结构

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2852040A1 (en) * 2013-09-20 2015-03-25 Alstom Technology Ltd Module
CN108712090A (zh) * 2018-07-03 2018-10-26 清华大学 一种高压直流输电混合换流器
CN112311274A (zh) * 2019-08-02 2021-02-02 全球能源互联网研究院有限公司 一种基于可控关断的混合式换流器拓扑结构及其控制方法
CN112311273A (zh) * 2019-08-02 2021-02-02 全球能源互联网研究院有限公司 一种基于谐振回路的混合式换流器拓扑结构及其控制方法
CN112803815A (zh) * 2021-02-01 2021-05-14 全球能源互联网研究院有限公司 一种混合式换流器拓扑结构及其控制方法
CN214380688U (zh) * 2021-02-01 2021-10-08 全球能源互联网研究院有限公司 一种混合式换流器拓扑结构

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