WO2021022953A1 - 基于可控关断的混合式换流器及其控制方法 - Google Patents

基于可控关断的混合式换流器及其控制方法 Download PDF

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Publication number
WO2021022953A1
WO2021022953A1 PCT/CN2020/099843 CN2020099843W WO2021022953A1 WO 2021022953 A1 WO2021022953 A1 WO 2021022953A1 CN 2020099843 W CN2020099843 W CN 2020099843W WO 2021022953 A1 WO2021022953 A1 WO 2021022953A1
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Prior art keywords
valve
auxiliary
bridge arm
series
converter
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PCT/CN2020/099843
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English (en)
French (fr)
Inventor
高冲
汤广福
盛财旺
贺之渊
周建辉
杨俊�
张娟娟
张静
李婷婷
Original Assignee
全球能源互联网研究院有限公司
国家电网有限公司
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Priority claimed from CN201910716089.4A external-priority patent/CN112311274B/zh
Application filed by 全球能源互联网研究院有限公司, 国家电网有限公司 filed Critical 全球能源互联网研究院有限公司
Publication of WO2021022953A1 publication Critical patent/WO2021022953A1/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
    • H02M7/66—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal
    • H02M7/68—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters
    • H02M7/72—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/75—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with 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
    • H02M7/757—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with 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
    • H02M7/7575—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with 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 for high voltage direct transmission link
    • 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
    • H02M1/06—Circuits specially adapted for rendering non-conductive gas discharge tubes or equivalent semiconductor devices, e.g. thyratrons, thyristors
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H02M1/34—Snubber circuits
    • 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
    • H02M7/66—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal
    • H02M7/68—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters
    • H02M7/72—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/75—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with 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
    • H02M7/757—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with 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
    • 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
    • H02M1/0048—Circuits or arrangements for reducing losses
    • 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
    • H02M1/325—Means for protecting converters other than automatic disconnection with means for allowing continuous operation despite a fault, i.e. fault tolerant converters
    • 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
    • H02M1/34—Snubber circuits
    • H02M1/346—Passive non-dissipative snubbers
    • 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
    • H02M1/34—Snubber circuits
    • H02M1/348—Passive dissipative snubbers
    • 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
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
    • 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

  • This application relates to the technical field of commutation in power electronics, for example, to a hybrid inverter and its control method.
  • 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 worldwide.
  • the converter is the core functional unit to realize the conversion of AC and DC power. Its operational reliability largely determines the operational reliability of the UHV DC grid.
  • each bridge arm is composed of multi-stage thyristors and their buffer components in series. Because the thyristors do not have the self-shutdown capability, the AC system fails. Under such circumstances, commutation failures are prone to occur, leading to a rapid increase in DC current and a rapid and large loss of DC transmission power, which brings more severe challenges to the stable and safe operation of the power grid.
  • CCC Capacitor Commutation Converter
  • the controllable capacitor module is formed by the combination of power electronic switches and capacitors to realize the controllable capacitor input and voltage direction, but the above-mentioned topology engineering based on capacitor commutation is realized The difficulty is greater.
  • the other is to form a hybrid converter by connecting a switchable device in series with a thyristor, so that each bridge arm of the converter has the ability to be switched off, avoiding the occurrence of commutation failure.
  • each bridge arm of the converter Due to the large transmission capacity of conventional DC transmission, each bridge arm of the converter bears high voltage and large current.
  • the shut-off pipe valve needs to be realized in a multi-stage series-parallel connection, and the pipe valve can be shut off for a long time. To withstand large currents, to withstand high voltage stress when the high current is turned off, more series series are required. Therefore, the engineering implementation cost and difficulty of this kind of technical solution are relatively high.
  • This application provides a hybrid converter and its control method, which can make full use of the current shut-off characteristics of the shut-off device, can quickly transfer the commutation current, flexibly control the time area of the thyristor valve commutation voltage, and ensure that the thyristor valve has sufficient
  • the reverse recovery time is reliably shut off, and at the same time, the use of a shut-off valve to assist commutation fundamentally avoids the occurrence of commutation failure in the DC system.
  • a hybrid converter based on a controllable shutdown is provided, the converter includes a three-phase six-leg circuit, and the three-phase six-leg circuit is connected to an AC power grid through a converter transformer;
  • the upper bridge arm and the lower bridge arm of each phase of the three-phase six bridge arm circuit are composed of valve modules
  • the valve module is composed of a main branch and an auxiliary valve that is connected in parallel with the main branch and has the capability of controllable shut-off of forward current and blocking of forward and reverse voltages;
  • the main branch is composed of a series-connected thyristor valve and a shut-off valve with controllable shut-off of forward current and blocking capability of forward voltage.
  • a control method of a hybrid inverter based on controllable shutdown is also provided, which includes:
  • a control method of a hybrid inverter based on controllable shutdown is also provided, which includes:
  • ⁇ t′′ off is the length of time that the thyristor valve of the i-th bridge arm of the converter is in the positive blocking state in one control period
  • ⁇ t is the conduction time of the shut-off valve
  • T is a control period, i ⁇ [1,6].
  • FIG. 1 is a schematic structural diagram of a hybrid converter topology based on controllable shutdown provided by an embodiment of the present application;
  • FIG. 2 is a schematic structural diagram of a shut-off valve in a controllable shut-off-based hybrid converter topology according to an embodiment of the present application
  • FIG. 3 is a schematic structural diagram of an auxiliary valve in a hybrid converter topology based on a controllable shutdown provided by an embodiment of the present application;
  • FIG. 4 is a schematic structural diagram of a buffer component in a hybrid inverter topology based on a controllable shutdown provided by an embodiment of the present application;
  • FIG. 5 is a current flow path diagram of a hybrid converter topology based on controllable turn-off provided by an embodiment of the present application during normal operation;
  • FIG. 6 is a control sequence diagram of a hybrid converter topology based on a controllable shutdown provided by an embodiment of the present application during normal operation;
  • FIG. 7 is a current flow path diagram when the topology of a hybrid converter based on controllable shutdown is faulty according to an embodiment of the present application
  • FIG. 8 is a control sequence diagram of a hybrid converter topology based on a controllable turn-off provided by an embodiment of the present application when the topology structure fails;
  • FIG. 9 is a control sequence diagram when a fault is detected in advance according to an embodiment of the present application.
  • the embodiment of the present application provides a hybrid converter topology based on controllable turn-off.
  • the topology is a three-phase six-leg circuit, and the three-phase six-leg circuit is
  • the current transformer is connected to the AC power grid; the upper and lower arms of each phase of the three-phase six-arm circuit are composed of valve modules; the valve module is composed of a main branch and a parallel connection with the main branch.
  • the main branch is composed of auxiliary valves with controllable shut-off of forward current and blocking capability of forward and reverse voltage; the main branch is composed of thyristor valves connected in series and a shut-off valve with controllable shut-off of forward current and blocking capability of forward voltage .
  • the controllable shut-off-based hybrid converter topology may further include a trigger control system for sending a control sequence to each valve and auxiliary valve in the main branch.
  • the thyristor valve is composed of a plurality of thyristors and a buffer component connected in series or in parallel with each of the plurality of thyristors.
  • the shut-off valve is composed of a single-stage or multi-stage series of fully controlled power electronic devices with at least forward current controllable shut-off and voltage blocking capabilities.
  • the circuit topology of the shut-off valve includes but is not limited to In single-stage, half-bridge or H-bridge topology.
  • the shut-off valve is set to shut off the main branch current and transfer the main branch current to the auxiliary valve.
  • FIG. 2(a) The structure of the shut-off valve is shown in Figure 2(a), which is composed of a single or multiple power modules connected in series and a buffer component connected in series or parallel to each of the multiple power modules in series .
  • the power module is composed of a fully-controlled power electronic device and a diode connected in anti-parallel with the fully-controlled power electronic device.
  • the structure of the shut-off valve can also be shown in Figure 2 (b), consisting of a plurality of first shut-off branches connected in series and each of the plurality of first shut-off branches connected in series.
  • the first switch-off branch is composed of buffer components connected in series or in parallel.
  • the first switch-off branch is composed of a first power module and a second switch-off branch connected in parallel with the first power module in parallel.
  • the second switchable branch is composed of a second power module and a capacitor connected in series.
  • Both the first power module and the second power module are composed of a fully-controlled power electronic device and a diode connected in anti-parallel to the fully-controlled power electronic device.
  • connection point between the first power module and the second power module and the connection point between the first power module and the capacitor are both external connection points of the switchable valve or with other first power modules in the switchable valve.
  • the connection point of the branch can be switched off.
  • the shut-off valve can be replaced by an auxiliary valve.
  • the auxiliary valve is composed of multiple stages of fully controlled power electronic devices with at least forward current controllable shut-off and forward and reverse voltage blocking capabilities.
  • the circuit topology of the auxiliary valve includes but is not limited to single stage, Half-bridge or H-bridge topology.
  • auxiliary valve The structure of the auxiliary valve is shown in Figure 3(a), which is composed of a plurality of auxiliary sub-modules connected in series and a buffer component connected in series or in parallel with each auxiliary sub-module of the plurality of auxiliary sub-modules in series. .
  • the auxiliary sub-module is composed of a power module and a diode connected in series with the power module.
  • the power module is composed of a fully-controlled power electronic device and a diode connected in anti-parallel with the fully-controlled power electronic device.
  • auxiliary valve The structure of the auxiliary valve is shown in Figure 3(b), which is composed of an auxiliary timing control branch and a diode branch connected in series.
  • the diode branch is composed of a plurality of forward-series diodes and a buffer component connected in series or in parallel with each of the plurality of forward-series diodes.
  • the auxiliary timing control branch is composed of a plurality of power modules connected in series and a buffer component connected in series or in parallel with each of the power modules connected in series.
  • the power module is composed of a fully-controlled power electronic device and a diode connected in anti-parallel with the fully-controlled power electronic device.
  • auxiliary valve The structure of the auxiliary valve is shown in Figure 3(c), which is composed of a plurality of first power electronic units connected in series.
  • the first power electronic unit is composed of a first auxiliary branch, a buffer component and a second auxiliary branch connected in parallel.
  • Both the first auxiliary branch and the second auxiliary branch are composed of two sets of auxiliary timing control branches connected in series in a forward direction.
  • the auxiliary timing control branch is composed of a plurality of power modules connected in series and a buffer component connected in series or in parallel with each of the power modules connected in series.
  • the power module is composed of a fully-controlled power electronic device and a diode connected in anti-parallel with the fully-controlled power electronic device.
  • connection points of the two sets of auxiliary timing control branches of the first auxiliary branch and the connection points of the two sets of auxiliary timing control branches of the second auxiliary branch are both external connection points of the auxiliary valve or with the auxiliary valve.
  • the connection point of the other first power electronic unit in the valve is both external connection points of the auxiliary valve or with the auxiliary valve.
  • auxiliary valve The structure of the auxiliary valve is shown in Figure 3(d), which is composed of a plurality of second power electronic units connected in series.
  • the second power electronic unit is composed of a third auxiliary branch connected in parallel, an auxiliary timing control branch, a buffer component and a fourth auxiliary branch.
  • Both the third auxiliary branch and the fourth auxiliary branch are composed of two groups of diode branches connected in series in a forward direction.
  • the diode branch is composed of a plurality of forward-series diodes and a buffer component connected in series or in parallel with each of the plurality of forward-series diodes.
  • the auxiliary timing control branch is composed of a plurality of power modules connected in series and a buffer component connected in series or in parallel with each of the power modules connected in series.
  • the power module is composed of a fully-controlled power electronic device and a diode connected in anti-parallel with the fully-controlled power electronic device.
  • Reverse resistance type fully-controlled power electronic devices are fully-controlled power electronic devices with reverse voltage blocking capability. Therefore, reverse resistance type fully-controlled power electronic devices in power modules do not require anti-parallel diodes; except for reverse resistance type Controlled power electronic devices are fully controlled power electronic devices that do not have reverse voltage blocking capability. Therefore, fully controlled power electronic devices other than the reverse resistance type in the power module require anti-parallel diodes.
  • connection points of the two groups of diode branches of the third auxiliary branch and the connection points of the two groups of diode branches of the fourth auxiliary branch are both external connection points of the auxiliary valve or in the auxiliary valve Connection point for other second power electronic units.
  • the fully-controlled power electronic device consists of an insulated gate bipolar transistor (Insulated Gate Bipolar Transistor, IGBT), an integrated gate-commutated thyristor (IGCT), and an injection enhanced gate. Transistors (Injection Enhanced Gate Transistor, IEGT), Turn-Off Thyristor (GTO) and Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) and other turn-off devices One or more of the components.
  • IGBT Insulated Gate Bipolar Transistor
  • IGCT integrated gate-commutated thyristor
  • IEGT Insertidirectional Gate Transistor
  • GTO Turn-Off Thyristor
  • MOSFET Metal-Oxide-Semiconductor Field-Effect Transistor
  • the buffer component is composed of one or more of capacitors, resistance-capacitance loops, diodes, inductors, and arresters in series or in parallel.
  • a control method based on the above-mentioned controllable turn-off hybrid converter topology includes:
  • Step 1 Turn on the thyristor valve of the i-th bridge arm based on the controllable shut-off hybrid converter topology, and perform step 2.
  • Step 2 After a control period T, return to step 1, where i ⁇ [1,6].
  • Sg1 is the control sequence of the thyristor valve
  • Sg12 is the control sequence of the shut-off valve
  • Sg13 is the control sequence of the auxiliary valve
  • t 0 is the initial trigger time
  • ⁇ t on is the conduction time of the thyristor valve
  • ⁇ t off is the off time of the thyristor valve
  • ⁇ t' off is the positive blocking time of the thyristor valve
  • the control period T is 2 ⁇ .
  • the auxiliary valve receives the trigger signal and turns on, and then the shut-off valve of the main branch receives the signal to turn off, completing the commutation process from the main branch to the auxiliary valve; as shown in Figure 7 (b), the main branch is closed During the auxiliary valve flow stage, the main branch has been completely shut off at this stage, and all the current is transferred to the auxiliary valve; as shown in Figure 7 (c), the main branch and auxiliary valve are off stage, and the auxiliary valve is closed at this stage. Turn off the signal to turn off the auxiliary valve. At this time, the thyristor valve is in a positive blocking state to withstand the forward voltage.
  • Sg1 is the control sequence of the thyristor valve
  • Sg12 is the control sequence of the shut-off valve
  • Sg13 is the control of the auxiliary valve.
  • t 1 is the initial trigger time
  • the control period T is 2 ⁇
  • ⁇ t 1 is the delay time of turning on the auxiliary valve of the i-th bridge arm
  • ⁇ t 2 is the delay time of turning off the shut-off valve of the i-th bridge arm
  • ⁇ t 3 is the on-time of the auxiliary valve.
  • the period from the main branch current zero crossing to the off of the auxiliary valve is the off time ⁇ t off of the thyristor valve
  • ⁇ t off needs to be greater than the minimum preset off time.
  • Step S1 is executed after the end of the control period in which t f is located, until the voltage of the controllable turn-off-based hybrid converter topology is restored to stability, turn on the controllable-turn-off hybrid converter topology Turn off the auxiliary valve of the i-th bridge arm based on the controllable shut-off hybrid converter topology, and perform step 1.
  • Step S1 Turn on the thyristor valve of the i-th bridge arm based on the controllable turn-off hybrid converter topology, and turn on the thyristor valve of the i-th bridge arm based on the controllable turn-off hybrid converter topology.
  • Step S2 Turn off the shut-off valve of the i-th bridge arm based on the controllable shut-off hybrid converter topology, and turn on the i-th bridge based on the controllable shut-off hybrid converter topology.
  • the auxiliary valve of the arm when the thyristor valve of the i-th bridge arm based on the controllable shut-off hybrid converter topology is in a positive blocking state, step S3 is executed.
  • Step S3 Turn off the auxiliary valve of the i-th bridge arm based on the controllable turn-off hybrid converter topology, after ⁇ t' off , return to step S1.
  • Step 2 in a control period duration of the forward blocking state of the thyristor valve based on the i-th arm of the hybrid converter topology controlled off.
  • the embodiment of the present application also provides another method for controlling the above-mentioned controllable shutdown-based hybrid converter topology.
  • the method is used for detecting in advance the controllable shutdown-based hybrid converter topology.
  • Step T1 Turn on the thyristor valve of the i-th bridge arm based on the controllable turn-off hybrid converter topology, and turn on the thyristor valve of the i-th bridge arm based on the controllable turn-off hybrid converter topology.
  • Step T2 Turn off the shutoff valve of the i-th bridge arm based on the controllable shut-off hybrid converter topology, and turn on the i-th bridge based on the controllable shutoff hybrid converter topology.
  • the auxiliary valve of the arm when the thyristor valve of the i-th bridge arm based on the controllable shut-off hybrid converter topology is in a positive blocking state, step T3 is executed.
  • Step T3 Turn off the auxiliary valve of the i-th bridge arm based on the controllable turn-off hybrid converter topology, after ⁇ t′′ off , return to Step T1.
  • ⁇ t′′ off is the length of time that the thyristor valve of the i-th bridge arm of the hybrid converter topology based on the controllable turn-off hybrid converter topology is in the positive blocking state in a control period, and T is a control period.
  • Sg1 is the control sequence of the thyristor valve
  • Sg12 is the control sequence of the shut-off valve
  • Sg13 is the control sequence of the auxiliary valve
  • ⁇ t on Is the conduction time of the thyristor valve
  • ⁇ t′′ off is the forward blocking time of the thyristor valve
  • the control period T is 2 ⁇
  • ⁇ t is the conduction time of the shut-off valve
  • ⁇ t off When the auxiliary valve is turned on length, primary branch to the auxiliary valve current zero period of time ⁇ t off off off time of the thyristor valve, ⁇ t off must be greater than a predetermined minimum off time.
  • This mode of operation is started when it is predicted that the commutation failure will occur, which can successfully avoid the commutation failure, and at the same time, it can realize the low cut-off angle operation, which effectively reduces the reactive power on the inverter side.
  • the hybrid converter based on controllable shutdown includes a three-phase six-leg circuit, the three-phase six-leg circuit is connected to an AC power grid through a converter transformer; the three-phase six-leg circuit
  • the upper bridge arm and lower bridge arm of each phase are composed of valve modules; the valve module is composed of a main branch and an auxiliary valve connected in parallel with the main branch; this structure can realize the auxiliary phase conversion of the converter valve , To avoid the occurrence of commutation failure; the auxiliary valve can quickly transfer the phase current and flexibly control the commutation time area of the thyristor valve.
  • the valve current is quickly transferred to the auxiliary valve, and the full-control device is turned off by high current It can quickly restore the commutation between the two bridge arms, greatly speeding up the recovery time of the converter after the commutation failure;
  • the main branch is composed of a thyristor valve and a shut-off valve connected in series, and the shut-off valve can be The current of the main branch is shut off in advance, and the reverse voltage is provided for the main branch at the same time, which increases the commutation time area of the thyristor valve of the main branch, and ensures the reliable shut-off of the thyristor valve.
  • the number of stages in series of the shut-off valve is small, and the total loss produced is low; the hybrid converter based on the controllable shut-off provided by the embodiment of the application can be put into use at any time with the auxiliary valve, which can effectively reduce the loss of the main branch valve. Achieve low-voltage and low-turn-off angle operation, which greatly reduces the reactive power on the inverter side; the first control method provided by the embodiment of this application, during normal operation, the auxiliary valve is not put into operation and only has to bear the voltage stress.
  • the auxiliary valve is immediately put into the auxiliary valve after the commutation failure or short circuit failure occurs, and the auxiliary commutation function is realized in a short time, and the switching between multiple bridge arms is quickly restored phase.
  • This technical solution makes full use of the advantages of thyristors and turn-off devices. Two branches are used in parallel. The main branch realizes current transfer through the turn-off device. The auxiliary valve is used to withstand greater turn-off voltage stress in the event of a fault.
  • the second control method provided by the embodiment of the application is a mode in which the main branch and the auxiliary valve alternately operate.
  • the operation mode can avoid the occurrence of failure faults or short-circuit faults, which is beneficial to improve the overall reliability of the converter.
  • the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, this application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, this application may use one or more computer-usable storage media (including but not limited to magnetic disk storage, Compact Disc Read-Only Memory (CD-ROM), and optical storage) containing computer-usable program codes. Etc.) in the form of a computer program product implemented on it.
  • CD-ROM Compact Disc Read-Only Memory
  • optical storage containing computer-usable program codes. Etc.
  • These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing equipment to work in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including the instruction device.
  • the device implements the functions specified in one process or multiple processes in the flowchart and/or one block or multiple blocks in the block diagram.
  • These computer program instructions can also be loaded on a computer or other programmable data processing equipment, so that a series of operation steps are executed on the computer or other programmable equipment to produce computer-implemented processing, so as to execute on the computer or other programmable equipment.
  • the instructions provide steps for implementing functions specified in a flow or multiple flows in the flowchart and/or a block or multiple blocks in the block diagram.

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Abstract

本文公开一种基于可控关断的混合式换流器及其控制方法。所述基于可控关断的混合式换流器包括三相六桥臂电路，所述三相六桥臂电路通过换流变压器接入交流电网；所述三相六桥臂电路的每相的上桥臂和下桥臂均由阀模块组成；所述阀模块由主支路和与所述主支路并联的具备正向电流可控关断和正反向电压阻断能力的辅助阀组成；所述主支路由串联的晶闸管阀和具备正向电流可控关断和正向电压阻断能力的可关断阀组成。

Description

基于可控关断的混合式换流器及其控制方法
本申请要求在2019年08月02日提交中国专利局、申请号为201910716089.4的中国专利申请的优先权，该申请的全部内容通过引用结合在本申请中。
技术领域
本申请涉及电力电子中的换流技术领域，例如涉及一种混合式换流器及其控制方法。
背景技术
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，给电网的稳定安全运行带来更严峻的挑战。
针对直流输电换相失败问题，已研究出了多种具有抵御换相失败功能的换流器拓扑结构。例如，一种是电容换相换流器(Capacitor Commutation Converter，CCC)拓扑，通过电容电压来增大阀换相电压时间面积保证其可靠关断。基于电容换相电路的基本原理演变出了多种拓扑结构，通过电力电子开关与电容组合构成可控电容模块用来实现电容投入和电压方向可控，但上述基于电容换相的拓扑结构工程实现难度较大。另一种是通过可关断器件与晶闸管串联构成混合换流器，使得换流器每一个桥臂具备可关断能力，避免了换相失败的发生。由于常规直流输电输送容量大，换流器每个桥臂承受高电压、大电流，该种拓扑中可关断管阀需采用多级串并联的方式来实现，同时可关断管阀长时间承受大电流，在大电流关断时承受较高的电压应力，需较多的串联级数，因此，该种技术方案的工程实现成本和难度均较高。
发明内容
本申请提供一种混合式换流器及其控制方法，充分利用可关断器件的电流关断特性，可以快速转移换相电流、灵活控制晶闸管阀换相电压时间面积，保 证晶闸管阀具有足够的反向恢复时间可靠关断，同时利用可关断阀辅助换相从根本上避免直流系统换相失败问题的发生。
提供了一种基于可控关断的混合式换流器，所述换流器包括三相六桥臂电路，所述三相六桥臂电路通过换流变压器接入交流电网；
所述三相六桥臂电路的每相的上桥臂和下桥臂均由阀模块组成；
所述阀模块由主支路和与所述主支路并联的具备正向电流可控关断和正反向电压阻断能力的辅助阀组成；
所述主支路由串联的晶闸管阀和具备正向电流可控关断和正向电压阻断能力的可关断阀组成。
还提供了一种基于可控关断的混合式换流器的控制方法，包括：
在所述换流器的第i个桥臂的可关断阀处于导通状态，且所述换流器的第i个桥臂的辅助阀处于关断状态的情况下，每隔一个控制周期导通所述换流器的第i个桥臂的晶闸管阀一次；
其中，i∈[1,6]。
还提供了一种基于可控关断的混合式换流器的控制方法，包括：
导通所述换流器的第i个桥臂的晶闸管阀和可关断阀，关断所述换流器的第i个桥臂的辅助阀；
经过Δt后，关断所述换流器的第i个桥臂的可关断阀，导通所述换流器的第i个桥臂的辅助阀；
在所述换流器的第i个桥臂的晶闸管阀处于正向阻断状态的情况下，关断所述换流器的第i个桥臂的辅助阀；经过Δt″ off后，返回执行导通所述换流器的第i个桥臂的晶闸管阀和可关断阀，关断所述换流器的第i个桥臂的辅助阀的步骤；
其中，Δt″ off为一个控制周期内所述换流器的第i个桥臂的晶闸管阀处于正向阻断状态的时长，Δt为可关断阀的导通时长，
Figure PCTCN2020099843-appb-000001
T为一个控制周期，i∈[1,6]。
附图说明
图1是本申请实施例提供的一种基于可控关断的混合式换流器拓扑结构的结构示意图；
图2是本申请实施例提供的一种基于可控关断的混合式换流器拓扑结构中可关断阀的结构示意图；
图3是本申请实施例提供的一种基于可控关断的混合式换流器拓扑结构中辅助阀的结构示意图；
图4是本申请实施例提供的一种基于可控关断的混合式换流器拓扑结构中缓冲部件的结构示意图；
图5是本申请实施例提供的一种基于可控关断的混合式换流器拓扑结构正常运行时的电流流通路径图；
图6是本申请实施例提供的一种基于可控关断的混合式换流器拓扑结构正常运行时的控制时序图；
图7是本申请实施例提供的一种基于可控关断的混合式换流器拓扑结构故障时的电流流通路径图；
图8是本申请实施例提供的一种基于可控关断的混合式换流器拓扑结构故障时的控制时序图；
图9是本申请实施例提供的一种预先检测到故障时的控制时序图。
具体实施方式
下面结合附图对本申请的具体实施方式进行说明。
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描述，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。
本申请实施例提供了一种基于可控关断的混合式换流器拓扑结构，如图1所示，所述拓扑结构为三相六桥臂电路，所述三相六桥臂电路通过换流变压器接入交流电网；所述三相六桥臂电路的每相的上桥臂和下桥臂均由阀模块组成；所述阀模块由主支路和与所述主支路并联的具备正向电流可控关断和正反向电压阻断能力的辅助阀组成；所述主支路由串联的晶闸管阀和具备正向电流可控关断和正向电压阻断能力的可关断阀组成。
所述基于可控关断的混合式换流器拓扑结构还可包括触发控制系统，用于对主支路中的每个阀和辅助阀发送控制时序。
所述晶闸管阀由多个晶闸管和与所述多个晶闸管中的每个晶闸管串联或并联的缓冲部件组成。
所述可关断阀由单级或多级至少具备正向电流可控关断和电压阻断能力的全控型电力电子器件串联组成，所述可关断阀的电路拓扑结构包括但不局限于单级、半桥或H桥型拓扑结构。所述可关断阀设置为关断主支路电流，将主支路电流转移至辅助阀。
所述可关断阀的结构如图2中(a)所示，由单个或多个串联的功率模块和与所述多个串联的功率模块中的每个功率模块串联或并联的缓冲部件组成。
所述功率模块由全控型电力电子器件和与所述全控型电力电子器件反并联的二极管组成。
所述可关断阀的结构还可以如图2中(b)所示，由多个串联的第一可关断支路和与所述多个串联的第一可关断支路中的每个第一可关断支路串联或并联的缓冲部件组成。
所述第一可关断支路由第一功率模块和与所述第一功率模块并联的第二可关断支路并联组成。
所述第二可关断支路由串联的第二功率模块和电容组成。
所述第一功率模块和所述第二功率模块均由全控型电力电子器件和与所述全控型电力电子器件反并联的二极管组成。
所述第一功率模块与第二功率模块的连接点和所述第一功率模块与电容的连接点均为所述可关断阀的对外连接点或与所述可关断阀中其他第一可关断支路的连接点。
所述可关断阀可由辅助阀代替。
所述辅助阀由多级至少具备正向电流可控关断和正反向电压阻断能力的全控型电力电子器件串联组成，所述辅助阀的电路拓扑结构包括但不局限于单级、半桥或H桥型拓扑结构。
所述辅助阀的结构如图3中(a)所示，由多个串联的辅助子模块和分别与所述多个串联的辅助子模块中的每个辅助子模块串联或并联的缓冲部件组成。
所述辅助子模块由功率模块和与所述功率模块串联的二极管组成。
所述功率模块由全控型电力电子器件和与所述全控型电力电子器件反并联的二极管组成。
所述辅助阀的结构如图3中(b)所示，由串联的辅助时序控制支路和二极管支路组成。
所述二极管支路由多个正向串联的二极管和与所述多个正向串联的二极管中的每个二极管串联或并联的缓冲部件组成。
所述辅助时序控制支路由多个串联的功率模块和与所述多个串联的功率模块中的每个功率模块串联或并联的缓冲部件组成。
所述功率模块由全控型电力电子器件和与所述全控型电力电子器件反并联 的二极管组成。
所述辅助阀的结构如图3中(c)所示，由多个第一电力电子单元串联组成。
所述第一电力电子单元由并联的第一辅助支路、缓冲部件和第二辅助支路组成。
所述第一辅助支路和所述第二辅助支路均由正向串联的两组辅助时序控制支路组成。
所述辅助时序控制支路由多个串联的功率模块和与所述多个串联的功率模块中的每个功率模块串联或并联的缓冲部件组成。
所述功率模块由全控型电力电子器件和与所述全控型电力电子器件反并联的二极管组成。
所述第一辅助支路的两组辅助时序控制支路的连接点和第二辅助支路的两组辅助时序控制支路的连接点均为所述辅助阀的对外连接点或与所述辅助阀中其他第一电力电子单元的连接点。
所述辅助阀的结构如图3中(d)所示，由多个第二电力电子单元串联组成。
所述第二电力电子单元由并联的第三辅助支路、辅助时序控制支路、缓冲部件和第四辅助支路组成。
所述第三辅助支路和所述第四辅助支路均由正向串联的两组二极管支路组成。
所述二极管支路由多个正向串联的二极管和与所述多个正向串联的二极管中的每个二极管串联或并联的缓冲部件组成。
所述辅助时序控制支路由多个串联的功率模块和与所述多个串联的功率模块中的每个功率模块串联或并联的缓冲部件组成。
所述功率模块由全控型电力电子器件和与所述全控型电力电子器件反并联的二极管组成。
逆阻型全控电力电子器件为具有反向电压阻断能力的全控型电力电子器件，因此，功率模块中逆阻型全控电力电子器件不需要反并联二极管；除逆阻型意外的全控电力电子器件为不具有反向电压阻断能力的全控型电力电子器件，因此，功率模块中除逆阻型以外的全控电力电子器件需要反并联二极管。
所述第三辅助支路的两组二极管支路的连接点和所述第四辅助支路的两组二极管支路的连接点均为所述辅助阀的对外连接点或与所述辅助阀中其他第二电力电子单元的连接点。
所述全控型电力电子器件由绝缘栅双极型晶体管绝缘栅双极型晶体管(Insulated Gate Bipolar Transistor，IGBT)、集成门极换流晶闸管(Integrated Gate-Commutated Thyristor，IGCT)、注入增强门极晶体管(Injection Enhanced Gate Transistor，IEGT)、可关断晶闸管(Gate Turn-Off Thyristor，GTO)和金属-氧化物半导体场效应晶体管(Metal-Oxide-Semiconductor Field-Effect Transistor，MOSFET)等可关断器件中的一种或多种构成。
如图4所示，所述缓冲部件由电容、阻容回路、二极管、电感和避雷器的一种或多种串联或并联组成。
一种如上述基于可控关断的混合式换流器拓扑结构的控制方法，包括：
正常运行时，导通基于可控关断的混合式换流器拓扑结构的第i个桥臂的可关断阀，关断基于可控关断的混合式换流器拓扑结构的第i个桥臂的辅助阀，并执行下述步骤：
步骤1：导通基于可控关断的混合式换流器拓扑结构的第i个桥臂的晶闸管阀，执行步骤2。
步骤2：经过一个控制周期T后返回步骤1，其中，i∈[1,6]。
如图5所示，为正常运行时，阀电流流通的路径，主支路周期性承受电压和电流应力，辅助阀一直处于关断状态；如图6所示，为正常运行时的多个阀的控制时序，其中，Sg1为晶闸管阀的控制时序，Sg12为可关断阀的控制时序，Sg13为辅助阀的控制时序，t 0为初始触发时刻，Δt on为晶闸管阀的导通时间，Δt off为晶闸管阀的关断时间，Δt′ off为晶闸管阀的正向阻断时间，控制周期T为2π。
当在t f时刻检测到基于可控关断的混合式换流器拓扑结构的第i个桥臂发生换相失败或短路故障时，在t f+Δt 1时刻导通第i个桥臂的辅助阀以及在t f+Δt 2时刻关断第i个桥臂的可关断阀，当基于可控关断的混合式换流器拓扑结构的第i个桥臂的晶闸管阀处于正向阻断状态时，关断第i个桥臂的辅助阀，如图7所示，该过程分为三个阶段，图7中(a)所示，为主支路向辅助阀换流阶段，该阶段辅助阀接收到触发信号导通，紧接着主支路的可关断阀接收到信号关断，完成主支路向辅助阀换流过程；图7中(b)所示，为主支路关断辅助阀通流阶段，该阶段主支路已完全关断，电流全部转移至辅助阀；图7中(c)所示，为主支路和辅助阀关断阶段，该阶段辅助阀接收到关断信号，关断辅助阀，此时，晶闸管阀处于正向阻断状态用于承受正向电压。如图8所示，为检测到换相失败或短路故障时的多个阀的控制时序，其中，Sg1为晶闸管阀的控制时序，Sg12为可关断阀的控制时序，Sg13为辅助阀的控制时序，t 1为初始触发时刻，控制周期T为2π，Δt 1为导通第i个桥臂的辅助阀的延迟时长，Δt 2为关断第i个桥臂的可 关断阀的延迟时长，t f+Δt 1＜t f+Δt 2，Δt 3为辅助阀的导通时间，图8中，主支路电流过零至辅助阀关断这段时间为晶闸管阀的关断时间Δt off，Δt off需大于最小预设关断时间。
当t f所处控制周期结束后执行步骤S1，直至所述基于可控关断的混合式换流器拓扑结构的电压恢复稳定时，导通基于可控关断的混合式换流器拓扑结构的第i个桥臂的可关断阀，关断基于可控关断的混合式换流器拓扑结构的第i个桥臂的辅助阀，并执行步骤1。
步骤S1：导通基于可控关断的混合式换流器拓扑结构的第i个桥臂的晶闸管阀，导通基于可控关断的混合式换流器拓扑结构的第i个桥臂的可关断阀，关断基于可控关断的混合式换流器拓扑结构的第i个桥臂的辅助阀，经过Δt后，执行步骤S2，
Figure PCTCN2020099843-appb-000002
步骤S2：关断基于可控关断的混合式换流器拓扑结构的第i个桥臂的可关断阀，导通基于可控关断的混合式换流器拓扑结构的第i个桥臂的辅助阀，当基于可控关断的混合式换流器拓扑结构的第i个桥臂的晶闸管阀处于正向阻断状态时，执行步骤S3。
步骤S3：关断基于可控关断的混合式换流器拓扑结构的第i个桥臂的辅助阀，经过Δt′ off后，返回步骤S1。
其中，Δt′ off为执行步骤1至步骤2的一个控制周期内基于可控关断的混合式换流器拓扑结构的第i个桥臂的晶闸管阀处于正向阻断状态的时长。
本申请实施例还提供另外一种对上述基于可控关断的混合式换流器拓扑结构的控制方法，该方法用于当预先检测到基于可控关断的混合式换流器拓扑结构的第i个桥臂将要发生换相失败或短路故障且第i个桥臂向第j个桥臂换相时，执行下述步骤：
步骤T1：导通基于可控关断的混合式换流器拓扑结构的第i个桥臂的晶闸管阀，导通基于可控关断的混合式换流器拓扑结构的第i个桥臂的可关断阀，关断基于可控关断的混合式换流器拓扑结构的第i个桥臂的辅助阀，经过Δt后，执行步骤T2，
Figure PCTCN2020099843-appb-000003
步骤T2：关断基于可控关断的混合式换流器拓扑结构的第i个桥臂的可关断阀，导通基于可控关断的混合式换流器拓扑结构的第i个桥臂的辅助阀，当基于可控关断的混合式换流器拓扑结构的第i个桥臂的晶闸管阀处于正向阻断状态时，执行步骤T3。
步骤T3：关断基于可控关断的混合式换流器拓扑结构的第i个桥臂的辅助 阀，经过Δt″ off后，返回步骤T1。
Δt″ off为一个控制周期内基于可控关断的混合式换流器拓扑结构的第i个桥臂的晶闸管阀处于正向阻断状态的时长，T为一个控制周期。
如图9所示，为预先检测到故障时的多个阀的控制时序，其中，Sg1为晶闸管阀的控制时序，Sg12为可关断阀的控制时序，Sg13为辅助阀的控制时序，Δt on为晶闸管阀的导通时间，Δt″ off为晶闸管阀的正向阻断时间，控制周期T为2π,Δt为可关断阀的导通时长，
Figure PCTCN2020099843-appb-000004
为辅助阀导通时长，主支路电流过零至辅助阀关断这段时间为晶闸管阀的关断时间Δt off，Δt off需大于最小预设关断时间。在预测到换相失败将要发生时启动此种运行模式，可成功避免换相失败发生，同时可以实现低关断角运行，有效降低了逆变侧无功功率。
本申请实施例提供的基于可控关断的混合式换流器包括三相六桥臂电路，所述三相六桥臂电路通过换流变压器接入交流电网；所述三相六桥臂电路的每相的上桥臂和下桥臂均由阀模块组成；所述阀模块由主支路和与所述主支路并联的辅助阀组成；这种结构可以实现换流阀的辅助换相，避免换相失败的发生；所述辅助阀可以快速转移相电流、灵活控制晶闸管阀换相时间面积，在换相失败发生后阀电流快速转移至辅助阀，通过全控型器件大电流关断的特性，可以快速恢复两桥臂间换相，大大加快了换相失败后换流器的恢复时间；所述主支路由串联的晶闸管阀和可关断阀组成，其中的可关断阀可以提前关断主支路的电流，同时为主支路提供反向电压，增大了主支路晶闸管阀换相时间面积，保证了晶闸管阀的可靠关断，所述主支路中的可关断阀串联级数较少，产生的总损耗较低；本申请实施例提供的基于可控关断的混合式换流器可随时投入使用辅助阀，可以有效降低主支路阀的损耗，可实现低电压和低关断角运行，大幅度降低了逆变侧的无功功率；本申请实施例提供的第一种控制方法，正常运行时，辅助阀不投入运行，只需承担电压应力，不会对换流阀的多种运行工况造成负面影响；换相失败故障或短路故障发生后立即投入辅助阀，在较短时间内实现辅助换相功能，快速恢复多个桥臂间的换相。该种技术方案充分利用了晶闸管和可关断器件的优点，采用两条支路并联，主支路通过可关断器件实现电流的转移，辅助阀用于故障时承受较大关断电压应力，无需长期承受电流应力，不会增加器件损耗，提高了可关断器件利用率，便于工程实施；本申请实施例提供的第二种控制方式为主支路和辅助阀交替运行的模式，这种运行模式可以避免失败故障或短路故障的发生，有利于提高换流器的整体可靠性。
本申请的实施例可提供为方法、系统、或计算机程序产品。因此，本申请可采用完全硬件实施例、完全软件实施例、或结合软件和硬件方面的实施例的形式。而且，本申请可采用在一个或多个其中包含有计算机可用程序代码的计 算机可用存储介质(包括但不限于磁盘存储器、光盘只读存储器(Compact Disc Read-Only Memory，CD-ROM)、光学存储器等)上实施的计算机程序产品的形式。
本申请是参照根据本申请实施例的方法、设备(系统)、和计算机程序产品的流程图和/或方框图来描述的。可由计算机程序指令实现流程图和/或方框图中的每一流程和/或方框、以及流程图和/或方框图中的流程和/或方框的结合。可提供这些计算机程序指令到通用计算机、专用计算机、嵌入式处理机或其他可编程数据处理设备的处理器以产生一个机器，使得通过计算机或其他可编程数据处理设备的处理器执行的指令产生设置为实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的装置。
这些计算机程序指令也可存储在能引导计算机或其他可编程数据处理设备以特定方式工作的计算机可读存储器中，使得存储在该计算机可读存储器中的指令产生包括指令装置的制造品，该指令装置实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能。
这些计算机程序指令也可装载到计算机或其他可编程数据处理设备上，使得在计算机或其他可编程设备上执行一系列操作步骤以产生计算机实现的处理，从而在计算机或其他可编程设备上执行的指令提供用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的步骤。

Claims (12)

  1. 一种基于可控关断的混合式换流器，包括三相六桥臂电路，所述三相六桥臂电路通过换流变压器接入交流电网；
    所述三相六桥臂电路的每相的上桥臂和下桥臂均由阀模块组成；
    所述阀模块由主支路和与所述主支路并联的具备正向电流可控关断和正反向电压阻断能力的辅助阀组成；
    所述主支路由串联的晶闸管阀和具备正向电流可控关断和正向电压阻断能力的可关断阀组成。
  2. 如权利要求1所述的换流器，其中，所述晶闸管阀由多个晶闸管和与每个晶闸管串联或并联的缓冲部件组成。
  3. 如权利要求1所述的换流器，其中，所述可关断阀由至少一个串联的功率模块和与每个功率模块串联或并联的缓冲部件组成；
    所述功率模块由具有反向电压阻断能力的全控型电力电子器件组成，或者由不具有反向电压阻断能力的全控型电力电子器件和与所述不具有反向电压阻断能力的全控型电力电子器件反并联的二极管组成。
  4. 如权利要求1所述的换流器，其中，所述可关断阀由1个或多个串联的第一可关断支路和与所述1个或多个串联的第一可关断支路中的每个第一可关断支路串联或并联的缓冲部件组成；
    所述第一可关断支路由第一功率模块和与所述第一功率模块并联的第二可关断支路并联组成；
    所述第二可关断支路由串联的第二功率模块和电容组成；
    所述第一功率模块和所述第二功率模块均由具有反向电压阻断能力的全控型电力电子器件组成，或者由不具有反向电压阻断能力的全控型电力电子器件和与所述不具有反向电压阻断能力的全控型电力电子器件反并联的二极管组成；
    所述第一功率模块与第二功率模块的连接点和所述第一功率模块与所述电容的连接点均为所述可关断阀的对外连接点或与所述可关断阀中其他第一可关断支路的连接点。
  5. 如权利要求1所述的换流器，其中，所述辅助阀由多个串联的辅助子模块和分别与所述多个串联的辅助子模块中的每个辅助子模块串联或并联的缓冲部件组成；
    所述辅助子模块由功率模块组成，或者由功率模块和与所述功率模块串联的二极管组成；
    所述功率模块由具有反向电压阻断能力的全控型电力电子器件组成，或者由不具有反向电压阻断能力的全控型电力电子器件和与所述不具有反向电压阻断能力的全控型电力电子器件反并联的二极管组成。
  6. 如权利要求1所述的换流器，其中，所述辅助阀由串联的辅助时序控制支路和二极管支路组成；
    所述二极管支路由多个正向串联的二极管和与所述多个正向串联的二极管中的每个二极管串联或并联的缓冲部件组成；
    所述辅助时序控制支路由多个串联的功率模块和与所述多个串联的功率模块中的每个功率模块串联或并联的缓冲部件组成；
    所述功率模块由具有反向电压阻断能力的全控型电力电子器件组成，或者由不具有反向电压阻断能力的全控型电力电子器件和与所述不具有反向电压阻断能力的全控型电力电子器件反并联的二极管组成。
  7. 如权利要求1所述的换流器，其中，所述辅助阀由多个第一电力电子单元串联组成；
    每个第一电力电子单元由并联的第一辅助支路、缓冲部件和第二辅助支路组成；
    所述第一辅助支路和所述第二辅助支路均由正向串联的两组辅助时序控制支路组成；
    每组辅助时序控制支路由多个串联的功率模块和与所述多个串联的功率模块中的每个功率模块串联或并联的缓冲部件组成；
    所述功率模块由具有反向电压阻断能力的全控型电力电子器件组成，或者由不具有反向电压阻断能力的全控型电力电子器件和与所述不具有反向电压阻断能力的全控型电力电子器件反并联的二极管组成；
    所述第一辅助支路的两组辅助时序控制支路的连接点和所述第二辅助支路的两组辅助时序控制支路的连接点均为所述辅助阀的对外连接点或与所述辅助阀中其他第一电力电子单元的连接点。
  8. 如权利要求1所述的换流器，其中，所述辅助阀由多个第二电力电子单元串联组成；
    每个第二电力电子单元由并联的第三辅助支路、辅助时序控制支路、缓冲部件和第四辅助支路组成；
    所述第三辅助支路和所述第四辅助支路均由正向串联的两组二极管支路组成；
    每组二极管支路由多个正向串联的二极管和与所述多个正向串联的二极管中的每个二极管串联或并联的缓冲部件组成；
    所述辅助时序控制支路由多个串联的功率模块和与所述多个串联的功率模块中的每个功率模块串联或并联的缓冲部件组成；
    所述功率模块由具有反向电压阻断能力的全控型电力电子器件组成，或者由不具有反向电压阻断能力的全控型电力电子器件和与所述不具有反向电压阻断能力的全控型电力电子器件反并联的二极管组成；
    所述第三辅助支路的两组二极管支路的连接点和所述第四辅助支路的两组二极管支路的连接点均为所述辅助阀的对外连接点或与所述辅助阀中其他第二电力电子单元的连接点。
  9. 如权利要求2-8中任一项所述的换流器，其中，所述缓冲部件由电容、阻容回路、二极管、电感和避雷器中的至少之一组成。
  10. 一种基于可控关断的混合式换流器的控制方法，包括：
    在所述换流器的第i个桥臂的可关断阀处于导通状态，且所述换流器的第i个桥臂的辅助阀处于关断状态的情况下，每隔一个控制周期导通所述换流器的第i个桥臂的晶闸管阀一次；其中，i∈[1,6]。
  11. 如权利要求10所述的方法，还包括：
    在t f时刻检测到所述换流器的第i个桥臂发生换相失败或短路故障的情况下，在t f+Δt 1时刻导通所述第i个桥臂的辅助阀以及在t f+Δt 2时刻关断所述第i个桥臂的可关断阀；
    在所述换流器的第i个桥臂的晶闸管阀处于正向阻断状态的情况下，关断所述第i个桥臂的辅助阀；
    在t f所处控制周期结束后重复执行以下步骤，直至所述换流器恢复正常运行，导通所述换流器的第i个桥臂的可关断阀，关断所述换流器的第i个桥臂的辅助阀：
    导通所述换流器的第i个桥臂的晶闸管阀和可关断阀，关断所述换流器的第i个桥臂的辅助阀；
    经过Δt后，关断所述换流器的第i个桥臂的可关断阀，导通所述换流器的第i个桥臂的辅助阀；
    在所述换流器的第i个桥臂的晶闸管阀处于正向阻断状态的情况下，关断所述换流器的第i个桥臂的辅助阀，经过Δt′ off后，返回执行导通所述换流器的第i个桥臂的晶闸管阀和可关断阀，关断所述换流器的第i个桥臂的辅助阀的步骤；
    其中，Δt′ off为一个控制周期内所述换流器的第i个桥臂的晶闸管阀处于正向阻断状态的时长，Δt 1为导通所述第i个桥臂的辅助阀的延迟时长，Δt 2为关断所述第i个桥臂的可关断阀的延迟时长，Δt为所述可关断阀的导通时长，
    Figure PCTCN2020099843-appb-100001
    T为一个控制周期，Δt 1＜Δt 2。
  12. 一种基于可控关断的混合式换流器的控制方法，包括：
    导通所述换流器的第i个桥臂的晶闸管阀和可关断阀，关断所述换流器的第i个桥臂的辅助阀；
    经过Δt后，关断所述换流器的第i个桥臂的可关断阀，导通所述换流器的第i个桥臂的辅助阀；
    在所述换流器的第i个桥臂的晶闸管阀处于正向阻断状态的情况下，关断所述换流器的第i个桥臂的辅助阀，经过Δt″ off后，返回执行导通所述换流器的第i个桥臂的晶闸管阀和可关断阀，关断所述换流器的第i个桥臂的辅助阀的步骤；
    其中，Δt″ off为一个控制周期内所述换流器的第i个桥臂的晶闸管阀处于正向阻断状态的时长，Δt为可关断阀的导通时长，
    Figure PCTCN2020099843-appb-100002
    T为一个控制周期，i∈[1,6]。
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