WO2022152124A1 - 模块化批量取能换流电路及控制方法 - Google Patents

模块化批量取能换流电路及控制方法 Download PDF

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Publication number
WO2022152124A1
WO2022152124A1 PCT/CN2022/071342 CN2022071342W WO2022152124A1 WO 2022152124 A1 WO2022152124 A1 WO 2022152124A1 CN 2022071342 W CN2022071342 W CN 2022071342W WO 2022152124 A1 WO2022152124 A1 WO 2022152124A1
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WIPO (PCT)
Prior art keywords
sub
module
unit
energy
bridge arm
Prior art date
Application number
PCT/CN2022/071342
Other languages
English (en)
French (fr)
Inventor
谢晔源
王宇
姚宏洋
姜田贵
朱铭炼
欧阳有鹏
胡兆庆
李海英
殷冠贤
段军
任铁强
Original Assignee
南京南瑞继保电气有限公司
南京南瑞继保工程技术有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Priority claimed from CN202110042119.5A external-priority patent/CN112924838B/zh
Priority claimed from CN202110425656.8A external-priority patent/CN113285621A/zh
Priority claimed from CN202111056378.XA external-priority patent/CN113922407A/zh
Priority claimed from CN202111056427.XA external-priority patent/CN113917251A/zh
Application filed by 南京南瑞继保电气有限公司, 南京南瑞继保工程技术有限公司 filed Critical 南京南瑞继保电气有限公司
Priority to KR1020237019681A priority Critical patent/KR20230107312A/ko
Priority to EP22739003.6A priority patent/EP4227692A1/en
Priority to JP2023531533A priority patent/JP2023550783A/ja
Publication of WO2022152124A1 publication Critical patent/WO2022152124A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/327—Testing of circuit interrupters, switches or circuit-breakers
    • G01R31/333—Testing of the switching capacity of high-voltage circuit-breakers ; Testing of breaking capacity or related variables, e.g. post arc current or transient recovery voltage
    • G01R31/3333—Apparatus, systems or circuits therefor
    • G01R31/3336—Synthetic testing, i.e. with separate current and voltage generators simulating distance fault conditions
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
    • G01R31/14—Circuits therefor, e.g. for generating test voltages, sensing circuits
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/40—Testing power supplies
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/52—Testing for short-circuits, leakage current or ground faults
    • 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
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0006—Arrangements for supplying an adequate voltage to the control circuit of 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
    • 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
    • H02M7/483—Converters with outputs that each can have more than two voltages levels
    • H02M7/4833—Capacitor voltage balancing
    • 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
    • H02M7/483—Converters with outputs that each can have more than two voltages levels
    • H02M7/4835—Converters with outputs that each can have more than two voltages levels comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage
    • 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
    • H02M7/493—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 the static converters being arranged for operation in parallel
    • 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 high-power power electronic converters, in particular to a modularized batch energy-extracting converter circuit and a control method.
  • the flexible DC transmission system is generally composed of several sub-modules connected in series or in parallel.
  • a bridge arm contains hundreds of sub-modules.
  • the test scheme of the prior art needs to apply a test power supply to each sub-module separately, and perform functional tests one by one.
  • the main problems are:
  • the existing test scheme can only carry out sub-module function test or insulation test and other sub-system tests, and lack of high-voltage and high-power operation test scheme for the entire converter circuit, resulting in incomplete test items and low test efficiency.
  • each sub-module in series needs to be able to establish communication with the valve control device, and the sub-module control unit, drive , power devices are normal, and output zero-level state.
  • the test will be forced to be interrupted, requiring a long time of discharge and maintenance, which will affect the test efficiency; The hidden danger of the gate not in place.
  • the grid connection of offshore wind power is an important application of flexible direct current transmission, and the flexible direct offshore converter station needs to be built on an offshore platform.
  • the flexible direct offshore converter station needs to be built on an offshore platform.
  • the offshore flexible-to-DC converter station arrives at the designated sea area and finds problems such as quality defects in large-scale equipment, the entire platform needs to be transported to the test terminal for processing, and the cost and time cost are very high.
  • the process of equipment testing on the wharf is very important, but the wharf usually can only provide low-voltage power supply with small capacity, and the existing test technology needs to test the commutator circuit with the help of high voltage.
  • the present application proposes a modularized batch energy-sampling converter circuit and a control method.
  • a modularized batch energy acquisition converter circuit which includes a batch energy acquisition unit and N sub-modules, the AC ends of the N sub-modules are connected in series, and N is an integer greater than or equal to 2.
  • the sub-module includes: a power unit, including a power semiconductor device, an AC terminal of the power unit is drawn out as an AC terminal of the sub-module; a capacitor unit is connected in parallel with the power unit;
  • the batch energy acquisition unit includes: The first energy-fetching power source, the negative electrode of the first energy-fetching power source is connected with the negative electrode of the capacitor unit of the head terminal module of the N sub-modules or connected through the current limiting unit; connected to the network, the input end of the connection network is connected to the The positive pole of the first energy-fetching power supply is directly connected or connected through a current limiting unit; the N output ends of the connection network are respectively connected with the positive pole of the capacitor unit or connected through the current limiting unit.
  • the sub-module power units in the commutation circuit are all half-bridge circuits, or all are full-bridge circuits, or are configured in a mixed configuration of full-bridge circuits and half-bridge circuits, wherein: the half-bridge circuits include upper tubes and lower tubes.
  • the upper tube and the lower tube are connected in series with the capacitor unit in parallel, and the collector and emitter of the upper tube or the lower tube are drawn out as the AC end of the sub-module;
  • the full-bridge circuit includes two upper tubes and two The lower tube, the upper tube and the lower tube are connected in series to form a bridge arm and then connected in parallel with the capacitor unit, and the midpoint of the bridge arm is drawn out as an AC output end of the sub-module; the upper tube and the lower tube are fully controlled power semiconductor devices or the device of the parallel.
  • connection network comprises: a parallel connection network, comprising N diode units, anodes of the N diode units are connected together as input terminals of the connection network, and cathodes of the N diode units are connected together. Lead out N output terminals as the connection network in turn; or connect the network in series, and the series connection network includes the following two:
  • Mode 1 including N diode units, the N diode units are connected in series in the same direction, the anode of the first diode unit is used as the input end of the connection network, and the cathode of the Nth diode unit is drawn out in turn as the connection network the output terminal;
  • Mode 2 including N-1 diode units, the N-1 diode units are connected in series in the same direction, the anode of the first diode unit is used as the input end of the connection network, the anode of the first diode is connected to the N-th diode The cathode of one diode unit is drawn out in turn as the output end of the connection network;
  • the diode unit includes a diode or a diode and a resistor or/and an inductor connected in series.
  • the method further comprises: a bypass switch connected in parallel with the AC terminals of the sub-modules; a discharge branch connected in parallel with the commutation circuit, the discharge branch comprising a discharge switch and a discharge resistor connected in series and /or a resonant tank formed by inductance and/or inductance and capacitance.
  • the first terminal module is the sub-module with the lowest potential in the commutation circuit.
  • a control method based on any one of the foregoing commutation circuits is proposed, comprising a combination of one or more of the following steps: batch sub-module function pre-test: the first Once the energy-fetching power supply is started, the discharge switch is closed, and the capacitor unit of the sub-module is charged through the connection network and the discharge resistance; batch sub-modules are pressurized step by step: the first energy-fetching power supply Start, the sub-module control unit controls the sub-module to output the zero-level state step by step, the capacitor units of the sub-module are charged one by one, and the sub-module function test is carried out; batch sub-module rapid discharge test: the batch sub-module function After the pre-test or the step-by-step pressurization test of the batch sub-modules is completed, the first energy-fetching power supply is disconnected
  • the capacitor units of the sub-modules are discharged one by one; batch sub-module discharge bypass test: after the batch sub-module rapid discharge test is completed, the capacitor units of the sub-module are discharged to a fixed value, and the automatic The bypass switch of the submodule is closed.
  • the step-by-step pressurization test of the batch of sub-modules includes: starting the first energy-fetching power supply to charge the capacitor units of the connected sub-modules; after the charging reaches a threshold, controlling the sub-modules power supply to the unit; control the power semiconductor device at the corresponding position in the power unit to be turned on to the zero-level state of the power unit through the sub-module control unit, and establish a conduction loop for the capacitor unit of the adjacent sub-module; the first The capacitor unit of the power source/pre-stage sub-module charges the capacitor unit of the adjacent sub-module, so that the sub-module control unit of the adjacent sub-module is charged; the capacitor units of all sub-modules are charged in turn, and the N sub-module control units are charged.
  • the conduction of the lower transistors of the power semiconductor device is defined as the zero-level state; for a full-bridge circuit, two upper transistors of the power semiconductor device are turned on at the same time or two of the upper transistors are turned on at the same time.
  • the simultaneous conduction of the lower transistors of the power semiconductor device is defined as the zero-level state.
  • a high-voltage operating circuit comprising: the modularized batch energy-fetching commutation circuit and a second commutating circuit as described in any of the foregoing; wherein: the second commutating circuit It includes M sub-modules, the AC ends of the M sub-modules are connected in series, and M is an integer greater than or equal to 2, or includes the batch energy-fetching commutation circuit described in any of the foregoing; the second commutating circuit The AC ends of the head terminal module and the tail terminal module are drawn out as the AC end of the second commutation circuit; the batch energy-fetching commutation circuit is connected with an AC end of the second commutation circuit through a connecting reactor, The other AC terminal is shorted.
  • a method for controlling a high-voltage operating circuit of a commutator circuit as described above including: cascade charging control, using the first energy-fetching power supply and the connection network to be the capacitors of all sub-modules Unit charging, the sub-module control unit operates after taking power from the capacitor unit; cascade operation control, after the cascade charging control is completed, the control voltage of the batch energy-fetching commutation circuit and the second commutating circuit is the same as that of the second commutation circuit.
  • the first energy-extracting power source supplements the energy loss for the batch energy-extracting commutation circuits and the second commutating circuits.
  • a low-pressure pressurization system for a flexible-to-DC converter station includes a flexible-to-DC converter valve and a valve controller, wherein: the flexible-to-DC converter valve includes 3 A parallel phase bridge arm, the phase bridge arm is the upper bridge arm and the lower bridge arm connected in series, the positive end of the upper bridge arm is connected to the DC positive terminal, the negative end of the upper bridge arm is connected to the positive end of the lower bridge arm, so The negative end of the lower bridge arm is connected to the DC negative electrode; according to the grounding method of the flexible DC converter valve, the corresponding upper bridge arm or lower bridge arm or phase bridge arm is configured as a batch energy exchange as described in any one of the preceding paragraphs.
  • the other bridge arms are configured as commutation circuits in which sub-modules are connected in series; the valve controller communicates with the sub-module control unit that controls the operation of the sub-modules.
  • the corresponding relationship between the configuration mode and the grounding mode includes one of the following: the DC negative electrode of the flexible DC converter valve is grounded, and at least one lower bridge arm or phase bridge arm is configured to obtain energy conversion in batches
  • the DC positive pole of the flexible DC converter valve is grounded, the first power source is isolated from the capacitor unit through an isolation module, and the upper bridge arm or the lower bridge arm or the phase bridge arm is configured to obtain energy in batches a converter circuit; when the absolute values of the DC positive pole and the DC negative pole of the flexible DC commutator valve are equal to or similar to the ground voltage, the upper bridge arm or the phase bridge arm is configured as a batch energy conversion circuit;
  • the DC converter valve is not grounded or is grounded through the grounding switch and the grounding switch is disconnected, and the upper bridge arm or the lower bridge arm or the phase bridge arm is configured as a batch energy conversion circuit.
  • a method for controlling a low-voltage pressurization system of a flexible-to-DC converter station as described in any of the foregoing comprising: the first energy-extracting power source is configured to be energy-extracting and converting in batches
  • the DC capacitors of the sub-modules of the circuit are charged, and the batch energy acquisition and commutation circuit is defined as a charging bridge arm; after the charging bridge arm is charged, the charging bridge arm starts to run, and the output controllable voltage is
  • the other bridge arms of the flexible-DC converter valve are charged; after the charging of the other bridge arms is completed, the upper bridge arm and the lower bridge arm of any phase are controlled as a voltage source, and the DC positive pole and the DC A DC voltage is equivalently applied to the negative electrode, and this process is defined as a pressurization process.
  • a first high-voltage switch is further included, which is connected in series with the first energy-fetching power supply. After the charging of the three-phase bridge arm is completed, the first high-voltage switch is disconnected, the three-phase bridge arm is unlocked, and the DC positive pole is turned off. .
  • the DC negative electrode presents a DC voltage
  • the midpoint of the three-phase bridge arm presents a three-phase AC voltage.
  • the method further includes: performing a withstand voltage test and/or sampling calibration on the DC, AC equipment or AC/DC lines during the pressurization process; when an insulation breakdown fault occurs during the pressurization process, using the bridge arm to rapidly overcurrent Protection and/or short-circuit protection of power semiconductor devices ensures device safety.
  • an on-site testing method for a converter valve includes 6 bridge arms and a valve control unit, the bridge arms include the above-mentioned any one of the above A commutation circuit, the commutation circuit includes N sub-modules, and the sub-modules are optically connected to the valve control unit, wherein the on-site testing method includes: connecting the N output ends of the connection network to N The positive pole of the capacitor unit of each sub-module; the first energy-receiving power source is activated; the valve control unit identifies whether the sub-modules established by communication are consistent with the physical location; batch energy is obtained, and the sub-modules perform functional tests or The valve control unit updates the program.
  • the present application has one or more of the following beneficial effects:
  • This application proposes a modular commutation circuit that can obtain energy in batches.
  • the sub-module capacitor is divided into a combination of two capacitors, which can be flexibly adapted according to the design of the internal power supply unit.
  • the module control unit supplies power, or a charging method equivalent to the real working condition, but uses less external power supply and lower voltage to ensure equipment and personal safety.
  • the point-to-point communication test can be performed.
  • the step-by-step test method can reduce the test risk and improve the test reliability.
  • This application proposes a scheme of pushing the power of two commutator chains in the opposite direction.
  • the low-voltage power supply is used to supply energy to charge one commutator chain, and the output voltage of one commutator chain can be used to charge the other commutator chain, and only one commutator chain is added.
  • the connection of the reactor realizes the power push between the two commutation chains, and the connection of the reactor can also use the bridge arm reactor in the project. The problem of high voltage and high power operation test.
  • the low-voltage pressurization test system and control method proposed in the present application can perform batch testing on sub-modules to improve the test efficiency; and the sub-module bypass switch is automatically opened by the system to solve the hidden danger of insufficient manual opening.
  • FIG. 1 is a schematic diagram of the composition of a modular commutation circuit that can obtain energy in batches according to an embodiment of the present application;
  • FIG. 2 is a schematic diagram of the composition of a capacitor unit according to an embodiment of the present application.
  • 3a is a schematic diagram of the composition of a power unit composed of a half-bridge circuit according to an embodiment of the present application
  • FIG. 3b is a schematic diagram of the composition of a power unit composed of a full-bridge circuit according to an embodiment of the present application
  • 3c is a schematic diagram of the composition of a power unit according to an embodiment of the present application.
  • FIG. 4 is a schematic diagram of the composition of a high-impedance interface unit according to an embodiment of the present application.
  • FIG. 5 is a schematic diagram of the composition of an interface unit in a blocking manner according to an embodiment of the present application.
  • FIG. 6 is a schematic diagram of the composition of a transformer unit according to an embodiment of the present application.
  • FIG. 7 is a schematic diagram of the composition of another transformer unit according to an embodiment of the present application.
  • connection network composition in a parallel connection is a schematic diagram of a connection network composition in a parallel connection according to an embodiment of the present application.
  • 9a is a schematic diagram of a connection network composition in a series connection according to an embodiment of the present application.
  • Fig. 9b is another embodiment of the schematic diagram of the connection network composition of a series connection of the present application.
  • connection network composition of a series connection of a plurality of first energy-fetching power sources according to an embodiment of the present application
  • FIG. 11 is a schematic diagram of the composition of a combined loop system of a modular commutation circuit that can obtain energy in batches according to an embodiment of the present application;
  • FIG. 12 is a schematic flowchart of a charging control method for a modular commutator circuit that can obtain energy in batches according to an embodiment of the present application;
  • FIG. 13 is a circuit structure diagram of a low-pressure pressure test system for a converter valve according to an embodiment of the present application
  • FIG. 14 is a circuit structure diagram of another converter valve low-pressure pressurization test system according to an embodiment of the present application.
  • FIG. 15 shows a flowchart of a control method for batch sub-module function pre-test of an exemplary embodiment
  • 16 shows a schematic diagram of a sub-module charging circuit of an exemplary embodiment
  • FIG. 17 shows a flowchart of a control method of a batch sub-module step-by-step pressurization test according to an exemplary embodiment
  • FIG. 18 shows a flowchart of a control method of a batch sub-module rapid discharge test according to an exemplary embodiment
  • FIG. 19 shows a flowchart of a control method for a batch sub-module discharge bypass test according to an exemplary embodiment.
  • 20 is a schematic diagram of a high-pressure operation circuit of a converter valve provided by an embodiment of the present application.
  • 21 is a schematic diagram of another high-pressure operation circuit of a converter valve provided by an embodiment of the present application.
  • 22a is a schematic diagram of a diode unit provided by an embodiment of the present application.
  • FIG. 22b is a schematic diagram of another diode unit provided by an embodiment of the present application.
  • FIG. 23 is a schematic diagram of a field test system of a high-voltage operating circuit of a converter valve provided by an embodiment of the present application.
  • 24 is a schematic diagram of a field test system of another high-voltage operating circuit of a converter valve provided by an embodiment of the present application;
  • 25 is a schematic diagram of the wiring of a field test system of a high-voltage operating circuit of a converter valve provided in an embodiment of the present application;
  • 26 is a schematic diagram of the single bridge arm wiring of a field test system of a high-voltage operating circuit of a converter valve provided in an embodiment of the present application;
  • FIG. 27 is a schematic flowchart of a control method for a high-pressure operation circuit of a converter valve provided by an embodiment of the present application
  • FIG. 29 is a schematic flowchart of a DC charging logic provided by an embodiment of the present application.
  • FIG. 30 is a schematic diagram of a cascade operation control process provided by an embodiment of the present application.
  • FIG. 31 is a schematic flowchart of bypass detection after operation provided by an embodiment of the present application.
  • FIG. 32 is a schematic diagram of a bypass detection flow of cascade operation control provided by an embodiment of the present application
  • FIG. 33 is a schematic diagram of a low-voltage pressurization system of a flexible DC converter station according to an embodiment of the present application.
  • Fig. 34 is a schematic diagram of another low-voltage pressurization system of a flexible DC converter station according to an embodiment of the present application.
  • FIG. 35 is a schematic diagram of another low-voltage pressurization system of a flexible DC converter station according to an embodiment of the present application.
  • FIG. 36 is a schematic diagram of another low-voltage pressurization system of a flexible DC converter station according to an embodiment of the present application.
  • 37a is a schematic diagram of a low-voltage power supply according to an embodiment of the present application.
  • FIG. 37b is a schematic diagram of yet another low-voltage power supply according to an embodiment of the present application.
  • 37c is a schematic diagram of another low-voltage power supply according to an embodiment of the present application.
  • FIG. 38 shows a flowchart of a method for controlling the charging of a first energy-fetching power source according to an exemplary embodiment
  • FIG. 39 is a flowchart of a bridge arm active voltage equalization control method according to an embodiment of the present application.
  • FIG. 40 is a flowchart of a method for controlling a split-phase DC voltage boost according to an embodiment of the present application.
  • FIG. 41 is a flowchart of a low-voltage pressurization control method for a flexible DC converter station according to an embodiment of the present application.
  • Example embodiments will now be described more fully with reference to the accompanying drawings.
  • Example embodiments can be embodied in various forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this application will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art.
  • the same reference numerals in the drawings denote the same or similar parts, and thus their repeated descriptions will be omitted.
  • FIG. 1 is one of the schematic diagrams of the composition of a modularized commutation circuit that can obtain energy in batches according to an embodiment of the present application.
  • the modular commutation circuit that can obtain energy in batches includes N sub-modules, the AC ends of the N sub-modules are connected in series, the unconnected AC ends of the first terminal module and the tail terminal module are drawn out as the AC end of the commutation circuit, and N is greater than or equal to 2 the integer.
  • the sub-module includes a power unit 1, a capacitor unit 2, a transformer unit 3, a sub-module control unit 4, a batch energy acquisition unit and a bypass switch.
  • the power unit 1 includes a power semiconductor device, and the AC end of the power unit 1 leads out as the AC end of the sub-module.
  • the capacitor unit 2 is connected in parallel with the power unit 1, and the capacitor unit 2 includes a first DC capacitor C1, as shown in FIG. 2 .
  • the transformer unit 3 is connected to the capacitor unit 2 , takes energy from the capacitor unit 2 , realizes DC voltage transformation, and supplies power to the sub-module control unit 4 .
  • the sub-module control unit 4 is connected to the transformer unit 3 and controls the power unit 1 to work.
  • the batch energy extraction unit includes a first energy extraction power source 6 and a connection network 30 .
  • the negative electrode of the first energy taking power source 6 is connected to the negative electrode of the first terminal module capacitor unit.
  • connection network 30 is directly connected to the positive pole of the first energy-fetching power supply 6 or connected through a current limiting unit, and the connection network 30 includes N output ends, and the N output ends are respectively directly connected to the positive poles of all the capacitor units or through the current limiting unit.
  • the unit is connected, and the current limiting unit includes a resistor or/and an inductor.
  • the bypass switch is connected in parallel with the AC terminals of the submodules.
  • the power unit 1 includes a half-bridge circuit or a full-bridge circuit, including a two-level or three-level half-bridge or full-bridge circuit.
  • the half-bridge circuit includes an upper tube and a lower tube, and the lower tube is connected in parallel with the AC output terminal of the sub-module, as shown in FIG. 3a.
  • the full-bridge circuit includes two upper tubes and two lower tubes, the upper tubes and the lower tubes are connected in series to form a bridge arm and then connected to the capacitor unit in parallel, and the midpoint of the bridge arm is drawn out as the AC output end of the sub-module, as shown in FIG. 3b Show.
  • the sub-module power units in the commutation circuit are all the same circuit, all half-bridge circuits or all full-bridge circuits or a hybrid configuration of full-bridge circuits and half-bridge circuits;
  • FIG. 3c is a full-bridge-like type. submodule circuit.
  • the AC end of the sub-module is also connected in parallel with a bypass switch, the bypass switch is electrically closed, and is maintained by mechanical force or magnetic force after closing.
  • the zero-level state of the power unit for a half-bridge circuit, the conduction of the lower transistor is defined as a zero-level state; for a full-bridge circuit, the simultaneous conduction of two upper transistors or the simultaneous conduction of two lower transistors is defined as a zero-level state .
  • the capacitor unit 2 further includes a second DC capacitor C2 and an interface unit 5, the interface unit 5 is connected between the first DC capacitor C1 and the second DC capacitor C2, and the second DC capacitor C2 is connected between the interface unit 5 and the transformer. between pressure units 3.
  • the composition mode of the interface unit 5 includes a high impedance mode or a blocking mode.
  • the interface unit 5 includes resistance or/and reactance, and the equivalent resistance of the interface unit 5 is greater than 10k ⁇ , as shown in FIG. 4 .
  • the interface unit 5 includes a blocking diode unit, the anode of the blocking diode unit points to the anode of the first DC capacitor C1, the cathode of the blocking diode unit points to the anode of the second DC capacitor C2, and the blocking diode unit includes a blocking diode unit. Turn off the diode, or block the diode and divider resistor network, as shown in Figure 5.
  • the transformer unit 3 includes at least one DC converter, and the input end of the DC converter is connected to the capacitor unit 2 , as shown in FIG. 6 .
  • the number of DC converters is greater than 1, the output ends of the DC converters are directly connected in parallel or connected in parallel after connecting diodes in series, as shown in Figure 7.
  • the connection network 30 includes a parallel connection network or a series connection network.
  • the parallel connection network includes N diode units, anodes of the N diode units are connected together as input terminals of the connection network, and cathodes of the N diode units are sequentially drawn out as N output terminals of the connection network, As shown in Figure 8.
  • the diode unit includes a diode or diodes connected in series and a resistor or/and an inductor.
  • the series connection network includes N-1 diode units, N-1 diode units are connected in series in the same direction, the anode of the first diode unit is used as the input terminal of the connection network, and the anodes of the N-1 diode units are connected in series. And the cathode of the N-1th diode unit is drawn out in turn as the output terminal of the connection network, as shown in Figure 9a.
  • the series connection network includes N diode units, the N diode units are connected in series in the same direction, the anode of the first diode unit is used as the input terminal of the connection network, and the cathode of the Nth diode unit is sequentially Lead out as the output of the connection network, as shown in Figure 9b.
  • the diode unit includes a diode or diodes connected in series with a resistor or/and an inductor.
  • the commutation circuit when the connection network 30 is connected to the network in series, the commutation circuit further includes M first energy-fetching power sources 6 .
  • M first energy taking power sources 6 are respectively connected in parallel with the capacitor units 2 of each sub-module, M is an integer, 1 ⁇ M ⁇ N-1, when M ⁇ 2, the output ends of the first energy taking power sources 6 are connected in series to prevent Reverse diode, the cathode of the anti-reverse diode points to the anode of the capacitor unit 2 .
  • M 2, as shown in FIG. 10 .
  • the technical solution provided by this embodiment is that the modular commutation circuit that can obtain energy in batches divides the sub-module capacitor into a combination of two capacitors, which can be flexibly adapted according to the design of the internal power supply unit.
  • the module control unit supplies power, or a charging method equivalent to the real working condition, but uses less external power supply and lower voltage to ensure equipment and personal safety.
  • the point-to-point communication test can be performed.
  • the step-by-step test method can reduce the test risk and improve the test reliability.
  • the external secondary low-voltage power supply and the power supply from the sub-module capacitor constitute redundancy, which more reliably ensures the control and power supply of the sub-module.
  • FIG. 11 is a schematic diagram showing the composition of a combined loop system of a modular commutation circuit capable of obtaining energy in batches according to an embodiment of the present application.
  • the synthetic loop system includes a modular commutation circuit capable of taking energy in batches, a valve base control unit 50 and a second energy taking power source 60 .
  • the valve base control unit 50 communicates with the N sub-module control units 4 .
  • the second energy source 60 is connected to the AC end of the commutation circuit.
  • the synthesis loop system further includes a discharge branch.
  • the discharge branch is connected in parallel with the second energy taking power source 60 , and the discharge branch includes a discharge switch 61 and a discharge resistor 62 connected in series, as shown in FIG. 11 .
  • FIG. 12 is a schematic flowchart of a charging control method for a modular commutator circuit that can obtain energy in batches according to an embodiment of the present application, including the following control process.
  • the first energy taking power source 6 is activated to charge the capacitor unit 2 of the connected sub-module.
  • the power semiconductor device at the corresponding position in the power unit 1 is controlled by the sub-module control unit 4 to be turned on to a zero-level state of the power unit, and a conduction loop is established for the capacitor units of the adjacent sub-modules.
  • the first energy-capturing power source 6 or/and the capacitor unit of the preceding sub-module charges the capacitor unit of the adjacent sub-module, so that the adjacent sub-module control unit is charged.
  • j is an integer, 1 ⁇ j ⁇ N-1, and the following control flow is also included.
  • FIG. 13 is another embodiment of a schematic diagram of the composition of a modular commutation circuit capable of obtaining energy in batches according to the present application.
  • the modular converter circuit that can obtain energy in batches includes a converter valve, a low-pressure pressurizing unit, and a load unit.
  • the converter valve includes the AC terminals of N sub-modules 1 connected in series.
  • N is an integer greater than or equal to 1.
  • the sub-module 1 is a half-bridge circuit or a full-bridge circuit connected in parallel with the capacitor unit, and the power device is connected in parallel with the bypass switch 2 .
  • the submodule 1 further comprises a submodule control unit.
  • the modular commutation circuit that can be energized in batches further includes a valve control system in communication with the sub-module control unit.
  • the low-voltage pressurizing unit includes a first energy source 3 and a connection network 4 .
  • the low-voltage pressurizing unit is connected to the capacitor unit of the sub-module.
  • the load unit includes a discharge switch 5 and a discharge resistor 6, and the load unit is connected in parallel with the converter valve.
  • the first energy-fetching power supply is started, the discharge switch is closed, and the capacitor units of all the sub-modules are charged at the same time through the connection network and the discharge resistor.
  • the negative pole of the first power supply is connected to the negative pole of the first terminal module capacitor unit; the input terminal of the connection network is directly connected to the positive pole of the first energy supply, the connection network includes N output terminals, and the N output terminals are respectively Connect to the positive terminal of all capacitor cells.
  • connection network includes two connection modes, parallel mode and series mode.
  • FIG 13 illustrates connecting networks in parallel, according to an example embodiment.
  • the parallel connection network includes N diodes.
  • the anodes of the N diode units are connected together as the input terminals of the connection network, and the cathodes of the N diode units are drawn out in sequence as the N output terminals of the connection network.
  • the batch-capable modular commutation circuit may implement one or more of the following control methods:
  • Step-by-step pressurization test of batch sub-modules The first power supply is activated, the valve control unit controls the sub-modules to output a zero-level state step by step, and the sub-module capacitor units are charged one by one, and the sub-module function test is carried out.
  • Rapid discharge test of batch sub-modules Disconnect the first energy-receiving power supply, close the discharge switch, and then turn on the power semiconductor devices in the corresponding positions in the power unit step by step through the valve control unit, and the sub-module capacitor units discharge one by one.
  • control methods can be combined into one or more of the following:
  • connection method of FIG. 14 is a serial connection.
  • the connection network includes N-1 diode units, the N-1 diode units are connected in series in the same direction, the anode of the first diode unit is used as the input end of the connection network, the anode of the N-1 diode units and the Nth diode unit are connected in series.
  • the cathodes of -1 diode unit are drawn out in sequence as the output end of the connection network, as shown in Figure 14.
  • FIG. 15 shows a flowchart of a control method for batch sub-module function pre-test in an exemplary embodiment.
  • the first energy-fetching power source is started, and the load switch is closed.
  • the first energy source is activated, and the load switch of the load unit is closed to form a closed loop.
  • the first energy-fetching power source charges the sub-module capacitor unit by connecting the network and the load resistance in the load unit.
  • valve control unit and the sub-module control unit communicate normally, and if there is a communication failure, the faulty sub-module is located.
  • if a faulty sub-module is detected go to S470; if there is no faulty sub-module, go to S480.
  • bypass switch of the faulty submodule is closed or the bypass switch of the faulty submodule is closed first, and then the faulty submodule is repaired.
  • the bypass switch of the faulty submodule is closed or the bypass switch of the faulty submodule is closed first, and then the faulty submodule is repaired, and then the process goes to S410.
  • FIG. 16 shows a schematic diagram of a sub-module charging circuit of an exemplary embodiment.
  • the first energy-fetching power source charges the sub-module capacitor unit by connecting the network and the load resistance in the load unit.
  • the capacitive units of the N sub-modules may be charged simultaneously.
  • FIG. 17 shows a flowchart of a control method of a batch sub-module step-by-step pressurization test according to an exemplary embodiment.
  • the first energy-fetching power supply is activated; the first terminal module capacitor unit is charged.
  • the first energy-extracting power source charges the capacitive unit of the sub-module directly connected to its negative pole.
  • the first terminal module control unit is activated, the power unit outputs zero level, and the adjacent sub-module capacitor units are charged.
  • the conduction of the lower transistors is defined as a zero-level state; for a full-bridge circuit, the simultaneous conduction of two upper transistors or the simultaneous conduction of two lower transistors is defined as a zero-level state.
  • the first terminal module control unit is activated to turn on the power unit of the first terminal module, and the first energy-fetching power supply charges the capacitor unit of the adjacent sub-module.
  • the adjacent sub-module control unit starts and outputs a zero-level state.
  • the power unit of the adjacent sub-module outputs a zero level, and the next adjacent sub-module capacitor unit is charged. In this way, charge step by step to charge all sub-module capacitor units; enable all sub-module control units to start.
  • sub-module functional testing includes capacitor voltage sampling verification.
  • V Smi is the voltage sampling value of the i-th sub-module capacitor unit
  • V SM(i-1) is the (i-1)-th sub-module capacitor unit voltage sampling value
  • V S is the first energy-fetching power supply voltage
  • V D is the diode tube Voltage drop
  • V G is the voltage drop of the power semiconductor device.
  • the capacitor voltage sampling verification compares the sampling value calculated according to the above-mentioned theory with the actual sampling value, and when the deviation is higher than the threshold value, it is determined that the test fails.
  • sub-module functional testing includes cross-communication checking, which includes two types:
  • the sub-module control unit communicates with the adjacent sub-module control unit in pairs, and communicates with two different channels of the valve control unit at the same time;
  • Cross-communication refers to reading different sub-module capacitor voltage sampling values from the same channel of the valve control unit. If the data conforms to the corresponding relationship of capacitor voltage sampling verification, the verification is passed.
  • FIG. 18 shows a flowchart of a control method for a rapid discharge test of a batch of submodules according to an exemplary embodiment.
  • the batch submodule function pre-test or the batch submodule step-by-step pressurization test is completed.
  • the first energy-fetching power supply is disconnected, and the load switch is closed.
  • power semiconductor devices at corresponding positions in the power unit of the sub-module are turned on step by step from the head end or the end.
  • the power semiconductor device at the corresponding position refers to an upper transistor of a half-bridge circuit or a pair of transistors of a full-bridge circuit.
  • the sub-module directly connected to the first energy-fetching power source is a head-end module, which can turn on the power semiconductor device at the corresponding position in the power unit of the head-end or end sub-module.
  • the theoretical voltage value is calculated according to the capacitance value of the sub-module capacitor unit, and the voltage at which the sub-module capacitor unit is discharged is determined.
  • the voltage deviation is higher than a threshold value, it is logged and an alarm is issued.
  • FIG. 19 shows a flowchart of a control method of a batch sub-module discharge bypass test according to an exemplary embodiment.
  • valve control unit or the sub-module control unit issues a command to close the sub-module bypass switch.
  • the high-voltage operation circuit of the converter valve includes two converter circuits, a connection reactor 2 , and one or two connection networks 1 .
  • the two commutation circuits respectively include N sub-modules 3 and M sub-modules 3, where N and M are integers greater than or equal to 1, one AC end of the two commutation circuits is connected through the connecting reactor 2, and the other of the two commutating circuits is connected. An AC terminal is shorted.
  • the sub-module 3 includes a parallel-connected DC capacitor C1 and a power unit, and the power unit includes a half-bridge circuit or/and a full-bridge circuit composed of power semiconductor devices.
  • the AC ends of the sub-modules 3 are connected in series, and the AC ends of the first terminal module and the tail terminal module are drawn out as the AC end of the commutation circuit.
  • the head terminal module is a submodule connected to the anode end of the connection network, and the tail terminal module is a submodule connected to the cathode end of the connection network.
  • the sub-module also includes a sub-module control unit, which controls the operation of the power unit.
  • connection network 1 comprises at least N-1 or at least M-1 diode units 4 .
  • the diode units 4 are connected in series in the same direction, the cathode end of the connection network 1 is connected to the positive electrode of the DC capacitor C1 of the tail terminal module, and the anode ends of all the diode units 4 are connected to the positive electrode of the DC capacitor C1 of the sub-module 3 corresponding to the commutation circuit one by one. Corresponding to or connected through the first current limiter.
  • the diode unit includes a diode, the anode of the diode points to the anode terminal of the diode unit, and the cathode points to the cathode terminal.
  • the high-voltage operation circuit of the converter valve further includes at least one first energy-acquisition power source 5, and the first energy-acquisition power source 5 is connected in parallel with the DC capacitor of the first terminal module of the corresponding converter circuit.
  • the first energy source 5 includes a power supply unit or a power supply unit and a diode connected in series, and the power supply unit includes a DC power supply, or an AC power supply and a rectifier.
  • the output voltage of the first energy taking power source 5 is fixed or adjustable. In this embodiment, the output voltage of the first energy taking power source 5 is lower than the withstand voltage value of the semiconductor device of the sub-module power unit. For example, if the withstand voltage of the power semiconductor device is 3300V, the first energy-extracting power supply 5 can adopt an output voltage of 1500V.
  • the number of the first energy source is 1, which is connected in parallel with the DC capacitor of the first terminal module of the commutator circuit configured to connect to the network, as shown in Figure 20.
  • the number of the first energy taking power sources is 2, which are respectively connected in parallel with the DC capacitors of the first terminal modules of the two commutation circuits, as shown in Figure 21.
  • the technical solution provided in this embodiment can solve the power supply problem of many sub-modules through the first energy-fetching power supply with low-voltage output, and can realize the charging of the entire commutator circuit through the low-voltage output, which reduces the test conditions and test requirements, and is suitable for on-site For occasions without high-voltage and high-power power supply.
  • the diode unit 4 further includes a second current limiter, which is mainly used to limit the current impact during the charging process.
  • the second current limiter is connected in series with the diode, and the second current limiter includes a resistor and/or or inductance.
  • the diode unit further includes an isolation switch, the isolation switch is connected in series with the diode, and the switching of the isolation switch is controlled by the control unit of the sub-module, as shown in Figure 22b.
  • the field test system of the converter valve high-voltage operation circuit includes at least one converter valve high-voltage operation circuit.
  • the two converter circuits of the high-pressure operation circuit of the converter valve are installed in the valve tower type, which is defined as the engineering valve tower 10 .
  • a beam is built between the engineering valve tower support insulators, and the connecting reactor 2 is installed on the beam 11.
  • the beam can be built at the N1, N2, N3 insulating support positions, and the connecting reactor 2 can also be placed on the ground independently.
  • connection reactor 2 includes a bridge arm reactor or a combination of bridge arm reactors, and the connection reactor 2 is connected between the engineering valve towers 10 .
  • each bridge arm includes two engineering valve towers 10. One end of the series connection of the two engineering valve towers is connected to AC, and the other is connected to AC. After one end is drawn out, it is connected to the bridge arm reactor 2 through the wall bushing 12 and then connected to the positive pole of the converter valve.
  • the existing wiring mode can also be modified, and the bridge arm reactor is used as the connection reactor 2. Taking one bridge arm as an example, the modified wiring is shown in FIG. 26 .
  • the modified operating circuit is the operating circuit shown in Figure 20.
  • FIG. 27 is a schematic flowchart of a control method for a high-voltage operation circuit of a converter valve provided by an embodiment of the present application, including two control modes of cascade charging control and cascade operation control.
  • the cascaded charging control utilizes the first energy-fetching power supply and the cascaded energy supply chain to charge the DC capacitors of all sub-modules, and the control unit of the sub-modules runs after drawing power from the DC capacitors.
  • the commutation circuit connected to the first energy source is set as the first commutator circuit, and the other commutator circuit is the second commutator circuit.
  • the first commutation circuit first executes the sequential control startup logic, and after the startup is completed, executes the DC charging logic to control the output voltage and charge the sub-modules of the second commutation circuit.
  • the two commutation circuits respectively execute the sequence control start logic.
  • the sequence control startup logic is shown in FIG. 28 , including: starting the first energy-fetching power supply, charging the DC capacitor of the first terminal module, and the first terminal module controlling the power-on operation of the electric element; controlling the power unit through the control unit of the sub-module
  • the power semiconductor device in the corresponding position is turned on, outputs a zero-level state, establishes a conduction loop for the DC capacitor of the adjacent sub-module, charges the DC capacitor of the adjacent sub-module, and the sub-module control unit is powered on; complete all sub-modules in turn.
  • the DC capacitor of the module is charged, so that the sub-module control units are charged.
  • the DC charging logic includes: adjusting the output voltage of the commutator circuit connected to the first energy-fetching power source, so that the voltage gradually increases from zero, which is the DC capacitor of the second commutator circuit sub-module charging until the second commutation circuit sub-module control unit is powered on; controlling the number of sub-modules in the second commutating circuit to be put into the charging loop so that the DC capacitor voltage of the second commutating circuit sub-module reaches a preset value.
  • the two commutation circuits control the voltage and current to reproduce the voltage and current stress of the sub-modules of the commutation circuit.
  • the first energy source continues to be two commutators during this process The circuit continuously replenishes the lost energy.
  • the cascade operation control is shown in FIG. 30 , including: unlocking and starting the power unit of any converter circuit sub-module, and outputting the target AC voltage value; after the AC voltage is stabilized, unlocking the power unit of another converter circuit sub-module Start, control the current flowing through the connected reactor to the target value; after the system is stable, detect the voltage and current of the current control commutation circuit, compare with the given value, and judge whether it meets the test requirements.
  • the setting of the AC voltage target value is adjusted according to the insulation level of the connected reactor and d1, d2, and d3.
  • control method further includes: bypass switch detection and control, performing cascade operation control bypass detection and bypass detection after the operation ends, for testing whether the bypass switch can work normally.
  • the bypass detection after the operation is completed includes: exiting the cascade operation control; stopping the output of the first energy-fetching power supply; bypassing the sub-modules of the two converter circuits in sequence; checking whether the bypass switch is The action is correct.
  • the cascade operation control bypass detection is shown in FIG. 32 , including: entering the cascade operation control; after stabilization, controlling the bypass switches of the sub-modules in the two converter circuits to bypass successively; If the running state is normal, reduce the AC voltage target value during cascade running control, otherwise, perform bypass detection after running.
  • the control method provided in this embodiment includes start-up charging, cascade operation control, and bypass detection.
  • the control method covers the key items of the converter valve test. Before this application, the field test of the converter valve could only complete the relevant sub-modules. Test, the method proposed in this application realizes the test of the converter circuit, and provides a reliable guarantee for the engineering application of the converter valve.
  • FIG. 33 is a schematic diagram of a low-voltage pressurization system of a flexible DC converter station according to an embodiment of the present application.
  • the flexible-to-DC converter station includes a flexible-to-DC converter valve and a valve controller.
  • the flexible DC converter valve includes three parallel phase bridge arms A-phase, B-phase and C-phase.
  • the A-phase, B-phase and C-phase of the phase bridge arm are connected in series with the upper bridge arm and the lower bridge arm, the positive terminal of the upper bridge arm is electrically connected to the DC positive terminal, the negative terminal of the upper bridge arm is electrically connected to the positive terminal of the lower bridge arm, and the negative terminal of the lower bridge arm is electrically connected. Connect DC negative.
  • the low voltage of the low voltage pressurization system is 300V-1500V.
  • the upper bridge arm includes N sub-modules 1 and bridge arm reactors 2, where N is an integer greater than or equal to 2.
  • the sub-module 1 includes two power semiconductor devices and one capacitor. The first power semiconductor device and the second power semiconductor device are connected in series in the same direction and then connected in parallel with the capacitor.
  • the DC positive electrode is electrically connected to the bridge arm reactor 2, the other end of the bridge arm reactor 2 is electrically connected to the midpoint in series of the two power semiconductor devices of the sub-module 1, and the other end of the second power semiconductor device is connected to the two power semiconductor devices of the next sub-module.
  • the submodules are connected in series in sequence, one end of the second power semiconductor device of the Nth submodule is connected to the midpoint of the series connection of the two power semiconductor devices of the submodule of the lower bridge arm, and the second power semiconductor of the Nth submodule of the lower bridge arm is connected in series.
  • One end of the device is electrically connected to the bridge arm reactor and then electrically connected to the DC negative electrode.
  • the A-phase, B-phase, and C-phase circuit structures are similar.
  • the sub-module 1 can be a half-bridge circuit, a full-bridge circuit, a three-level circuit or a combination thereof; the sub-module 1 further includes a sub-module controller, which can control the operation of the sub-module.
  • the valve controller communicates with the sub-module controller to control the operation of the low pressure pressurization system of the flexible DC converter station.
  • the low-voltage pressurization system 3 includes a first energy source 4 and a connection network 5 .
  • the positive pole of the first energy source 4 is electrically connected to the positive pole of the connection network 5 .
  • connection network 5 comprises at least N-1 or 2N-1 diode cells.
  • connection network 5 is connected to A of the upper bridge arm, and includes N ⁇ 1 diode units.
  • connection network 5 when the connection network 5 is connected to the phase bridge arm, it includes 2N-1 diode units.
  • the diode unit comprises a diode or a diode is connected in series with the current limiting unit 6 .
  • the diode unit is connected to the sub-module through a current limiting unit.
  • the diode cells are connected in series in the same direction, the diode anode port is defined as the anode terminal of the diode cell, and the diode cathode port is defined as the cathode terminal.
  • the anode terminals of all the diode units and the cathode terminals of the terminal diode units constitute the same number of lead-out points as the sub-modules, which are connected to the positive electrodes of the DC capacitors of the sub-modules in one-to-one correspondence or after passing through the current limiting unit 6 . .
  • the anode terminals of all diode units and the cathode terminals of the terminal diode units constitute the same number of lead-out points as the number of sub-modules, which correspond one-to-one with the positive electrodes of the DC capacitors of the sub-modules after passing through the current limiting unit 6 connect.
  • the current limiting unit 6 consists of a resistor and/or an inductor.
  • the first energy source 4 when the absolute values of the DC positive and negative voltages of the flexible DC converter valve are equal to or similar to the ground, the first energy source 4 is connected in parallel with the DC capacitor of any sub-module at the negative terminal of the upper bridge arm; the connection network connects the DC capacitors in sequence. The positive pole of the DC capacitor of other sub-modules of the bridge arm.
  • the first energy-fetching power supply 4 is connected in parallel with the DC capacitors of any lower bridge arm or the negative terminal of the phase bridge arm; As shown in Figure 34.
  • the isolation module 7 is an isolation transformer.
  • the first energy-capturing power source 4 is connected in parallel with any sub-module DC capacitor of the upper bridge arm, the lower bridge arm or the negative terminal of the phase bridge arm;
  • the network is connected to the positive poles of the DC capacitors of other sub-modules of the bridge arm in turn, as shown in Figure 36.
  • the first energy source is a DC power source, in which the negative electrode is grounded, as shown in Figure 37a.
  • the first energy source includes a diode 9 and a DC power supply, and the anode of the diode 9 is connected to the anode of the DC power supply, as shown in Figure 37b.
  • the output of the first power source is connected in series with the first high-voltage switch 10, and the insulation voltage level of the first high-voltage switch 10 is not lower than the AC side voltage of the flexible DC converter valve, as shown in Figure 37c.
  • FIG. 38 shows a flowchart of a method for controlling the charging of a first energy-fetching power source according to an exemplary embodiment.
  • the first energy-fetching power source is activated to charge the DC capacitor of the sub-module connected to the first energy-fetching power source in the charging bridge arm, and the sub-module controller is powered on to run.
  • the first energy taking power supply is started to charge the DC capacitor of the Nth sub-module of the upper bridge arm of phase A, and the upper bridge arm of phase A is charged.
  • the Nth sub-module controller of the arm is powered on to run, and controls the second power semiconductor of the Nth sub-module to conduct.
  • the sub-modules are controlled to output a zero level, and a charging loop is established for the DC capacitors of the adjacent sub-modules, and the voltage of the DC capacitors of the adjacent sub-modules reaches the starting value Vc1.
  • the sub-module controller of the upper arm of phase A controls the sub-module to output zero level, and establishes a charging loop for the DC capacitors of adjacent sub-modules, that is, the Nth sub-module of the upper arm of phase A
  • the second power semiconductor device is turned on, so that the DC capacitor voltage of the N-1 th sub-module of the upper bridge arm of the A phase reaches the starting value Vc1, and the N-1 th sub-module controller is powered on and operates to control the N-1 th sub-module.
  • the second power semiconductor device of the module is turned on.
  • the upper arm of phase A completes the charging of the DC capacitors of all sub-modules in sequence, the DC capacitor voltage of the sub-modules of the upper arm of phase A reaches the starting value Vc1, and the sub-module controllers of the charging arm are charged .
  • FIG. 39 is a flowchart of a bridge arm active voltage equalization control method according to an embodiment of the present application.
  • the lower arm of the A-phase is recorded as the charging in-phase arm.
  • the charging bridge arm sub-modules are charged in a cyclic bypass bypass and equalizing charging, so that the DC capacitor voltage of the sub-modules reaches the rated value Vc2, and the valve controller controls the charging bridge arm to output the first controlled voltage source.
  • the second power semiconductor devices of the sub-modules of the upper arm of phase A are controlled to be turned on in turn, so that the DC capacitor voltage of the sub-module reaches the rated value Vc2 , the DC capacitance of the upper bridge arm of phase A is the output voltage of the first controlled voltage source.
  • the first controlled voltage source charges the in-phase bridge arms in series to charge the DC capacitors of the other two-phase bridge arm sub-modules.
  • the DC capacitors of the submodules of the upper and lower bridge arms of the B phase and the C phase are charged, so that the submodules of the upper and lower bridge arms of the B phase and the C phase are charged.
  • the DC capacitor voltage reaches the start-up value Vc1.
  • the second power semiconductor devices of the sub-modules of the upper and lower bridge arms of the B-phase and C-phase are controlled to be turned on in turn, so that the DC power of the sub-modules is turned on.
  • the capacitor voltage reaches the rated value Vc2.
  • the step ends; if the charging bridge arm is not a phase bridge arm, continue to perform the following steps.
  • the upper and lower bridge arms of any phase different from the charging bridge arm respectively output the second controlled voltage source and the third controlled voltage source.
  • the valve controller controls the upper and lower bridge arms of any phase different from the charging bridge arms to output the second controlled voltage source and the third controlled voltage source, respectively. That is, the upper and lower bridge arms of the B-phase and the C-phase respectively output the second controlled voltage source and the third controlled voltage source.
  • the charging non-inverting bridge arm is charged.
  • the first controlled voltage source, the second controlled voltage source, and the third controlled voltage source form a loop with the charging in-phase bridge arm to charge the charging in-phase bridge arm. That is, the upper bridge arm of phase A, the upper and lower bridge arms of phase B and phase C charge the lower bridge arm of phase A, so that the DC capacitor voltage of the sub-module of the lower bridge arm of phase A reaches Vc1.
  • the sub-modules of the charging non-inverting bridge arm are charged in a cyclic bypass and equalizing charging, so that the DC capacitor voltage of the sub-modules reaches the rated value Vc2.
  • the second power semiconductor devices of the sub-modules of the lower arm of phase A are controlled to be turned on in turn, so that the DC capacitor voltage of the sub-module reaches the rated value Vc2 .
  • the active voltage equalization control of the bridge arms is completed, and the process ends.
  • FIG. 40 is a flowchart of a method for controlling a phase-split DC voltage boost according to an embodiment of the present application.
  • the output controlled voltage source of any one-phase or multi-phase bridge arm is adjusted so that the entire phase bridge arm outputs a direct current voltage of 2Udc.
  • the first controlled voltage source, the second controlled voltage source, and the third controlled voltage source may all output a direct current voltage, so that the entire phase bridge arm outputs a direct current voltage of 2Udc.
  • the magnitude of the DC voltage Udc can be adjusted, including the following two methods: adjusting the number of sub-modules of the output voltage Vc2 in the upper or/and lower bridge arm; or adjusting each sub-module in the upper or/and lower bridge arm The DC capacitor rated voltage value Vc2.
  • Udc Vc2*P
  • P is the number of sub-modules that output the voltage Vc2 in the upper or lower bridge arm. P finally stabilizes at N/2.
  • the rising rate of the output DC voltage of the controlled voltage source can be adjusted, and the discharge current is controlled to be less than a preset value.
  • the controlled voltage source is charging other bridge arms on the DC bus, while the DC power supply in its own sub-module is in a discharging state. Therefore, if the above-mentioned rate of adjusting the output DC voltage is too fast, the discharge current will be too large. , it is necessary to choose the rise rate reasonably and control the discharge current to be less than the preset value.
  • the split-phase DC boost control method determines whether the sub-modules work normally by inputting different phases or switching input of different sub-modules, observing the output voltage and waveform.
  • FIG. 41 is a flowchart of a low-voltage pressurization control method for a flexible DC converter station according to an embodiment of the present application.
  • the step of active voltage equalization of the bridge arm is completed, and the step is shown in FIG. 7 ; if there is a first high voltage switch 10 in the first energy obtaining power supply, the first high voltage switch 10 is disconnected.
  • the flexible-DC converter valve is unlocked, the positive and negative electrodes of the DC present a DC voltage, and the midpoint of the three-phase bridge arm presents a three-phase AC voltage.
  • the flexible DC converter valve is blocked and the test is stopped.
  • the present application also has one or more of the accessibility benefits:
  • the bridge arm fast overcurrent protection is to detect the bridge arm current through the valve controller.
  • the flexible DC converter valve is blocked and the test is stopped;
  • the short circuit protection of the power semiconductor device is to detect the occurrence of the power device through the sub-module controller.
  • the sub-modules are blocked and bypassed immediately, and the fault is reported to the valve controller.
  • the number of sub-modules faulty at the same time exceeds a certain number, the flexible DC converter valve is blocked and the test is stopped.

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Abstract

一种模块化批量取能换流电路及控制方法，模块化批量取能换流电路包括批量取能单元和N个子模块，N个子模块的交流端串联连接，N为大于等于2的整数，子模块包括：功率单元（1），包括功率半导体器件，功率单元（1）的交流端引出作为子模块的交流端；电容单元（2），与功率单元（1）并联连接；批量取能单元包括：第一取能电源（6），第一取能电源（6）的负极与N个子模块的首端子模块的电容单元（2）的负极连接或经限流单元连接；连接网络（30），连接网络（30）的输入端与第一取能电源（6）的正极直接连接或经限流单元连接；连接网络（30）的N个输出端分别和电容单元（2）的正极连接或经限流单元连接。

Description

模块化批量取能换流电路及控制方法 技术领域
本申请涉及大功率电力电子变流技术领域，具体涉及模块化批量取能换流电路及控制方法。
背景技术
随着电力电子技术在电力系统中的应用和发展，电力电子设备向着高压大容量模块化方向发展，尤其在柔性直流输电系统和链式静止无功发生器等领域得到广泛的应用。其中，柔性直流输电系统一般由若干个串联或者并联连接的子模块组成。
在子模块运输到现场，组装成阀塔后，由于运输以及安装过程中可能出现意外，需要再进行一遍子模块以及整个换流电路的功能测试，以确保设备顺利投入运行。
以高压大容量柔性直流输电系统为例，一个桥臂包含几百个子模块。现有技术的测试方案需要对每个子模块单独施加测试电源，逐个进行功能测试，主要问题的在于：
(1)子模块数量多，测试工作量大，测试时间长，测试难度大，子模块组成阀塔后操作困难。(2)在测试过程中需要插拔光纤，插拔光纤的过程存在光纤接口和光纤本身损坏的风险，经常的插拔也会影响寿命，对设备的可靠性造成不利的影响。(3)在测试过程中或检修维护过程中，如果需要更换子模块控制单元程序，采用单独加电源的方式工作量很大，人工操作也容易出现问题。
一方面，现有试验方案只能进行子模块功能试验或者绝缘试验等分系统试验，缺少整个换流电路的高压大功率运行试验方案，导致试验项目不完整，且试验效率低。
另一方面，在安装调试初期，批量子模块中可能存在较多的故障子模块，如果采用自动测试，需要串联的子模块每一个都能与阀控装置建立通信，而且子模块控制单元、驱动、功率器件均正常，并输出零电平状态。一旦中间出现故障的子模块，试验就会被迫中断，需要经过较长时间的放电、检修，影响测试效率；在试验结束后，存在手动分闸子模块旁路开关的行为，也可能存在分闸不到位的隐患。
以海上风电柔直系统举例，海上风电并网是柔性直流输电的一个重要应用，柔直海上换流站需要建设在海上平台。考虑海上施工条件限制，无法在海上完成大型设备的安装和试验，需要在码头上进行设备安装、调试后把海上平台整体送至指定海域。若海上柔直换流站到达指定海域后发现大型设备出现质量缺陷等问题，需要把平台整体运输至试验码头进行处理，费用和时间成本非常高。
因此，对于上述应用工况，在码头上进行设备试验的环节至关重要，但码头通常只能提供小容量的低压电源，而现有试验技术需要借助高压对换流电路进行试验。
为了解决前述问题，本申请提出一种模块化批量取能换流电路及控制方法。
在所述背景技术部分公开的上述信息仅用于加强对本申请的背景的理解，因此它可以包括不构成对本领域普通技术人员已知的现有技术的信息。
发明内容
根据本申请的一方面，提出一种模块化批量取能换流电路，包括批量取能单元和N个子模块，N个所述子模块的交流端串联连接，N为大于等于2的整数。所述子模块包括：功率单元，包括功率半导体器件，所述功率单元的交流端引出作为所述子模块的交流端；电容单元，与所述功率单元并联连接；所述批量取能单元包括：第一取能电源，所述第一取能电源的负极与所述N个子模块的首端 子模块的电容单元的负极连接或经限流单元连接；连接网络，所述连接网络的输入端与所述第一取能电源的正极直接连接或经限流单元连接；所述连接网络的N个输出端分别和所述电容单元的正极连接或经限流单元连接。
根据一些实施例，所述换流电路中的子模块功率单元全部为半桥电路或全部为全桥电路或为全桥电路和半桥电路混合配置，其中：半桥电路，包括上管与下管，述上管与下管串联后与所述电容单元并联，所述上管或下管的集电极与发射极引出作为子模块的交流端；全桥电路，包括两个上管与两个下管，上管与下管串联构成桥臂后与所述电容单元并联，桥臂中点引出作为子模块交流输出端；所述上管和下管为全控型功率半导体器件或所述器件的并联。
根据一些实施例，所述连接网络包括：并联方式连接网络，包括N个二极管单元，所述N个二极管单元的阳极连接在一起作为所述连接网络的输入端，所述N个二极管单元的阴极依次引出作为所述连接网络的N个输出端；或者串联方式连接网络，所述串联方式连接网络包括以下两种：
方式1：包括N个二极管单元，所述N个二极管单元同方向串联连接，第一个二极管单元的阳极作为所述连接网络的输入端，第N个二极管单元的阴极依次引出作为所述连接网络的输出端；
方式2：包括N-1个二极管单元，所述N-1个二极管单元同方向串联连接，第一个二极管单元的阳极作为所述连接网络的输入端，第1个二极管的阳极和第N-1个二极管单元的阴极依次引出作为所述连接网络的输出端；
其中，所述二极管单元包括二极管或串联连接的二极管与电阻或/和电感。
根据一些实施例，还包括：旁路开关，并联连接所述子模块的交流端；放电支路，与所述换流电路并联连接，所述放电支路包括串联连接的放电开关和放电电阻和/或电感和/或电感电容构成的谐振回路。
根据一些实施例，所述首端子模块为换流电路中电位最低的子模块。根据本申请的另一方面，提出一种基于前文中任一项所述的换流电路的控制方法，包括以下步骤中的一种或多种的组合：批量子模块功能预试验：所述第一取能电源启动，闭合所述放电开关，通过所述连接网络和所述放电电阻为所述子模块的所述电容单元充电；批量子模块逐级加压试验：所述第一取能电源启动，子模块控制单元控制所述子模块逐级输出零电平状态，所述子模块的所述电容单元逐一充电，开展子模块功能试验；批量子模块快速放电试验：所述批量子模块功能预试验或所述批量子模块逐级加压试验完成后，断开所述第一取能电源，闭合所述放电开关，通过所述子模块控制单元逐级开通所述功率单元中对应位置的功率半导体器件，所述子模块的所述电容单元逐一放电；批量子模块放电旁路试验：所述批量子模块快速放电试验完成后，所述子模块的所述电容单元放电至定值，自动闭合所述子模块的所述旁路开关。
根据一些实施例，所述批量子模块逐级加压试验包括：启动所述第一取能电源，向所连接的子模块的所述电容单元充电；充电达到阈值后，为所述子模块控制单元供电；通过所述子模块控制单元控制所述功率单元中的对应位置的功率半导体器件导通为功率单元零电平状态，为相邻子模块的电容单元建立导通回路；所述第一取能电源/前级子模块的电容单元向相邻子模块的电容单元充电，使相邻子模块的子模块控制单元带电；依次完成所有子模块的电容单元充电，N个子模块控制单元带电。
根据一些实施例，对于半桥电路，所述功率半导体器件下管导通定义为所述零电平状态；对于全桥电路，两个所述功率半导体器件上管同时导通或两个所述功率半导体器件下管同时导通定义为所述零电平状态。
根据本申请的另一方面，提出一种高压运行电路，包括：如前文中任一项所述的模块化批量取 能换流电路和第二换流电路；其中：所述第二换流电路包括M个子模块，M个所述子模块的交流端串联连接，M为大于等于2的整数，或包括如前文中任一项所述的批量取能换流电路；所述第二换流电路的首端子模块和尾端子模块的交流端引出作所述第二换流电路的交流端；所述批量取能换流电路与所述第二换流电路的一交流端经连接电抗器连接，另一交流端短接。
根据本申请的另一方面，提出一种如前文所述的换流电路高压运行电路的控制方法，包括：级联充电控制，利用所述第一取能电源和连接网络为所有子模块的电容单元充电，子模块控制单元从所述电容单元取电后运行；级联运行控制，所述级联充电控制完成后，所述批量取能换流电路与所述第二换流电路控制电压与电流，所述第一取能电源为所述批量取能换流电路与所述第二换流电路补充损耗能量。
根据本申请的另一方面，提出一种柔直换流站低压加压系统，所述柔直换流站包括柔直换流阀、阀控制器，其中：所述柔直换流阀包括3个并联的相桥臂，所述相桥臂为上桥臂和下桥臂串联，所述上桥臂正端连接直流正极，所述上桥臂负端连接所述下桥臂正端，所述下桥臂负端连接直流负极；根据所述柔直换流阀的接地方式，相应的上桥臂或下桥臂或相桥臂配置为如前文中任一项所述的批量取能换流电路，其他桥臂配置为子模块串联的换流电路；所述阀控制器与控制子模块工作的子模块控制单元通信。
根据一些实施例，配置方式与所述接地方式的对应关系包括下述之一：所述柔直换流阀的所述直流负极接地，至少一个下桥臂或相桥臂配置为批量取能换流电路；所述柔直换流阀的所述直流正极接地，所述第一取能电源经隔离模块与所述电容单元隔离，上桥臂或下桥臂或相桥臂配置为批量取能换流电路；所述柔直换流阀的所述直流正极和所述直流负极对地电压绝对值相等或相近时，上桥臂或相桥臂配置为批量取能换流电路；所述柔直换流阀不接地或经接地开关接地且接地开关断开，上桥臂或下桥臂或相桥臂配置为批量取能换流电路。
根据本申请的另一方面，提出一种如前文中任一项所述的柔直换流站低压加压系统的控制方法，包括：所述第一取能电源为配置为批量取能换流电路的所述子模块的所述直流电容充电，该所述批量取能换流电路定义为充电桥臂；所述充电桥臂充电完成后，所述充电桥臂启动运行，输出可控电压为所述柔直换流阀的其他桥臂充电；所述其他桥臂充电完成后，任一相所述上桥臂、所述下桥臂控制为电压源，在所述直流正极和所述直流负极上等效施加直流电压，该过程定义为加压过程。
根据一些实施例，还包括第一高压开关，与所述第一取能电源串联，三相桥臂充电完成后，分断所述第一高压开关,所述三相桥臂解锁，所述直流正极、所述直流负极呈现直流电压，所述三相桥臂中点呈现三相交流电压。
根据一些实施例，还包括：在加压过程中对直流、交流设备或交直流线路进行耐压试验和/或采样校准；在加压过程中发生绝缘击穿故障时，利用桥臂快速过流保护和/或功率半导体器件短路保护保障设备安全。
根据本申请的另一方面，提出一种用于换流阀的现场测试方法，所述换流阀包括6个桥臂和阀控制单元，所述桥臂包括如前文中任一项所述的换流电路，所述换流电路包括N个子模块，所述子模块和所述阀控制单元光纤连接，其特征在于，所述现场测试方法包括：所述连接网络的N个输出端连接至N个子模块的所述电容单元的正极；所述第一取能电源启动；所述阀控制单元识别通信建立的所述子模块与物理位置是否一致；批量取能，所述子模块进行功能测试或所述阀控制单元更新程序。
根据示例实施例，本申请具有以下有益效果中的一个或多个：
(1)本申请提出一种可批量取能的模块化换流电路将子模块电容分为两个电容的组合，根据内 部电源单元的设计不同，可以灵活适应，一是电容快速充电，为子模块控制单元供电，或者与真实工况等效的充电方式，但采用了较少的外部电源和较低的电压，保证设备和人身安全。子模块控制单元上电后，可进行通讯对点试验，分步骤试验的方式可以降低试验风险，提高试验可靠性。
(2)本申请提出了两个换流链功率对推的方案，利用低压电源供能，为一换流链充电，可利用一换流链输出电压为另一个换流链充电，仅增加一个连接电抗器即实现了两个换流链之间的功率对推，连接电抗器也可以利用工程中的桥臂电抗器，该方案成本低，可靠性高，解决了现有换流链难以进行高压大功率运行试验的问题。
(3)本申请提出的低压加压试验系统和控制方法，可以对子模块进行批量检测，提高测试效率；并且通过系统自动分闸子模块旁路开关，解决手动分闸不到位的隐患。
应当理解的是，以上的一般描述和后文的细节描述仅是示例性的，并不能限制本申请。
附图说明
通过参照附图详细描述其示例实施例，本申请的上述和其它目标、特征及优点将变得更加显而易见。下面描述的附图仅仅是本申请的一些实施例，而不是对本申请的限制。
图1是本申请实施例的一种可批量取能的模块化换流电路组成示意图；
图2是本申请实施例的一种电容单元组成示意图；
图3a是本申请实施例的一种半桥电路组成的功率单元组成示意图；
图3b是本申请实施例的一种全桥电路组成的功率单元组成示意图；
图3c是本申请实施例的一种功率单元组成示意图；
图4是本申请实施例的一种高阻抗方式的接口单元组成示意图；
图5是本申请实施例的一种阻断方式的接口单元组成示意图；
图6是本申请实施例的一种变压单元组成示意图；
图7是本申请实施例的另一种变压单元组成示意图；
图8是本申请实施例的一种并联方式的连接网络组成示意图；
图9a是本申请实施例的一种串联方式的连接网络组成示意图；
图9b是本申请的一种串联方式的连接网络组成示意图的又一实施例；
图10是本申请实施例的一多个第一取能电源的串联方式的连接网络组成示意图；
图11是本申请实施例的一种可批量取能的模块化换流电路的合成回路系统组成示意图；
图12是本申请实施例的一种可批量取能的模块化换流电路的充电控制方法流程示意图；
图13是本申请实施例的一种换流阀低压加压试验系统的电路结构图；
图14是本申请实施例的另一种换流阀低压加压试验系统的电路结构图；
图15示出一示例性实施例的批量子模块功能预试验的控制方法的流程图；
图16示出一示例性实施例的子模块充电回路的示意图；
图17示出一示例性实施例的批量子模块逐级加压试验的控制方法的流程图；
图18示出一示例性实施例的批量子模块快速放电试验的控制方法的流程图；
图19示出一示例性实施例的批量子模块放电旁路试验的控制方法的流程图
图20是本申请实施例提供的一种换流阀高压运行电路示意图；
图21是本申请实施例提供的另一种换流阀高压运行电路示意图；
图22a是本申请实施例提供的一种二极管单元示意图；
图22b是本申请实施例提供的另一种二极管单元示意图；
图23是本申请实施例提供的一种换流阀高压运行电路的现场试验系统示意图；
图24是本申请实施例提供的另一种换流阀高压运行电路的现场试验系统示意图；
图25是本申请实施例提供的一种换流阀高压运行电路的现场试验系统接线示意图；
图26是本申请实施例提供的一种换流阀高压运行电路的现场试验系统单桥臂接线示意图；
图27是本申请实施例提供的一种换流阀高压运行电路的控制方法流程示意图；
图28是本申请实施例提供的一种顺控启动逻辑流程示意图；
图29是本申请实施例提供的一种直流充电逻辑流程示意图；
图30是本申请实施例提供的一种级联运行控制流程示意图；
图31是本申请实施例提供的一种运行结束后旁路检测流程示意图；
图32是本申请实施例提供的一种级联运行控制旁路检测流程示意图
图33是本申请实施例的一种柔直换流站低压加压系统的示意图；
图34是本申请实施例的另一种柔直换流站低压加压系统的示意图；
图35是本申请实施例的另一种柔直换流站低压加压系统的示意图；
图36是本申请实施例的另一种柔直换流站低压加压系统的示意图；
图37a是本申请实施例的一种低压电源的示意图；
图37b是本申请实施例的又一种低压电源的示意图；
图37c是本申请实施例的又一种低压电源的示意图；
图38示出一示例性实施例的一种第一取能电源充电控制方法的流程图；
图39是本申请实施例的一种桥臂主动均压控制方法的流程图；
图40是本申请实施例的一种分相直流加压控制方法的流程图；
图41是本申请实施例的一种柔直换流站低压加压控制方法的流程图。
具体实施方式
现在将参考附图更全面地描述示例实施例。然而，示例实施例能够以多种形式实施，且不应被理解为限于在此阐述的实施例；相反，提供这些实施例使得本申请将全面和完整，并将示例实施例的构思全面地传达给本领域的技术人员。在图中相同的附图标记表示相同或类似的部分，因而将省略对它们的重复描述。
附图中所示的流程图仅是示例性说明，不是必须包括所有的内容和操作/步骤，也不是必须按所描述的顺序执行。例如，有的操作/步骤还可以分解，而有的操作/步骤可以合并或部分合并，因此实际执行的顺序有可能根据实际情况改变。
本申请的说明书和权利要求书及上述附图中的术语“第一”、“第二”等是用于区别不同对象，而不是用于描述特定顺序。此外，术语“包括”和“具有”以及它们任何变形，意图在于覆盖不排他的包含。例如包含了一系列步骤或单元的过程、方法、系统、产品或设备没有限定于已列出的步骤或单元，而是可选地还包括没有列出的步骤或单元，或可选地还包括对于这些过程、方法、产品或设备固有的其他步骤或单元。
本领域技术人员可以理解，附图只是示例实施例的示意图，附图中的模块或流程并不一定是实施本申请所必须的，因此不能用于限制本申请的保护范围。
下面描述本申请的装置实施例，其可以用于执行本申请方法实施例。对于本申请装置实施例中未披露的细节，可参照本申请方法实施例。
图1是本申请实施例的一种可批量取能的模块化换流电路组成示意图之一。
可批量取能的模块化换流电路包括N个子模块，N个子模块的交流端串联连接，首端子模块和尾端子模块未连接的交流端引出作为换流电路的交流端，N为大于等于2的整数。
子模块包括功率单元1、电容单元2、变压单元3、子模块控制单元4、批量取能单元和旁路开关。
功率单元1包括功率半导体器件，功率单元1的交流端引出作为子模块的交流端。电容单元2与功率单元1并联连接，电容单元2包括第一直流电容C1,如图2所示。变压单元3连接电容单元2，从电容单元2取能，实现直流电压变换，为子模块控制单元4供电。子模块控制单元4连接变压单元3，控制功率单元1工作。批量取能单元包括第一取能电源6和连接网络30。第一取能电源6的负极连接首端子模块电容单元的负极。连接网络30的输入端与第一取能电源6的正极直接连接或经限流单元连接，连接网络30包括N个输出端，N个输出端分别与所有电容单元的正极直接连接或经限流单元连接，限流单元包括电阻或/和电感。旁路开关并联连接子模块的交流端。
功率单元1包括半桥电路或全桥电路，包括两电平或三电平的半桥或全桥电路。
根据一些实施例，半桥电路包括上管与下管，下管与子模块的交流输出端并联连接，如图3a所示。
根据一些实施例，全桥电路包括两个上管与两个下管，上管与下管串联构成桥臂后与电容单元并联，桥臂中点引出作为子模块交流输出端，如图3b所示。
根据一些实施例，换流电路中的子模块功率单元全部为相同的电路，全为半桥电路或全部为全桥电路或为全桥电路和半桥电路混合配置；图3c为类全桥型子模块电路。
可选地，子模块的交流端还并联旁路开关，旁路开关电动合闸，合闸后依靠机械力或磁力保持。
定义功率单元零电平状态：对于半桥电路，下管导通定义为零电平状态；对于全桥电路，两个上管同时导通或两个下管同时导通定义为零电平状态。
可选地，电容单元2还包括第二直流电容C2与接口单元5，接口单元5连接在第一直流电容C1与第二直流电容C2之间，第二直流电容C2连接在接口单元5与变压单元3之间。接口单元5的组成方式包括高阻抗方式或阻断方式。
高阻抗方式中，接口单元5包括电阻或/和电抗，接口单元5的等效阻值大于10kΩ，如图4所示。
阻断方式中，接口单元5包括阻断二极管单元，阻断二极管单元的阳极指向第一直流电容C1的正极，阻断二极管单元的阴极指向第二直流电容C2的正极，阻断二极管单元包括阻断二极管，或阻断二极管与分压电阻网络,如图5所示。
变压单元3包括至少一个直流变换器，直流变换器的输入端与电容单元2连接，如图6所示。直流变换器的数量大于1时，直流变换器的输出端直接并联连接或经串联二极管后再并联连接，如图7所示。
连接网络30包括并联方式连接网络或者串联方式连接网络。
根据一些实施例，并联方式连接网络包括N个二极管单元，N个二极管单元的阳极连接在一起作为连接网络的输入端，N个二极管单元的阴极依次引出作为所述连接网络的N个输出端，如图8所示。二极管单元包括二极管或串联连接的二极管与电阻或/和电感。
根据一些实施例，串联方式连接网络包括N-1个二极管单元，N-1个二极管单元同方向串联连接，第1个二极管单元的阳极作为连接网络的输入端，N-1个二极管单元的阳极以及第N-1个二极管单元的阴极依次引出作为连接网络的输出端，如图9a所示。
根据一些实施例，串联方式连接网络包括N个二极管单元，所述N个二极管单元同方向串联连接，第一个二极管单元的阳极作为所述连接网络的输入端，第N个二极管单元的阴极依次引出作为所述连接网络的输出端，如图9b所示。二极管单元包括二极管或串联连接的二极管与电阻或/和电 感。
可选地，连接网络30为串联方式连接网络时，换流电路还包括M个第一取能电源6。M个第一取能电源6分别与各个子模块的电容单元2并联连接，M为整数，1≤M≤N-1,当M≥2时，第一取能电源6的输出端串联连接防反二极管，防反二极管的阴极指向电容单元2的正极。本实施例中M＝2，如图10所示。
本实施例提供的技术方案，可批量取能的模块化换流电路将子模块电容分为两个电容的组合，根据内部电源单元的设计不同，可以灵活适应，一是电容快速充电，为子模块控制单元供电，或者与真实工况等效的充电方式，但采用了较少的外部电源和较低的电压，保证设备和人身安全。子模块控制单元上电后，可进行通讯对点试验，分步骤试验的方式可以降低试验风险，提高试验可靠性。同时，外部二次低压电源和来自子模块电容的电源构成冗余，更可靠的保证了子模块的控制供电。
图11是本申请实施例的一种可批量取能的模块化换流电路的合成回路系统组成示意图。
合成回路系统包括可批量取能的模块化换流电路、阀基控制单元50和第二取能电源60。阀基控制单元50与N个子模块控制单元4通信。第二取能电源60与换流电路的交流端连接。
可选地，合成回路系统还包括放电支路。放电支路与第二取能电源60并联连接，放电支路包括串联连接的放电开关61和放电电阻62，如图11所示。
图12是本申请实施例的一种可批量取能的模块化换流电路的充电控制方法流程示意图，包括以下控制流程。
在S10中，启动第一取能电源6，向所连接的子模块的电容单元2充电。
在S20中，充电达到阈值后，启动变压单元3中的直流变换器，为子模块控制单元4供电。
在S30中，通过子模块控制单元4控制功率单元1中的对应位置的功率半导体器件导通为功率单元零电平状态，为相邻子模块的电容单元建立导通回路。
在S40中，第一取能电源6或/和前级子模块的电容单元向相邻子模块的电容单元充电，使相邻子模块控制单元带电。
在S50中，依次完成所有子模块的电容单元充电，N个子模块控制单元4带电。
检测到第j子模块出现故障或第j+1子模块控制单元无法正常带电时，j为整数，1≤j≤N-1,还包括以下控制流程。
闭合第j子模块的旁路开关。如第j+1个子模块控制单元仍然无法正常带电，则结束充电，对第j子模块或/和第j+1子模块进行检修。如第j+1个子模块控制单元正常带电，则继续充电，并标记第j子模块故障，后续处理。
图13是本申请的一种可批量取能的模块化换流电路组成示意图的又一实施例。
如图13所示，可批量取能的模块化换流电路包括换流阀、低压加压单元和负载单元。
根据示例实施例，换流阀包括N个子模块1的交流端串联连接。N为大于等于1的整数。
根据示例实施例，子模块1为半桥电路或全桥电路与电容单元并联，功率器件与旁路开关2并联。
根据一些实施例，子模块1还包括子模块控制单元。
根据一些实施例，可批量取能的模块化换流电路还包括阀控系统，与子模块控制单元通信。
根据示例实施例，低压加压单元包括第一取能电源3和连接网络4。低压加压单元与子模块的电容单元连接。
根据示例实施例，负载单元包括放电开关5和放电电阻6，负载单元与换流阀并联。
第一取能电源启动，闭合放电开关，通过连接网络和放电电阻同时为所有所述子模块的所述电 容单元充电。
根据一些实施例，第一取能电源的负极连接首端子模块电容单元的负极；连接网络的输入端与第一取能电源的正极直接连接，连接网络包括N个输出端，N个输出端分别与所有电容单元的正极连接。
根据一些实施例，连接网络包括两种连接方式，并联方式和串联方式。
根据示例实施例，图13示出并联方式连接网络。并联方式连接网络包括N个二极管。N个二极管单元的阳极连接在一起作为连接网络的输入端，N个二极管单元的阴极依次引出作为连接网络的N个输出端。
根据一些实施例，可批量取能的模块化换流电路可实施下列控制方法中的一个或多个：
1、批量子模块功能预试验：第一取能电源启动，闭合放电开关，通过连接网络和放电电阻为所有子模块电容单元充电。
2、批量子模块逐级加压试验：第一取能电源启动，阀控单元控制子模块逐级输出零电平状态，子模块电容单元逐一充电，开展子模块功能试验。
3、批量子模块快速放电试验：断开第一取能电源，闭合放电开关，再通过阀控单元逐级开通功率单元中对应位置的功率半导体器件，子模块电容单元逐一放电。
4、批量子模块放电旁路试验：子模块电容单元放电至定值时自动闭合该子模块旁路开关。
根据一些实施例，上述控制方法可以组合成以下的一种或多种：
1、先进行批量子模块功能预试验和/或批量子模块逐级加压试验，试验完成后子模块电容单元自然放电。
2、先进行批量子模块功能预试验和/或批量子模块逐级加压试验，再进行批量子模块快速放电试验，试验完成后子模块电容单元快速放电。
3、先进行批量子模块功能预试验和/或批量子模块逐级加压试验，再进行批量子模块快速放电试验和批量子模块放电旁路试验，试验完成后子模块电容单元快速放电并闭合旁路开关。
4、先进行批量子模块功能预试验和/或批量子模块逐级加压试验，再进行批量子模块快速放电试验和批量子模块放电旁路试验，试验完成后子模块电容单元快速放电并闭合旁路开关，再手动分开旁路开关，再执行批量子模块功能预试验和/或批量子模块逐级加压试验，试验完成后子模块电容单元自然放电，或执行批量子模块功能预试验和/或批量子模块逐级加压试验，再进行批量子模块快速放电试验，试验完成后子模块电容单元快速放电，检查旁路开关分闸是否到位。
图14的连接网络连接方式为串联式。连接网络包括N-1个二极管单元，所述N-1个二极管单元同方向串联连接，第1个二极管单元的阳极作为所述连接网络的输入端，N-1个二极管单元的阳极以及第N-1个二极管单元的阴极依次引出作为所述连接网络的输出端，如图14所示。
图15示出一示例性实施例的批量子模块功能预试验的控制方法的流程图。
在S410，第一取能电源启动，闭合负载开关。
根据示例实施例，第一取能电源启动，闭合负载单元的负载开关，形成闭合回路。
在S420，第一取能电源通过连接网络和负载单元中的负载电阻为子模块电容单元充电。
在S430，子模块电容单元电压达到启动门槛值后，子模块控制单元启动。
在S440，检查阀控单元与子模块控制单元是否正常通信。
根据示例实施例，检查阀控单元与子模块控制单元是否正常通信，如出现通信故障，则定位故障子模块。
在S450，开展子模块功能试验。
在S460，判断是否有故障子模块。
根据示例实施例，若检测到有故障子模块，则转到S470；若没有故障子模块，则转到S480。
在S470，闭合故障子模块旁路开关或先闭合故障子模块旁路开关，再检修故障子模块。
根据示例实施例，若检测到子模块故障后，闭合故障子模块旁路开关或先闭合故障子模块旁路开关，再检修故障子模块后，转到S410。
在S480，结束。
图16示出一示例性实施例的子模块充电回路的示意图。
如图16所示，第一取能电源通过连接网络和负载单元中的负载电阻为子模块电容单元充电。
根据一些实施例，N个子模块的电容单元可以同时进行充电。
图17示出一示例性实施例的批量子模块逐级加压试验的控制方法的流程图。
在S610，第一取能电源启动；首端子模块电容单元充电。
根据示例实施例，第一取能电源为与其负极直接相连的子模块的电容单元充电。
在S620，首端子模块控制单元启动，功率单元输出零电平；为相邻子模块电容单元充电。
根据一些实施例，对于半桥电路，下管导通定义为零电平状态；对于全桥电路，两个上管同时导通或两个下管同时导通定义为零电平状态。
根据示例实施例，首端子模块电容单元充电完成后，首端子模块控制单元启动，使首端子模块的功率单元导通，第一取能电源给相邻子模块的电容单元充电。
在S630，相邻子模块控制单元启动并输出零电平状态。
根据示例实施例，相邻子模块电容单元充电完成后，相邻子模块的功率单元输出零电平，下一个相邻子模块电容单元充电。以此方式逐级充电，为所有子模块电容单元充电；使所有子模块控制单元启动。
在S640，开展子模块功能试验。
根据一些实施例，子模块功能试验包括电容电压采样校验。
根据一些实施例，采用并联方式连接网络时，第i个子模块电容单元电压采样值V SMi＝V S-V D-V G*(i-1)或者采样值V SMi＝V SM(i-1)-V G；
根据一些实施例，采用串联方式连接网络时，第i个子模块电容单元电采样值V SMi＝V S-V D*(i-1)-V G*(i-1)或者V SMi＝V SM(i-1)-V G-V D；
其中，V Smi第i个子模块电容单元电压采样值，V SM(i-1)第(i-1)个子模块电容单元电压采样值，V S为第一取能电源电压；V D为二极管管压降；V G为功率半导体器件管压降。
根据一些实施例，电容电压采样校验根据上述理论计算的采样值与实际采样值比较，当偏差高于门槛值时，判定试验不通过。
根据一些实施例，子模块功能试验包括交叉通信校验，交叉通信包括两种类型：
1)子模块控制单元与相邻的子模块控制单元两两交叉通信，并同时与阀控单元的两个不同通道通信；
2)多个子模块控制单元串联通信，并首尾两个子模块控制单元与阀控单元的两个不同通道通信；
交叉通信是指分别从阀控单元的同一个通道读取不同子模块电容电压采样值，如果数据符合电容电压采样校验的对应关系，则校验通过。
图18示出一示例性实施例的批量子模块快速放电试验的控制方法的流程图。
在S710，批量子模块功能预试验或批量子模块逐级加压试验执行完毕。
在S720，断开第一取能电源，闭合负载开关。
在S730，自首端或末端逐级开通子模块功率单元中对应位置的功率半导体器件。
根据一些实施例，所述对应位置的功率半导体器件是指半桥电路的上管或全桥电路的对管。
根据示例实施例，与第一取能电源直接相连的子模块为首端子模块，可以开通首端或者末端子模块的功率单元中的对应位置的功率半导体器件。
在S740，根据子模块电容单元的容值计算理论电压值，判断子模块电容单元放电的电压。
根据示例实施例，若电压偏差高于门槛值，记录并报警。
图19示出一示例性实施例的批量子模块放电旁路试验的控制方法的流程图。
在S810，批量子模块快速放电试验执行完毕。
在S820，子模块电容单元放电到低电压定值时，阀控单元或子模块控制单元下发命令闭合子模块旁路开关。
图20是本申请实施例提供的一种换流阀高压运行电路示意图，换流阀高压运行电路包括两个换流电路、连接电抗器2、一个或两个连接网络1。
两个换流电路分别包括N个子模块3和M个子模块3，N、M为大于等于1的整数，两个换流电路的一交流端经连接电抗器2连接，两个换流电路的另一交流端短接。
子模块3包括并联连接的直流电容C1与功率单元，功率单元包括功率半导体器件构成的半桥电路或/和全桥电路。子模块3的交流端串联连接，首端子模块和尾端子模块的交流端引出作为换流电路交流端，两个换流电路的一交流端经连接电抗器2连接，另一交流端短接。首端子模块为与连接网络的阳极端连接的子模块，尾端子模块为与连接网络的阴极端连接的子模块。子模块还包括子模块控制单元，控制功率单元工作。
连接网络1包括至少N-1个或至少M-1个二极管单元4。
二极管单元4同方向串联连接，连接网络1的阴极端与尾端子模块的直流电容C1的正极连接，所有二极管单元4的阳极端与对应换流电路的子模块3的直流电容C1的正极一一对应或经过第一限流器连接。二极管单元包括二极管，二极管阳极指向二极管单元的阳极端，阴极指向阴极端。
可选地，换流阀高压运行电路还包括至少一个第一取能电源5，第一取能电源5与对应换流电路的首端子模块的直流电容并联连接。第一取能电源5包括电源单元或串联连接的电源单元和二极管，电源单元包括直流电源，或交流电源与整流器。
第一取能电源5的输出电压固定或可调整，在本实施例中，第一取能电源5的输出电压小于子模块功率单元半导体器件的耐压值。如功率半导体器件耐压值是3300V，第一取能电源5可采用1500V的输出电压。
当一个换流电路配置连接网络时，第一取能电源的数量为1，与配置连接网络的换流电路首端子模块的直流电容并联连接，如图20所示。
当两个换流电路都配置连接网络时，第一取能电源的数量为2，分别与两个换流电路首端子模块的直流电容并联，如图21所示。
本实施例提供的技术方案，通过低压输出的第一取能电源可以解决众多子模块的供电问题，通过低压输出即可实现整个换流电路的充电，降低了试验条件和试验需求，适用于现场不具备高压大功率电源的场合。
可选地，二极管单元4还包括第二限流器，主要用于限制充电过程中的电流冲击，如图22a所示，第二限流器与二极管串联，第二限流器包括电阻和/或电感。
可选地，二极管单元还包括隔离开关，隔离开关与二极管串联连接，隔离开关的分合受子模块的控制单元控制，如图22b所示。
图23是本申请实施例提供的一种换流阀高压运行电路的现场试验系统示意图，换流阀高压运行电路的现场试验系统包括至少一个换流阀高压运行电路。
其中，换流阀高压运行电路的两个换流电路以阀塔型式安装，定义为工程阀塔10。
如图23所示，工程阀塔支撑绝缘子之间搭建横梁，连接电抗器2安装在横梁11上。横梁可以搭建在N1,N2,N3绝缘支撑位置，连接电抗器2也可独立放置于地面。
连接电抗器2与地电位之间保持绝缘距离d1，与两个工程阀塔之间保持绝缘距离分别为d2和d3，如图24所示。
连接电抗器2包括桥臂电抗器或桥臂电抗器的组合，连接电抗器2接入工程阀塔10之间。
在实际工程应用中，接线方式如图25所示，包括三相六桥臂，本实施例中每个桥臂包括两个工程阀塔10，两个工程阀塔的串联连接一端连接交流，另一端引出后通过穿墙套管12与桥臂电抗器2连接后与换流阀正极连接。
根据一些实施例，也可对现有接线方式进行更改，利用桥臂电抗器作为连接电抗器2，以一个桥臂为例，更改后接线如图26所示。更改后构成的运行电路即为图20所示的运行电路。
图27是本申请实施例提供的一种换流阀高压运行电路的控制方法流程示意图，包括级联充电控制和级联运行控制两种控制模式。
级联充电控制利用第一取能电源及级联式供能链为所有子模块直流电容充电，子模块的控制单元从直流电容取电后运行。
级联充电控制中，当第一取能电源的数量为1时，与第一取能电源连接的换流电路设为第一换流电路，另一个换流电路为第二换流电路。第一换流电路先执行顺控启动逻辑，启动完成后，执行直流充电逻辑，控制输出电压，为第二换流电路的子模块充电。当第一取能电源的数量为2时，2个换流电路分别执行顺控启动逻辑。
根据一些实施例，顺控启动逻辑如图28所示，包括：启动第一取能电源，为首端子模块直流电容充电，首端子模块控制电元上电运行；通过子模块的控制单元控制功率单元中的对应位置的功率半导体器件导通，输出零电平状态，为相邻子模块的直流电容建立导通回路，为相邻子模块直流电容充电，子模块控制单元上电；依次完成所有子模块的直流电容充电，使子模块控制单元均带电。
根据一些实施例，直流充电逻辑如图29所示，包括：调节与第一取能电源连接的换流电路输出电压，使电压由零逐渐升高，为第二换流电路子模块的直流电容充电，直至使第二换流电路子模块控制单元上电；控制第二换流电路中投入到充电回路中的子模块数量，使第二换流电路子模块直流电容电压达到预设值。
级联运行控制，级联充电控制完成后，两个换流电路控制电压与电流，复现换流电路的子模块电压和电流应力，第一取能电源在此过程中持续为两个换流电路持续补充损耗能量。
根据一些实施例，级联运行控制如图30所示，包括：任一换流电路子模块功率单元解锁启动，输出交流电压目标值；待交流电压稳定，另一换流电路子模块功率单元解锁启动，控制流过连接电抗器电流到目标值；待系统稳定后，检测电流控制换流电路的电压、电流，与给定值比较，判断是否满足试验要求。
其中，控制方法应用于现场试验系统时，交流电压目标值的设定根据连接电抗器的绝缘水平以及d1,d2,d3调整。
可选地，控制方法还包括：旁路开关检测控制，进行级联运行控制旁路检测以及运行结束后旁路检测，用于测试旁路开关是否能够正常工作。
根据一些实施例，运行结束后旁路检测如图31所示，包括：退出级联运行控制；停止第一取能 电源输出；依次旁路两个换流电路的子模块；检查旁路开关是否动作正确。
根据一些实施例，级联运行控制旁路检测如图32所示，包括：进入级联运行控制；稳定后，控制两个换流电路中子模块的旁路开关相继旁路动作；检测动作后运行状态正常，则减小级联运行控制时的交流电压目标值，否则执行运行结束后旁路检测。
本实施例提供的控制方法，包括启动充电、级联运行控制以及旁路检测，控制方法覆盖了换流阀试验的关键项目，本申请之前在换流阀现场试验时仅能够完成子模块的相关试验，本申请提出的方法实现了换流电路试验，为换流阀的工程应用提供了可靠保障。
图33是本申请实施例的一种柔直换流站低压加压系统的示意图。
本实施例提供一种柔直换流站低压加压系统，柔直换流站包括柔直换流阀、阀控制器。如图33所示，柔直换流阀包括3个并联的相桥臂A相、B相和C相。相桥臂A相、B相和C相为上桥臂和下桥臂串联，上桥臂正端电连接直流正极，上桥臂负端电连接下桥臂正端，下桥臂负端电连接直流负极。
根据一些实施例，低压加压系统的低电压为300V-1500V。
如图33所示，以A相为例，上桥臂和下桥臂结构相似，故没有画出下桥臂的具体结构。上桥臂包括N个子模块1和桥臂电抗器2，N为大于等于2的整数。子模块1包括2个功率半导体器件和1个电容，第一功率半导体器件和第二功率半导体器件同向串联后与电容并联。直流正极电连接桥臂电抗器2，桥臂电抗器2另一端电连接子模块1的2个功率半导体器件串联中点，第二功率半导体器件另一端连接下一个子模块的2个功率半导体器件串联中点，子模块依次串联，第N个子模块的第二功率半导体器件一端连接下桥臂的子模块的2个功率半导体器件串联中点，下桥臂的第N个子模块的第二功率半导体器件一端电连接桥臂电抗器后电连接直流负极。
根据示例实施例，A相、B相和C相电路结构相似。
根据一些实施例，子模块1可以为半桥电路、全桥电路、三电平电路或其组合；子模块1还包括子模块控制器，可以控制子模块运行。
根据示例实施例，阀控制器和子模块控制器通信，控制柔直换流站低压加压系统的运行。
如图33所示，低压加压系统3包括第一取能电源4和连接网络5。第一取能电源4正极电连接连接网络5的正极。
根据一些实施例，连接网络5包括至少N-1或2N-1个二极管单元。
如图33所示，本实施例中，连接网络5与上桥臂的A相连接，包括N-1个二极管单元。
根据一些实施例，连接网络5与相桥臂连接时，包含2N-1个二极管单元。
根据一些实施例，二极管单元包括二极管或二极管与限流单元6串联。
如图33所示，本实施例中，二极管单元与子模块连接时是通过限流单元连接。
根据示例实施例，二极管单元同方向串联连接，二极管阳极端口定义为二极管单元的阳极端，二极管阴极端口定义为阴极端。
根据一些实施例，所有二极管单元的阳极端以及末端二极管单元的阴极端构成与子模块数量相同的引出点，与子模块直流电容的正极一一对应连接或经过限流单元6后一一对应连接。
如图33所示，本实施例中，所有二极管单元的阳极端以及末端二极管单元的阴极端构成与子模块数量相同的引出点，与子模块直流电容的正极经过限流单元6后一一对应连接。
根据一些实施例，限流单元6由电阻和/或电感构成。
根据示例实施例，当柔直换流阀直流正极和负极对地电压绝对值相等或相近时，第一取能电源4与任意上桥臂负端的子模块直流电容并联连接；连接网络依次连接该桥臂其他子模块的直流电容正 极。
当柔直换流阀直流负极接地时，第一取能电源4与任意下桥臂或相桥臂负端的子模块直流电容并联连接；连接网络依次连接该桥臂其他子模块的直流电容正极，如图34所示。
当柔直换流阀直流正极接地时，第一取能电源4经过隔离模块7后与任意上桥臂、下桥臂或相桥臂负端的子模块直流电容并联连接；连接网络依次连接该桥臂其他子模块的直流电容正极，如图35所示。根据一些实施例，隔离模块7为隔离变压器。
当柔直换流阀不接地或经接地开关接地且接地开关8断开时，第一取能电源4与任意上桥臂、下桥臂或相桥臂负端的子模块直流电容并联连接；连接网络依次连接该桥臂其他子模块的直流电容正极，如图36所示。
第一取能电源为直流电源，其中负极接地，如图37a所示。
第一取能电源包括二极管9和直流电源，二极管9阳极连接直流电源正极，如图37b所示。
第一取能电源输出串联第一高压开关10,第一高压开关10的绝缘电压水平不低于柔直换流阀交流侧电压，如图37c所示。
图38示出一示例性实施例的一种第一取能电源充电控制方法的流程图。
在S601，第一取能电源启动，为充电桥臂中与第一取能电源连接的子模块直流电容充电，该子模块控制器上电运行。
根据示例实施例，以第一取能电源给A相上桥臂充电为例，第一取能电源启动，为A相的上桥臂的第N个子模块的直流电容充电，A相的上桥臂的第N个子模块控制器上电运行，控制第N个子模块的第二功率半导体导通。
在S603，控制所述子模块输出零电平，为相邻子模块的直流电容建立充电回路，相邻子模块直流电容电压达到启动值Vc1。
根据示例实施例，A相的上桥臂的子模块控制器控制所述子模块输出零电平，为相邻子模块的直流电容建立充电回路，即A相的上桥臂的第N个子模块的第二功率半导体器件导通，使A相的上桥臂的第N-1个子模块的直流电容电压达到启动值Vc1，第N-1个子模块控制器上电运行，控制第N-1个子模块的第二功率半导体器件导通。
在S605，依次完成所有子模块的直流电容充电，该充电桥臂的子模块控制器均带电。
根据示例实施例，A相的上桥臂依次完成所有子模块的直流电容充电，A相的上桥臂的子模块的直流电容电压达到启动值Vc1，该充电桥臂的子模块控制器均带电。
图39是本申请实施例的一种桥臂主动均压控制方法的流程图。
在S701，如充电桥臂为上桥臂或下桥臂时，同相的另一桥臂记做充电同相桥臂；如充电桥臂为相桥臂，则充电同相桥臂等效为短接。
根据示例实施例，以第一取能电源给A相上桥臂充电为例，则A相的下桥臂记做充电同相桥臂。
在S702，充电桥臂子模块循环旁路均压充电，使其子模块直流电容电压达到额定值Vc2，阀控制器控制充电桥臂输出第一受控电压源。
根据示例实施例，A相的上桥臂的直流电容电压达到Vc1后，控制A相的上桥臂的子模块的第二功率半导体器件轮流导通，使其子模块直流电容电压达到额定值Vc2，A相的上桥臂的直流电容为第一受控电压源输出电压。
在S703，第一受控电压源串联充电同相桥臂，为另外两相桥臂子模块直流电容充电。
根据示例实施例，A相的上桥臂与下桥臂串联后，给B相、C相的上下桥臂的子模块的直流电容充电，使B相、C相的上下桥臂的子模块的直流电容电压达到启动值Vc1。
在S704，另外两相桥臂子模块分别或同时进行循环旁路均压充电，使其子模块直流电容电压达到额定值Vc2。
根据示例实施例，B相、C相的上下桥臂的直流电容电压达到Vc1后，控制B相、C相的上下桥臂的子模块的第二功率半导体器件轮流导通，使其子模块直流电容电压达到额定值Vc2。
在S705，判断充电桥臂是否为相桥臂。
若充电桥臂是相桥臂，则步骤结束；若充电桥臂不是相桥臂，则继续执行下面步骤。
在S706，与充电桥臂不同的任一相上下桥臂分别输出第二受控电压源和第三受控电压源。
根据示例实施例，阀控制器控制与充电桥臂不同的任一相上下桥臂分别输出第二受控电压源和第三受控电压源。即B相和C相的上下桥臂分别输出第二受控电压源和第三受控电压源。
在S707，对充电同相桥臂进行充电。
根据示例实施例，第一受控电压源、第二受控电压源和第三受控电压源与充电同相桥臂组成回路，对充电同相桥臂进行充电。即A相的上桥臂，B相和C相的上下桥臂对A相的下桥臂进行充电，使A相的下桥臂的子模块的直流电容电压达到Vc1。
在S708，充电同相桥臂子模块循环旁路均压充电，使其子模块直流电容电压达到额定值Vc2。
根据示例实施例，A相的下桥臂的直流电容电压达到Vc1后，控制A相的下桥臂的子模块的第二功率半导体器件轮流导通，使其子模块直流电容电压达到额定值Vc2。
在S709，结束。
根据示例实施例，完成桥臂主动均压控制，流程结束。
图40是本申请实施例的一种分相直流加压控制方法的流程图。
在S801，完成桥臂主动均压控制步骤。
桥臂主动均压控制步骤如图7所示。
在S803，调节任一相或多相桥臂输出受控电压源，使相桥臂整体输出直流电压2Udc。
根据示例实施例，第一受控电压源、第二受控电压源和第三受控电压源可以均输出直流电压，使相桥臂整体输出直流电压2Udc。
根据示例实施例，直流电压Udc的大小可以调整，包括以下两种方法：调节上或/和下桥臂中输出电压Vc2的子模块个数；或调节上或/和下桥臂中每个子模块的直流电容额定电压值Vc2。
其中，Udc＝Vc2*P，P为上或下桥臂中输出电压Vc2的子模块个数。P最后稳定在N/2。
根据示例实施例，所述受控电压源输出直流电压的上升速率可以调整，控制放电电流小于预设值。在此状态下，受控电压源为直流母线上的其他桥臂充电，而自身子模块中直流电源处于放电状态，因此，若调节输出直流电压的上述速率如果过快，会导致放电电流过大，需要合理的选择上升速率，控制放电电流小于预设值。
根据示例实施例，模拟实际工况，第二受控电压源、第三受控电压源分别为合成电压Uac 1和Uac2，合成电压由交流电压Uac和直流电压Udc叠加，其中，Uac1＝Udc+Uac，Uac2＝Udc-Uac，Uac1+Uac2＝2Udc。
根据示例实施例，分相直流加压控制方法通过投入不同的相或者切换投入不同的子模块，观测输出的电压和波形，判断子模块是否正常工作。
图41是本申请实施例的一种柔直换流站低压加压控制方法的流程图。
在S910，完成桥臂主动均压步骤。
根据示例实施例，完成桥臂主动均压步骤，步骤如图7所示；若第一取能电源中有第一高压开关10，则分断第一高压开关10。
在S930，解锁柔直换流阀，直流正负极呈现直流电压，三相桥臂中点呈现三相交流电压。
在S950，子模块电容电压下降到阈值后，闭锁柔直换流阀，停止试验。
根据示例实施例，子模块运行过程中消耗电能，使得子模块电容电压下降到一定阈值，则闭锁柔直换流阀，停止试验。
根据示例实施例，本申请还具有辅助功能有益效果中的一个或多个：
1、在加压过程中对直流、交流附属设备进行耐压试验和采样校准。
2、在加压过程中发生绝缘击穿故障，利用桥臂快速过流保护和/或功率半导体器件短路保护保障设备安全。桥臂快速过流保护是通过阀控制器检测桥臂电流，当电流超过动作门槛值时，闭锁柔直换流阀，停止试验；功率半导体器件短路保护是通过子模块控制器检测到功率器件发生短路故障后，立即闭锁并旁路子模块，并将故障上报给阀控制器，当同时发生故障的子模块超过一定数量时，闭锁柔直换流阀，停止试验。
应清楚地理解，本申请描述了如何形成和使用特定示例，但本申请不限于这些示例的任何细节。相反，基于本申请公开的内容的教导，这些原理能够应用于许多其它实施例。
此外，需要注意的是，上述附图仅是根据本申请示例性实施例的方法所包括的处理的示意性说明，而不是限制目的。易于理解，上述附图所示的处理并不表明或限制这些处理的时间顺序。另外，也易于理解，这些处理可以是例如在多个模块中同步或异步执行的。
以上具体地示出和描述了本申请的示例性实施例。应可理解的是，本申请不限于这里描述的详细结构、设置方式或实现方法；相反，本申请意图涵盖包含在所附权利要求的精神和范围内的各种修改和等效设置。

Claims (16)

  1. 一种模块化批量取能换流电路，包括批量取能单元和N个子模块，N个所述子模块的交流端串联连接，N为大于等于2的整数，其特征在于，
    所述子模块包括：
    功率单元，包括功率半导体器件，所述功率单元的交流端引出作为所述子模块的交流端；
    电容单元，与所述功率单元并联连接；
    所述批量取能单元包括：
    第一取能电源，所述第一取能电源的负极与所述N个子模块的首端子模块的电容单元的负极连接或经限流单元连接；
    连接网络，所述连接网络的输入端与所述第一取能电源的正极直接连接或经限流单元连接；所述连接网络的N个输出端分别和所述电容单元的正极连接或经限流单元连接。
  2. 如权利要求1所述的换流电路，其特征在于，
    所述换流电路中的子模块功率单元全部为半桥电路或全部为全桥电路或为全桥电路和半桥电路混合配置，其中：
    半桥电路，包括上管与下管，述上管与下管串联后与所述电容单元并联，所述上管或下管的集电极与发射极引出作为子模块的交流端；
    全桥电路，包括两个上管与两个下管，上管与下管串联构成桥臂后与所述电容单元并联，桥臂中点引出作为子模块交流输出端；
    所述上管和下管为全控型功率半导体器件或所述器件的并联。
  3. 如权利要求1所述的换流电路，其特征在于，所述连接网络包括：
    并联方式连接网络，包括N个二极管单元，所述N个二极管单元的阳极连接在一起作为所述连接网络的输入端，所述N个二极管单元的阴极依次引出作为所述连接网络的N个输出端；或者
    串联方式连接网络，所述串联方式连接网络包括以下两种：
    方式1：包括N个二极管单元，所述N个二极管单元同方向串联连接，第一个二极管单元的阳极作为所述连接网络的输入端，第N个二极管单元的阴极依次引出作为所述连接网络的输出端；
    方式2：包括N-1个二极管单元，所述N-1个二极管单元同方向串联连接，第一个二极管单元的阳极作为所述连接网络的输入端，第1个二极管的阳极和第N-1个二极管单元的阴极依次引出作为所述连接网络的输出端；
    其中，所述二极管单元包括二极管或串联连接的二极管与电阻或/和电感。
  4. 如权利要求1所述的换流电路，其特征在于，还包括：
    旁路开关，并联连接所述子模块的交流端；
    放电支路，与所述换流电路并联连接，所述放电支路包括串联连接的放电开关和放电电阻和/或电感和/或电感电容构成的谐振回路。
  5. 如权利要求1所述的换流电路，其特征在于，所述首端子模块为换流电路中电位最低的子模块。
  6. 一种基于权利要求1-5中任一项所述的换流电路的控制方法，其特征在于，包括以下步骤中的一种或多种的组合：
    批量子模块功能预试验：所述第一取能电源启动，闭合所述放电开关，通过所述连接网络和所述放电电阻为所述子模块的所述电容单元充电；
    批量子模块逐级加压试验：所述第一取能电源启动，子模块控制单元控制所述子模块逐级输出零电平状态，所述子模块的所述电容单元逐一充电，开展子模块功能试验；
    批量子模块快速放电试验：所述批量子模块功能预试验或所述批量子模块逐级加压试验完成后，断开所述第一取能电源，闭合所述放电开关，通过所述子模块控制单元逐级开通所述功率单元中对应位置的功率半导体器件，所述子模块的所述电容单元逐一放电；
    批量子模块放电旁路试验：所述批量子模块快速放电试验完成后，所述子模块的所述电容单元放电至定值，自动闭合所述子模块的所述旁路开关。
  7. 如权利要求6所述的控制方法，其特征在于，所述批量子模块逐级加压试验包括：
    启动所述第一取能电源，向所连接的子模块的所述电容单元充电；
    充电达到阈值后，为所述子模块控制单元供电；
    通过所述子模块控制单元控制所述功率单元中的对应位置的功率半导体器件导通为功率单元零电平状态，为相邻子模块的电容单元建立导通回路；
    所述第一取能电源/前级子模块的电容单元向相邻子模块的电容单元充电，使相邻子模块的子模块控制单元带电；
    依次完成所有子模块的电容单元充电，N个子模块控制单元带电。
  8. 如权利要求6所述的控制方法，其特征在于：
    对于半桥电路，所述功率半导体器件下管导通定义为所述零电平状态；
    对于全桥电路，两个所述功率半导体器件上管同时导通或两个所述功率半导体器件下管同时导通定义为所述零电平状态。
  9. 一种高压运行电路，其特征在于，包括：
    如权利要求1-3中任一项所述的模块化批量取能换流电路和第二换流电路；其中：
    所述第二换流电路包括M个子模块，M个所述子模块的交流端串联连接，M为大于等于2的整数，或包括如权利要求1-3中任一项所述的批量取能换流电路；
    所述第二换流电路的首端子模块和尾端子模块的交流端引出作所述第二换流电路的交流端；
    所述批量取能换流电路与所述第二换流电路的一交流端经连接电抗器连接，另一交流端短接。
  10. 一种基于权利9所述的高压运行电路的控制方法，其特征在于，包括：
    级联充电控制，利用所述第一取能电源和连接网络为所有子模块的电容单元充电，子模块控制单元从所述电容单元取电后运行；
    级联运行控制，所述级联充电控制完成后，所述批量取能换流电路与所述第二换流电路控制电压与电流，所述第一取能电源为所述批量取能换流电路与所述第二换流电路补充损耗能量。
  11. 一种柔直换流站低压加压系统，其特征在于，所述柔直换流站包括柔直换流阀、阀控制器，其中：
    所述柔直换流阀包括3个并联的相桥臂，所述相桥臂为上桥臂和下桥臂串联，所述上桥臂正端连接直流正极，所述上桥臂负端连接所述下桥臂正端，所述下桥臂负端连接直流负极；
    根据所述柔直换流阀的接地方式，相应的上桥臂或下桥臂或相桥臂配置为如权利要求1-5中任一项所述的批量取能换流电路，其他桥臂配置为子模块串联的换流电路；
    所述阀控制器与控制子模块工作的子模块控制单元通信。
  12. 如权利要求11所述的柔直换流站低压加压系统，配置方式与所述接地方式的对应关系包括下述之一：
    所述柔直换流阀的所述直流负极接地，至少一个下桥臂或相桥臂配置为批量取能换流电路；
    所述柔直换流阀的所述直流正极接地，所述第一取能电源经隔离模块与所述电容单元隔离，上桥臂或下桥臂或相桥臂配置为批量取能换流电路；
    所述柔直换流阀的所述直流正极和所述直流负极对地电压绝对值相等或相近时，上桥臂或相桥臂配置为批量取能换流电路；
    所述柔直换流阀不接地或经接地开关接地且接地开关断开，上桥臂或下桥臂或相桥臂配置为批量取能换流电路。
  13. 一种如权利要求11-12中任一项所述的柔直换流站低压加压系统的控制方法，其特征在于，包括：
    所述第一取能电源为配置为批量取能换流电路的所述子模块的所述直流电容充电，该所述批量取能换流电路定义为充电桥臂；
    所述充电桥臂充电完成后，所述充电桥臂启动运行，输出可控电压为所述柔直换流阀的其他桥臂充电；
    所述其他桥臂充电完成后，任一相所述上桥臂、所述下桥臂控制为电压源，在所述直流正极和所述直流负极上等效施加直流电压，该过程定义为加压过程。
  14. 如权利要求13所述的控制方法，其特征在于，还包括第一高压开关，与所述第一取能电源串联，三相桥臂充电完成后，分断所述第一高压开关,所述三相桥臂解锁，所述直流正极、所述直流负极呈现直流电压，所述三相桥臂中点呈现三相交流电压。
  15. 如权利要求13所述的控制方法，其特征在于，还包括：
    在加压过程中对直流、交流设备或交直流线路进行耐压试验和/或采样校准；
    在加压过程中发生绝缘击穿故障时，利用桥臂快速过流保护和/或功率半导体器件短路保护保障设备安全。
  16. 一种用于换流阀的现场测试方法，所述换流阀包括6个桥臂和阀控制单元，所述桥臂包括如权利要求1-5中任一项所述的换流电路，所述换流电路包括N个子模块，所述子模块和所述阀控制单元光纤连接，其特征在于，所述现场测试方法包括：
    所述连接网络的N个输出端连接至N个子模块的所述电容单元的正极；
    所述第一取能电源启动；
    所述阀控制单元识别通信建立的所述子模块与物理位置是否一致；
    批量取能，所述子模块进行功能测试或所述阀控制单元更新程序。
PCT/CN2022/071342 2021-01-13 2022-01-11 模块化批量取能换流电路及控制方法 WO2022152124A1 (zh)

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