Converter valve high-voltage operation circuit, on-site test system and control method

Abstract

The present application provides a commutation valve high-voltage operation circuit, a field test system and a control method. The operation circuit includes two commutation chains and one or two cascaded energy supply chains. The two commutation chains respectively include N sub-modules and M sub-modules; the cascaded energy supply chain includes at least N - 1 or at least M - 1 diode units; the sub-module includes a DC capacitor and a power unit connected in parallel; the AC ends of the sub-modules are connected in series, and the AC ends of the first terminal sub-module and the last terminal sub-module are led out as the AC ends of the commutation chain. One AC end of the two commutation chains is connected through a connection reactor, and the other AC end is short-circuited; the diode units are connected in series in the same direction. The cathode end of the cascaded energy supply chain is connected to the positive electrode of the DC capacitor of the last terminal sub-module, and the anode ends of all diode units are connected to the positive electrodes of the DC capacitors of the corresponding sub-modules of the commutation chain one by one or through a first current limiter.

Description

Technical Field

[0001] This application relates to the technical field of high-power power electronic conversion, and specifically relates to a commutation valve high-voltage operation circuit, a field test system, and a control method. Background Art

[0002] With the application and development of power electronic technology in the power system, power electronic devices are developing towards the direction of high voltage, large capacity, and modularization, and are widely used in fields such as flexible DC transmission systems and chain static var generators, which are generally composed of several series-connected or parallel-connected sub-modules.

[0003] Taking the flexible DC system of offshore wind power as an example, the grid connection of offshore wind power is an important application of flexible DC transmission. The flexible DC offshore converter station needs to be built on an offshore platform. Considering the limitations of offshore construction conditions, it is impossible to install and test large equipment at sea. The equipment needs to be installed and debugged at the dock and then the entire offshore platform is transported to the designated sea area. If quality defects or other problems are found in large equipment after the flexible DC offshore converter station reaches the designated sea area, the entire platform needs to be transported to the test dock for processing, and the cost and time cost are very high.

[0004] Therefore, for the above application conditions, the link of equipment testing at the dock is crucial, but the dock usually can only provide low-capacity low-voltage power supplies. Existing testing technologies need to use high voltage to test the commutation chain. For example, in the patent "CN107561456A, a power module testing device and testing method", this scheme needs to use an externally applied high-voltage power supply to charge the sub-modules of the commutation chain and cannot complete the experiment relying on a low-capacity low-voltage power supply. The patent "CN111026082 A, a commutation chain and its valve base controller testing circuit and testing method" also provides a commutation chain testing circuit and testing method. This method uses an auxiliary commutation valve with a low-voltage output and a connecting reactor to construct a constant current source, and uses the low-voltage constant current source to supply energy to the commutation valve to be tested. Due to the limitation of the output voltage of the DC auxiliary power supply of the auxiliary commutation valve, it cannot output high voltage through cascade connection. Therefore, during the charging and testing process, the two ends of the commutation valve to be tested cannot withstand high voltage, and most of the commutation valve sub-modules are in a bypass state, and only a few sub-modules are rotated and put into the circuit. Essentially, it is still a low-voltage testing system, with low testing efficiency and unable to verify the operating conditions of high-voltage and high-power operation.

[0005] On the other hand, taking the flexible DC transmission project as an example, usually during the project construction process, the sub-modules need to be assembled into a valve tower first, and then the commutation valve is tested. After the commutation valve forms a tower, the flexibility of the test is greatly restricted. Existing test schemes can only perform subsystem tests such as sub-module function tests or insulation tests; due to the lack of a high-voltage and high-power operation test scheme for the entire commutation chain, the test items are incomplete and the test efficiency is low. Summary of the Invention

[0006] An embodiment of the present application provides a high-voltage operation circuit for a commutation valve, which includes two commutation chains and one or two cascaded energy supply chains. The two commutation chains respectively include N sub-modules and M sub-modules, where N and M are integers greater than or equal to 1. The cascaded energy supply chain includes at least N - 1 or at least M - 1 diode units. The sub-module includes a DC capacitor and a power unit connected in parallel. 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 are connected in series, and the AC ends of the first terminal sub-module and the last terminal sub-module are led out as the AC ends of the commutation chain. One AC end of the two commutation chains is connected through a connection reactor, and the other AC end is short-circuited. The first terminal sub-module is the sub-module connected to the anodic end of the cascaded energy supply chain, and the last terminal sub-module is the sub-module connected to the cathodic end of the cascaded energy supply chain. The diode units are connected in series in the same direction. The cathodic end of the cascaded energy supply chain is connected to the positive electrode of the DC capacitor of the last terminal sub-module, and the anodic ends of all diode units are in one-to-one correspondence with the positive electrodes of the DC capacitors of the corresponding sub-modules of the commutation chain or are connected through a first current limiter.

[0007] According to some embodiments, the high-voltage operation circuit further includes at least one charging and energy supplementing module, and the charging and energy supplementing module is connected in parallel with the DC capacitor of the first terminal sub-module of the corresponding commutation chain. The charging and energy supplementing module includes a power supply unit or a power supply unit and a diode connected in series. The power supply unit includes a DC power supply, or an AC power supply and a rectifier.

[0008] According to some embodiments, the diode unit further includes a second current limiter, and the second current limiter is connected in series with the diode. Both the first current limiter and the second current limiter include a resistor and / or an inductor.

[0009] According to some embodiments, the diode unit further includes a disconnector, and the disconnector is connected in series with the diode. The opening and closing of the disconnector are controlled by the control unit of the sub-module.

[0010] According to some embodiments, the half-bridge circuit includes an upper tube and a lower tube connected in series. After the upper tube and the lower tube are connected in series, they are connected in parallel with the DC capacitor. The collector and emitter of the upper tube or the lower tube are led out as the AC end of the sub-module. The full-bridge circuit includes two bridge arms connected in parallel. Each bridge arm includes two upper tubes and two lower tubes connected in series. The bridge arm is connected in parallel with the DC capacitor, and the midpoint of the two bridge arms is led out as the AC end of the sub-module. All the sub-module power units in the commutation chain are all half-bridge circuits or all full-bridge circuits or a mixed configuration of full-bridge circuits and half-bridge circuits. The AC ends of the sub-modules are also connected in parallel with a bypass switch. The bypass switch is electrically closed and remains closed by mechanical force or magnetic force after closing.

[0011] According to some embodiments, the commutation chain further includes a water cooling unit, a control unit, and a measurement unit. The cooling unit provides cooling for the operation of the commutation chain. The control unit includes a main control unit and a valve control unit. The main control unit communicates with the valve control unit, and the valve control unit communicates with the control units of the sub-modules. The measurement unit is configured to measure the current and voltage of the connecting reactor and / or the commutation chain to provide monitoring for the operation of the commutation chain.

[0012] The embodiment of the present application further provides a field test system for a commutation valve high-voltage operation circuit, including at least one commutation valve high-voltage operation circuit as described above. Among them, at least two commutation chains are installed in the form of a valve tower, defined as an engineering valve tower. An insulation distance d1 is maintained between the connecting reactor and the ground potential, and insulation distances d2 and d3 are maintained between the connecting reactor and the two engineering valve towers respectively.

[0013] According to some embodiments, a crossbeam is built between the support insulators of the engineering valve tower, and the connecting reactor is installed on the crossbeam. The connecting reactor includes a bridge arm reactor or a combination of bridge arm reactors, and the connecting reactor is connected between the engineering valve towers.

[0014] The embodiment of the present application further provides a control method, which is applied to the commutation valve high-voltage operation circuit as described above or the field test system of the commutation valve high-voltage operation circuit. The control method includes: cascade charging control, using the charging and energy supplement module and the cascade energy supply chain to charge the DC capacitors of all sub-modules. After the control unit of the sub-module takes power from the DC capacitor, it operates; cascade operation control, after the cascade charging control is completed, the two commutation chains control the voltage and current, and the charging and energy supplement module continuously supplements the loss energy for the two commutation chains during this process.

[0015] According to some embodiments, the control method further includes: bypass switch detection control, performing cascade operation control bypass detection and bypass detection after operation ends to test whether the bypass switch can work normally.

[0016] According to some embodiments, in the cascade charging control, when the number of charging and energy supplement modules is 1, the commutation chain connected to the charging and energy supplement module first executes the sequence control start logic. After the start is completed, it executes the DC charging logic to control the output voltage and charge the sub-modules of the other commutation chain. When the number of charging and energy supplement modules is 2, the two commutation chains respectively execute the sequence control start logic.

[0017] According to some embodiments, the sequence control start-up logic includes: starting the charging and energy supplementing module to charge the DC capacitor of the first terminal module, and the first terminal module controls the electrical element to be powered on and operate; controlling the power semiconductor device at the corresponding position in the power unit to conduct through the control unit of the sub-module, outputting a zero-level state, establishing a conduction loop for the DC capacitor of the adjacent sub-module, charging the DC capacitor of the adjacent sub-module, and powering on the sub-module control unit; sequentially completing the charging of the DC capacitors of all sub-modules to make all sub-module control units charged.

[0018] According to some embodiments, the DC charging logic includes: adjusting the output voltage of the commutation chain connected to the charging and energy supplementing module to gradually increase the voltage from zero to charge the DC capacitor of another commutation chain sub-module until the control unit of another commutation chain sub-module is powered on; controlling the number of sub-modules put into the charging circuit in the other commutation chain to make the DC capacitor voltage of the other commutation valve sub-module reach a preset value.

[0019] According to some embodiments, the cascaded operation control includes: unlocking and starting the power unit of any commutation chain sub-module to output an AC voltage target value; waiting for the AC voltage to be stable, unlocking and starting the power unit of another commutation chain sub-module, and controlling the current flowing through the connecting reactor to the target value; after the system is stable, detecting the voltage and current of the current-controlled commutation chain, comparing with the given value, and judging whether the test requirements are met.

[0020] According to some embodiments, when the control method is applied to the on-site test system, the setting of the AC voltage target value is adjusted according to the insulation level of the connecting reactor and d1, d2, d3.

[0021] According to some embodiments, the bypass detection after operation includes: exiting the cascaded operation control; stopping the output of the charging and energy supplementing module; bypassing the sub-modules of the two commutation chains in sequence; checking whether the bypass switch operates correctly.

[0022] According to some embodiments, the cascaded operation control bypass detection includes: entering the cascaded operation control; after stabilization, controlling the bypass switches of the sub-modules in the two commutation chains to perform bypass operations successively; if the operating state is normal after detection, reducing the AC voltage target value during the cascaded operation control, otherwise performing the bypass detection after operation.

[0023] The technical solution provided by the embodiments of this application uses a cascaded power supply chain to achieve the step-by-step charging of the DC capacitors of the sub-modules. Combining the technical advantages of the commutation chain that can extract energy at low voltage, this application also proposes a scheme of power push-pull between two commutation chains. Using a low-voltage power supply to supply energy to charge one commutation chain, and then the output voltage of one commutation chain can be used to charge another commutation chain. By simply adding a connecting reactor, the power push-pull between the two commutation chains is achieved. The connecting reactor can also use the arm reactor in the project. This scheme has low cost and high reliability, and solves the problem that it is difficult for the existing commutation chain to conduct high-voltage and high-power operation tests. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of this application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0025] Figure 1 It is a schematic diagram of a commutation valve high-voltage operation circuit provided by the embodiments of this application.

[0026] Figure 2 It is another schematic diagram of a commutation valve high-voltage operation circuit provided by the embodiments of this application.

[0027] Figure 3a It is a schematic diagram of a diode unit provided by the embodiments of this application.

[0028] Figure 3b It is another schematic diagram of a diode unit provided by the embodiments of this application.

[0029] Figure 4a It is a schematic diagram of a power unit provided by the embodiments of this application.

[0030] Figure 4b It is another schematic diagram of a power unit provided by the embodiments of this application.

[0031] Figure 4c It is yet another schematic diagram of a power unit provided by the embodiments of this application.

[0032] Figure 5 It is a schematic diagram of a field test system for a commutation valve high-voltage operation circuit provided by the embodiments of this application.

[0033] Figure 6 It is another schematic diagram of a field test system for a commutation valve high-voltage operation circuit provided by the embodiments of this application.

[0034] Figure 7It is a schematic wiring diagram of a field test system for a converter valve high-voltage operation circuit provided by an embodiment of the present application.

[0035] Figure 8 It is a schematic single-bridge arm wiring diagram of a field test system for a converter valve high-voltage operation circuit provided by an embodiment of the present application.

[0036] Figure 9 It is a schematic flowchart of a control method for a converter valve high-voltage operation circuit provided by an embodiment of the present application.

[0037] Figure 10 It is a schematic flowchart of a sequence control start-up logic provided by an embodiment of the present application.

[0038] Figure 11 It is a schematic flowchart of a DC charging logic provided by an embodiment of the present application.

[0039] Figure 12 It is a schematic flowchart of a cascade operation control provided by an embodiment of the present application.

[0040] Figure 13 It is a schematic flowchart of a bypass detection process after operation provided by an embodiment of the present application.

[0041] Figure 14 It is a schematic flowchart of a cascade operation control bypass detection provided by an embodiment of the present application. Detailed implementation manners

[0042] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present application.

[0043] It should be understood that the terms "first", "second", etc. in the claims, the description, and the drawings of the present application are used to distinguish different objects, rather than to describe a specific order. The terms "including" and "comprising" used in the description and claims of the present application indicate the presence of the described features, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0044] Figure 1 It is a schematic diagram of a converter valve high-voltage operation circuit provided by an embodiment of the present application. The converter valve high-voltage operation circuit includes two converter chains, a connecting reactor 2, and one or two cascade energy supply chains 1.

[0045] The two commutation chains 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 terminal of the two commutation chains is connected via a connecting reactor 2, and the other AC terminals of the two commutation chains are short-circuited.

[0046] The sub-module 3 includes a DC capacitor C1 and a power unit connected in parallel. The power unit includes a half-bridge circuit and / or a full-bridge circuit composed of power semiconductor devices. The AC terminals of the sub-modules 3 are connected in series, and the AC terminals of the first sub-module and the last sub-module are led out as the AC terminals of the commutation chain. One AC terminal of the two commutation chains is connected via a connecting reactor 2, and the other AC terminal is short-circuited. The first sub-module is the sub-module connected to the anodic end of the cascaded energy supply chain, and the last sub-module is the sub-module connected to the cathodic end of the cascaded energy supply chain. The sub-module also includes a sub-module control unit to control the operation of the power unit.

[0047] The cascaded energy supply chain 1 includes at least N - 1 or at least M - 1 diode units 4.

[0048] The diode units 4 are connected in series in the same direction. The cathodic end of the cascaded energy supply chain 1 is connected to the positive electrode of the DC capacitor C1 of the last sub-module, and the anodic ends of all the diode units 4 are in one-to-one correspondence with or connected to the positive electrodes of the DC capacitors C1 of the sub-modules 3 of the corresponding commutation chain through a first current limiter. The diode unit includes a diode, with the anode of the diode pointing to the anodic end of the diode unit and the cathode pointing to the cathodic end.

[0049] Optionally, the commutation valve high-voltage operation circuit further includes at least one charging and energy supplementing module 5, which is connected in parallel with the DC capacitor of the first sub-module of the corresponding commutation chain. The charging and energy supplementing module 5 includes a power supply unit or a power supply unit and a diode connected in series. The power supply unit includes a DC power supply, or an AC power supply and a rectifier.

[0050] The output voltage of the charging and energy supplementing module 5 is fixed or adjustable. In this embodiment, the output voltage of the charging and energy supplementing module 5 is less than the withstand voltage value of the semiconductor device of the sub-module power unit. For example, if the withstand voltage value of the power semiconductor device is 3300V, the charging and energy supplementing module 5 can adopt an output voltage of 1500V.

[0051] When a commutation chain is configured with a cascaded energy supply chain, the number of charging and energy supplementing modules is 1, which is connected in parallel with the DC capacitor of the first sub-module of the commutation chain configured with the cascaded energy supply chain, as Figure 1 shown.

[0052] When both commutation chains are configured with cascaded energy supply chains, the number of charging and energy supplementing modules is 2, which are respectively connected in parallel with the DC capacitors of the first sub-modules of the two commutation chains, as Figure 2 shown.

[0053] The technical solution provided by this embodiment can solve the power supply problems of many sub-modules through the charging and energy replenishment module with low-voltage output. The charging of the entire commutation chain can be achieved through low-voltage output, reducing the test conditions and test requirements, and is applicable to the occasions where high-voltage high-power power supplies are not available on site.

[0054] Optionally, the diode unit 4 further includes a second current limiter, which is mainly used to limit the current impact during the charging process, such as Figure 3a shown, the second current limiter is connected in series with the diode, and the second current limiter includes a resistor and / or an inductor.

[0055] Optionally, the diode unit further includes a disconnector, the disconnector is connected in series with the diode, and the opening and closing of the disconnector are controlled by the control unit of the sub-module, such as Figure 3b shown.

[0056] In the power unit, the half-bridge circuit includes an upper transistor and a lower transistor connected in series. After the upper transistor and the lower transistor are connected in series, they are connected in parallel with the DC capacitor. The collector and emitter of the upper transistor or the lower transistor are led out as the AC terminal of the sub-module, such as Figure 4a shown. The direction of the antiparallel diode of the power device at the AC terminal of the half-bridge circuit sub-module is the same as that of the diode of the cascaded energy supply system. Such as Figure 1 shown.

[0057] In the power unit, the full-bridge circuit includes two bridge arms connected in parallel. Each bridge arm includes two upper transistors and lower transistors connected in series. The bridge arm is connected in parallel with the DC capacitor, and the midpoint of the two bridge arms is led out as the AC terminal of the sub-module, such as Figure 4b shown.

[0058] All the sub-module power units in the commutation chain are the same circuits, all are half-bridge circuits or all are full-bridge circuits or all are mixed configurations of full-bridge circuits and half-bridge circuits;

[0059] Optionally, a bypass switch is also connected in parallel to the AC terminal of the sub-module. The bypass switch is electrically closed and remains closed by mechanical force or magnetic force after closing, such as Figure 4c shown.

[0060] Specifically, the commutation chain further includes a water cooling unit or / and a control unit or / and a measurement unit.

[0061] The water cooling unit provides cooling for the operation of the commutation chain. The control unit includes a main control unit and a valve control unit. The main control unit communicates with the valve control unit, and the valve control unit communicates with the control unit of the sub-module. The measurement unit is configured to measure the current and voltage of the connecting reactor or / and the commutation chain, and provides monitoring for the operation of the commutation chain.

[0062] Figure 5It is a schematic diagram of a field test system for a converter valve high-voltage operation circuit provided by an embodiment of the present application. The field test system for the converter valve high-voltage operation circuit includes at least one converter valve high-voltage operation circuit.

[0063] Among them, two converter chains of the converter valve high-voltage operation circuit are installed in the form of a valve tower, which is defined as engineering valve tower 10.

[0064] As Figure 5 shown, a crossbeam is built between the support insulators of the engineering valve tower, and the connecting reactor 2 is installed on the crossbeam 11. The crossbeam can be built at the N1, N2, N3 insulation support positions, and the connecting reactor 2 can also be independently placed on the ground.

[0065] An insulation distance d1 is maintained between the connecting reactor 2 and the ground potential, and insulation distances d2 and d3 are maintained between the connecting reactor 2 and the two engineering valve towers respectively, as Figure 6 shown.

[0066] The connecting reactor 2 includes a bridge arm reactor or a combination of bridge arm reactors, and the connecting reactor 2 is connected between the engineering valve towers 10.

[0067] In actual engineering applications, the wiring method is as Figure 7 shown, including three-phase six bridge arms. In this embodiment, each bridge arm includes two engineering valve towers 10. One end of the series connection of the two engineering valve towers is connected to the alternating current, and the other end is led out and connected to the bridge arm reactor 2 through the wall bushing 12 and then connected to the positive pole of the converter valve.

[0068] According to some embodiments, the existing wiring method can also be changed, and the bridge arm reactor is used as the connecting reactor 2. Taking one bridge arm as an example, the changed wiring is as Figure 8 shown. The operating circuit formed after the change is the Figure 1 shown operating circuit.

[0069] Figure 9 It is a schematic diagram of a control method flow for a converter valve high-voltage operation circuit provided by an embodiment of the present application, including two control modes: cascade charging control and cascade operation control.

[0070] The cascade charging control uses a charging and energy supplementing module and a cascaded energy supply chain to charge the DC capacitors of all sub-modules, and the control unit of the sub-module operates after taking power from the DC capacitor.

[0071] In the cascade charging control, when the number of charging and energy supplementing modules is 1, the converter chain connected to the charging and energy supplementing module is set as the first converter chain, and the other converter chain is the second converter chain. The first converter chain first executes the sequence control start logic. After the start is completed, the DC charging logic is executed to control the output voltage to charge the sub-modules of the second converter chain. When the number of charging and energy supplementing modules is 2, the two converter chains respectively execute the sequence control start logic.

[0072] According to some embodiments, the sequence control start logic is as follows Figure 10 shown, including: starting the charging and energy supplementing module to charge the DC capacitor of the first terminal module, and powering on the control elements of the first terminal module to operate; controlling the power semiconductor devices at corresponding positions in the power unit through the control unit of the sub-module to conduct, outputting a zero-level state, establishing a conduction path for the DC capacitor of the adjacent sub-module, charging the DC capacitor of the adjacent sub-module, and powering on the control unit of the sub-module; sequentially completing the charging of the DC capacitors of all sub-modules to make the control units of all sub-modules charged.

[0073] According to some embodiments, the DC charging logic is as follows Figure 11 shown, including: adjusting the output voltage of the commutation chain connected to the charging and energy supplementing module to gradually increase the voltage from zero to charge the DC capacitor of the second commutation chain sub-module until the control unit of the second commutation chain sub-module is powered on; controlling the number of sub-modules in the charging circuit in the second commutation chain to make the DC capacitor voltage of the second commutation chain sub-module reach a preset value.

[0074] Cascaded operation control: After the cascaded charging control is completed, the two commutation chains control the voltage and current to reproduce the voltage and current stresses of the sub-modules of the commutation chain, and the charging and energy supplementing module continuously supplements the loss energy for the two commutation chains during this process.

[0075] According to some embodiments, the cascaded operation control is as follows Figure 12 shown, including: unlocking and starting the power unit of any commutation chain sub-module to output the AC voltage target value; waiting for the AC voltage to be stable, unlocking and starting the power unit of the other commutation chain sub-module, and controlling the current flowing through the connecting reactor to the target value; after the system is stable, detecting the voltage and current of the current-controlled commutation chain, comparing with the given value, and determining whether the test requirements are met.

[0076] Among them, when the control method is applied to the field test system, the setting of the AC voltage target value is adjusted according to the insulation level of the connecting reactor and d1, d2, d3.

[0077] Optionally, the control method further includes: bypass switch detection control, performing cascaded operation control bypass detection and bypass detection after operation to test whether the bypass switch can work properly.

[0078] According to some embodiments, the bypass detection after operation is as follows Figure 13 shown, including: exiting the cascaded operation control; stopping the output of the charging and energy supplementing module; bypassing the sub-modules of the two commutation chains in sequence; checking whether the bypass switch operates correctly.

[0079] According to some embodiments, the cascaded operation control bypass detection is as follows Figure 14As shown, it includes: entering cascade operation control; after stabilization, controlling the bypass switches of the sub-modules in two commutation chains to perform bypass operations successively; if the operating state is normal after detection of the operation, reducing the AC voltage target value during cascade operation control, otherwise performing bypass detection after the operation ends.

[0080] 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. Previously, only relevant tests of the sub-modules could be completed during the on-site test of the converter valve. The method proposed in this application realizes the converter chain test and provides a reliable guarantee for the engineering application of the converter valve.

[0081] The embodiments of the present application have been introduced in detail above. Specific examples are used herein to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application. At the same time, any changes or deformations made by those skilled in the art based on the idea of the present application, within the specific implementation manner and application scope of the present application, fall within the protection scope of the present application. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A high-voltage operation circuit for a converter valve, comprising: Two converter chains, respectively including N sub-modules and M sub-modules, where N and M are integers greater than or equal to 1; One or two cascaded energy supply chains, including at least N - 1 or at least M - 1 diode units; The sub-module includes a DC capacitor and a power unit connected in parallel. The power unit includes a half-bridge circuit or / and a full-bridge circuit composed of power semiconductor devices; the AC terminals of the sub-modules are connected in series, and the AC terminals of the first sub-module and the last sub-module are led out as the AC terminals of the converter chain. One AC terminal of the two converter chains is connected through a connecting reactor, and the other AC terminal is short-circuited. The first sub-module is the sub-module connected to the positive terminal of the cascaded energy supply chain, and the last sub-module is the sub-module connected to the negative terminal of the cascaded energy supply chain; The diode units are connected in series in the same direction. The negative terminal of the cascaded energy supply chain is connected to the positive electrode of the DC capacitor of the last sub-module, and the positive terminals of all diode units are connected to the positive electrodes of the DC capacitors of the corresponding sub-modules of the converter chain one by one or through a first current limiter; At least one charging and energy supplementing module, connected in parallel with the DC capacitor of the first sub-module of the corresponding converter chain; the charging and energy supplementing module includes a power supply unit or a power supply unit and a diode connected in series. The power supply unit includes a DC power supply, or an AC power supply and a rectifier; The high-voltage operation circuit for the converter valve is used for: Cascaded charging control, using the charging and energy supplementing module and the cascaded energy supply chain to charge the DC capacitors of all sub-modules. The control unit of the sub-module operates after taking power from the DC capacitor; Cascaded operation control. After the cascaded charging control is completed, the two converter chains control the voltage and current, and the charging and energy supplementing module continuously supplements the loss energy for the two converter chains during this process.

2. The high-voltage operating circuit according to claim 1, wherein, The diode unit further includes a second current limiter, and the second current limiter is connected in series with the diode. Both the first current limiter and the second current limiter include a resistor and / or an inductor.

3. The high-voltage operating circuit according to claim 1, wherein, The diode unit further includes a disconnector, and the disconnector is connected in series with the diode. The opening and closing of the disconnector are controlled by the control unit of the sub-module.

4. The high-voltage operation circuit according to claim 1, wherein, The half-bridge circuit includes an upper tube and a lower tube connected in series. After the upper tube and the lower tube are connected in series, they are connected in parallel with the DC capacitor. The collector and emitter of the upper tube or the lower tube are led out as the AC terminal of the sub-module; The full-bridge circuit includes two bridge arms connected in parallel. Each bridge arm includes two upper tubes and two lower tubes connected in series. The bridge arm is connected in parallel with the DC capacitor, and the midpoint of the two bridge arms is led out as the AC terminal of the sub-module; The power units of the sub-modules in the converter chain are all half-bridge circuits or all full-bridge circuits or a mixed configuration of all full-bridge circuits and half-bridge circuits; The AC terminal of the sub-module is also connected in parallel with a bypass switch; the bypass switch is electrically closed and remains closed by mechanical force or magnetic force after closing.

5. The high-voltage operating circuit according to claim 1, wherein The converter chain further includes: A water cooling unit, providing cooling for the operation of the converter chain; A control unit, including a main control unit and a valve control unit, where the main control unit communicates with the valve control unit, and the valve control unit communicates with the control units of sub-modules; A measurement unit, configured to measure the current and voltage of the connecting reactor and / or the commutation chain, and provide monitoring for the operation of the commutation chain.

6. A field test system for a commutation valve high-voltage operation circuit, including: At least one commutation valve high-voltage operation circuit according to any one of claims 1 to 5; wherein, at least two commutation chains are installed in the form of valve towers, defined as engineering valve towers, and an insulation distance d1 is maintained between the connecting reactor and the ground potential, and insulation distances d2 and d3 are maintained between the connecting reactor and the two engineering valve towers respectively.

7. The in-situ test system according to claim 6, wherein, A crossbeam is built between the support insulators of the engineering valve tower, the connecting reactor is installed on the crossbeam, the connecting reactor includes a bridge arm reactor or a combination of bridge arm reactors, and the connecting reactor is connected between the engineering valve towers.

8. A commutation valve high-voltage operation control method, applied to the commutation valve high-voltage operation circuit according to any one of claims 1 to 5 or the field test system of the commutation valve high-voltage operation circuit according to claim 6 or 7, the control method includes: Cascaded charging control, using a charging energy supplement module and a cascaded energy supply chain to charge the DC capacitors of all sub-modules, and the control unit of the sub-module operates after taking power from the DC capacitor. Cascaded operation control, after the cascaded charging control is completed, the two commutation chains control the voltage and current, and the charging energy supplement module continuously supplements the loss energy for the two commutation chains during this process.

9. The control method according to claim 8, further including: Bypass switch detection control, performing bypass detection during cascaded operation control and bypass detection after operation ends, for testing whether the bypass switch can work properly.

10. The control method according to claim 8, wherein, In the cascaded charging control, When the number of charging energy supplement modules is 1, the commutation chain connected to the charging energy supplement module first executes the sequence control start logic. After the start is completed, the DC charging logic is executed to control the output voltage to charge the sub-modules of another commutation chain. When the number of charging energy supplement modules is 2, the two commutation chains respectively execute the sequence control start logic.

11. The control method according to claim 10, wherein, The sequence control start logic includes: Start the charging energy supplement module to charge the DC capacitor of the first terminal sub-module, and the control element of the first terminal sub-module is powered on and operates. Control the power semiconductor devices at the corresponding positions in the power unit to conduct through the control unit of the sub-module, output a zero-level state, establish a conduction loop for the DC capacitor of the adjacent sub-module, charge the DC capacitor of the adjacent sub-module, and the control unit of the sub-module is powered on. Complete the charging of the DC capacitors of all sub-modules in sequence, so that the control units of all sub-modules are charged.

12. The control method according to claim 10, wherein, The DC charging logic includes: Adjust the output voltage of the commutation chain connected to the charging energy supplement module to gradually increase the voltage from zero to charge the DC capacitor of the sub-module of another commutation chain until the control unit of the sub-module of another commutation chain is powered on. Control the number of sub-modules put into the charging circuit in the other commutation chain to make the DC capacitor voltage of the sub-module of the other commutation chain reach the preset value.

13. The control method according to claim 8, wherein, The cascaded operation control includes: Any power unit of the converter chain sub-module is unlocked and started to output the target value of the AC voltage; After the AC voltage is stabilized, the power unit of another converter chain sub-module is unlocked and started to control the current flowing through the connecting reactor to the target value; After the system is stable, the voltage and current of the current-controlled converter chain are detected and compared with the given values to determine whether the test requirements are met.

14. The control method according to claim 13, wherein, When the control method is applied to the field test system, the setting of the target value of the AC voltage is adjusted according to the insulation level of the connecting reactor and d1, d2, d3.

15. The control method according to claim 9, wherein, The bypass detection after the operation ends includes: Exit the cascade operation control; Stop the output of the charging and energy supplement module; Bypass the sub-modules of the two converter chains in sequence; Check whether the bypass switch operates correctly.

16. The control method according to claim 9, wherein, The cascade operation control bypass detection includes: Enter the cascade operation control; After stabilization, control the bypass switches of the sub-modules in the two converter chains to perform bypass operations successively; If the operating state is normal after the detection action, reduce the target value of the AC voltage during the cascade operation control, otherwise perform the bypass detection after the operation ends.

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