An automated cascaded multilevel converter valve sub-module batch test system and method

Abstract

The application discloses a kind of automatic cascade multilevel converter valve submodule batch test system and method, test system includes AC step-up transformer T, the positive pole of AC step-up transformer T secondary side is connected the positive pole of submodule test product in turn through first IGCT switch T1, first loop switch K1 and current measuring device CT, the negative pole of submodule test product is connected the negative pole of AC step-up transformer T secondary side again;Voltage measurement branch is also connected between the both ends of submodule test product;IGCT switch module, resistance module and capacitor module are provided with in series on voltage measurement branch, IGCT switch module includes second IGCT switch T2 and third IGCT switch T3 of anti-parallel, resistance module includes resistor R and second loop switch K2 being arranged in parallel with resistor R, capacitor module includes capacitor C and voltage measuring device PT being arranged in parallel with capacitor C.The application can quickly complete multistage submodule function test in batch.

Description

Technical Field

[0001] This invention belongs to the field of power electronics technology, specifically relating to an automated cascaded multilevel converter valve submodule batch testing system and method. Background Technology

[0002] With the development of power electronics technology, the application of fully controllable devices in the power transmission and distribution field has become more mature and widespread. Flexible DC transmission and medium- and high-voltage large-capacity SVG generally adopt cascaded multi-level converter structures. However, as voltage levels continue to increase, the number of converter sub-modules also increases rapidly. Taking a ±500kV flexible DC transmission project already in operation in China as an example, the number of sub-modules in a single converter approaches four thousand. As the operating time of the operational flexible DC projects increases year by year, the demand for the speed and accuracy of on-site testing of converter valve sub-modules is becoming increasingly strong. Existing power module testing methods mostly perform testing on individual sub-modules sequentially, requiring several weeks of power outage time window to complete all tests, which seriously affects the availability of flexible DC projects.

[0003] For example, the portable automatic tester designed in the literature “Ji Panpan, Dong Chaoyang, Liu Jingyi, Yang Fengyuan. Design of Automatic Tester for Power Module of Flexible DC Transmission Converter Valve [J]. Power Electronics Technology, 2020, 54(01):110-112+117” can automatically test the capacitors, resistors, insulated gate bipolar transistors (IGBTs), bypass switches, etc. of individual sub-modules. The literature “Hao Liangshou, Wang Feng, Li Ning, Liao Qiyan. An Improved Test Device for Power Module of Flexible DC Transmission Converter Valve [J]. Electrical Technology, 2020, 21(06):102-105+110” designed an improved test device that can self-test and test individual sub-modules and automatically discharge. However, the existing designs all study how to test individual modules. This requires disconnecting, reconnecting, and testing each power module individually. Completing all tests requires a power outage window of several weeks, which seriously affects the availability of flexible DC projects. Therefore, sampling inspection is generally used, which also poses a safety hazard of missed inspections. Summary of the Invention

[0004] The purpose of this invention is to address the problems in the prior art by providing an automated batch testing system and method for cascaded multilevel converter valve submodules. Depending on whether the submodule of the converter valve bridge arm is a half-bridge, full-bridge, or hybrid type, the corresponding circuit structure is selected to execute different test steps, which can automatically complete batch testing of cascaded multilevel converter valve submodules.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] An automated cascaded multilevel converter valve submodule batch testing system includes an AC step-up transformer T. The positive terminal of the secondary side of the AC step-up transformer T is connected to the positive terminal of a submodule test specimen via a connecting cable, which is then connected to the positive terminal of the submodule test specimen via a first IGCT switch T1, a first loop switch K1, and a current measuring device CT. The negative terminal of the submodule test specimen is connected to the negative terminal of the secondary side of the AC step-up transformer T via a connecting cable. A voltage measurement branch is also connected in parallel between the two ends of the submodule test specimen. One end of the voltage measurement branch is connected to the connecting cable between the first loop switch K1 and the current measuring device CT, and the other end is connected between the negative terminal of the submodule test specimen and the negative terminal of the secondary side of the AC step-up transformer T. The voltage measurement branch is connected in series with an IGCT switch module, a resistor module, and a capacitor module. The IGCT switch module includes a second IGCT switch T2 and a third IGCT switch T3 connected in anti-parallel. The resistor module includes a resistor R and a second circuit switch K2 connected in parallel with the resistor R. The capacitor module includes a capacitor C and a voltage measuring device PT connected in parallel with the capacitor C. The first IGCT switch T1, the second IGCT switch T2, the third IGCT switch T3, the first circuit switch K1, the second circuit switch K2, the current measuring device CT, and the voltage measuring device PT are connected to a control and protection device.

[0007] As a preferred embodiment of the automated cascaded multilevel converter valve submodule batch testing system of the present invention, the control and protection device includes a main processor board and an optical fiber communication board and an IO interface board connected to the main processor board.

[0008] The fiber optic communication board connects the sub-module test sample and the first IGCT switch T1, the second IGCT switch T2 and the third IGCT switch T3 via fiber optic cables.

[0009] The IO interface board connects to the first circuit switch K1, the second circuit switch K2, the current measuring device CT, and the voltage measuring device PT via cables.

[0010] As a preferred embodiment of the automated cascaded multilevel converter valve submodule batch testing system of the present invention, the control and protection device further includes a human-machine interface and a waveform recording device connected to the main processor board;

[0011] The human-machine interface is used to set the number of sub-modules, adjust the test voltage, and select test functions.

[0012] The waveform recording device is used to record and store the measured current, voltage, and submodule status information.

[0013] As a preferred embodiment of the automated cascaded multilevel converter valve submodule batch testing system of the present invention, a diode valve D is provided on the cable connecting the first circuit switch K1, the second circuit switch K2, the current measuring device CT, the voltage measuring device PT and the IO interface board.

[0014] A test method for a batch testing system of an automated cascaded multilevel converter valve submodule includes the following steps:

[0015] First, determine if a system reset command is detected. If a system reset command is detected, stop the test, reset each IGCT switch and loop switch, and discharge the capacitor. If no system reset command is detected, proceed to control each branch test item according to the test mode control word M: when M==1, it is a half-bridge valve module test; when M==2, it is a full-bridge valve module test; when M==3, it is a half-bridge / full-bridge hybrid valve module test. After the corresponding branch test is completed, the test ends.

[0016] As a preferred embodiment of the test method of the present invention, the test procedure for the half-bridge valve module is as follows:

[0017] Close the first circuit switch K1, turn on the first IGCT switch T1, and charge the sub-module sample;

[0018] Determine if the voltage of all submodules is greater than the preset value. If not, continue charging the submodule test sample. If yes, turn off the first IGCT switch T1 and issue a submodule reset command.

[0019] Determine if there is a fault message. If so, stop the machine for inspection. Otherwise, open the third IGCT switch T3, close the second circuit switch K2, and sequentially trigger the upper IGBT switches of submodules 1 to n.

[0020] If there is a fault indication and the voltage of capacitor C is not equal to the sum of the voltages of the triggered sub-modules, then stop the machine for inspection; otherwise, turn on the second IGCT switch T2, open the second circuit switch K2, turn off the upper IGBT switches of all sub-modules, and trigger the lower IGBT switches of all sub-modules.

[0021] Determine if the following conditions are met: Uc / R0 > Measured Current > (Uc-Un) / R0, where Uc is the voltage across capacitor C, Un is the submodule voltage, and R0 is the resistance of resistor R. Otherwise, stop the machine for inspection. If the conditions are met, issue a submodule bypass command and then determine if the bypass is successful. Otherwise, stop the machine for inspection. If the conditions are met, the test of the submodule is complete, the submodule has no abnormalities, and the test report is printed.

[0022] As a preferred embodiment of the test method of the present invention, the test procedure for the full-bridge valve module is as follows:

[0023] Close the first circuit switch K1, turn on the first IGCT switch T1, and charge the sub-module sample;

[0024] Determine if the voltage of all submodules is greater than the preset value. If not, continue charging the submodule test sample. If yes, turn off the first IGCT switch T1 and issue a submodule reset command.

[0025] Determine if there is a fault message. If yes, stop the machine for inspection. Otherwise, open the third IGCT switch T3, close the second circuit switch K2, and sequentially trigger the IGBT switches S1 and S4 of submodules 1 to n.

[0026] If there is a fault indication and the voltage of capacitor C is not equal to the sum of the voltages of the triggered sub-modules, then stop the machine for inspection; otherwise, turn on the second IGCT switch T2, turn on the second circuit switch K2, turn off the IGBT switches S1 and S4 of all sub-modules, and trigger the IGBT switches S2 and S3 of all sub-modules.

[0027] Determine if the following conditions are met: 2*Uc / R0 > measured current > (2*Uc-Un) / R0, where Uc is the voltage across capacitor C, Un is the submodule voltage, and R0 is the resistance value of resistor R. Otherwise, stop the machine for inspection. If the conditions are met, issue a submodule bypass command and then determine if the bypass is successful. Otherwise, stop the machine for inspection. If the conditions are met, the test of the submodule is completed, the submodule has no abnormalities, and a test report is printed.

[0028] As a preferred embodiment of the test method of the present invention, the test of the semi-bridge and full-bridge hybrid valve module is carried out by first completing the test process of the semi-bridge valve module in the sub-module sample, and then completing the test process of the full-bridge valve module.

[0029] As a preferred embodiment of the test method of the present invention, after the corresponding branch test is completed, the waveform recording file is uploaded, the test analysis report is automatically generated, the test results are displayed on the interface, and the test ends.

[0030] Compared with the prior art, the present invention has at least the following beneficial effects:

[0031] Flexible DC transmission and medium- and high-voltage large-capacity SVG generally adopt a cascaded multilevel converter structure. The basic unit constituting the converter is the submodule, and the submodules of the bridge arm generally use three structures: half-bridge, full-bridge, or a hybrid of half- and full-bridge. This invention can automatically complete the entire process control of the cascaded multilevel converter submodule test by issuing different control commands to the control and protection devices connected to the first IGCT switch T1, the second IGCT switch T2, the third IGCT switch T3, the first loop switch K1, the second loop switch K2, the current measuring device CT, and the voltage measuring device PT, based on different cascaded (half-bridge, full-bridge, or hybrid) multilevel converter submodule test samples. It automatically performs data analysis based on the module voltage and system feedback signals, records relevant analog and digital quantities, generates a test report, and provides an indication of whether the module is functioning correctly. This invention can quickly complete multi-level submodule functional tests in batches and generate test reports, significantly improving on-site maintenance efficiency. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 A schematic diagram of the automated cascaded multilevel converter valve submodule batch testing system according to an embodiment of the present invention;

[0034] Figure 2 Schematic diagram of the cascaded multilevel converter valve half-bridge and full-bridge sub-module structure;

[0035] Figure 3 A typical structural diagram of a medium- and high-voltage, large-capacity SVG;

[0036] Figure 4 Flowchart of the batch testing method for the automated cascaded multilevel converter valve submodule according to an embodiment of the present invention;

[0037] Figure 5 Flowchart of the test method for the half-bridge valve module according to an embodiment of the present invention;

[0038] Figure 6 Flowchart of the test method for the full-bridge valve module in this invention. Detailed Implementation

[0039] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0040] Based on the embodiments of the present invention, those skilled in the art can make several simple modifications and refinements without creative effort, and all other embodiments obtained are within the scope of protection of the present invention.

[0041] In this invention, reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0042] like Figure 2 , Figure 3 As shown, flexible DC transmission and medium- and high-voltage large-capacity SVG generally adopt a converter structure based on cascaded multilevel converters. The basic unit constituting the converter is the submodule, and the submodules of the bridge arm generally use three structures: half-bridge, full-bridge, or a hybrid of half- and full-bridge. Figure 2 In the flexible DC converter structure shown, the half-bridge submodule has two IGBTs (S1, S2) and two anti-parallel diodes, while the full-bridge submodule has four IGBTs (S1, S2, S3, S4) and four anti-parallel diodes. Therefore, testing the full-bridge submodule is more complex than that of the half-bridge submodule. The submodules in a typical medium-voltage, high-capacity SVG structure are full-bridge submodules.

[0043] Please see Figure 1This invention proposes an automated batch testing system for cascaded multilevel converter valve submodules. This system automatically controls the entire testing process of cascaded multilevel converter submodules, automatically analyzes data based on module voltage and system feedback signals, records relevant analog and digital quantities, generates a test report, and indicates whether the module is functioning correctly. The test system structure includes a 380V / 10kV AC step-up transformer T. The positive terminal of the secondary side of the AC step-up transformer T is connected to the positive terminal of the submodule test specimen via a connecting cable, passing through a first IGCT switch T1, a first loop switch K1, and a current measuring device CT. The negative terminal of the submodule test specimen is connected to the negative terminal of the secondary side of the AC step-up transformer T via a connecting cable. A voltage measurement branch is also connected in parallel between the two ends of the submodule test specimen. One end of the voltage measurement branch is connected to the connecting cable between the first loop switch K1 and the current measuring device CT, and the other end is connected to the connecting cable between the negative terminal of the submodule test specimen and the negative terminal of the secondary side of the AC step-up transformer T. An IGCT switch module, a resistor module, and a capacitor module are connected in series on the voltage measurement branch. The IGCT switch module includes a second IGCT switch T2 and a third IGCT switch T3 connected in anti-parallel. The resistor module includes a resistor R and a second loop switch K2 connected in parallel with the resistor R. The capacitor module includes a capacitor C and a voltage measuring device PT connected in parallel with the capacitor C. In this embodiment of the invention, the first IGCT switch T1, the second IGCT switch T2, and the third IGCT switch T3, as well as the first loop switch K1, the second loop switch K2, the current measuring device CT, and the voltage measuring device PT in the test system are connected to a control and protection device. Simultaneously, a diode valve D is installed on the cable connecting the first loop switch K1, the second loop switch K2, the current measuring device CT, and the voltage measuring device PT to the IO interface board.

[0044] Furthermore, the control and protection device in this embodiment includes a main processor board and an optical fiber communication board and an I / O interface board connected to the main processor board. The optical fiber communication board connects the sub-module test specimen and the first IGCT switch T1, the second IGCT switch T2, and the third IGCT switch T3 via optical fiber. The I / O interface board connects the first loop switch K1, the second loop switch K2, the current measuring device CT, and the voltage measuring device PT via cables. The control and protection device also includes a human-machine interface and a waveform recording device connected to the main processor board. The human-machine interface is used to set the number of sub-modules, adjust the test voltage, and select test functions. The waveform recording device is used to record and store the measured current, voltage, and sub-module status information. The control and protection device can issue different control commands based on different cascaded multilevel converter sub-module test specimens, such as half-bridge, full-bridge, and hybrid half-full-bridge types, automatically perform different test procedures, automatically generate test reports, and display the test results on the interface.

[0045] like Figure 4As shown, another embodiment of the present invention also proposes a test method for the batch testing system of the automated cascaded multilevel converter valve submodule, including the following steps:

[0046] First, the control and protection device determines whether there is a system reset command. If a system reset command is detected, the test is stopped, each IGCT switch and circuit switch is reset, and the capacitor is discharged.

[0047] If no system reset command is given, the test mode control word M will be used to control each branch test item:

[0048] When M==1, it is a half-bridge valve module test;

[0049] When M = 2, it is a full-bridge valve module test;

[0050] When M = 3, it is a test of a semi-full-bridge hybrid valve module;

[0051] The experiment ends after the corresponding branch experiment is completed.

[0052] See Figure 5 In one possible implementation, the components that need to be tested in the half-bridge submodule include the upper IGBT, the lower IGBT, the PMC board, the bypass switch, and the fiber optic loop. The following half-bridge valve module test procedure can comprehensively test the above components:

[0053] Close the first circuit switch K1, turn on the first IGCT switch T1, and charge the sub-module sample;

[0054] Determine if the voltage of all submodules is greater than the preset value. If not, continue charging the submodule test sample. If yes, turn off the first IGCT switch T1 and issue a submodule reset command.

[0055] Determine if there is a fault message. If so, stop the machine for inspection. Otherwise, open the third IGCT switch T3, close the second circuit switch K2, and sequentially trigger the upper IGBT switches of submodules 1 to n.

[0056] If there is a fault indication and the voltage of capacitor C is not equal to the sum of the voltages of the triggered sub-modules, then stop the machine for inspection; otherwise, turn on the second IGCT switch T2, open the second circuit switch K2, turn off the upper IGBT switches of all sub-modules, and trigger the lower IGBT switches of all sub-modules.

[0057] Determine if the following conditions are met: Uc / R0 > Measured Current > (Uc-Un) / R0, where Uc is the voltage across capacitor C, Un is the submodule voltage, and R0 is the resistance of resistor R. Otherwise, stop the machine for inspection. If the conditions are met, issue a submodule bypass command and then determine if the bypass is successful. Otherwise, stop the machine for inspection. If the conditions are met, the test of the submodule is complete, the submodule has no abnormalities, and the test report is printed.

[0058] See Figure 6 In one possible implementation, the components that need to be tested in the full-bridge submodule include two upper IGBTs (S1, S2), two lower IGBTs (S3, S4), PMC board, bypass switch, fiber optic loop, etc. The above components can be comprehensively tested through the following full-bridge valve module test procedure:

[0059] Close the first circuit switch K1, turn on the first IGCT switch T1, and charge the sub-module sample;

[0060] Determine if the voltage of all submodules is greater than the preset value. If not, continue charging the submodule test sample. If yes, turn off the first IGCT switch T1 and issue a submodule reset command.

[0061] Determine if there is a fault message. If yes, stop the machine for inspection. Otherwise, open the third IGCT switch T3, close the second circuit switch K2, and sequentially trigger the IGBT switches S1 and S4 of submodules 1 to n.

[0062] If there is a fault indication and the voltage of capacitor C is not equal to the sum of the voltages of the triggered sub-modules, then stop the machine for inspection; otherwise, turn on the second IGCT switch T2, turn on the second circuit switch K2, turn off the IGBT switches S1 and S4 of all sub-modules, and trigger the IGBT switches S2 and S3 of all sub-modules.

[0063] Determine if the following conditions are met: 2*Uc / R0 > measured current > (2*Uc-Un) / R0, where Uc is the voltage across capacitor C, Un is the submodule voltage, and R0 is the resistance value of resistor R. Otherwise, stop the machine for inspection. If the conditions are met, issue a submodule bypass command and then determine if the bypass is successful. Otherwise, stop the machine for inspection. If the conditions are met, the test of the submodule is completed, the submodule has no abnormalities, and a test report is printed.

[0064] In one possible implementation, the semi-bridge / full-bridge hybrid valve module test is conducted by first completing the semi-bridge valve module test process in the sub-module sample, and then completing the full-bridge valve module test process. The semi-bridge valve module test process is completely consistent with the full-bridge valve module test process. The specific process mainly includes: after entering the branch test control process, the system is cyclically judged to see if it is normal. If it is normal, the mode loop switch control is performed, the corresponding mode switch is closed, and the primary test loop is connected; after the switch control is completed, the sample charging control is performed; after the sample charging is completed, the first loop switch K1 is opened; the start test command is cyclically judged. If an external start test command is received, the module state is reset, and the step-by-step detailed test begins. After the test is completed, the test completion signal is returned, and the capacitor C discharge control is performed; the waveform recording file is uploaded, and the test analysis report is generated; the test ends.

[0065] The automated batch testing system and method for cascaded multilevel converter valve submodules of the present invention can automatically complete the entire process control of the testing of cascaded multilevel converter submodules. It can automatically perform data analysis based on module voltage and loop feedback signals, record relevant analog and digital quantities, generate test reports, and provide indications of whether the module is normal.

[0066] The present invention has been described above in conjunction with specific features and embodiments. It is obvious that various modifications and combinations can be made without departing from the spirit and scope of the invention. Accordingly, this specification and accompanying drawings are merely exemplary descriptions of the invention as defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the present invention, and these modifications and modifications that do not depart from the spirit and scope of the invention also fall within the scope of the claims and their equivalents.

Claims

1. An automated batch testing system for cascaded multilevel converter valve submodules, characterized in that: The system includes an AC step-up transformer T. The positive terminal of the secondary side of the AC step-up transformer T is connected to the positive terminal of the submodule test object via a connecting cable, which is then connected to the first IGCT switch T1, the first circuit switch K1, and the current measuring device CT. The negative terminal of the submodule test object is connected to the negative terminal of the secondary side of the AC step-up transformer T via a connecting cable. A voltage measuring branch is also connected in parallel between the two ends of the submodule test object. One end of the voltage measuring branch is connected to the connecting cable between the first circuit switch K1 and the current measuring device CT, and the other end is connected to the connecting cable between the negative terminal of the submodule test object and the negative terminal of the secondary side of the AC step-up transformer T. An IGCT switch module, a resistor module, and a capacitor module are connected in series on the current-to-voltage branch. The IGCT switch module includes a second IGCT switch T2 and a third IGCT switch T3 connected in anti-parallel. The resistor module includes a resistor R and a second circuit switch K2 connected in parallel with the resistor R. The capacitor module includes a capacitor C and a voltage measuring device PT connected in parallel with the capacitor C. The first IGCT switch T1, the second IGCT switch T2, the third IGCT switch T3, the first circuit switch K1, the second circuit switch K2, the current measuring device CT, and the voltage measuring device PT are connected to a control and protection device.

2. The automated cascaded multilevel converter valve submodule batch testing system according to claim 1, characterized in that: The control and protection device includes a main processor board and an optical fiber communication board and an I / O interface board connected to the main processor board. The fiber optic communication board connects the sub-module test sample and the first IGCT switch T1, the second IGCT switch T2 and the third IGCT switch T3 via fiber optic cables. The IO interface board connects to the first circuit switch K1, the second circuit switch K2, the current measuring device CT, and the voltage measuring device PT via cables.

3. The automated cascaded multilevel converter valve submodule batch testing system according to claim 2, characterized in that: The control and protection device also includes a human-machine interface and a waveform recording device connected to the main processor board. The human-machine interface is used to set the number of sub-modules, adjust the test voltage, and select test functions. The waveform recording device is used to record and store the measured current, voltage, and submodule status information.

4. The automated cascaded multilevel converter valve submodule batch testing system according to claim 2, characterized in that: A diode valve D is installed on the cable connecting the first circuit switch K1, the second circuit switch K2, the current measuring device CT, the voltage measuring device PT, and the IO interface board.

5. A test method for a batch testing system of an automated cascaded multilevel converter valve submodule as described in any one of claims 1-4, characterized in that, Includes the following steps: First, determine if a system reset command is detected. If a system reset command is detected, stop the test, reset each IGCT switch and loop switch, and discharge the capacitor. If no system reset command is detected, proceed to control each branch test item according to the test mode control word M: when M==1, it is a half-bridge valve module test; when M==2, it is a full-bridge valve module test; when M==3, it is a half-bridge / full-bridge hybrid valve module test. After the corresponding branch test is completed, the test ends.

6. The test method according to claim 5, characterized in that, The test procedure for the half-bridge valve module is as follows: Close the first circuit switch K1, turn on the first IGCT switch T1, and charge the sub-module sample; Determine if the voltage of all submodules is greater than the preset value. If not, continue charging the submodule test sample. If yes, turn off the first IGCT switch T1 and issue a submodule reset command. Determine if there is a fault message. If so, stop the machine for inspection. Otherwise, open the third IGCT switch T3, close the second circuit switch K2, and sequentially trigger the upper IGBT switches of submodules 1 to n. If there is a fault indication and the voltage of capacitor C is not equal to the sum of the voltages of the triggered sub-modules, then stop the machine for inspection; otherwise, turn on the second IGCT switch T2, open the second circuit switch K2, turn off the upper IGBT switches of all sub-modules, and trigger the lower IGBT switches of all sub-modules. Determine if the following conditions are met: Uc / R0 > Measured Current > (Uc-Un) / R0, where Uc is the voltage across capacitor C, Un is the submodule voltage, and R0 is the resistance of resistor R. Otherwise, stop the machine for inspection. If the conditions are met, issue a submodule bypass command and then determine if the bypass is successful. Otherwise, stop the machine for inspection. If the conditions are met, the test of the submodule is complete, the submodule has no abnormalities, and the test report is printed.

7. The test method according to claim 5, characterized in that, The testing procedure for the full-bridge valve module is as follows: Close the first circuit switch K1, turn on the first IGCT switch T1, and charge the sub-module sample; Determine if the voltage of all submodules is greater than the preset value. If not, continue charging the submodule test sample. If yes, turn off the first IGCT switch T1 and issue a submodule reset command. Determine if there is a fault message. If yes, stop the machine for inspection. Otherwise, open the third IGCT switch T3, close the second circuit switch K2, and sequentially trigger the IGBT switches S1 and S4 of submodules 1 to n. If there is a fault indication and the voltage of capacitor C is not equal to the sum of the voltages of the triggered sub-modules, then stop the machine for inspection; otherwise, turn on the second IGCT switch T2, turn on the second circuit switch K2, turn off the IGBT switches S1 and S4 of all sub-modules, and trigger the IGBT switches S2 and S3 of all sub-modules. Determine if the following conditions are met: 2*Uc / R0 > measured current > (2*Uc-Un) / R0, where Uc is the voltage across capacitor C, Un is the submodule voltage, and R0 is the resistance value of resistor R. Otherwise, stop the machine for inspection. If the conditions are met, issue a submodule bypass command and then determine if the bypass is successful. Otherwise, stop the machine for inspection. If the conditions are met, the test of the submodule is completed, the submodule has no abnormalities, and a test report is printed.

8. The test method according to claim 5, characterized in that, The semi-bridge / full-bridge hybrid valve module test is conducted by first completing the semi-bridge valve module test procedure in the sub-module sample, and then completing the full-bridge valve module test procedure.

9. The test method according to claim 5, characterized in that, After the corresponding branch test is completed, the waveform recording file is uploaded, the test analysis report is automatically generated, the test results are displayed on the interface, and the test ends.

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