DC circuit breaker closed-loop switching submodule test method

Abstract

A method for testing a closed-loop on / off submodule of a DC circuit breaker. The present invention first accepts user instructions, and then outputs control signals to a test circuit and a communication interface DBC&VBC according to the user instructions, driving them to output various signals to trigger the main branch or transfer branch submodule of the DC circuit breaker to be tested. The triggered main branch or transfer branch submodule of the DC circuit breaker outputs a corresponding voltage or current signal, and the test controller obtains the signal through the test circuit for analysis, thereby determining the status of the DC circuit breaker. The test equipment of the present invention is simple and easy to use, easy to operate, and can test full-bridge modules and mechanical switches, and has a wide range of application scenarios.

Description

Technical Field

[0001] The present invention relates to the technical field of direct current (DC) power transmission, and in particular to a DC circuit breaker closed-loop on / off submodule testing technology. Background Art

[0002] DC fault protection is a technical bottleneck faced by DC grid construction. To achieve DC fault protection, DC circuit breakers are usually required to implement flexible DC grid control and protection.

[0003] However, existing DC circuit breakers lack compatible testing technology, making it impossible to determine whether their internal circuit components are operating normally. Furthermore, during the engineering development and application of DC circuit breakers, closed-loop testing of the circuit breaker's opening and closing submodules is required. However, there are no reference technical basis or industry standards for such testing.

[0004] Considering that DC circuit breaker on / off submodule testing is a mandatory test throughout the entire DC circuit breaker development, manufacturing, and delivery process, and is also a test relied upon for regular maintenance during DC grid operation, reports or records of DC circuit breaker closed-loop on / off submodule testing are crucial information that must be tracked during product development, manufacturing, and delivery management. Therefore, a method is needed to test the operating status of the DC circuit breaker closed-loop on / off submodule, as well as the functionality and performance of key components tested. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention provides a closed-loop on / off submodule testing method for a DC circuit breaker. By analyzing the voltage and current signals generated by the DC circuit breaker's main branch or transfer branch submodule in response to an opening command, closing command, or test trigger excitation signal, the present invention accurately determines the DC circuit breaker's status. Specifically, the present invention employs the following technical solutions.

[0006] First, to achieve the above-mentioned purpose, a DC circuit breaker closed-loop on-off submodule test method is proposed, wherein the test steps include: a first step, receiving a user's instruction, and outputting a control signal to the test circuit and the communication interface DBC&VBC according to the instruction; wherein the user's instruction includes: a test start time signal, a test category mark, a test parameter, a test progress signal, a test result signal, and a trigger emergency protection signal; a second step, the communication interface DBC&VBC outputs an opening instruction or a closing instruction to the mechanical switch in the DC circuit breaker according to the control signal output by the test controller, and sends an on-off control signal to the integrated driver; a third step, the integrated driver outputs a test trigger excitation signal according to the on-off control signal output by the communication interface DBC&VBC, triggering each circuit element in the main branch or transfer branch submodule of the DC circuit breaker; in a fourth step, the test circuit receives the voltage signal and current signal generated by each circuit element in the main branch or transfer branch submodule of the DC circuit breaker in response to the opening instruction, closing instruction or test trigger excitation signal, and converts the voltage signal and current signal into detection data for output; in a fifth step, the test controller receives the data detected and output by the test circuit, analyzes the time of change of the voltage signal and current signal based on the data, calculates the state of the main branch or transfer branch submodule of the DC circuit breaker and the equivalent resistance and equivalent capacitance, so as to determine the state of the main branch or transfer branch submodule of the DC circuit breaker and determine whether the circuit elements in the main branch or transfer branch submodule of the DC circuit breaker have failed.

[0007] Optionally, in the above-mentioned DC circuit breaker closed-loop opening and closing sub-module test method, the fifth step also includes the following steps: a test controller receives the data detected and output by the test circuit, and determines whether the switching element in the main branch or transfer branch sub-module of the DC circuit breaker meets the following conditions: when not opened, the loop current decreases and the voltage increases; when opened, the voltage drops to 0 and the current increases; when the switching element is turned off, the current gradually decreases to close to 0 and the voltage continues to rise; when the above conditions are met, further performing a Rogowski coil current test.

[0008] Optionally, in the above-mentioned closed-loop opening and closing submodule test method of the DC circuit breaker, the Rogowski coil current test includes the following test steps: performing a Rogowski coil current test on each switching element in the main branch or transfer branch submodule of the DC circuit breaker separately; when it is determined that the current obtained by the Rogowski coil current test differs from the loop current in the data detected and output by the test circuit by 1 / 2, determining that the status of the main branch or transfer branch submodule of the DC circuit breaker is normal; otherwise, determining that one switching element in the main branch or transfer branch submodule of the DC circuit breaker is normal and one switching element has failed to open.

[0009] Optionally, in the above-mentioned closed-loop opening and closing sub-module test method of the DC circuit breaker, in the fifth step, if the equivalent resistance of the main branch or transfer branch sub-module of the DC circuit breaker is calculated to be between 10 and 300 kΩ and the equivalent capacitance is between 10 and 300 μF, then the status of the main branch or transfer branch sub-module of the DC circuit breaker is judged to be normal.

[0010] Optionally, in the above-mentioned DC circuit breaker closed-loop opening and closing sub-module test method, the fifth step also includes: the test controller receives the data detected and output by the test circuit, obtains the time difference between the time when the mechanical switch break voltage in the DC circuit breaker changes and the time when the communication interface DBC&VBC outputs the opening command or closing command, and judges whether the mechanical action delay of the mechanical switch meets the technical specification requirements based on the time difference.

[0011] Optionally, in the above-mentioned DC circuit breaker closed-loop opening and closing sub-module test method, in the second step, the communication interface DBC&VBC outputs an opening command or a closing command to the mechanical switch in the DC circuit breaker through an optical fiber, and sends an opening and closing control signal to the integrated drive.

[0012] Optionally, the above-mentioned DC circuit breaker closed-loop opening and closing sub-module test method, wherein the first step also includes: connecting the two ends of the main branch or transfer branch sub-module of the DC circuit breaker to a low-voltage power supply and a current-limiting resistor connected in series, and the low-voltage power supply and current-limiting resistor output a low-voltage DC power supply signal not exceeding 100V to the main branch or transfer branch sub-module of the DC circuit breaker.

[0013] Optionally, in the above-mentioned DC circuit breaker closed-loop opening and closing sub-module test method, the first step also includes: connecting the integrated drive to a power supply, the power supply having an isolation circuit and a voltage stabilizing circuit, providing a DC voltage stable at 20V to the integrated drive.

[0014] Beneficial effects

[0015] The present invention first accepts user instructions, and then outputs control signals to the test circuit and communication interface DBC&VBC according to the user instructions, driving them to output various signals to trigger the main branch or transfer branch submodule of the DC circuit breaker to be tested. The main branch or transfer branch submodule of the triggered DC circuit breaker outputs a corresponding voltage or current signal, and the test controller obtains the signal through the test circuit for analysis. Thus, the present invention can realize the judgment of the status of the DC circuit breaker. The test equipment of the present invention is simple and easy to operate, and can test full-bridge modules and mechanical switches. It has a wide range of application scenarios and can meet the test requirements of each stage in the engineering research and development and engineering application of DC circuit breakers.

[0016] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0018] Figure 1 Schematic diagram of the DC circuit breaker closed-loop on / off submodule test equipment of the present invention used to test the main branch module of the DC circuit breaker;

[0019] Figure 2 Schematic diagram of the DC circuit breaker closed-loop on / off submodule test equipment of the present invention used to test the transfer branch submodule of the DC circuit breaker;

[0020] Figure 3 This is the experimental circuit diagram of the IGBT on / off submodule in the present invention;

[0021] Figure 4 This is the signal waveform diagram of the IGBT in the normal state in the above test;

[0022] Figure 5 This is the signal waveform diagram of the IGBT in the above test under the failure state of turn-on;

[0023] Figure 6 This is the signal waveform diagram of the IGBT in the above test under the shutdown failure state;

[0024] Figure 7 This is the signal waveform diagram of one IGBT in normal state and one IGBT in failure state in the above test;

[0025] Figure 8 This is the signal waveform diagram of one IGBT in normal state and one IGBT in shutdown failure state in the above test;

[0026] Figure 9 This is a signal waveform diagram when two IGBTs are in a breakdown state in the above test.

[0027] In the figure, 1 represents the test controller; 2 represents the communication interface DBC&VBC; 3 represents the integrated drive; 4 represents the test circuit; 51 represents the full-bridge circuit; 52 represents the mechanical switch; 6 represents the low-voltage power supply; and 7 represents the current-limiting resistor. DETAILED DESCRIPTION

[0028] To make the purpose and technical solutions of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art in the art to which the present invention pertains. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and, unless defined as such herein, will not be interpreted in an idealized or overly formal sense.

[0030] Figure 1 The invention provides a DC circuit breaker closed loop on / off submodule test device, which can be used to detect the main branch submodule of the DC circuit breaker, or can also be used to detect Figure 2 The transfer branch submodule of the DC circuit breaker is shown in FIG. Figure 1 as well as Figure 2 Two application scenarios, the DC circuit breaker closed-loop on-off submodule test equipment includes:

[0031] The test controller 1 is connected to the test circuit 4 and the communication interface DBC&VBC2;

[0032] Communication interface DBC&VBC2, connected to the test controller 1, the integrated drive 3, and the mechanical switch 52 in the DC circuit breaker;

[0033] Integrated driver 3, connected to the communication interface DBC&VBC2 and the main branch or transfer branch submodule of the DC circuit breaker;

[0034] The test circuit 4 is connected to the main branch or transfer branch submodule of the DC circuit breaker and the test controller 1 .

[0035] The DC circuit breaker it detects is referenced Figure 3, including: a full-bridge module, a mechanical switch 52, and various switching elements including IGBT transistors. During testing, the DC circuit breaker's main branch or transfer branch submodule was also connected to a low-voltage power supply 6 and a current-limiting resistor 7 connected in series. These low-voltage power supply 6 and current-limiting resistor 7 were connected in series across the DC circuit breaker's main branch or transfer branch submodule, outputting a low-voltage DC power supply signal not exceeding 100V to the module. The current-limiting resistor 7 was selected to be approximately 20Ω to limit the current.

[0036] The above units constitute a system that can be operated by the user to perform the following test steps:

[0037] In the first step, the test controller 1 receives a user command and outputs a control signal to the test circuit 4 and the communication interface DBC & VBC2 according to the command. The user command includes: a test start time signal, a test type mark, test parameters, a test progress signal, a test result signal, and a triggering emergency protection signal.

[0038] In the second step, the communication interface DBC&VBC2 outputs an opening command or a closing command to the mechanical switch 52 in the DC circuit breaker according to the control signal output by the test controller 1, and sends an opening and closing control signal to the integrated drive 3;

[0039] In the third step, the integrated driver 3 outputs a test trigger excitation signal according to the on / off control signal output by the communication interface DBC&VBC2, triggering each circuit element in the main branch or transfer branch submodule of the DC circuit breaker;

[0040] In the fourth step, the test circuit 4 receives the voltage and current signals generated by each circuit element in the main branch or transfer branch submodule of the DC circuit breaker in response to the opening command, closing command or test trigger excitation signal, and converts the voltage and current signals into detection data for output;

[0041] In the fifth step, the test controller 1 receives the data detected and output by the test circuit 4, analyzes the time of change of the voltage and current signals based on the data, and calculates the status, equivalent resistance, and equivalent capacitance of the main branch or transfer branch submodule of the DC circuit breaker to determine the status of the main branch or transfer branch submodule of the DC circuit breaker and whether the circuit components in the main branch or transfer branch submodule of the DC circuit breaker have failed. Generally, the judgment criteria can be selected as follows: if the calculated equivalent resistance of the main branch or transfer branch submodule of the DC circuit breaker is between 10 and 300 kΩ and the equivalent capacitance is between 10 and 300 μF, then the status of the main branch or transfer branch submodule of the DC circuit breaker is determined to be normal.

[0042] Wherein, the integrated drive 3 can be Figure 1 or Figure 2 The test trigger is integrated into the DC circuit breaker to be tested. It is connected to the communication interface DBC & VBC2 and the main branch or transfer branch submodule of the DC circuit breaker, and is configured to output a test trigger excitation signal based on the on / off control signal output by the communication interface DBC & VBC2, thereby triggering each circuit element in the main branch or transfer branch submodule of the DC circuit breaker.

[0043] In one implementation, the device further includes a power supply 9 connected to the integrated driver 3 . The power supply 9 has an isolation circuit and a voltage stabilization circuit, and can provide a DC voltage stable at 20V to the integrated driver 3 during the test.

[0044] To distinguish control signals from collected current and voltage data signals, the present invention can further configure the communication interface DBC & VBC2 to connect the test controller 1, the integrated driver 3, and the mechanical switch 52 in the DC circuit breaker via optical fiber. Cables are used to connect the integrated driver 3 to the main branch or transfer branch submodule of the DC circuit breaker, the integrated driver 3 to the power supply 9, the main branch or transfer branch submodule of the DC circuit breaker and the test circuit 4, and the test circuit and the test controller 1. The voltage and current data collected by the test circuit 4 via the cables includes the first current and first voltage generated by the full-bridge module in the DC circuit breaker under the DC signal. Based on this, the test controller can further calculate the capacitance and resistance values ​​of the full-bridge module based on the first current and first voltage as a basis for determining whether it is operating normally.

[0045] In addition, to ensure safety, the test communication interface DBC&VBC is also used to perform an emergency stop operation, output an emergency stop signal, and control the cancellation of the drive to each circuit element when an abnormality occurs during the test.

[0046] because Figures 4 to 9In the signal waveforms in the main branch or transfer branch submodule of the DC circuit breaker, the waveforms are similar in the two cases when the IGBT is in the normal state and when one IGBT is normal and the other IGBT is turned on and failed. Therefore, in the above-mentioned fifth step, the test controller 1 receives the data detected and output by the test circuit 4, and determines whether the switching element in the main branch or transfer branch submodule of the DC circuit breaker meets the following conditions: when not turned on, the loop current decreases and the voltage increases; when turned on, the voltage drops to 0 and the current increases; when the switching element is turned off, the current gradually decreases to close to 0 and the voltage continues to rise. , the following test steps are further performed to determine which situation occurs: first, a Rogowski coil current test is performed on each switching element in the main branch or transfer branch submodule of the DC circuit breaker; then, when it is determined that the current obtained by the Rogowski coil current test differs by 1 / 2 from the loop current in the data detected and output by the test circuit 4, the status of the main branch or transfer branch submodule of the DC circuit breaker is determined to be normal; otherwise, it is determined that one switching element in the main branch or transfer branch submodule of the DC circuit breaker is normal and the other switching element is turned on and failed.

[0047] Because mechanical switch 52 is a mechanical switch for the DC circuit breaker's main branch and is connected in series with the main branch submodule, the test circuit can send control closing and opening commands to the mechanical switch via DBC&VBC to determine whether the switch is functioning properly and operating according to the commands. Specifically, to detect mechanical switch delay, the fifth step further includes: utilizing the test controller 1 to receive data detected and output by the test circuit 4, and obtaining the time difference between the time when the voltage at the mechanical switch 52 in the DC circuit breaker changes and the time when the communication interface DBC&VBC2 outputs the opening or closing command. This time difference corresponds to the second voltage and second current generated by the mechanical switch when performing opening and closing operations under the DC signal. The test controller compares the second voltage with a preset voltage value and / or the second current with a preset current value, and based on this time difference, determines whether the mechanical operation delay of the mechanical switch 52 meets technical specifications.

[0048] In a more specific implementation method, the present invention uses a test controller 1 to obtain a test instruction input by a user, sends a test instruction to the communication interface DBC&VBC2 according to the test instruction, and sends a start test command to the test circuit 4; the communication interface DBC&VBC2 obtains the test instruction, sends an on / off control signal to the integrated driver 3 of the submodule according to the test instruction, and receives return status information from the integrated driver 3, including on / off status, IGBT status, power supply status and communication status, etc.; the integrated driver 3 receives the control signal and sends a test trigger excitation signal to the DC circuit breaker submodule to be tested; the test circuit 4 collects the test data generated by the DC circuit breaker to be tested under the test trigger excitation signal, and sends the test data to the test controller 1, and sends the test result to the communication interface DBC&VBC2. The test result is a result of whether the test is passed by the test circuit after a comprehensive analysis of the measured voltage, current and drive return status. This method can conveniently test the full-bridge module 51, mechanical switch 52, and power supply 9 in the DC circuit breaker closed-loop opening and closing submodule test equipment; and can meet the test requirements of each stage in the engineering development and engineering application process of the DC circuit breaker.

[0049] Specifically, in one implementation, the DC circuit breaker 5 to be tested includes a full-bridge module 51, and the test controller 1 obtains the test instruction input by the user, and sends the test instruction to the communication interface DBC&VBC2 according to the test instruction; the communication interface DBC&VBC obtains the test instruction, and the test instruction includes the type of the full-bridge module 51, the test items, the test time, etc. According to the test instruction, an on / off control signal is sent to the integrated driver board 3 of the submodule; the integrated driver 3 receives the control signal, sends a 19V low-voltage signal to the main branch and transfer branch submodules of the DC circuit breaker to be tested, and detects whether the IGBT devices, drive signals and power supplies are correct, and whether the components are normal; the test circuit 4 collects the current and voltage signals generated by the full-bridge module 51 under the DC signal, and the test controller calculates the capacitance and resistance values ​​of the full-bridge module 51 based on the test data, and detects whether the basic functions of the submodule, such as trigger monitoring, electrical path, IGBT on / off, and bypass switch, are correct. For example, the specific test circuit and parameters for the parallel IGBT on / off test are as follows: Figure 2 The low-voltage circuit is 100V and the current-limiting resistor is 20Ω. The voltage and current across the device are monitored during the test.

[0050] In a specific implementation, the calculation process can adopt a calculation method in the prior art, and determine whether the full-bridge module 51 meets the requirements based on the calculated capacitance and resistance values ​​to obtain a test result. For example, the qualified value range of the capacitance value is 10 to 300 μF, and the qualified value range of the resistance value is 10 to 300 kΩ. When the calculated capacitance value and resistance value are within their respective qualified value ranges, the test result is normal; otherwise, the full-bridge module 51 is determined to be abnormal. It should be noted that the above ranges are for illustration only and are not intended to limit the present invention. In actual applications, the qualified value ranges for capacitance and resistance values ​​can be adjusted according to actual needs.

[0051] In practical applications, the test controller can also obtain test parameters such as maximum voltage, maximum current, and commutation time during the test, and further generate and store test waveforms based on the calculated capacitance and resistance values ​​of the full-bridge module 51. Based on the IGBT status, the following six operating conditions can be classified: both IGBTs are normal, both IGBTs fail to turn on, IGBT fail to turn off, one IGBT normal and one IGBT fails to turn on, one IGBT normal and one IGBT fails to turn off, and one of the two IGBTs has breakdown.

[0052] Specifically, the two IGBTs are tested normally with waveforms such as Figure 4 As shown in the figure, when the IGBT is not turned on, the loop current begins to decrease and the voltage begins to rise by 35V. At 0.003ms, the IGBT is turned on, the voltage drops to zero, and the current rises to 5A and lasts for 3ms. At 0.006ms, the IGBT is turned off, and the current begins to decrease, approaching zero after about 20ms, while the voltage continues to rise to 100V.

[0053] If the IGBT is in abnormal switching state due to abnormal driving, fiber breakage, weak light intensity, etc., the two IGBT turn-on failure waveforms are as follows Figure 5 When both IGBTs fail to turn on, the loop current drops to zero after about 20ms and the voltage starts to rise by 100V.

[0054] If the IGBT is turned off abnormally due to abnormal driving or power supply, the test waveform is as follows: Figure 6 shown.

[0055] In addition, reference Figure 8 , one IGBT in the submodule is normal and the other IGBT fails to turn off and Figure 6 The waveforms of the two IGBT turn-off failures are consistent, so these two types are uniformly attributed to the same type of failure of the sub-module.

[0056] because Figure 7 One IGBT is normal and the other IGBT is turned on faulty. Figure 1 The neutron module's normal waveform is consistent, requiring further verification of the fault type. In this case, a separate IGBT current test is performed. During the test, the current of one IGBT is measured using a Rogowski coil. If the difference between the two currents is 1 / 2 of the loop current, the test is successful; otherwise, a fault has occurred.

[0057] By comparing the above submodule operating conditions, it can be seen that when the submodule is normal, two IGBTs of the submodule are turned on, one IGBT of the submodule is broken down, and one IGBT of the submodule is normal and the other is turned off, the fault type can be determined by testing its voltage and current waveforms.

[0058] Specifically, in one embodiment, the DC circuit breaker 5 under test further includes a mechanical switch 52. The communication interface DBC&VBC2 is used to send opening and closing commands to the mechanical switch 52. The integrated driver 3 receives the start test command and sends a DC signal of a low voltage of 19V DC to the main branch and transfer branch submodules of the DC circuit breaker 5 under test. The test circuit 4 collects the voltage and current generated by the mechanical switch 52 when performing opening and closing operations under the DC signal. The test controller 1 determines the execution status of the mechanical switch 52's commands based on the voltage and current generated by the mechanical switch 52 during the opening and closing operations. For example, when a trip command is sent to the mechanical switch 52, the voltage across the break of the mechanical switch 52 is detected. In the initial state, since the mechanical switch 52 is in the closed state, its break voltage is zero. If the voltage of the break is detected to increase to the power supply voltage, it is determined that the mechanical switch 52 has been successfully tripped. By testing the time of voltage change, the delay in the tripping action of the mechanical switch 52 can be obtained, and by receiving the reaching distance signal and the trip position status signal of the mechanical switch 52, it can be determined whether the mechanical characteristics of the mechanical switch 52 meet the technical specifications.

[0059] The DC circuit breaker closed-loop on / off submodule test equipment also includes a low-voltage power supply 6 and a current-limiting resistor 7, which are used to provide power to the full-bridge module 51 of the DC circuit breaker 5 under test. By adjusting the output voltage range of the low-voltage power supply 6, the supply voltage of the full-bridge submodule 51 is tested to determine whether the voltage is within the required technical specifications. Specifically, the output voltage of the low-voltage power supply 6 is 100V, and the resistance of the current-limiting resistor 7 is 20Ω.

[0060] Specifically, the DC circuit breaker closed-loop opening and closing submodule test equipment includes a test controller 1, which is used to receive user-selected test items and test parameters, generate the above-mentioned test instructions, and send the test instructions to the communication interface DBC&VBC2. The test instructions mainly include test start, test type, test progress, test results, emergency trigger protection, etc.

[0061] In a preferred embodiment, the DC circuit breaker closed-loop on / off submodule test equipment of the embodiment of the present invention further includes a power supply 9 to provide a power supply voltage for the integrated drive 3. The power supply 9 is a regulated power supply with an isolated 20V DC voltage.

[0062] In actual application, the DBC&VBC2 communication interface initiates an emergency stop if an anomaly occurs during testing. This anomaly refers to a dangerous condition such as a short circuit or damage in the DC circuit breaker closed-loop on / off submodule test equipment, protecting equipment and personnel. The DC circuit breaker closed-loop on / off submodule test equipment also features overvoltage and overcurrent protection, safeguarding all components of the test equipment.

[0063] The above is merely an embodiment of the present invention, and its description is relatively specific and detailed, but it should not be understood as limiting the scope of the present invention. It should be pointed out that those skilled in the art can make a number of modifications and improvements without departing from the concept of the present invention, and these modifications and improvements are all within the scope of protection of the present invention.

Claims

1. A DC circuit breaker closed-loop on / off submodule test method, characterized in that: The test steps include: The first step is to receive a user's instruction and output a control signal to the test circuit (4) and the communication interface (2) according to the instruction; wherein the user's instruction includes: a test start time signal, a test category mark, a test parameter, a test progress signal, a test result signal, and a trigger emergency protection signal; In the second step, the communication interface (2) outputs an opening command or a closing command to the mechanical switch (52) in the DC circuit breaker according to the control signal output by the test controller (1), and sends an opening and closing control signal to the integrated drive (3); In the third step, the integrated driver (3) outputs a test trigger excitation signal according to the on / off control signal output by the communication interface (2), thereby triggering each circuit element in the main branch or transfer branch submodule of the DC circuit breaker; In the fourth step, the test circuit (4) receives the voltage signal and current signal generated by each circuit element in the main branch or transfer branch submodule of the DC circuit breaker in response to the opening instruction, closing instruction or test trigger excitation signal, and converts the voltage signal and current signal into detection data output; In the fifth step, the test controller (1) receives the data detected and output by the test circuit (4), analyzes the time of change of the voltage signal and the current signal based on the data, calculates the state of the main branch or transfer branch submodule of the DC circuit breaker and the equivalent resistance and equivalent capacitance, so as to determine the state of the main branch or transfer branch submodule of the DC circuit breaker and determine whether the circuit elements in the main branch or transfer branch submodule of the DC circuit breaker are failed; The fifth step also includes the following steps: the test controller (1) receives the data detected and output by the test circuit (4), and determines whether the switch element in the main branch or transfer branch submodule of the DC circuit breaker meets the following conditions: when not switched on, the loop current decreases and the voltage increases; when switched on, the voltage drops to 0 and the current increases; when the switch element is switched off, the current gradually decreases to close to 0 and the voltage continues to increase; and when the above conditions are met, further performing the Rogowski coil current test; The Rogowski coil current test includes the following test steps: Performing a Rogowski coil current test on each switching element in the main branch or transfer branch submodule of the DC circuit breaker individually; When it is determined that the current obtained by the Rogowski coil current test differs from the loop current in the data detected and output by the test circuit (4) by 1 / 2 of the loop current, it is determined that the state of the main branch or transfer branch submodule of the DC circuit breaker is normal; otherwise, it is determined that one switching element in the main branch or transfer branch submodule of the DC circuit breaker is normal and one switching element is turned on and failed.

2. The DC circuit breaker closed-loop on / off submodule test method according to claim 1, characterized in that: In the fifth step, if the equivalent resistance of the main branch or transfer branch submodule of the DC circuit breaker is calculated to be between 10 and 300 kΩ and the equivalent capacitance is between 10 and 300 μF, it is determined that the status of the main branch or transfer branch submodule of the DC circuit breaker is normal.

3. The DC circuit breaker closed-loop on / off submodule test method according to claim 1, characterized in that: The fifth step also includes: the test controller (1) receives the data detected and output by the test circuit (4), obtains the time difference between the time when the voltage of the mechanical switch (52) in the DC circuit breaker changes and the time when the communication interface DBC&VBC (2) outputs the opening command or the closing command, and determines whether the mechanical action delay of the mechanical switch (52) meets the technical specification requirements based on the time difference.

4. The DC circuit breaker closed-loop on / off submodule test method according to any one of claims 1 to 3, characterized in that: In the second step, the communication interface (2) outputs an opening command or a closing command to the mechanical switch (52) in the DC circuit breaker via an optical fiber, and sends an opening and closing control signal to the integrated drive (3).

5. The DC circuit breaker closed-loop on / off submodule test method according to claim 1, characterized in that: The first step also includes: connecting the two ends of the main branch or transfer branch submodule of the DC circuit breaker to a low-voltage power supply (6) and a current-limiting resistor (7) connected in series, and the low-voltage power supply (6) and the current-limiting resistor (7) output a low-voltage DC power supply signal not exceeding 100V to the main branch or transfer branch submodule of the DC circuit breaker.

6. The DC circuit breaker closed-loop on / off submodule test method according to claim 1, characterized in that: The first step also includes: connecting the integrated driver (3) to a power supply (9), wherein the power supply (9) has an isolation circuit and a voltage stabilization circuit, and provides a DC voltage stabilized at 20V to the integrated driver (3).

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