Thyristor level test method
By conducting multiple tests on the thyristor stage using a full-sequence testing method, the problem of insufficient comprehensiveness and accuracy in existing technologies is solved, achieving efficient and accurate thyristor stage evaluation and reducing the operational risks of high-voltage direct current transmission systems.
Patent Information
- Application Number
- CN202410942764.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-15
- Publication Date
- 2025-11-14
AI Technical Summary
In existing technologies, the comprehensiveness and accuracy of thyristor-level testing are insufficient, making it difficult to guarantee the reliability of converter valves and increasing the operational risks of high-voltage direct current transmission systems.
The full-sequence testing method is adopted to perform multiple tests on the thyristor stage, including impedance, short circuit, energy storage, low voltage triggering, current discontinuity, reverse recovery protection triggering, reverse recovery end withstand, positive and negative polarity impact, and positive overvoltage protection. By accurately measuring and analyzing the timing logic of the report signal, all test items can be completed in one go.
It significantly improves the comprehensiveness and accuracy of thyristor-level testing, simplifies the testing process, shortens the testing cycle, reduces human error and time costs, improves testing efficiency, enables timely detection of potential faults, and reduces system operation risks.
Smart Images
Figure CN120948992A_ABST
Abstract
Description
Technical Field
[0001] This disclosure pertains to the field of high-voltage direct current transmission, specifically relating to a thyristor-level testing method. Background Technology
[0002] High-voltage direct current (HVDC) transmission has developed rapidly due to its advantages in long-distance power transmission and asynchronous interconnection. However, thyristor converter valves are subjected to long-term electrothermal stress during operation, posing a risk of systemic failure. Therefore, the reliability of the converter valves largely determines the reliability of the DC system.
[0003] To ensure reliable operation of the converter valve, it is necessary to test it both before and during system power outages. Since the converter valve is composed of numerous thyristor stages connected in a modular fashion, testing typically involves testing each thyristor stage individually. Therefore, developing a converter valve thyristor stage testing system and an efficient measurement method is of significant practical value.
[0004] The information disclosed in the background section is only intended to enhance the understanding of the background of the present invention, and therefore may contain information that does not constitute prior art known to those skilled in the art. Summary of the Invention
[0005] In view of the shortcomings of the prior art, the purpose of this disclosure is to provide a thyristor-level testing method, which can significantly improve the comprehensiveness and accuracy of thyristor-level testing.
[0006] To achieve the above objectives, this disclosure provides the following technical solutions:
[0007] A thyristor-level testing method includes the following steps:
[0008] Connect the thyristor stage under test to the test circuit;
[0009] Impedance testing is performed on the thyristor stage under test.
[0010] Perform a short-circuit test on the thyristor stage under test;
[0011] Energy storage tests were performed on the thyristor stage under test.
[0012] Perform low-voltage triggering test on the thyristor stage under test;
[0013] Perform current discontinuity testing on the thyristor stage under test;
[0014] Perform reverse recovery protection trigger test and reverse recovery termination tolerance test on the thyristor stage under test;
[0015] Positive and negative polarity impact tests were performed on the thyristor stage under test.
[0016] Perform forward overvoltage protection testing on the thyristor stage under test.
[0017] Optionally, the impedance test of the thyristor stage under test includes:
[0018] Set the test parameters and apply a voltage pulse signal to both ends of the thyristor stage under test;
[0019] Test the voltage and current, calculate the impedance value at the corresponding frequency, and determine whether the impedance of the thyristor stage under test is within a reasonable range.
[0020] Optionally, the impedance test includes DC impedance test and AC impedance test. The DC impedance test requires the application of a DC voltage pulse signal, and the AC impedance test requires the application of an AC voltage pulse signal.
[0021] Optionally, the short-circuit test on the thyristor stage under test includes:
[0022] Acquire the voltage waveform across the thyristor stage under test;
[0023] The number of report pulses is counted, and the number of report pulses is used to determine whether a short circuit has occurred in the thyristor stage under test.
[0024] Optionally, the energy storage test performed on the thyristor stage under test includes:
[0025] The voltage waveform and feedback pulse waveform across the thyristor stage under test are collected when the test circuit is powered off.
[0026] The energy storage time of the thyristor stage under test is obtained by counting the number of statistical report signals.
[0027] Optionally, the low-voltage triggering test performed on the thyristor stage under test includes:
[0028] Send a check signal to the thyristor stage under test, and simultaneously test the trigger voltage and current of the thyristor stage under test;
[0029] The timing logic of the feedback signal is used to complete the low-voltage trigger test of the thyristor under test.
[0030] Optionally, the current discontinuity test performed on the thyristor stage under test includes:
[0031] Measure the voltage across the thyristor during the intermittent period after it is triggered to conduct;
[0032] Determine whether the voltage at both ends exceeds the threshold.
[0033] The timing logic of the feedback signal is used to complete the current discontinuity test of the thyristor stage under test.
[0034] Optionally, the reverse recovery protection trigger test and reverse recovery termination withstand test performed on the thyristor stage under test include:
[0035] A voltage pulse signal of a certain amplitude is applied during the reverse recovery period of the thyristor stage under test;
[0036] The protection voltage threshold and the current waveform after triggering are tested to complete the reverse recovery protection trigger test and reverse recovery end withstand test of the thyristor stage under test.
[0037] Optionally, the positive polarity impulse test and negative polarity impulse test performed on the thyristor stage under test include:
[0038] Positive and negative impulse voltages are applied to the thyristor stage under test;
[0039] The amplitude of the impulse voltage and the corresponding current waveform are tested to complete the positive and negative impulse tests of the thyristor stage under test.
[0040] Optionally, the forward overvoltage protection test on the thyristor stage under test includes:
[0041] Apply an impulse voltage to the thyristor stage under test;
[0042] Test the impulse voltage amplitude and the corresponding current waveform to complete the positive overvoltage protection test.
[0043] Compared with the prior art, the beneficial effects of this disclosure are as follows:
[0044] 1. By conducting comprehensive tests on the thyristor stage, including impedance testing, short-circuit testing, energy storage testing, low-voltage triggering testing, current discontinuity testing, reverse recovery protection triggering testing, reverse recovery termination withstand testing, positive and negative polarity impulse testing, and forward overvoltage protection testing, this solution can more accurately evaluate the performance of the thyristor stage, significantly improve the comprehensiveness and accuracy of testing, help to detect potential faults in advance, and reduce the operational risks of high-voltage direct current transmission systems caused by thyristor failures.
[0045] 2. The full-sequence testing function adopted in this application allows all test items to be completed at once, which not only simplifies the testing process, but also greatly shortens the testing cycle, improves testing efficiency, and reduces human error and testing time costs that may be caused by multiple separate tests.
[0046] 3. By accurately measuring the amplitude of the impulse voltage and the corresponding current waveform, as well as analyzing the timing logic of the feedback signal, this application can quickly and accurately identify problems in the thyristor stage, providing a scientific basis for fault diagnosis and facilitating timely maintenance measures. Attached Figure Description
[0047] Figure 1 This is a schematic diagram of the structure of a thyristor-level test circuit provided in one embodiment of this application;
[0048] Figure 2 This is a schematic diagram of the thyristor stage circuit structure provided in one embodiment of this application;
[0049] Figure 3(a) is a waveform diagram of thyristor-level DC impedance test provided in an embodiment of this application;
[0050] Figure 3(b) is a waveform diagram of a 100Hz impedance test provided in an embodiment of this application;
[0051] Figure 3(c) is a 10Hz impedance test waveform diagram provided in an embodiment of this application;
[0052] Figure 4(a) is a diagram of the voltage waveform and feedback pulse waveform across the thyristor during a short-circuit test provided in an embodiment of this application;
[0053] Figure 4(b) is a waveform diagram of the return pulse of a thyristor stage provided in an embodiment of this application;
[0054] Figure 5 This is a schematic diagram of the energy storage test waveform of the thyristor stage provided in one embodiment of this application;
[0055] Figure 6(a) is a waveform diagram of the inspection signal generated by the test platform provided in an embodiment of this application;
[0056] Figure 6(b) is a waveform diagram of the voltage across the thyristor during low-voltage triggering according to an embodiment of this application;
[0057] Figure 7 This is a waveform diagram of the voltage signal across the thyristor during a current discontinuity test provided in one embodiment of this application;
[0058] Figure 8 This is a waveform diagram of the two ends of the thyristor during the reverse recovery period protection trigger test provided in one embodiment of this application;
[0059] Figure 9 This is a waveform diagram of the two ends of the thyristor at the end of the reverse recovery period provided in one embodiment of this application. Detailed Implementation
[0060] The following will refer to the appendix. Figures 1 to 9 Specific embodiments of this disclosure are described in detail. While specific embodiments of this disclosure are shown in the accompanying drawings, it should be understood that this disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art.
[0061] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions are preferred embodiments for carrying out this disclosure; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of this disclosure. The scope of protection of this disclosure is determined by the appended claims.
[0062] To facilitate understanding of the embodiments of this disclosure, further explanations and descriptions will be provided below with reference to the accompanying drawings and specific embodiments. The accompanying drawings do not constitute a limitation on the embodiments of this disclosure.
[0063] In one embodiment, this application provides a thyristor-level testing method, comprising the following steps:
[0064] Connect the thyristor stage under test to the test circuit;
[0065] Impedance testing is performed on the thyristor stage under test.
[0066] Perform a short-circuit test on the thyristor stage under test;
[0067] Energy storage tests were performed on the thyristor stage under test.
[0068] Perform low-voltage triggering test on the thyristor stage under test;
[0069] Perform current discontinuity testing on the thyristor stage under test;
[0070] Perform reverse recovery protection trigger test and reverse recovery termination tolerance test on the thyristor stage under test;
[0071] Positive and negative polarity impact tests were performed on the thyristor stage under test.
[0072] Perform forward overvoltage protection testing on the thyristor stage under test.
[0073] In this embodiment, the test main circuit and the thyristor stage circuit of the test sample are as follows: Figure 1 , Figure 2 As shown. Figure 2In the circuit, R1 and R2 are static voltage equalizing resistors, with parameters consisting of two 51kΩ resistors connected in series. C1, C2, C3, R3, and R4 form two energy extraction circuits, while C1, C3, and R4 form the thyristor absorption circuit. The designed parameters for C1, C2, C3, R3, and R4 are 1.8μF, 0.68μF, 4μF, 940Ω, and 30Ω, respectively.
[0074] This application adopts full-sequence testing, which allows all test items to be completed at once. This not only simplifies the testing process but also greatly shortens the testing cycle, improves testing efficiency, and reduces human error and testing time costs that may result from multiple separate tests.
[0075] In another embodiment, the impedance test of the thyristor stage under test includes:
[0076] Set the test parameters and apply a voltage pulse signal to both ends of the thyristor stage under test;
[0077] Test the voltage and current, calculate the impedance value at the corresponding frequency, and determine whether the impedance of the thyristor stage under test is within a reasonable range.
[0078] In another embodiment, the impedance test includes a DC impedance test and an AC impedance test. The DC impedance test requires the application of a DC voltage pulse signal, and the AC impedance test requires the application of an AC voltage pulse signal.
[0079] In this embodiment, the impedance test is mainly used to measure and verify whether the impedance of the DC equalizing resistor and the other two energy extraction branches is correct. Since the impedances of the three branches differ significantly at different frequencies, the test is divided into DC resistance test, 100Hz impedance test, and 10kHz impedance test. Figure 3(a) shows the voltage waveform across the thyristor during the DC impedance test. It can be seen that the excitation waveform is a 60V DC voltage lasting approximately 2 seconds. By measuring the voltage and current signals, its DC resistance can be calculated. Figure 3(b) shows the voltage waveform across the thyristor during the 100Hz impedance test. It can be seen that the excitation waveform is an AC voltage with an effective value of approximately 60V and a frequency of 100Hz, lasting approximately 4.5 seconds. By measuring the voltage and current signals, its impedance value under the 100Hz AC voltage can be calculated. Figure 3(c) shows the voltage waveform across the thyristor during the 10kHz impedance test. It can be seen that the excitation waveform is an AC voltage with an effective value of about 60V and a frequency of 10kHz, lasting for about 12s. By measuring the voltage and current signals, the impedance value under the 10kHz AC voltage can be calculated.
[0080] In another embodiment, the short-circuit test on the thyristor stage under test includes:
[0081] Acquire the voltage waveform across the thyristor stage under test;
[0082] The number of report pulses is counted, and the number of report pulses is used to determine whether a short circuit has occurred in the thyristor stage under test.
[0083] In this embodiment, the number of report pulses at the thyristor stage under test = the number of cycles during the duration - the number of cycles required before power-on to complete energy harvesting.
[0084] For example, Figure 4(a) shows the voltage waveform and feedback pulse waveform across the thyristor under test during a short-circuit test. It can be seen that the excitation waveform is a power frequency voltage with an amplitude of approximately 600V, lasting for 40 cycles. As shown in Figure 4(a), starting from the third power frequency cycle, the TTM should have completed power-on and begun sending feedback pulses. Each feedback pulse is sent approximately at +37V after the power frequency voltage changes from negative to positive. By measuring the voltage and counting the feedback pulses, it can be determined whether a short circuit has occurred. When no short circuit has occurred, the number of feedback pulses should be 38, with the waveform shown in Figure 4(b) and a pulse width of 6μs. If the feedback pulse fiber is disconnected during the short-circuit test, the test will fail. Furthermore, the short-circuit test is independent of whether the trigger fiber is inserted.
[0085] In another embodiment, the energy storage test on the thyristor under test includes:
[0086] The voltage waveform and feedback pulse waveform across the thyristor stage under test are collected when the test circuit is powered off.
[0087] The energy storage time of the thyristor stage under test is obtained by counting the number of statistical report signals.
[0088] In this embodiment, the purpose of the energy storage test is to verify whether the energy storage capacitor on the TTM board can maintain the operation time of the logic circuit on the board in the event of a power failure after a sufficiently long charging time. Figure 5 The waveforms of the voltage across the thyristor and the feedback pulse during energy storage testing are shown. It can be seen that the excitation waveform is a power frequency voltage with an amplitude of approximately 600V, lasting for 40 cycles. After the power frequency voltage lasts for 40 cycles, power is cut off. After power failure, at each power frequency cycle, the test platform sends a check signal to the TTM board, and the TTM board responds to this check signal by generating a feedback signal of equal width. By counting the number of feedback signals, the duration the energy storage capacitor can sustain operation can be determined. Note that the trigger and feedback pulse widths should be confirmed.
[0089] In another embodiment, the low-voltage triggering test of the thyristor stage under test includes:
[0090] Send a check signal to the thyristor stage under test, and simultaneously test the trigger voltage and current of the thyristor stage under test;
[0091] The timing logic of the feedback signal is used to complete the low-voltage trigger test of the thyristor under test.
[0092] In this embodiment, the purpose of the low-voltage triggering test is to verify whether the thyristor stage can be triggered normally under a lower voltage. Figure 7 The waveform of the voltage across the thyristor during the low-voltage trigger test shows that the excitation waveform is a power frequency voltage with an amplitude of approximately 600V, lasting for 32 cycles. The 32nd cycle of the power frequency voltage triggers the test. The trigger signal is a double pulse. After triggering and conduction, immediately following the reverse recovery of the negative half-wave of the voltage, the test platform sends the following signal: Figure 7 The check signal is shown. Logically, the TTM board will respond to the check signal by sending a message to the test platform as shown. Figure 7 The reported signal is shown. Analysis suggests this action aims to verify whether the thyristor can normally resume blocking, and further confirms that the thyristor's trigger conduction is normal. During this process, by measuring the thyristor trigger voltage and current, and judging the timing logic of the reported signal, it can be determined whether the low-voltage trigger test has passed. Note that the pulse waveforms of the check signal and the corresponding reported signal should be confirmed during the negative half-wave.
[0093] In another embodiment, the current discontinuity test on the thyristor stage under test includes:
[0094] Measure the voltage across the thyristor during the intermittent period after it is triggered to conduct;
[0095] Determine whether the voltage at both ends exceeds the threshold.
[0096] The timing logic of the feedback signal is used to complete the current discontinuity test of the thyristor stage under test.
[0097] In this embodiment, the purpose of the current discontinuity test is to verify whether the automatic re-trigger function of the thyristor stage is normal when the voltage is higher than a certain threshold during the current discontinuity period. Figure 7 The waveform of the voltage across the thyristor during the discontinuous current test shows that the excitation waveform is a power frequency voltage with an amplitude of approximately 600V, lasting for 43 cycles. The 43rd cycle of the power frequency voltage triggers the current discontinuity phenomenon, which is then generated by controlling the internal excitation source of the test platform. During this period, if the voltage across the thyristor exceeds a certain threshold, the TTM board automatically re-triggers it. Figure 7 As shown, the red waveform here is the thyristor gate trigger signal waveform, and further... Figure 7 It can be seen that the trigger is not sent by the test platform. Figure 7The red waveform also shows that when discontinuous conduction occurs, the voltage across the thyristor increases from zero to a certain value, generating a corresponding feedback signal. It's easy to understand that by measuring whether the voltage across the thyristor exceeds a certain threshold and observing the current waveform during the discontinuous conduction period after the thyristor is triggered, and by judging the timing logic of the feedback signal, the success of the discontinuous current test can be determined. It should be noted that the check signal delay after conduction ends is later than in the low-voltage trigger test, which is presumably related to the increased reverse recovery time during the discontinuous conduction test.
[0098] In another embodiment, the reverse recovery protection trigger test and reverse recovery termination tolerance test performed on the thyristor stage under test include:
[0099] A voltage pulse signal of a certain amplitude is applied during the reverse recovery period of the thyristor stage under test;
[0100] The protection voltage threshold and the current waveform after triggering are tested to complete the reverse recovery protection trigger test and reverse recovery end withstand test of the thyristor stage under test.
[0101] In this embodiment, the main purpose of the reverse recovery protection trigger test is to verify whether the protective trigger function of the TTM board is normal during the reverse recovery period of the thyristor. Figure 8 The waveform shown is the reverse recovery period protection trigger test voltage waveform. After forward conduction triggering, a voltage pulse of a certain amplitude is applied during the reverse recovery period of the thyristor. The TTM board should perform protective triggering. However, due to a certain fault in the converter valve test system VTE used in this embodiment, the applied pulse voltage does not meet the conditions for protective triggering, so protection is not shown in the waveform. However, this does not affect the understanding of this experiment. By detecting the protection voltage threshold and the current waveform after triggering, it can be determined whether the test result is passed.
[0102] Furthermore, the main purpose of the reverse recovery end withstand test is to verify whether the thyristor stage can withstand a certain amplitude of impulse voltage after the reverse recovery period of the thyristor ends. Figure 9 The waveform of the withstand voltage at the end of the reverse recovery period is shown. The test method and judgment principle are similar to those of the reverse recovery protection trigger test, and will not be repeated here.
[0103] In another embodiment, the positive and negative polarity impact tests performed on the thyristor stage under test include:
[0104] Apply an impulse voltage to the thyristor stage under test;
[0105] The amplitude of the impulse voltage and the corresponding current waveform are tested to complete the positive and negative impulse tests of the thyristor stage under test.
[0106] In this embodiment, the main purpose of the positive impulse test is to verify whether the thyristor stage can withstand a positive impulse voltage of a certain amplitude. Based on the positive impulse test voltage waveform, it can be seen that the applied voltage is an impulse voltage of approximately 5kV. The test result can be determined by measuring the impulse voltage amplitude and the corresponding current waveform.
[0107] Furthermore, the main purpose of the positive overvoltage protection trigger test is to verify whether the thyristor stage can be protectively triggered when subjected to a positive impulse voltage exceeding its threshold. Based on the voltage waveform of the positive overvoltage protection trigger test, it can be seen that the applied voltage is an impulse voltage with an amplitude of approximately 6kV. Although the VTE equipment in this paper did not generate a pulse voltage that would trigger the thyristor stage protection due to a certain fault, it does not affect the understanding of this experiment. The test results can be determined by measuring the impulse voltage amplitude and the corresponding current waveform.
[0108] Furthermore, the main purpose of the negative polarity impulse test is to verify whether the thyristor stage can withstand a negative polarity impulse voltage of a certain amplitude. The test results can be determined by measuring the impulse voltage amplitude and the corresponding current waveform.
[0109] In another embodiment, the forward overvoltage protection test on the thyristor stage under test includes:
[0110] Apply an impulse voltage to the thyristor stage under test;
[0111] Test the impulse voltage amplitude and the corresponding current waveform to complete the positive overvoltage protection test.
[0112] In this embodiment, the main purpose of the positive overvoltage protection trigger test is to verify whether the thyristor stage can be protectively triggered when subjected to a positive impulse voltage exceeding its threshold. The voltage waveform of the positive overvoltage protection trigger test shows that the applied voltage is an impulse voltage with an amplitude of approximately 6kV. Although a pulse voltage that would trigger the thyristor stage protection was not generated due to a certain fault in the VTE equipment in this embodiment, it does not affect the understanding of this experiment. The test results can be determined by measuring the impulse voltage amplitude and the corresponding current waveform.
[0113] Although embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, and not restrictive. Those skilled in the art can make many other forms based on the guidance of this specification and without departing from the scope of protection of the claims of the present invention, and all of these are within the scope of protection of the present invention.
Claims
1. A thyristor-level testing method, comprising the following steps: Connect the thyristor stage under test to the test circuit; Impedance testing is performed on the thyristor stage under test. Perform a short-circuit test on the thyristor stage under test; Energy storage tests were performed on the thyristor stage under test. Perform low-voltage triggering test on the thyristor stage under test; Perform current discontinuity testing on the thyristor stage under test; Perform reverse recovery protection trigger test and reverse recovery termination tolerance test on the thyristor stage under test; Positive and negative polarity impact tests were performed on the thyristor stage under test. Perform forward overvoltage protection testing on the thyristor stage under test.
2. The method according to claim 1, wherein, Preferably, the impedance test of the thyristor stage under test includes: Set the test parameters and apply a voltage pulse signal to both ends of the thyristor stage under test; Test the voltage and current, calculate the impedance value at the corresponding frequency, and determine whether the impedance of the thyristor stage under test is within a reasonable range.
3. The method according to claim 2, wherein, The impedance test includes DC impedance test and AC impedance test. The DC impedance test requires the application of a DC voltage pulse signal, and the AC impedance test requires the application of an AC voltage pulse signal.
4. The method according to claim 1, wherein, The short-circuit test of the thyristor stage under test includes: Acquire the voltage waveform across the thyristor stage under test; The number of report pulses is counted, and the number of report pulses is used to determine whether a short circuit has occurred in the thyristor stage under test.
5. The method according to claim 1, wherein, The energy storage test of the thyristor stage under test includes: The voltage waveform and feedback pulse waveform across the thyristor stage under test are collected when the test circuit is powered off. The energy storage time of the thyristor stage under test is obtained by counting the number of statistical report signals.
6. The method according to claim 1, wherein, The low-voltage triggering test of the thyristor stage under test includes: Send a check signal to the thyristor stage under test, and simultaneously test the trigger voltage and current of the thyristor stage under test; The timing logic of the feedback signal is used to complete the low-voltage trigger test of the thyristor under test.
7. The method according to claim 1, wherein, The current discontinuity test of the thyristor stage under test includes: Measure the voltage across the thyristor during the intermittent period after it is triggered to conduct; Determine whether the voltage at both ends exceeds the threshold. The timing logic of the feedback signal is used to complete the current discontinuity test of the thyristor stage under test.
8. The method according to claim 1, wherein, The reverse recovery protection trigger test and reverse recovery termination tolerance test performed on the thyristor stage under test include: A voltage pulse signal of a certain amplitude is applied during the reverse recovery period of the thyristor stage under test; The protection voltage threshold and the current waveform after triggering are tested to complete the reverse recovery protection trigger test and reverse recovery end withstand test of the thyristor stage under test.
9. The method according to claim 1, wherein, The positive and negative polarity impulse tests performed on the thyristor stage under test include: Positive and negative impulse voltages are applied to the thyristor stage under test; The amplitude of the impulse voltage and the corresponding current waveform are tested to complete the positive and negative impulse tests of the thyristor stage under test.
10. The method according to claim 1, wherein, The forward overvoltage protection test of the thyristor stage under test includes: Apply an impulse voltage to the thyristor stage under test; Test the impulse voltage amplitude and the corresponding current waveform to complete the positive overvoltage protection test.