Flexible direct-current converter valve submodule passive bypass explosion-proof performance test device and flexible direct-current converter valve submodule passive bypass explosion-proof performance test method

Abstract

The invention belongs to the field of flexible direct-current power transmission tests, and discloses a flexible direct-current converter valve submodule passive bypass explosion-proof performance test device and method, and the test device comprises a high-voltage capacitor tower direct-current charging loop and a capacitor tower LC oscillation loop. By introducing a relatively independent voltage source system, efficient and stable charging of the capacitor of the capacitor tower is realized; due to the introduction of the capacitance tower LC oscillation circuit, a single-cycle short-circuit charging current can be quickly provided in the test process and acts on a test sample sub-module, so that the capacitance voltage of the test sample sub-module is raised to a threshold voltage in a short time, and the instantaneous raising state of the voltage of the sub-module when a fault occurs is accurately simulated; by adopting the device, the short-circuit charging current is accurately introduced into the test object according to the set time, and the capacitor voltage of the sub-module is raised within dozens of milliseconds, so that the reliability and the effectiveness of the test are enhanced, and the explosion-proof performance and the passive bypass function of the flexible direct current converter valve sub-module under the extreme working condition can be more accurately evaluated.

Description

Technical Field

[0001] The present invention belongs to the technical field of flexible direct current transmission test, and in particular relates to a device and method for testing the passive bypass explosion-proof performance of a flexible direct current converter valve submodule. Background Art

[0002] As the core part of the MMC system, the flexible DC converter valve submodule determines and affects the working state of the MMC by its structure and working mode. The half-bridge submodule has become the most commonly used topology in flexible DC transmission projects due to its simple structure, low cost, high efficiency, high reliability and strong flexibility. When a bridge arm submodule in the MMC system has a serious fault, it needs to be isolated by a bypass switch to prevent the fault from spreading and protect the entire system. In particular, when the bypass switch refuses to operate due to uncontrollable reasons, the power devices in the submodule may be subjected to overvoltage breakdown under extreme working conditions due to increased electrical stress, and may even cause a direct short circuit of the DC capacitor. The released energy will cause serious damage to the submodule body or other adjacent modules. Therefore, other methods are needed to bypass the submodule from the operating loop in time without affecting the operating state of the entire system.

[0003] At present, in the research and development and design stage of the flexible DC converter valve submodule, efforts need to be made to improve the stability of the product and reduce the deviation of the product, so as to minimize the probability of bypass at the submodule outlet. For submodules that must be removed due to serious faults, multiple bypass mechanisms are implemented. When the active bypass functions such as fault bypass, downstream communication fault self-bypass, software overvoltage bypass, hardware overvoltage bypass and hardware voltage self-bypass fail, the submodule passive bypass mechanism is adopted, and the failure characteristics of IGBT devices or turning thyristors with long-term current-carrying capacity are used to form a stable current-carrying loop, so as to realize the bypass removal of the submodule, so as not to affect the operation of the system. In order to ensure that the port of the sub-module is in a stable, low-resistance and reliable short-circuit state after the bypass switch of the sub-module fails to operate and that the entire MMC system operates stably, it is necessary to verify that the sub-module has a passive bypass function under this extreme condition. However, this will cause a direct short circuit of the capacitor in the sub-module, causing an explosion, which is destructive. Therefore, the sub-module is required to have high explosion-proof performance. Therefore, how to verify the passive bypass function and explosion-proof performance of the sub-module under extreme fault conditions through experiments is crucial to the optimization and iteration of sub-module design and the stable operation of the MMC system.

[0004] However, traditional test platforms generally use a small ampere DC power supply, which cannot reach the overvoltage breakdown threshold voltage of the test submodule within tens of milliseconds. As a result, it is impossible to accurately simulate the instantaneous increase in capacitor voltage when a submodule fails, affecting the accuracy of the final test results. Summary of the invention

[0005] The present invention provides a device and method for testing the passive bypass explosion-proof performance of a flexible DC converter valve submodule, in order to solve the technical problem that a traditional test platform generally adopts a small-ampere DC power supply, which cannot reach the overvoltage breakdown threshold voltage of a test submodule within tens of milliseconds, resulting in an inability to accurately simulate the instantaneous rise in capacitor voltage of the submodule when a fault occurs, thereby affecting the accuracy of the final test result. The device and method can verify the feasibility of the passive bypass mechanism of the submodule when multiple active bypass functions fail, and can verify the explosion-proof performance of the submodule under extreme working conditions.

[0006] In order to achieve the above object, the present invention adopts the following technical contents: In a first aspect, the present invention provides a flexible DC converter valve submodule passive bypass explosion-proof performance test device, comprising: A high-voltage capacitor tower DC charging circuit includes a high-voltage test power supply S and a capacitor tower capacitor C1; the high-voltage test power supply S is connected to the capacitor tower capacitor C1, and the high-voltage test power supply S is used to charge the capacitor tower capacitor C1; The capacitor tower LC oscillation circuit shares the same capacitor tower capacitor C1 with the high-voltage capacitor tower DC charging circuit; the capacitor tower LC oscillation circuit is used to provide a short-circuit charging current so that the capacitor voltage of the test submodule Vt is raised to a threshold voltage.

[0007] Furthermore, the high-voltage capacitor tower DC charging circuit also includes a first isolating switch KS1, a second isolating switch KR1 and a current-limiting resistor R1; the first isolating switch KS1 is connected in series in the high-voltage capacitor tower DC charging circuit, and the second isolating switch KR1 and the current-limiting resistor R1 are connected in series with the capacitor tower capacitor C1 and then connected in parallel to both ends of the high-voltage test power supply S.

[0008] Furthermore, the capacitor tower LC oscillation circuit also includes a first adjustable reactor L1_1, a second adjustable reactor L1_2, a third isolating switch KV1, a thyristor valve V1 and a current limiting reactor L2 which are connected in series in sequence; the high-voltage end of the capacitor tower capacitor C1 is connected to the first adjustable reactor L1_1, and the low-voltage end is connected to the low-voltage end of the port of the test module Vt; the current limiting reactor L2 is connected to the high-voltage end of the port of the test module Vt.

[0009] Furthermore, the test submodule Vt is divided into a submodule with long-term current carrying capacity after IGBT failure and a submodule without long-term current carrying capacity after IGBT failure according to whether the IGBT power device has long-term current carrying capacity after failure.

[0010] Furthermore, the submodule with long-term current carrying capacity after the IGBT fails includes: an upper tube diode D1, a lower tube diode D2, an upper tube IGBT T1, a lower tube IGBT T2 and a capacitor C; the upper tube diode D1 is connected in parallel with the upper tube IGBT T1, the lower tube diode D2 is connected in parallel with the lower tube IGBT T2, and the upper tube IGBT T1 and the lower tube IGBT T2 are connected in series and then connected in parallel at both ends of the capacitor C; The submodule that does not have long-term current-carrying capacity after the IGBT fails includes: an upper tube diode D1, a lower tube diode D2, an upper tube IGBT T1, a lower tube IGBT T2, a capacitor C and a turning thyristor T; the upper tube diode D1 is connected in parallel with the upper tube IGBT T1, the lower tube diode D2 is connected in parallel with the lower tube IGBT T2, the upper tube IGBT T1 and the lower tube IGBT T2 are connected in series and then connected in parallel at both ends of the capacitor C, and the turning thyristor T is connected in parallel at both ends of the lower tube IGBT T2.

[0011] Furthermore, low-voltage ends of the high-voltage test power supply S, the capacitor C1 of the capacitor tower, and the capacitor C of the test submodule are all grounded.

[0012] A method for testing the passive bypass explosion-proof performance of a flexible DC converter valve submodule is provided, based on the above-mentioned device for testing the passive bypass explosion-proof performance of a flexible DC converter valve submodule, comprising: Remove the bypass switch in the test submodule Vt, thereby simulating the bypass switch refusal state of the test submodule; Start the high-voltage test power supply S of the high-voltage capacitor tower DC charging circuit to charge the capacitor C1 of the capacitor tower; Through the capacitor tower LC oscillation circuit, a short-circuit charging current is generated and introduced into the test submodule Vt; the capacitor voltage of the test submodule Vt is raised to the threshold voltage, causing the internal device of the test submodule Vt to overvoltage and breakdown, resulting in capacitor direct discharge, releasing energy and causing explosion; Disconnect the test power supply S, discharge to ground, and after the Vt capacitor of the test submodule is discharged to ground, record the physical state of the Vt capacitor of the test submodule after the test as the test result of the explosion-proof performance test; Conduct a current flow test for a preset time on the submodule Vt of the test product after the explosion, and record the port voltage, current and impedance as the test results for the passive bypass function verification; According to the recorded test results of explosion-proof performance test and passive bypass function verification, combined with multi-dimensional judgment basis, it is judged whether the explosion-proof performance of the test submodule meets the requirements and whether the passive bypass function is reliable.

[0013] Furthermore, before the test, a wave modulation process is performed, which specifically includes: The first adjustable reactor L1_1, the second adjustable reactor L1_2 and the DC output voltage Us of the test power supply in the capacitor tower LC oscillation circuit are adjusted so that the short-circuit charging current oscillation width meets 18-20 ms and the current peak meets the test requirements. The specific formula is as follows: Short circuit charging current oscillation width T d :

[0014] Where, L = L1_1+L1_2+L2; Short circuit charging current peak I peak :

[0015] Where, T d Indicates the oscillation width of the short-circuit charging current; C1 indicates the capacitance value of the capacitor tower; L indicates the total reactance value of the oscillation circuit; L1_1 indicates the reactance value of the first adjustable reactor; L1_2 indicates the reactance value of the second adjustable reactor; L2 indicates the reactance value of the current limiting reactor; Us indicates the DC output voltage of the high-voltage test power supply.

[0016] Furthermore, the specific process of the capacitor through-discharge formed inside the test submodule Vt is as follows: For the submodules with long-term current-carrying capacity after IGBT failure, the short-circuit charging current of the capacitor tower flows through the upper tube diode D1 to charge the capacitor C of the test submodule Vt. After reaching the threshold voltage, the active clamping action in the driver board of the lower tube IGBT T2 causes the lower tube IGBT T2 to turn on, and the upper tube diode D1 reversely breaks down. The upper tube diode D1 and the lower tube IGBT T2 form a discharge loop, and the energy released by the capacitor short-circuit causes an explosion. For the sub-module that does not have long-term current-carrying capacity after IGBT failure, the capacitor tower short-circuit charging current flows through the upper tube diode D1 to charge the test sub-module Vt capacitor C. After reaching the threshold voltage, the transition thyristor T is over-voltage-broken, and the upper tube diode D1 is reversely broken down. The upper tube diode D1 and the transition thyristor T form a discharge loop, and the capacitor is directly short-circuited. Energy is released and causes an explosion.

[0017] Furthermore, the multi-dimensional determination is based on: The internal busbar of the test submodule does not fall off or break when impacted, the external frame does not fall off, no solid splashes outside the module, and the cooling water pipe does not leak; the test submodule is subjected to current flow for a preset time at the maximum operating current, there is no open flame during the current flow period, and the port impedance is less than the specified value; if the test results of the explosion-proof performance test and the test results of the passive bypass function verification meet the test judgment basis, it is judged that the test submodule is in a reliable short-circuit state, and the explosion-proof performance and passive bypass function of the test submodule meet the engineering application requirements; otherwise, it is judged that the explosion-proof performance and passive bypass function of the test submodule do not meet the engineering application requirements.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a flexible DC converter valve submodule passive bypass explosion-proof performance test device, the test device comprises a high-voltage capacitor tower DC charging circuit and a capacitor tower LC oscillation circuit; by introducing a relatively independent voltage source system, efficient and stable charging of the capacitor tower capacitor is achieved; the introduction of the capacitor tower LC oscillation circuit enables a single-cycle short-circuit charging current to be quickly provided during the test, and acts on the test submodule at the same time, so that its capacitor voltage is raised to a threshold voltage in a short time, thereby accurately simulating the instantaneous raising state of the submodule voltage when a fault occurs; the device is used to accurately introduce the short-circuit charging current into the test product according to the set time, and raise the submodule capacitor voltage within tens of milliseconds, thereby enhancing the reliability and effectiveness of the test, and being able to more accurately evaluate the explosion-proof performance and passive bypass function of the flexible DC converter valve submodule under extreme working conditions; it provides technical support for the explosion-proof capability of the flexible DC converter valve under extreme working conditions, and significantly improves the safety performance of a large-capacity flexible DC system.

[0019] Preferably, in the present invention, a first isolating switch, a second isolating switch and a current limiting resistor are added to the DC charging circuit of the high-voltage capacitor tower, thereby enhancing the safety and controllability of the circuit. The isolating switch can be used to isolate the power supply and the capacitor tower capacitor, and the current limiting resistor can limit the charging current to prevent damage to the circuit due to excessive current.

[0020] Preferably, in the present invention, an adjustable reactor, an isolating switch, a thyristor valve and a current limiting reactor are added to the capacitor tower LC oscillation circuit, so that the short-circuit charging current can be accurately adjusted to meet different test requirements; at the same time, the stability and flexibility of the circuit are also enhanced.

[0021] Preferably, in the present invention, the test submodules are divided into two categories according to whether the IGBT power device has long-term current-carrying capacity after failure, so that the test is more targeted and accurate; this helps researchers better understand the performance of different types of submodules when they fail.

[0022] The present invention also provides a method for testing the passive bypass explosion-proof performance of a flexible DC converter valve submodule. Based on the above-mentioned device for testing the passive bypass explosion-proof performance of a flexible DC converter valve submodule, the method first removes the bypass switch in the test submodule to simulate the extreme situation that the bypass switch refuses to operate; then, by opening the high-voltage capacitor tower DC charging circuit, the capacitor of the capacitor tower is efficiently charged to ensure that there is sufficient energy reserve for subsequent voltage increase; then, through the capacitor tower LC oscillation circuit, the capacitor tower LC oscillation circuit is used to generate a short-circuit charging current and introduce it into the test submodule, quickly raising the capacitor voltage of the test submodule to a threshold voltage, thereby causing the overvoltage breakdown of the internal components of the test submodule, resulting in capacitor through-discharge, and releasing The release of energy causes an explosion; finally, the recorded test results are combined with a multi-dimensional judgment basis to determine whether the explosion-proof performance of the test submodule meets the requirements and whether the passive bypass function is reliable; this method generates a single-cycle short-circuit charging current by using a high-voltage current capacitor tower DC charging test power supply and a capacitor tower LC oscillation circuit test device, and accurately introduces the single-cycle short-circuit charging current into the test product according to the set time, raising the submodule capacitor voltage to a threshold voltage within tens of milliseconds, causing the internal components of the submodule to overvoltage and break down to form a discharge circuit, resulting in a capacitor short-circuit release of energy; this method provides technical support for the explosion-proof capability of the flexible DC converter valve under extreme working conditions, and significantly improves the safety performance of large-capacity flexible DC systems.

[0023] Preferably, in the present invention, the test submodules are divided into submodules with long-term current-carrying capacity after IGBT failure and submodules without long-term current-carrying capacity after IGBT failure; this helps researchers to have a deeper understanding of the discharge mechanism of different types of submodules during failure, and provides strong support for explosion-proof performance evaluation.

[0024] Preferably, in the present invention, specific multi-dimensional judgment bases are provided for judging whether the explosion-proof performance and passive bypass function of the test submodule meet the requirements of engineering applications. The multi-dimensional judgment bases specifically include that the busbar does not fall off or break when impacted, the external frame does not fall off, no solid splashes outside the module, the cooling water pipe does not leak, and the test submodule has no open flame when the maximum operating current is passed for 168 hours and the port impedance is less than the specified value; these judgment bases provide a strong guarantee for the accuracy and reliability of the test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of a flexible DC converter valve submodule passive bypass explosion-proof performance test device provided in an embodiment of the present invention; Figure 2 A submodule having long-term current-carrying capability after an IGBT fails provided in an embodiment of the present invention; Figure 3The submodule provided in the embodiment of the present invention does not have the long-term current-carrying capability after the IGBT fails. DETAILED DESCRIPTION

[0026] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail in the following specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the 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] like Figure 1 As shown, this embodiment provides a flexible DC converter valve submodule passive bypass explosion-proof performance test device, including a high-voltage capacitor tower DC charging circuit of part I and a capacitor tower LC oscillation circuit of part II; wherein the high-voltage capacitor tower DC charging circuit is composed of a high-voltage test power supply S, a capacitor tower capacitor C1, a first isolating switch KS1, a current-limiting resistor R1 and a second isolating switch KR1; the capacitor tower LC oscillation circuit is composed of a capacitor tower capacitor C1, a first adjustable reactor L1_1, a second adjustable reactor L1_2, a third isolating switch KV1, a thyristor valve V1 and a current-limiting reactor L2; Figure 1 In FIG. 1 , III is the test submodule Vt and the submodule discharge branch. The test submodule Vt adopts a flexible DC converter valve half-bridge submodule. The submodule discharge branch includes a fourth isolation switch KR2 and a discharge resistor R2, which are connected in parallel at both ends of the submodule capacitor C.

[0030] Among them, the high-voltage capacitor tower DC charging circuit and the capacitor tower LC oscillation circuit share the capacitor C1; the high-voltage test power supply S is connected in series with the first isolating switch KS1, the second isolating switch KR1 and the current limiting resistor R1 in sequence, and then connected in parallel with the capacitor tower capacitor C1, which is used to charge the capacitor tower capacitor C1; the capacitor tower capacitor C1 forms an LC oscillation circuit with the first adjustable reactor L1_1, the second adjustable reactor L1_2, the thyristor valve V1 and the current limiting reactor L2 to generate a single-cycle short-circuit charging current, which is used to be introduced into the test product to raise the sub-module capacitor voltage; the high-voltage end of the test product half-bridge sub-module Vt port is connected to the low-voltage end of the current limiting reactor in the capacitor tower LC oscillation circuit, and the low-voltage end of the test product half-bridge sub-module Vt port, the low-voltage end of the high-voltage test power supply S, the low-voltage end of the capacitor tower capacitor C1, the low-voltage end of the current limiting resistor R1 and the low-voltage end of the sub-module discharge branch are connected to the primary grounding terminal of the test circuit.

[0031] In this embodiment, the half-bridge submodule Vt of the test product is divided into a submodule with long-term current carrying capacity after IGBT failure and a submodule without long-term current carrying capacity after IGBT failure according to whether the IGBT power device has long-term current carrying capacity after failure; Figure 2 As shown, the submodules with long-term current carrying capacity after the IGBT fails include: an upper tube diode D1, a lower tube diode D2, an upper tube IGBT T1, a lower tube IGBT T2 and a capacitor C; the upper tube diode D1 is connected in parallel with the upper tube IGBT T1, the lower tube diode D2 is connected in parallel with the lower tube IGBT T2, the upper tube IGBT T1 and the lower tube IGBT T2 are connected in series and then connected in parallel at both ends of the capacitor C; Figure 3 As shown, the structure of the submodule that does not have long-term current-carrying capacity after IGBT failure is different from the submodule that has long-term current-carrying capacity after IGBT failure; the submodule that does not have long-term current-carrying capacity after IGBT failure includes: an upper tube diode D1, a lower tube diode D2, an upper tube IGBT T1, a lower tube IGBT T2, a capacitor C and a turning thyristor T; the upper tube diode D1 is connected in parallel with the upper tube IGBT T1, the lower tube diode D2 is connected in parallel with the lower tube IGBT T2, the upper tube IGBT T1 and the lower tube IGBT T2 are connected in series and then connected in parallel at both ends of the capacitor C, and the turning thyristor T is connected in parallel at both ends of the lower tube IGBT T2.

[0032] This embodiment also provides a test method based on the flexible DC converter valve submodule passive bypass explosion-proof performance test device, including: Step 1: Remove the bypass switch in the test submodule Vt to simulate the bypass switch refusal state of the test submodule Vt, and divide the test submodule Vt into two categories according to whether the IGBT used in the test submodule Vt has long-term current carrying capacity after failure, one category is the submodule with long-term current carrying capacity after IGBT failure; the other category is the submodule without long-term current carrying capacity after IGBT failure; Step 2: For submodules that have long-term current-carrying capacity after IGBT failure, no turning thyristor T is configured; for devices that do not have long-term current-carrying capacity after failure, turning thyristor T is configured; Step 3: Pass room temperature cooled deionized water into the test flexible submodule Vt to meet the basic requirements of the test; Step 4: Wave modulation processing before the test: Adjustment Figure 1 The size of the adjustable reactor L1_1 / L1_2 in the middle II part is used to make the bottom width of the short-circuit charging current waveform T d Meet 18ms~20ms; adjust Figure 1 Part I: High-voltage current capacitor tower DC charging test power supply S DC output voltage Us, change the peak value of short-circuit charging current I peak , so that the short-circuit charging current can raise the capacitor voltage of the test submodule to the threshold voltage when the internal device is over-voltage-broken; Short circuit charging current oscillation width T d :

[0033] Among them, L=L1_1+L1_2+L2; Short circuit charging current peak I peak :

[0034] Where, T d Indicates the short-circuit charging current oscillation width; C 1 Represents the capacitance value of the capacitor tower; L represents the total reactance value of the oscillation circuit; L1_1 represents the reactance value of the first adjustable reactor; L1_2 represents the reactance value of the second adjustable reactor; L2 represents the reactance value of the current limiting reactor; Us represents the DC output voltage of the high-voltage test power supply.

[0035] Step 5: Charging process: close the first isolating switch KS1 and the second isolating switch KR1, charge the capacitor C1 of the capacitor tower through the high-voltage current capacitor tower DC charging test power supply S, and after reaching the test preset voltage Us, disconnect the first isolating switch KS1 and the second isolating switch KR1; Step 6: short-circuit charging current triggering event method: close the third isolating switch KV1, trigger the thyristor valve V1 to conduct forward, the capacitor C1 of the capacitor tower and the first adjustable reactor L1_1, the second adjustable reactor L1_2, the thyristor valve V1 and the return current limiting reactor L2 form a DC short-circuit oscillation circuit to generate a single-cycle short-circuit charging current; Step 7: For the test submodule with long-term current carrying capacity after IGBT failure, the specific electrical structure is as follows: Figure 2As shown, the test module includes an upper tube IGBT T1, an upper tube diode D1, a lower tube IGBT T2, a lower tube diode D2 and a DC capacitor C; during the explosion test: the single-cycle short-circuit charging current generated by the capacitor tower LC oscillation circuit flows through the upper tube diode D1 to charge the capacitor C. After reaching the threshold voltage, the active clamping action in the lower tube IGBT T2 driver board causes the lower tube IGBT T2 to turn on, the upper tube diode D1 reversely breaks down, the upper tube diode D1 and the lower tube IGBT T2 device form a discharge circuit, and the capacitor directly short-circuits to release energy and cause an explosion; For submodules that do not have long-term current-carrying capacity after IGBT failure, the specific electrical structure is as follows: Figure 3 As shown, the test object includes an upper tube IGBT T1, an upper tube diode D1, a lower tube IGBT T2, a lower tube diode D2, a DC capacitor C and a turning thyristor T; during the explosion test: the short-circuit charging current generated by the capacitor tower LC oscillation circuit flows through the upper tube diode D1 to charge the capacitor C. After reaching the threshold voltage, the turning thyristor T is over-voltage-broken, the upper tube diode D1 is reversely broken down, the upper tube diode D1 and the turning thyristor T form a discharge circuit, and the capacitor directly short-circuits to release energy and cause an explosion; Step 8: Disconnect the high-voltage test power supply S, ground discharge, close the fourth isolating switch KS2, and after the capacitor of the test submodule is grounded and discharged, record the physical state of the test submodule Vt after the test as the test result of the explosion-proof performance test; Step 9: Carry out a 168-hour long-term current flow test on the test submodule after the explosion, and record the port voltage, current and impedance as the test results for the passive bypass function verification; Step 10: Based on the recorded explosion-proof performance test results, the passive bypass function verification test results and the multi-dimensional judgment basis, determine whether the explosion-proof performance of the test submodule meets the requirements and whether the passive bypass function is reliable.

[0036] The multi-dimensional judgment basis is as follows: the internal busbar of the test submodule does not fall off or break under impact, the external frame does not fall off, no solid splashes outside the module, and the cooling water pipe does not leak; the test submodule flows under the maximum operating current for 168 hours, there is no open flame during the flow, and the port impedance is less than the specified value. If the recorded test results of the explosion-proof performance test and the test results of the passive bypass function verification meet the multi-dimensional judgment basis, it is determined that the test submodule is in a reliable short-circuit state, and the explosion-proof performance and passive bypass function of the test submodule meet the engineering application requirements; otherwise, it is determined that the explosion-proof performance and passive bypass function of the test submodule do not meet the engineering application requirements.

[0037] In summary, the present invention provides a device and method for testing the passive bypass explosion-proof performance of a flexible DC converter valve submodule. The passive bypass function verification and explosion-proof performance test of the flexible DC converter valve half-bridge submodule are carried out by using a high-voltage capacitor tower DC charging test system and a capacitor tower LC oscillation circuit. The provided test method has been verified by relevant tests and is feasible, stable and reliable.

[0038] The above embodiment is only one of the implementation methods that can realize the technical solution of the present invention. The scope of protection claimed by the present invention is not limited only to this embodiment, but also includes changes, replacements and other implementation methods that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention.

Claims

1. A passive bypass explosion-proof performance test device for flexible DC converter valve submodule, characterized in that: include: A high-voltage capacitor tower DC charging circuit includes a high-voltage test power supply S and a capacitor tower capacitor C1; the high-voltage test power supply S is connected to the capacitor tower capacitor C1, and the high-voltage test power supply S is used to charge the capacitor tower capacitor C1; The capacitor tower LC oscillation circuit shares the same capacitor tower capacitor C1 with the high-voltage capacitor tower DC charging circuit; the capacitor tower LC oscillation circuit is used to provide a short-circuit charging current so that the capacitor voltage of the test submodule Vt is raised to a threshold voltage.

2. The passive bypass explosion-proof performance test device for flexible DC converter valve submodule according to claim 1 is characterized in that: The high-voltage capacitor tower DC charging circuit also includes a first isolating switch KS1, a second isolating switch KR1 and a current-limiting resistor R1; the first isolating switch KS1 is connected in series in the high-voltage capacitor tower DC charging circuit, and the second isolating switch KR1 and the current-limiting resistor are connected in series R1 and then connected in parallel with the capacitor tower capacitor C1 to both ends of the high-voltage test power supply S.

3. The passive bypass explosion-proof performance test device for flexible DC converter valve submodule according to claim 1 is characterized in that: The capacitor tower LC oscillation circuit also includes a first adjustable reactor L1_1, a second adjustable reactor L1_2, a third isolating switch KV1, a thyristor valve V1 and a current limiting reactor L2 which are connected in series in sequence; the high voltage end of the capacitor C1 of the capacitor tower is connected to the first adjustable reactor L1_1, and the low voltage end is connected to the low voltage end of the port of the test module Vt; the current limiting reactor L2 is connected to the high voltage end of the port of the test module Vt.

4. The passive bypass explosion-proof performance test device for flexible DC converter valve submodule according to claim 1 is characterized in that: The test submodule Vt is divided into a submodule with long-term current carrying capacity after IGBT failure and a submodule without long-term current carrying capacity after IGBT failure according to whether the IGBT power device has long-term current carrying capacity after failure.

5. The passive bypass explosion-proof performance test device for flexible DC converter valve submodule according to claim 4 is characterized in that: The submodule having long-term current carrying capacity after the IGBT fails comprises: an upper tube diode D1, a lower tube diode D2, an upper tube IGBT T1, a lower tube IGBT T2 and a capacitor C; the upper tube diode D1 is connected in parallel with the upper tube IGBT T1, the lower tube diode D2 is connected in parallel with the lower tube IGBT T2, the upper tube IGBT T1 and the lower tube IGBT T2 are connected in series and then connected in parallel at both ends of the capacitor C; The submodule that does not have long-term current-carrying capacity after the IGBT fails includes: an upper tube diode D1, a lower tube diode D2, an upper tube IGBT T1, a lower tube IGBT T2, a capacitor C and a turning thyristor T; the upper tube diode D1 is connected in parallel with the upper tube IGBT T1, the lower tube diode D2 is connected in parallel with the lower tube IGBT T2, the upper tube IGBT T1 and the lower tube IGBT T2 are connected in series and then connected in parallel at both ends of the capacitor C, and the turning thyristor T is connected in parallel at both ends of the lower tube IGBT T2.

6. The passive bypass explosion-proof performance test device for flexible DC converter valve submodule according to claim 1 is characterized in that: The low-voltage ends of the high-voltage test power supply S, the capacitor C1 of the capacitor tower and the capacitor C of the test submodule are all grounded.

7. A method for testing the passive bypass explosion-proof performance of a flexible DC converter valve submodule, characterized in that: The passive bypass explosion-proof performance test device of the flexible DC converter valve submodule according to any one of claims 1 to 6 comprises: Remove the bypass switch in the test submodule Vt, thereby simulating the bypass switch refusal state of the test submodule; Start the high-voltage test power supply S of the high-voltage capacitor tower DC charging circuit to charge the capacitor C1 of the capacitor tower; Through the capacitor tower LC oscillation circuit, a short-circuit charging current is generated and introduced into the test submodule Vt; the capacitor voltage of the test submodule Vt is raised to the threshold voltage, causing the internal device of the test submodule Vt to overvoltage and breakdown, resulting in capacitor direct discharge, releasing energy and causing explosion; Disconnect the test power supply S, discharge to ground, and after the Vt capacitor of the test submodule is discharged to ground, record the physical state of the Vt capacitor of the test submodule after the test as the test result of the explosion-proof performance test; Conduct a current flow test for a preset time on the submodule Vt of the test product after the explosion, and record the port voltage, current and impedance as the test results for the passive bypass function verification; According to the recorded test results of explosion-proof performance test and passive bypass function verification, combined with multi-dimensional judgment basis, it is judged whether the explosion-proof performance of the test submodule meets the requirements and whether the passive bypass function is reliable.

8. The method for testing the passive bypass explosion-proof performance of a flexible DC converter valve submodule according to claim 7 is characterized in that: Before the test, the wave modulation process is carried out, including: The first adjustable reactor L1_1, the second adjustable reactor L1_2 and the DC output voltage Us of the test power supply in the capacitor tower LC oscillation circuit are adjusted so that the short-circuit charging current oscillation width meets 18-20 ms and the current peak meets the test requirements. The specific formula is as follows: Short circuit charging current oscillation width T d : Where, L = L1_1+L1_2+L2; Short circuit charging current peak I peak : Where, T d Indicates the oscillation width of the short-circuit charging current; C1 indicates the capacitance value of the capacitor tower; L indicates the total reactance value of the oscillation circuit; L1_1 indicates the reactance value of the first adjustable reactor; L1_2 indicates the reactance value of the second adjustable reactor; L2 indicates the reactance value of the current limiting reactor; Us indicates the DC output voltage of the high-voltage test power supply.

9. The method for testing the passive bypass explosion-proof performance of a flexible DC converter valve submodule according to claim 7 is characterized in that: The specific process of capacitor through-discharge formed inside the test submodule Vt is as follows: For the submodules with long-term current-carrying capacity after IGBT failure, the short-circuit charging current of the capacitor tower flows through the upper tube diode D1 to charge the capacitor C of the test submodule Vt. After reaching the threshold voltage, the active clamping action in the driver board of the lower tube IGBT T2 causes the lower tube IGBT T2 to turn on, and the upper tube diode D1 reversely breaks down. The upper tube diode D1 and the lower tube IGBT T2 form a discharge loop, and the energy released by the capacitor short-circuit causes an explosion. For the sub-module that does not have long-term current-carrying capacity after IGBT failure, the capacitor tower short-circuit charging current flows through the upper tube diode D1 to charge the test sub-module Vt capacitor C. After reaching the threshold voltage, the transition thyristor T is over-voltage-broken, and the upper tube diode D1 is reversely broken down. The upper tube diode D1 and the transition thyristor T form a discharge loop, and the capacitor is directly short-circuited. Energy is released and causes an explosion.

10. The method for testing the passive bypass explosion-proof performance of a flexible DC converter valve submodule according to claim 7, characterized in that: The multi-dimensional determination is based on: The internal busbar of the test submodule does not fall off or break when impacted, the external frame does not fall off, no solid splashes outside the module, and the cooling water pipe does not leak; the test submodule is subjected to current flow for a preset time at the maximum operating current, there is no open flame during the current flow period, and the port impedance is less than the specified value; if the test results of the explosion-proof performance test and the test results of the passive bypass function verification meet the test judgment basis, it is judged that the test submodule is in a reliable short-circuit state, and the explosion-proof performance and passive bypass function of the test submodule meet the engineering application requirements; otherwise, it is judged that the explosion-proof performance and passive bypass function of the test submodule do not meet the engineering application requirements.

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