A reliability test method and device for a flexible direct current valve submodule bypass switch

Abstract

This invention discloses a reliability testing method and apparatus for a bypass switch of a flexible DC-DC converter valve submodule, relating to the field of flexible DC-DC transmission technology. The method includes: constructing a test circuit for the bypass switch based on the operating condition of the flexible DC-DC converter valve submodule at an overvoltage fault point. The test circuit includes: a first pre-charge circuit and its disconnecting switch, a first capacitor and its discharge resistor, an IGBT, a diode, a second pre-charge circuit and its disconnecting switch, a second capacitor and its discharge resistor, an air-core reactor, and a bypass switch; pre-charging the capacitor and then turning on the IGBT; turning off the IGBT when the voltage of the first capacitor is less than the termination discharge voltage; closing the bypass switch when the voltage of the second capacitor is greater than the fault point voltage; obtaining and analyzing the voltage and current waveform data of each component during the test to obtain the reliability test results of the bypass switch. This invention solves the problem of low accuracy in existing test schemes and improves the accuracy of bypass switch reliability testing.

Description

Technical Field

[0001] This invention relates to the field of flexible DC transmission technology, and in particular to a reliability testing method and apparatus for a bypass switch of a flexible DC converter valve submodule. Background Technology

[0002] Flexible high-voltage direct current (HVDC) transmission utilizes MMC (Modular Multilevel Converter) topology converter valves to achieve high-quality and highly flexible power conversion between high-voltage AC and high-voltage DC. It plays a crucial role in new power system applications such as ultra-long-distance clean energy transmission, asynchronous grid interconnection, flexible multi-terminal interconnection, and deep-sea renewable energy transmission. Ultra-high-voltage (UHVDC) flexible HVDC converter valves, located within UHVDC lines, require extremely high reliability and availability; a single fault causing a converter valve trip and resulting in line shutdown is generally unacceptable. MMC sub-modules (SMs) are the smallest functional units in the MMC topology. In some unknown fault or failure modes, they may cause overvoltage in the sub-modules, posing further risks to the stable operation of the converter valves. The bypass switch, as a critical primary protection against sub-module overvoltage faults, must reliably operate in the event of a fault to ensure the UHVDC flexible HVDC converter valve can continue operating without tripping even under a single sub-module fault. If the bypass switch is triggered promptly when a sub-module fault occurs, the fault point can be bypassed, limiting the impact of the fault to the faulty module itself. Because the bypass switch remains in a tripped state for an extended period during the operation of the converter valve, and the triggering circuit that activates the bypass switch is also inactive for a long time, it is difficult to detect potential functional failures. Therefore, it is necessary to fully verify the reliable operation capability of the bypass switch before the converter valve is put into operation.

[0003] However, existing bypass switch reliability testing schemes typically lack relevant fault simulation conditions, resulting in low accuracy. Summary of the Invention

[0004] To address the above technical problems, this invention provides a reliability testing method and apparatus for a bypass switch of a flexible DC converter valve submodule. This method can accurately simulate the operating conditions of the primary protection bypass switch when an overvoltage fault occurs in a submodule of an ultra-high voltage flexible DC converter valve, thereby improving the accuracy of the bypass switch reliability test.

[0005] This invention provides a reliability testing method for a bypass switch of a flexible DC-DC converter valve submodule, comprising: constructing a test circuit for the bypass switch based on the operating conditions of the flexible DC-DC converter valve submodule at an overvoltage fault point; the test circuit includes: a first pre-charge circuit, a first disconnecting switch, a first capacitor, a first discharge resistor, an IGBT (Insulated-Gate Bipolar Transistor), a diode, a second pre-charge circuit, a second disconnecting switch, a second capacitor, a second discharge resistor, an air-core reactor, and a bypass switch;

[0006] Precharge the first capacitor and the second capacitor;

[0007] Turn on the IGBT until the voltage of the first capacitor is less than the preset termination discharge voltage, then turn off the IGBT; when the voltage of the second capacitor is greater than the preset fault point voltage, close the bypass switch.

[0008] When the test circuit is detected to have finished discharging, the waveform data of the voltage and current of each component in the test circuit during the test process are obtained, and the waveform data is analyzed to obtain the reliability test results of the bypass switch.

[0009] As an improvement to the above scheme, the test circuit specifically includes:

[0010] The first pre-charge circuit is connected to the first capacitor through the first disconnect switch, and is used to pre-charge the first capacitor; the first capacitor is connected in parallel with the first discharge resistor;

[0011] The second pre-charge circuit is connected to the second capacitor via the second disconnect switch for pre-charging the second capacitor; the second capacitor is connected in parallel with the second discharge resistor.

[0012] The collector of the IGBT is connected to the first capacitor, and the emitter of the IGBT is connected to the negative terminal of the diode; one end of the second capacitor is connected to the positive terminal of the diode, and the other end of the second capacitor is connected to one end of the bypass switch; the other end of the bypass switch is connected to the negative terminal of the diode; the air-core reactor is connected in parallel with the bypass switch.

[0013] As an improvement to the above solution, the test circuit for constructing a bypass switch based on the overpressure fault condition of the flexible DC converter valve submodule includes:

[0014] Based on the preset fault point voltage and current, the preset test circuit is calculated or simulated to obtain the basic electrical parameters of each component in the test circuit, the initial voltage and initial current of each component, the operating time point or operating threshold of the IGBT and the bypass switch, and the test circuit of the bypass switch is built.

[0015] As an improvement to the above solution, the pre-charging of the first capacitor and the second capacitor includes: closing the first isolation switch so that the first pre-charging circuit charges the first capacitor;

[0016] When the voltage of the first capacitor is greater than the preset initial voltage, the first isolating switch is disconnected;

[0017] Close the second disconnect switch to allow the second pre-charge circuit to charge the second capacitor;

[0018] When the voltage of the second capacitor is greater than the preset initial voltage, the second isolating switch is disconnected.

[0019] As an improvement to the above solution, the IGBT has the ability to turn off at any current point under the preset discharge condition of the first capacitor, and the static withstand voltage rating of the IGBT is greater than the maximum voltage across the IGBT during the test.

[0020] This invention also provides a reliability testing device for a bypass switch of a flexible DC-DC converter valve submodule, comprising: a test circuit construction module for constructing a test circuit for the bypass switch based on the operating conditions of the flexible DC-DC converter valve submodule at an overvoltage fault point; the test circuit includes: a first pre-charge circuit, a first disconnecting switch, a first capacitor, a first discharge resistor, an insulated gate bipolar transistor (IGBT), a diode, a second pre-charge circuit, a second disconnecting switch, a second capacitor, a second discharge resistor, an air-core reactor, and a bypass switch;

[0021] A capacitor pre-charging module is used to pre-charge the first capacitor and the second capacitor;

[0022] A capacitor discharge module is used to turn on the IGBT until the voltage of the first capacitor is less than a preset termination discharge voltage, and then turn off the IGBT.

[0023] The bypass switch action module is used to close the bypass switch when the voltage of the second capacitor is greater than the preset fault point voltage.

[0024] The test result analysis module is used to obtain the voltage and current waveform data of each component in the test circuit during the test process when the test circuit is detected to be discharged, and to analyze the waveform data to obtain the reliability test results of the bypass switch.

[0025] Furthermore, the test circuit specifically includes:

[0026] The first pre-charge circuit is connected to the first capacitor through the first disconnect switch, and is used to pre-charge the first capacitor; the first capacitor is connected in parallel with the first discharge resistor;

[0027] The second pre-charge circuit is connected to the second capacitor via the second disconnect switch for pre-charging the second capacitor; the second capacitor is connected in parallel with the second discharge resistor.

[0028] The collector of the IGBT is connected to the first capacitor, and the emitter of the IGBT is connected to the negative terminal of the diode; one end of the second capacitor is connected to the positive terminal of the diode, and the other end of the second capacitor is connected to one end of the bypass switch; the other end of the bypass switch is connected to the negative terminal of the diode; the air-core reactor is connected in parallel with the bypass switch.

[0029] Furthermore, the test loop construction module is specifically used for:

[0030] Based on the preset fault point voltage and current, the preset test circuit is calculated or simulated to obtain the basic electrical parameters of each component in the test circuit, the initial voltage and initial current of each component, the operating time point or operating threshold of the IGBT and the bypass switch, and the test circuit of the bypass switch is built.

[0031] Furthermore, the capacitor pre-charging module is specifically used for:

[0032] Close the first disconnect switch to allow the first pre-charge circuit to charge the first capacitor.

[0033] When the voltage of the first capacitor is greater than the preset initial voltage, the first isolating switch is disconnected;

[0034] Close the second disconnect switch to allow the second pre-charge circuit to charge the second capacitor;

[0035] When the voltage of the second capacitor is greater than the preset initial voltage, the second isolating switch is disconnected.

[0036] Furthermore, the IGBT has the ability to turn off at any current point during a preset discharge condition of the first capacitor, and the static withstand voltage rating of the IGBT is greater than the maximum voltage across the IGBT during the test.

[0037] Compared to existing technologies, the beneficial effects of the reliability testing method and apparatus for a bypass switch of a flexible DC-DC converter valve submodule provided in this invention are as follows: A test circuit for the bypass switch is constructed based on the operating conditions of the flexible DC-DC converter valve submodule at an overvoltage fault point. The test circuit includes: a first pre-charge circuit and its disconnecting switch, a first capacitor and its discharge resistor, an insulated gate bipolar transistor (IGBT), a diode, a second pre-charge circuit and its disconnecting switch, a second capacitor and its discharge resistor, an air-core reactor, and a bypass switch; the first and second capacitors are pre-charged; the IGBT is turned on until the voltage of the first capacitor is less than a preset termination discharge voltage. Turn off the IGBT; when the voltage of the second capacitor is greater than the preset fault point voltage, close the bypass switch; when the test circuit discharge is detected to be complete, obtain the waveform data of voltage and current of each component in the test circuit during the test process, and analyze the waveform data to obtain the reliability test results of the bypass switch; the embodiment of the present invention can accurately simulate the working condition of the first-level protection bypass switch when an overvoltage fault occurs in the submodule of the UHV flexible DC converter valve, which is beneficial to the inspection of the protection characteristics of the submodule before the project is put into operation and the restoration of similar overvoltage protection faults after the project is put into operation, and can improve the accuracy of the reliability test of the bypass switch of the UHV flexible DC converter valve submodule. Attached Figure Description

[0038] Figure 1 This is a flowchart illustrating a reliability test method for a bypass switch of a flexible DC converter valve submodule provided in an embodiment of the present invention.

[0039] Figure 2 This is a schematic diagram of a bypass switch test circuit provided in an embodiment of the present invention;

[0040] Figure 3 This is a schematic diagram of a bypass switch test circuit for reactor energy storage provided in an embodiment of the present invention;

[0041] Figure 4 This is a schematic diagram of the circuit switched when a bypass switch test circuit reaches a preset voltage and current test point, according to an embodiment of the present invention.

[0042] Figure 5 This is a schematic diagram of a bypass switch test circuit after the bypass switch is activated, provided by an embodiment of the present invention.

[0043] Figure 6 This is a schematic diagram of the structure of a reliability testing device for a bypass switch of a flexible DC converter valve submodule provided in an embodiment of the present invention; wherein, the reference numerals are explained as follows:

[0044] 1. Second pre-charge circuit; 2. IGBT; 3. Diode; 4. First capacitor; 5. Second capacitor; 6. Bypass switch; 7. First discharge resistor; 8. Second discharge resistor; 9. Air-core reactor; 10. First disconnect switch; 11. First pre-charge circuit; 12. Second disconnect switch. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] Please see Figure 1 , Figure 1 This is a flowchart illustrating a reliability testing method for a bypass switch of a flexible DC-DC converter valve submodule provided in an embodiment of the present invention. The reliability testing method for the bypass switch of the flexible DC-DC converter valve submodule includes:

[0047] S1: Based on the operating conditions of the flexible DC converter valve submodule at the overvoltage fault point, construct a test circuit for the bypass switch; the test circuit includes: a first pre-charge circuit 11, a first disconnect switch 10, a first capacitor 4, a first discharge resistor 7, an insulated gate bipolar transistor IGBT 2, a diode 3, a second pre-charge circuit 1, a second disconnect switch 12, a second capacitor 5, a second discharge resistor 8, an air-core reactor 9, and a bypass switch 6;

[0048] S2: Precharge the first capacitor 4 and the second capacitor 5;

[0049] S3: Turn on the IGBT2 until the voltage of the first capacitor 4 is less than the preset termination discharge voltage, then turn off the IGBT2; S4: When the voltage of the second capacitor 5 is greater than the preset fault point voltage, close the bypass switch 6.

[0050] S5: When the test circuit is detected to have finished discharging, obtain the waveform data of the voltage and current of each component in the test circuit during the test process, and analyze the waveform data to obtain the reliability test results of the bypass switch.

[0051] Specifically, this test method is independent of the converter valve submodule topology and mainly simulates the reliable operation of the submodule bypass switch under near-realistic operating conditions when a fault occurs. First, the parameters and initial values ​​of each component in the expected bypass switch test circuit are calculated based on the fault point voltage and current, obtaining the required specifications and control parameters for the components. Then, based on the calculation results, suitable capacitors and their discharge resistors, IGBTs (interruptible devices), capacitor pre-charge circuits and their disconnect switches, diodes, and air-core reactors are selected. Before the test, the experimental circuit is connected to the bypass switch under test according to the test circuit. Before the formal test, the relevant parameters of the test control program are configured according to the calculated initial setpoints. The local control program requires logic configuration of the FPGA (Field Programmable Gate Array) on the local control board, and the remote control program requires programming the DSP (Digital Signal Processor) on the remote control board. During the formal test, the first and second capacitors are pre-charged first. After the pre-charge circuit is disconnected, the pre-charge circuit isolation switch is disconnected. After the pre-charge operation is completed, the formal test is carried out. Finally, the test waveform is recorded and the test results are verified before the test ends.

[0052] Achieving the expected fault point voltage and current conditions involves timely control of multiple switches in the test circuit. Each component of the selected test circuit should ensure that the voltage and current of each part are basically consistent with the expectation when each switch operates. After the IGBT is turned on, the first capacitor begins to discharge to the air-core reactor. Current flows through the first capacitor, IGBT, and air-core reactor, forming a path. The current in this path rises and remains positive, while the voltage of the first capacitor decreases from its initial voltage and remains positive. After the IGBT is turned off, the air-core reactor begins to discharge to the second capacitor. Current flows through the air-core reactor, second capacitor, and diode, forming a path. The current in this path decreases and remains positive, while the voltage of the second capacitor rises from its initial voltage and remains positive. When the bypass switch closes, the voltage across the bypass switch and the current in the air-core reactor at the moment of closing are the expected simulated fault point voltage and current. Thereafter, current flows through the air-core reactor and bypass switch until the reactor's energy is exhausted. The first and second capacitors continue to discharge through their respective discharge resistors until the capacitors are exhausted.

[0053] Furthermore, construct a test circuit for the bypass switch, such as... Figure 2 As shown, this test circuit is used to generate the expected fault point voltage and current operating conditions and to verify the reliability of the bypass switch performing the closing action at the simulated fault point.

[0054] As one optional embodiment, the test circuit specifically includes:

[0055] The first pre-charge circuit 11 is connected to the first capacitor 4 through the first isolation switch 10, and is used to pre-charge the first capacitor 4; the first capacitor 4 is connected in parallel with the first discharge resistor 7.

[0056] The second pre-charge circuit 1 is connected to the second capacitor 5 through the second isolation switch 12, and is used to pre-charge the second capacitor 5; the second capacitor 5 is connected in parallel with the second discharge resistor 8;

[0057] The collector of IGBT 2 is connected to one end of the first capacitor 4, and the emitter of IGBT 2 is connected to the negative terminal of the diode 3; the other end of the first capacitor 4 is connected to one end of the bypass switch 6; one end of the second capacitor 5 is connected to the positive terminal of the diode 3, and the other end of the second capacitor 5 is connected to one end of the bypass switch 6; the other end of the bypass switch 6 is connected to the negative terminal of the diode 3; the air-core reactor 9 is connected in parallel with the bypass switch 6.

[0058] As one optional embodiment, the test circuit for constructing the bypass switch based on the overpressure fault condition of the flexible DC converter valve submodule includes:

[0059] Based on the preset fault point voltage and current, the preset test circuit is calculated or simulated to obtain the basic electrical parameters of each component in the test circuit, the initial voltage and initial current of each component, the operating time point or operating threshold of the IGBT and the bypass switch, and the test circuit of the bypass switch is built.

[0060] Specifically, based on the expected failure point voltage and current of the submodule reliability test, the voltage and current of each component in the test circuit are calculated or simulated. The calculation or simulation results should include the basic electrical parameters of each component in the test circuit, the initial voltage and current of each component, and the switching action time or action threshold of the turn-off IGBT 2 and bypass switch 6. Based on the calculation or simulation results, the components for building the test circuit are pre-selected, and based on the selected components, according to... Figure 2 The circuit shown connects all components to build a complete reliability test circuit for the bypass switch of the flexible DC converter valve submodule.

[0061] Furthermore, based on the calculated or simulated test circuit control parameters, the relevant parameters of the test control program are configured, and the logic configuration of the FPGA on the local control board and the program writing of the DSP on the remote control board are completed. Then, based on the calculated or simulated initial voltages of the first capacitor 4 and the second capacitor 5, pre-charging operations are performed on the first capacitor 4 and the second capacitor 5 respectively, and the test is immediately initiated after reaching the preset voltage value. After completing the test operation, the voltage and current in the test circuit are both discharged below safe values, and a further complete discharge operation is performed to end the test. Simultaneously, the relevant waveforms are recorded, and the test results are analyzed and verified.

[0062] Furthermore, the IGBT has the ability to turn off at any current point during a preset discharge condition of the first capacitor, and the static withstand voltage rating of the IGBT is greater than the maximum voltage across the IGBT during the test.

[0063] Furthermore, in addition to ensuring that the specifications and models of each component meet the calculation and analysis of the electrical stress of each component, other connection parts of the circuit should select cables or busbars of appropriate specifications according to the current magnitude, and take appropriate insulation withstand voltage measures according to the possible overvoltage levels.

[0064] Specifically, the diode has the same current and voltage ratings as the IGBT; both the first and second capacitors meet the voltage and current ratings and capacitance values ​​required for the initial discharge voltage, termination discharge voltage, and termination discharge current in the above calculations or simulations; the bypass switch, i.e., the test bypass switch, is selected based on the bypass switch product to be verified in the test; both the first and second discharge resistors are commonly used discharge resistors in flexible DC engineering, employing natural heat dissipation to meet the temperature rise requirements during discharge; the air-core reactor meets the voltage and current ratings, I²t (amperes squared seconds), and inductance values ​​required for the initial discharge voltage, termination discharge voltage, and termination discharge current of both the first and second capacitors; the disconnecting switch meets the requirements for performing no-load closing / opening operations during the pre-charging process of the first capacitor; and the pre-charging circuit meets the requirements for charging the capacitor to reach the expected initial voltage.

[0065] As one optional embodiment, the pre-charging of the first capacitor and the second capacitor includes: closing the first isolation switch 10 so that the first pre-charging circuit 11 charges the first capacitor 4;

[0066] When the voltage of the first capacitor 4 is greater than the preset initial voltage, the first isolation switch 10 is disconnected;

[0067] Close the second isolation switch 12 to charge the second capacitor 5 using the second pre-charge circuit 1.

[0068] When the voltage of the second capacitor 5 is greater than the preset initial voltage, the second isolation switch 12 is disconnected.

[0069] Specifically, the isolating switch 10 of the first pre-charge circuit 11 is closed, and charging of the first capacitor 4 begins. The charging state is maintained until the preset initial voltage of the first capacitor 4 is reached. Then, the isolating switch 10 of the first pre-charge circuit 11 is opened, clearly disconnecting the first pre-charge circuit 11 from the first capacitor 4. The isolating switch 12 of the second pre-charge circuit 1 is closed, and charging begins. The charging state is maintained until the preset initial voltage of the second capacitor 5 is reached. Then, the isolating switch 12 of the second pre-charge circuit 1 is opened, clearly disconnecting the second pre-charge circuit 1 from the second capacitor 5. The pre-charge operation ends.

[0070] Furthermore, the controllable turn-off device IGBT 2 is turned on, and the first capacitor 4 forms a circuit through IGBT 2 and the air-core reactor 9. The first capacitor 4 discharges into the air-core reactor 9, such as... Figure 3 As shown.

[0071] When the first capacitor 4 discharges to a level lower than the set termination discharge voltage, the IGBT 2 is turned off. Subsequently, the first capacitor 4 is disconnected from the circuit and discharges itself through the discharge resistor 7 across its terminals. After this action, the air-core reactor 9 forms a circuit through the second capacitor 5 and the diode 3, and the air-core reactor 9 discharges into the second capacitor 5, as... Figure 4 As shown. When the voltage of the second capacitor 5 rises to a level higher than the expected simulated fault point voltage, the bypass switch 6 is triggered to perform a closing action.

[0072] After the bypass switch 6 closes, the air-core reactor 9 forms a circuit with the bypass switch 6. The air-core reactor 9 begins to discharge itself through the bypass switch 6, while the second capacitor 5 discharges itself through the discharge resistor 8 connected in parallel across its two ends. Figure 5 As shown.

[0073] If the initial settings, pre-charge voltage, and operation are correct, the voltage and current changes during the test circuit switching and the final voltage and current across the bypass switch should meet the parameter values ​​required for the expected fault simulation. This completes a verification test of the bypass switch's closing action under the simulated fault point. Based on the test results, the reliability of the flexible DC converter valve submodule under this type of fault can be evaluated. Specifically, the collected waveform data is compared with the expected parameters (such as the expected discharge termination voltage of the capacitor and the voltage threshold when the bypass switch closes). If the waveform data is within the set tolerance range, it indicates that the bypass switch of this submodule can operate normally under the set fault conditions and has high reliability.

[0074] The embodiments of the present invention can accurately simulate the operating conditions of the primary protection bypass switch when an overvoltage fault occurs in a submodule of an ultra-high voltage flexible DC converter valve. By calculating and adjusting the expected fault point voltage and current, it is helpful to verify the protection characteristics of the submodule before the project is put into operation and to restore similar overvoltage protection faults after the project is put into operation. It is also helpful to conduct research on the reliability of the bypass switch itself.

[0075] Accordingly, the present invention also provides a reliability testing device for a bypass switch of a flexible DC converter valve submodule, which can realize all the processes of the reliability testing method for the bypass switch of the flexible DC converter valve submodule in the above embodiments.

[0076] Please see Figure 6 , Figure 6 This is a schematic diagram of the structure of a reliability testing device for a bypass switch of a flexible DC-DC converter valve submodule provided in an embodiment of the present invention. The reliability testing device for the bypass switch of the flexible DC-DC converter valve submodule includes:

[0077] The test circuit construction module 601 is used to construct a test circuit for the bypass switch based on the operating conditions of the flexible DC converter valve submodule at the overvoltage fault point; the test circuit includes: a first pre-charge circuit, a first disconnecting switch, a first capacitor, a first discharge resistor, an insulated gate bipolar transistor (IGBT), a diode, a second pre-charge circuit, a second disconnecting switch, a second capacitor, a second discharge resistor, an air-core reactor, and a bypass switch;

[0078] The capacitor pre-charging module 602 is used to pre-charge the first capacitor and the second capacitor;

[0079] The capacitor discharge module 603 is used to turn on the IGBT until the voltage of the first capacitor is less than the preset termination discharge voltage, and then turn off the IGBT.

[0080] The bypass switch action module 604 is used to close the bypass switch when the voltage of the second capacitor is greater than the preset fault point voltage.

[0081] The test result analysis module 605 is used to obtain the voltage and current waveform data of each component in the test circuit during the test process when the test circuit is detected to be discharged, and to analyze the waveform data to obtain the reliability test results of the bypass switch.

[0082] Preferably, the test circuit specifically includes:

[0083] The first pre-charge circuit is connected to the first capacitor through the first disconnect switch, and is used to pre-charge the first capacitor; the first capacitor is connected in parallel with the first discharge resistor;

[0084] The second pre-charge circuit is connected to the second capacitor via the second disconnect switch for pre-charging the second capacitor; the second capacitor is connected in parallel with the second discharge resistor.

[0085] The collector of the IGBT is connected to the first capacitor, and the emitter of the IGBT is connected to the negative terminal of the diode; one end of the second capacitor is connected to the positive terminal of the diode, and the other end of the second capacitor is connected to one end of the bypass switch; the other end of the bypass switch is connected to the negative terminal of the diode; the air-core reactor is connected in parallel with the bypass switch.

[0086] Preferably, the test loop construction module 601 is specifically used for:

[0087] Based on the preset fault point voltage and current, the preset test circuit is calculated or simulated to obtain the basic electrical parameters of each component in the test circuit, the initial voltage and initial current of each component, the operating time point or operating threshold of the IGBT and the bypass switch, and the test circuit of the bypass switch is built.

[0088] Preferably, the capacitor pre-charging module 602 is specifically used for:

[0089] Close the first disconnect switch to allow the first pre-charge circuit to charge the first capacitor.

[0090] When the voltage of the first capacitor is greater than the preset initial voltage, the first isolating switch is disconnected;

[0091] Close the second disconnect switch to allow the second pre-charge circuit to charge the second capacitor;

[0092] When the voltage of the second capacitor is greater than the preset initial voltage, the second isolating switch is disconnected.

[0093] Preferably, the IGBT has the ability to turn off at any current point during a preset discharge condition of the first capacitor, and the static withstand voltage rating of the IGBT is greater than the maximum voltage across the IGBT during the test.

[0094] In specific implementation, the working principle, control process and technical effect of the reliability test device for the bypass switch of the flexible DC converter valve submodule provided in this embodiment of the invention are the same as the reliability test method for the bypass switch of the flexible DC converter valve submodule in the above embodiment, and will not be repeated here.

[0095] This invention provides a reliability testing method and apparatus for a bypass switch of a flexible DC-DC converter valve submodule. Its advantages lie in: constructing a test circuit for the bypass switch based on the operating conditions of the flexible DC-DC converter valve submodule at an overvoltage fault point. The test circuit includes: a first pre-charge circuit and its disconnecting switch, a first capacitor and its discharge resistor, an insulated gate bipolar transistor (IGBT), a diode, a second pre-charge circuit and its disconnecting switch, a second capacitor and its discharge resistor, a hollow reactor, and a bypass switch; pre-charging the first and second capacitors; turning on the IGBT until the voltage of the first capacitor is less than a preset termination discharge voltage, then turning off the IGBT. GBT; When the voltage of the second capacitor is greater than the preset fault point voltage, the bypass switch is closed; When the test circuit is detected to be discharged, the waveform data of the voltage and current of each component in the test circuit during the test process are obtained, and the waveform data are analyzed to obtain the reliability test results of the bypass switch; The embodiments of the present invention can accurately simulate the working conditions of the first-level protection bypass switch when an overvoltage fault occurs in the submodule of the UHV flexible DC converter valve, which is beneficial to the inspection of the protection characteristics of the submodule before the project is put into operation and the restoration of similar overvoltage protection faults after the project is put into operation, thus improving the accuracy of the reliability test of the bypass switch of the UHV flexible DC converter valve submodule.

[0096] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A reliability test method for a bypass switch of a flexible DC converter valve submodule, characterized in that, include: Based on the operating conditions of the flexible DC converter valve submodule at the overvoltage fault point, a test circuit for the bypass switch is constructed; the test circuit includes: a first pre-charge circuit, a first disconnecting switch, a first capacitor, a first discharge resistor, an insulated gate bipolar transistor (IGBT), a diode, a second pre-charge circuit, a second disconnecting switch, a second capacitor, a second discharge resistor, an air-core reactor, and a bypass switch; Precharge the first capacitor and the second capacitor; Turn on the insulated gate bipolar transistor (IGBT) until the voltage of the first capacitor is less than the preset termination discharge voltage, then turn off the insulated gate bipolar transistor (IGBT). When the voltage of the second capacitor is greater than the preset fault point voltage, the bypass switch is closed; When the test circuit is detected to have finished discharging, the waveform data of the voltage and current of each component in the test circuit during the test process are obtained, and the waveform data is analyzed to obtain the reliability test results of the bypass switch. The test circuit specifically includes: The first pre-charge circuit is connected to the first capacitor through the first disconnect switch, and is used to pre-charge the first capacitor; the first capacitor is connected in parallel with the first discharge resistor; The second pre-charge circuit is connected to the second capacitor via the second disconnect switch for pre-charging the second capacitor; the second capacitor is connected in parallel with the second discharge resistor. The collector of the insulated gate bipolar transistor (IGBT) is connected to the first capacitor, and the emitter of the IGBT is connected to the negative terminal of the diode; one end of the second capacitor is connected to the positive terminal of the diode, and the other end of the second capacitor is connected to one end of the bypass switch; the other end of the bypass switch is connected to the negative terminal of the diode; the air-core reactor is connected in parallel with the bypass switch. The test circuit for constructing the bypass switch based on the overpressure fault condition of the flexible DC converter valve submodule includes: Based on the preset fault point voltage and current, the preset test circuit is calculated or simulated to obtain the basic electrical parameters of each component in the test circuit, the initial voltage and initial current of each component, the operating time point or operating threshold of the insulated gate bipolar transistor (IGBT) and the bypass switch, and the test circuit of the bypass switch is built.

2. The reliability test method for the bypass switch of the flexible DC converter valve submodule as described in claim 1, characterized in that, The pre-charging of the first capacitor and the second capacitor includes: Close the first disconnect switch to allow the first pre-charge circuit to charge the first capacitor. When the voltage of the first capacitor is greater than the preset initial voltage, the first isolating switch is disconnected; Close the second disconnect switch to allow the second pre-charge circuit to charge the second capacitor; When the voltage of the second capacitor is greater than the preset initial voltage, the second isolating switch is disconnected.

3. The reliability test method for the bypass switch of the flexible DC converter valve submodule as described in claim 1, characterized in that, The insulated gate bipolar transistor (IGBT) has the ability to turn off at any current point under a preset discharge condition of the first capacitor, and the static withstand voltage rating of the IGBT is greater than the maximum voltage across the IGBT during the test.

4. A reliability testing device for a bypass switch of a flexible DC converter valve submodule, characterized in that, include: The test circuit construction module is used to construct a test circuit for the bypass switch based on the operating conditions of the flexible DC converter valve submodule at the overvoltage fault point; the test circuit includes: a first pre-charge circuit, a first disconnecting switch, a first capacitor, a first discharge resistor, an insulated gate bipolar transistor (IGBT), a diode, a second pre-charge circuit, a second disconnecting switch, a second capacitor, a second discharge resistor, an air-core reactor, and a bypass switch; A capacitor pre-charging module is used to pre-charge the first capacitor and the second capacitor; A capacitor discharge module is used to turn on the insulated gate bipolar transistor (IGBT) until the voltage of the first capacitor is less than a preset termination discharge voltage, and then turn off the IGBT. The bypass switch action module is used to close the bypass switch when the voltage of the second capacitor is greater than the preset fault point voltage. The test result analysis module is used to obtain the waveform data of voltage and current of each component in the test circuit during the test process when the test circuit is detected to have finished discharging, and to analyze the waveform data to obtain the reliability test results of the bypass switch. The test circuit specifically includes: The first pre-charge circuit is connected to the first capacitor through the first disconnect switch, and is used to pre-charge the first capacitor; the first capacitor is connected in parallel with the first discharge resistor; The second pre-charge circuit is connected to the second capacitor via the second disconnect switch for pre-charging the second capacitor; the second capacitor is connected in parallel with the second discharge resistor. The collector of the insulated gate bipolar transistor (IGBT) is connected to the first capacitor, and the emitter of the IGBT is connected to the negative terminal of the diode; one end of the second capacitor is connected to the positive terminal of the diode, and the other end of the second capacitor is connected to one end of the bypass switch; the other end of the bypass switch is connected to the negative terminal of the diode; the air-core reactor is connected in parallel with the bypass switch. The test circuit construction module is specifically used for: Based on the preset fault point voltage and current, the preset test circuit is calculated or simulated to obtain the basic electrical parameters of each component in the test circuit, the initial voltage and initial current of each component, the operating time point or operating threshold of the insulated gate bipolar transistor (IGBT) and the bypass switch, and the test circuit of the bypass switch is built.

5. The reliability testing device for the bypass switch of the flexible DC converter valve submodule as described in claim 4, characterized in that, The capacitor pre-charging module is specifically used for: Close the first disconnect switch to allow the first pre-charge circuit to charge the first capacitor. When the voltage of the first capacitor is greater than the preset initial voltage, the first isolating switch is disconnected; Close the second disconnect switch to allow the second pre-charge circuit to charge the second capacitor; When the voltage of the second capacitor is greater than the preset initial voltage, the second isolating switch is disconnected.

6. The reliability testing device for the bypass switch of the flexible DC converter valve submodule as described in claim 4, characterized in that, The insulated gate bipolar transistor (IGBT) has the ability to turn off at any current point under a preset discharge condition of the first capacitor, and the static withstand voltage rating of the IGBT is greater than the maximum voltage across the IGBT during the test.

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