Converter valve short-circuit current test system and method

Abstract

The invention relates to the technical field of electrical engineering, and discloses a converter valve short-circuit current test system and method, and a generator branch in the system comprises a short-circuit generator, a short-circuit control unit and a bidirectional thyristor valve; one end of the generator branch is connected to one end of the sample valve through the short circuit control unit and the bidirectional thyristor valve in sequence; the other end of the sample valve is connected to the other end of the generator branch; the capacitor branch is arranged at two ends of the sample valve in parallel; the capacitor branch comprises a short-circuit valve body control unit, a capacitor bank and a direct-current power supply; one end of the short-circuit valve body control unit is connected to one end of the sample valve, and the other end is connected to the other end of the sample valve through the capacitor bank; the direct-current power supply is arranged on the capacitor bank in parallel; according to the invention, independent decoupling adjustment of the alternating current component and the direct current component of the short-circuit current is realized, and the test requirements on the gradually increased peak value of the short-circuit current, the thermal capacity and the short-circuit current containing the high-proportion direct current component are met.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical engineering, and particularly to a short-circuit current test system and method for a converter valve. Background Art

[0002] The short-circuit current test is a key test item for the type test of converter valves, which focuses on evaluating the performance of converter valves under fault conditions and is an important means to evaluate the working reliability of converter valves and their ability to withstand short-circuit faults. The current test method is the direct test of a short-circuit generator based on the fault current test of thyristor converter valves, which can meet the test requirements of voltage source converter valves with a low proportion of DC components in the short-circuit current.

[0003] With the further increase in the capacity of flexible DC transmission converter valves, as well as the continuous deepening and development of the hybrid DC transmission technology composed of conventional DC and flexible DC, the short-circuit capacity of related projects has been increasing continuously. On the other hand, the continuous increase in the capacitance value of the DC support capacitor of the flexible DC transmission converter valve further increases the proportion of the DC component in the short-circuit current, making the assessment of the short-circuit current tolerance of MMC converter valves more and more stringent. Based on the above factors, the short-circuit current test has higher and higher requirements for the test method and test parameter control, and the AC / DC components of the short-circuit current must meet the requirements of independent and precise control.

[0004] The current technology is a direct test using a generator system. A short-circuit generator system is used as the test power supply, and by adjusting the parameter adjustment equipment and the valve trigger control timing, a multi-cycle short-circuit current containing a DC component is generated. In the direct test method using a generator system, the AC component and the DC component of the short-circuit test current are both generated according to the inherent characteristics of the generator branch, and the AC and DC components cannot be independently decoupled and adjusted. The maximum value of its DC component is 100% of the AC component, which cannot meet the test requirements for the gradually increasing short-circuit current peak value and heat capacity assessment. Summary of the Invention

[0005] The purpose of the present invention is to provide a short-circuit current test system and method for a converter valve, so as to solve the technical problems in the prior art that the AC and DC components cannot be independently decoupled and adjusted, and cannot meet the test requirements for the gradually increasing short-circuit current peak value, heat capacity, and short-circuit current with a high proportion of DC components.

[0006] The present invention is realized through the following technical solutions: In a first aspect, the present invention provides a short-circuit current test system for a converter valve, including a generator branch, a capacitor branch, a test valve, and a valve control device; The generator branch includes a short-circuit generator, a short-circuit control unit, and a bidirectional thyristor valve; one end of the generator branch is sequentially connected to one end of the test valve through the short-circuit control unit and the bidirectional thyristor valve; the other end of the test valve is connected to the other end of the generator branch; The capacitor branch is arranged in parallel at both ends of the test valve, and the capacitor branch includes a short-circuit valve body control unit, a capacitor bank, and a DC power supply; one end of the short-circuit valve body control unit is connected to one end of the test valve, and the other end is connected to the other end of the test valve after passing through the capacitor bank; the DC power supply is arranged in parallel on the capacitor bank; The control ends of the valve control device are respectively connected to the bidirectional thyristor valve and the short-circuit valve body control unit through signal communication.

[0007] Preferably, the short-circuit control unit includes a short-circuit transformer, a first reactor bank, and a first switch; One end of the short-circuit transformer is connected to one end of the short-circuit generator, and the other end is sequentially connected to the bidirectional thyristor valve through the first reactor bank and the first switch.

[0008] Preferably, the short-circuit valve body control unit includes a second switch, a unidirectional thyristor valve, and a second reactor bank; One end of the second switch is connected to one end of the test valve, and the other end is sequentially connected to the capacitor bank through the unidirectional thyristor valve and the second reactor bank.

[0009] Furthermore, the unidirectional thyristor valve is connected to the control end of the valve control device.

[0010] Preferably, a freewheeling diode valve is also arranged in parallel on the capacitor bank.

[0011] Preferably, a current-limiting resistor is arranged between the DC power supply and the capacitor bank.

[0012] In a second aspect, the present invention also provides a commutation valve short-circuit current test method, based on the above-mentioned commutation valve short-circuit current test system, including: Closing the second switch of the capacitor branch, the DC power supply charges the capacitor bank through the current-limiting resistor; after the voltage of the capacitor bank is charged to the required value, the DC power supply is disconnected from the capacitor bank; Closing the first switch of the generator branch, the short-circuit generator applies excitation; By respectively adjusting the valve trigger control timings of the unidirectional thyristor valve and the bidirectional thyristor valve through the valve control device, the loop is made conductive, so that the current peak value of the generator branch and the current peak value of the capacitor branch are superimposed at the same moment. According to the number of cycles required for the short-circuit current, the valve control device controls the trigger times of the bidirectional thyristor valve, and injects the short-circuit current into the test valve.

[0013] Preferably, a short-circuit generator is used as the test power source for the generator branch. By adjusting the parameters of the short-circuit generator and the trigger control timing of the bidirectional thyristor valve, the short-circuit current is injected into the test valve.

[0014] Preferably, for the capacitor branch, a DC power source charges the capacitor bank through a current-limiting resistor. The capacitor bank and the trigger timing of the single-phase thyristor valve are adjusted, and through the freewheeling diode valve, a decaying DC component of the short-circuit current is generated and injected into the test valve.

[0015] Preferably, the test valve has a single-phase conduction characteristic, so that the short-circuit current of the generator branch and the short-circuit current of the capacitor branch are superimposed and injected into the test valve.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention provides a commutation valve short-circuit current test system. Through the parallel arrangement of the generator branch and the capacitor branch, and the independent control of the valve control device over the bidirectional thyristor valve and the short-circuit valve body control unit, independent adjustment of the AC component and the DC component in the short-circuit current can be achieved, enabling the test to more accurately simulate the short-circuit situation in actual operation, thereby more accurately evaluating the performance of the commutation valve. Components such as the short-circuit generator, capacitor bank, and DC power source in the system provide flexible adjustment means. By adjusting the parameters of these components, the peak value, duration, and the ratio of AC and DC components of the short-circuit current can be conveniently changed to meet different test requirements and assessment criteria. By independently adjusting the AC and DC components and flexibly adjusting the short-circuit current parameters, the present invention can greatly reduce the number of tests and the test time, contributing to improving the test efficiency.

[0017] Furthermore, by adjusting the excitation of the short-circuit generator, the turns ratio of the short-circuit transformer, and the parameters and configuration of the reactor bank, the test requirements for short-circuit currents of different types and specifications of commutation valves can be met.

[0018] Furthermore, the single-phase thyristor valve and the freewheeling diode ensure that the current in the capacitor branch can only flow in one direction. By adjusting the parameters and configuration of the capacitor bank and the second reactor bank, the system can meet the test requirements for different types and specifications of commutation valves.

[0019] Even further, the valve control device can precisely control the single-phase thyristor valve, including turn-on and conduction angle, etc., enabling the system to more accurately simulate the short-circuit current situation in actual operation and improving the accuracy of the test.

[0020] Furthermore, by limiting the charging current, the current-limiting resistor protects the DC power source and the capacitor bank from large current impacts, extends the service life of the equipment, and improves the reliability of the system.

[0021] The present invention also provides a method for short-circuit current test of a converter valve. By first charging the capacitor bank, then applying excitation to the short-circuit generator, and adjusting the trigger control timing sequences of the unidirectional thyristor valve and the bidirectional thyristor valve, it is possible to accurately simulate the short-circuit conditions that the converter valve may encounter during actual operation. This accurate simulation helps to more accurately evaluate the performance of the converter valve under short-circuit conditions. By adjusting the trigger control timing sequence of the thyristor valve through the valve control device and controlling the trigger times of the bidirectional thyristor valve according to the required number of cycles, parameters such as the peak value, duration, and superposition moment of the short-circuit current can be flexibly controlled. This flexibility enables the test to adapt to different types and specifications of converter valves, as well as different test requirements and assessment criteria. The charging process of the capacitor bank is protected by a current-limiting resistor to avoid large current shocks during the initial charging stage. At the same time, during the short-circuit current injection process, through the precise control of the thyristor valve, the stable flow of current can be ensured, reducing the risk of equipment damage caused by current mutations, and improving the safety and reliability of the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic structural diagram of a short-circuit current test system for a converter valve in an embodiment of the present invention; Figure 2 is a schematic diagram of the internal detailed structure of a short-circuit current test for a converter valve in an embodiment of the present invention; In the figure: 1, generator branch; 2, capacitor branch; 3, test valve; 4, valve control device; 11, short-circuit generator; 12, short-circuit transformer; 13, first reactor bank; 14, first switch; 15, bidirectional thyristor valve; 21, second switch; 22, unidirectional thyristor valve; 23, second reactor bank; 24, freewheeling diode valve; 25, capacitor bank; 26, current-limiting resistor; 27, DC power supply. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0024] The purpose of the present invention is to provide a short-circuit current test system and method for a converter valve to solve the technical problems in the prior art that the AC and DC components cannot be independently decoupled and adjusted, and the test requirements for gradually increasing short-circuit current peak values, heat capacities, and assessments cannot be met.

[0025] The following further describes the present invention in detail with reference to the accompanying drawings: Embodiment 1 See Figure 1 and Figure 2 In an embodiment of the present invention, a commutation valve short-circuit current test system is provided, which includes a generator branch 1, a capacitor branch 2, a test valve 3, and a valve control device 4; one end of the generator branch 1 is sequentially connected to one end of the test valve 3 through a short-circuit control unit and a bidirectional thyristor valve 15; the other end of the test valve 3 is connected to the other end of the generator branch 1; the capacitor branch 2 is arranged in parallel at both ends of the test valve 3, and the capacitor branch 2 includes a short-circuit valve body control unit, a capacitor bank 25, and a DC power supply 27; one end of the short-circuit valve body control unit is connected to one end of the test valve 3, and the other end is connected to the other end of the test valve 3 after passing through the capacitor bank 25; the DC power supply 27 is arranged in parallel on the capacitor bank 25; the control ends of the valve control device 4 are respectively connected to the bidirectional thyristor valve 15 and the short-circuit valve body control unit through signal communication.

[0026] Specifically, the short-circuit control unit includes a short-circuit transformer 12, a first reactor bank 13, and a first switch 14; one end of the short-circuit transformer 12 is connected to one end of the short-circuit generator 11, and the other end is sequentially connected to the bidirectional thyristor valve 15 through the first reactor bank 13 and the first switch 14.

[0027] In this embodiment, by adjusting the excitation of the short-circuit generator 11, the turns ratio of the short-circuit transformer 12, and the parameters and configurations of the reactor bank, the short-circuit current test requirements of different types and specifications of commutation valves can be met. Specifically, the short-circuit valve body control unit includes a second switch 21, a unidirectional thyristor valve 22, and a second reactor bank 23; one end of the second switch 21 is connected to one end of the test valve 3, and the other end is sequentially connected to the capacitor bank 25 through the unidirectional thyristor valve 22 and the second reactor bank 23.

[0028] In this embodiment, the unidirectional thyristor valve 22 and the freewheeling diode ensure that the current in the capacitor branch 2 can only flow in one direction. By adjusting the parameters and configurations of the capacitor bank 25 and the second reactor bank 23, the system can meet the test requirements of different types and specifications of commutation valves.

[0029] Among them, the unidirectional thyristor valve 22 is connected to the control end of the valve control device 4.

[0030] In this embodiment, the valve control device 4 can accurately control the unidirectional thyristor valve 22, including turn-on and conduction angle, etc., so that the system can more accurately simulate the short-circuit current situation in actual operation and improve the accuracy of the test.

[0031] Specifically, a freewheeling diode valve 24 is also connected in parallel to the capacitor bank 25.

[0032] Specifically, a current-limiting resistor 26 is provided between the DC power supply 27 and the capacitor bank 25.

[0033] In this embodiment, by limiting the charging current, the current-limiting resistor 26 protects the DC power supply 27 and the capacitor bank 25 from large current impacts, extends the service life of the equipment, and improves the reliability of the system.

[0034] In this embodiment, the single-phase thyristor valve 22, the bidirectional thyristor valve 15, and the freewheeling diode valve 24 are installed in an integral valve tower. The first layer is the freewheeling diode valve 24 connected in series beside the single-phase thyristor valve 22, and the second layer is the bidirectional thyristor valve 15, which is composed of two single-phase thyristor valves connected in antiparallel. The thyristor valve assembly includes thyristor levels, damping absorption circuits, voltage equalizing circuits, thyristor control units TCU, valve control protection and detection functional units, busbars and cables, and valve cooling pipelines, etc. The diode valve assembly includes diode levels, voltage equalizing circuit busbars and cables, and valve cooling pipelines, etc. The thyristor valve drive power supply adopts the power energy transfer method of a power frequency isolation transformer and a magnetic ring CT.

[0035] In this embodiment, the capacitor bank 25 and the reactor bank are equipped with switching disconnectors / change-over switches, and are also equipped with corresponding connecting busbars or cables and short-circuit switches, etc., and the parameters can be freely adjusted according to requirements. The capacitor bank 25 is integrally installed in a metal tower. Sufficient insulation distances are reserved between two layers and two capacitors, and safety discharge resistors and local / remote safety discharge switches are provided.

[0036] The DC power supply 27 should provide a charging power supply for the capacitor bank 25, and it charges the capacitor bank 25 through the current-limiting resistor 26. The corresponding number of DC power supplies 27 is provided according to the capacitor bank 25.

[0037] In summary, for a commutation valve short-circuit current test system provided by this embodiment, through the parallel arrangement of the generator branch 1 and the capacitor branch 2, and the independent control of the bidirectional thyristor valve 15 and the short-circuit valve body control unit by the valve control device 4, the independent adjustment of the AC component and the DC component in the short-circuit current can be realized, so that the test can more accurately simulate the short-circuit situation in actual operation, and thus more accurately evaluate the performance of the commutation valve. Components such as the short-circuit generator 11, the capacitor bank 25, and the DC power supply 27 in the system provide flexible adjustment means. By adjusting the parameters of these components, the peak value, duration, and the ratio of the AC and DC components of the short-circuit current can be easily changed to meet different test requirements and assessment criteria. By independently adjusting the AC and DC components and flexibly adjusting the short-circuit current parameters, the present invention can greatly reduce the number of tests and the test time, which helps to improve the test efficiency.

[0038] Embodiment 2 This embodiment provides a method for testing the short-circuit current of a converter valve. Based on the above-mentioned short-circuit current test system for a converter valve, it includes: Close the second switch 21 of the capacitor branch 2, and the DC power supply 27 charges the capacitor bank 25 through the current-limiting resistor 26; after the voltage of the capacitor bank 25 is charged to the required value, the DC power supply 27 is disconnected from the capacitor bank 25; Close the first switch 14 of the generator branch 1, and apply excitation to the short-circuited generator 11; Respectively adjust the valve trigger control timings of the unidirectional thyristor valve 22 and the bidirectional thyristor valve 15 through the valve control device 4, so that the loop conducts, and the current peak of the generator branch 1 and the current peak of the capacitor branch 2 are superimposed at the same moment. According to the number of cycles required for the short-circuit current, control the trigger times of the bidirectional thyristor valve 15 through the valve control device 4, and inject the short-circuit current into the test valve 3.

[0039] In this embodiment, the multi-cycle short-circuit current is generated by synthesizing the generator branch 1 and the capacitor branch 2. The generator branch 1 uses the short-circuited generator 11 system as the test power supply. By adjusting the generator parameters, reactor parameters, and the trigger control timing of the bidirectional thyristor valve 15, a short-circuit current containing AC and DC components is generated according to the inherent characteristics of the generator branch 1. Its DC component reaches the maximum value at the peak of the first half-wave and is 100% of the AC component. The capacitor branch 2 uses the DC power supply 27 to charge the capacitor bank 25 through the current-limiting resistor 26, adjusts the parameters of the capacitor bank 25 and the reactor bank, and controls the trigger timing of the single-phase thyristor valve through the freewheeling diode valve 24 to generate a decaying DC component of the short-circuit current. The test valve 3 conducts single-phase conduction, the current of the generator branch 1 is superimposed on the current of the capacitor branch 2, and the short-circuit current is injected into the test valve 3.

[0040] This embodiment uses a converter valve short-circuit current test system synthesized by the capacitor branch 2 and the generator branch 1 to realize independent adjustment of the AC and DC components of the short-circuit test current. It can provide a multi-cycle short-circuit current containing a high proportion (exceeding 100%) of DC components. The current adjustment range of this test loop is wide, and it can meet the requirements of the test for AC and DC components, I 2 t and the number of short-circuit cycles, and the short-circuit waveform generated by the generator branch 1 can better meet the actual requirements.

[0041] In the present invention, the capacitor bank 25 is integrally designed and installed in the tower, and is equipped with switching switches, etc.

[0042] In this embodiment, the test sample valve 3 has a single-phase conduction characteristic, enabling the short-circuit current of the generator branch 1 and the short-circuit current of the capacitor branch 2 to be superimposed and injected into the test sample valve 3. The test sample valve 3 is a half-bridge module, that is, the current flows through the diode, and the diode has the characteristic of single-phase conduction. The test sample valve 3 can also be a thyristor, but the thyristor also needs to be triggered by a valve control trigger signal before it conducts, and it also has the characteristic of single-phase conduction.

[0043] The capacitor bank 25 is equipped with a safety discharge resistor, a short-circuit switch, and local / remote discharge control, which can ensure rapid and safe discharge after the test. The thyristor valve and the diode valve are internally provided with a voltage equalizing circuit, a damping absorption circuit, and a valve cooling pipeline to prevent the device from overvoltage or overheating. The drive power supply adopts the power transmission method of a power frequency isolation transformer and a magnetic ring CT, which is safer, more convenient, and more stable.

[0044] In this embodiment, a converter valve short-circuit current test system synthesized by the capacitor bank 25 and the generator circuit is adopted. By adjusting parameters such as the DC power supply 27, the capacitor bank 25, and the reactor bank, the DC component of the short-circuit current can be adjusted. By adjusting the excitation current, the AC component of the short-circuit current can be adjusted, so as to realize the independent adjustment of the AC and DC components of the short-circuit test current. By adjusting the trigger angle of the single / directional thyristor valve 15 respectively through the control and protection device and triggering, the current peak value of the generator branch 1 and the current peak value of the capacitor branch 2 are superimposed at the same moment.

[0045] In summary, a converter valve short-circuit current test method provided by this embodiment can accurately simulate the short-circuit conditions that the converter valve may encounter in actual operation by first charging the capacitor bank 25, then applying excitation to the short-circuit generator 11, and adjusting the trigger control timing of the unidirectional thyristor valve 22 and the bidirectional thyristor valve 15. This accurate simulation helps to more accurately evaluate the performance of the converter valve under short-circuit conditions. By adjusting the trigger control timing of the thyristor valve through the valve control device 4 and controlling the trigger times of the bidirectional thyristor valve 15 according to the required number of cycles, parameters such as the peak value, duration, and superposition moment of the short-circuit current can be flexibly controlled. This flexibility enables the test to adapt to different types and specifications of converter valves, as well as different test requirements and assessment criteria. The charging process of the capacitor bank 25 is protected by the current-limiting resistor 26 to avoid large current impact in the initial charging stage. At the same time, during the short-circuit current injection process, through the precise control of the thyristor valve, the stable flow of the current can be ensured, reducing the risk of equipment damage caused by current mutation. These measures together improve the safety and reliability of the test.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent replacements can still be made to the specific implementation manners of the present invention, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A commutation valve short-circuit current test system, characterized in that It includes a generator branch (1), a capacitor branch (2), a test valve (3) and a valve control device (4); The generator branch (1) includes a short-circuit generator (11), a short-circuit control unit and a bidirectional thyristor valve (15); one end of the generator branch (1) is sequentially connected to one end of the test valve (3) through the short-circuit control unit and the bidirectional thyristor valve (15); the other end of the test valve (3) is connected to the other end of the generator branch (1); The capacitor branch (2) is arranged in parallel at both ends of the test valve (3), and the capacitor branch (2) includes a short-circuit valve body control unit, a capacitor bank (25) and a DC power supply (27); one end of the short-circuit valve body control unit is connected to one end of the test valve (3), and the other end is connected to the other end of the test valve (3) after passing through the capacitor bank (25); the DC power supply (27) is arranged in parallel on the capacitor bank (25); The control end of the valve control device (4) is respectively connected to the bidirectional thyristor valve (15) and the short-circuit valve body control unit through signal communication.

2. The commutation valve short-circuit current test system according to claim 1, wherein, The short-circuit control unit includes a short-circuit transformer (12), a first reactor bank (13) and a first switch (14); One end of the short-circuit transformer (12) is connected to one end of the short-circuit generator (11), and the other end is sequentially connected to the bidirectional thyristor valve (15) through the first reactor bank (13) and the first switch (14).

3. The commutation valve short-circuit current test system according to claim 1, wherein The short-circuit valve body control unit includes a second switch (21), a unidirectional thyristor valve (22) and a second reactor bank (23); One end of the second switch (21) is connected to one end of the test valve (3), and the other end is sequentially connected to the capacitor bank (25) through the unidirectional thyristor valve (22) and the second reactor bank (23).

4. The commutation valve short-circuit current test system according to claim 3, wherein, The unidirectional thyristor valve (22) is connected to the control end of the valve control device (4).

5. The commutation valve short-circuit current test system according to claim 1, wherein A freewheeling diode valve (24) is also arranged in parallel on the capacitor bank (25).

6. The commutation valve short-circuit current test system according to claim 1, wherein, A current-limiting resistor (26) is arranged between the DC power supply (27) and the capacitor bank (25).

7. A short-circuit current test method for a commutation valve, characterized in that, A commutation valve short-circuit current test system according to any one of claims 1-6, comprising: Closing the second switch (21) of the capacitor branch (2), and the DC power supply (27) charges the capacitor bank (25) through the current-limiting resistor (26); after the voltage of the capacitor bank (25) is charged to the required value, the DC power supply (27) is disconnected from the capacitor bank (25); Closing the first switch (14) of the generator branch (1), and the short-circuit generator (11) applies excitation; Respectively adjusting the valve trigger control timings of the unidirectional thyristor valve (22) and the bidirectional thyristor valve (15) through the valve control device (4) to make the loop conduct, so that the current peak value of the generator branch (1) and the current peak value of the capacitor branch (2) are superimposed at the same moment, and according to the number of cycles required for the short-circuit current, controlling the trigger times of the bidirectional thyristor valve (15) through the valve control device (4), and injecting the short-circuit current into the test valve (3).

8. A commutation valve short-circuit current test method according to claim 7, characterized in that The generator branch (1) uses a short-circuit generator (11) as the test power source. By adjusting the parameters of the short-circuit generator (11) and the trigger control timing of the bidirectional thyristor valve (15), the short-circuit current is injected into the test valve (3).

9. A commutation valve short-circuit current test method according to claim 7, characterized in that The capacitor branch (2) uses a DC power source (27) to charge the capacitor bank (25) through a current-limiting resistor (26). Adjust the capacitor bank (25) and the trigger timing of the single-phase thyristor valve, and through the freewheeling diode valve, generate a decaying DC component of the short-circuit current and inject it into the test valve (3).

10. A commutation valve short-circuit current test method according to claim 7, characterized in that, The test valve (3) has a single-phase conduction characteristic, so that the short-circuit current of the generator branch (1) is superimposed with the short-circuit current of the capacitor branch (2) and injected into the test valve (3).

Images