Active turn-off test circuit and method for hybrid commutation converter valve

Abstract

The invention provides an active turn-off test circuit and method for a hybrid commutation converter valve, and particularly, the active turn-off test circuit comprises a high voltage source which is used for providing voltage stress with controllable amplitude and polarity for the hybrid commutation converter valve, namely an HCC-HVDC converter valve, equivalent voltage stress withstood by the converter valve test product Vt in the actual small extinction angle operation condition of the direct current system is obtained; the large-current direct current source is used for providing amplitude-adjustable rectangular wave current for the HCC-HVDC converter valve so as to be equivalent to the conducted steady-state current stress of the converter valve test product Vt in the actual small extinction angle operation condition of the direct current system; and the fault current source is used for providing amplitude-adjustable fault current stress for the HCC-HVDC converter valve. According to the invention, various voltage and current stresses tolerated by the converter valve test object under the small extinction angle working condition of the direct current system can be equivalently realized, the construction cost of the test platform is low, and the test equivalence is strong.

Description

Technical Field

[0001] The present invention belongs to the technical field of safety control of hybrid phase-commutation converter valves, and in particular relates to an active shut-off test circuit and method for hybrid phase-commutation converter valves. Background Art

[0002] LCC-HVDC (line commutated converter-High Voltage Direct Current) technology based on semi-controlled thyristor device converter valves is widely used and has played an important role in long-distance large-capacity power transmission, urban power grid interconnection and other fields, and has produced good economic benefits. With the development of the power grid, the number of LCC-HVDC projects in the power grid has continued to increase, resulting in a continuous decrease in the short-circuit ratio of the receiving power grid and a continuous weakening of the power grid strength; at the same time, the LCC-HVDC technology based on thyristor devices has a long reverse recovery period when the device is turned off and does not have a controllable shutdown capability. When the voltage of the power grid is disturbed, commutation failure is very likely to occur. In severe cases, it will cause the converter valve to lock and stop operating, the power grid load to oscillate, and even a large-scale power outage in the power grid. Therefore, the commutation failure problem of the DC transmission system has become an important core technical problem that the current power grid urgently needs to solve.

[0003] In recent years, with the development of power electronics technology, high-voltage and high-power fully controlled semiconductor devices have been favored by the industry in the field of DC transmission. Based on the fully controlled asymmetric IGBT (Insulate-Gate Bipolar Transistor) converter valve as the core, the VSC-HVDC (Voltage-Source-Converter-High Voltage Direct Current) technology does not have commutation failure, and the DC voltage, active and reactive power can be flexibly controlled, but the control is complex, the cost is expensive, and the investment economy is poor. Based on the fully controlled reverse resistance IGCT (Integrated Gate-Commutated Thyristor) converter valve as the core, the HCC-HVDC (Hybridcommutated converter-High Voltage Direct Current) technology, the core IGCT semiconductor device has a short turn-off reverse recovery period and a controllable turn-off capability, which can effectively suppress and resist the commutation failure of the DC transmission system. At the same time, the cost is moderate and the technical economy is good.

[0004] The HCC-HVDC converter valve with a fully controlled reverse-resistance IGCT converter valve as the core is based on the LCC-HVDC converter valve, and is formed by replacing the core semiconductor devices. The basic working principle and electrical topology are the same as those of the LCC-HVDC converter valve, and the test verification methods and test technical requirements are basically the same. The operating function and transient and steady-state characteristics of the converter valve are inspected and verified on a synthetic equivalent test platform in accordance with relevant national standards and common practices in the industry. The difference is that the HCC-HVDC converter valve has added an active shutdown test to verify the ability to resist commutation failure.

[0005] The purpose of the HCC-HVDC converter valve active shutdown test is to verify its ability to resist commutation failure by forcing commutation through active shutdown strategy when the inverter side converter valve fails to commutate under small arc extinction angle conditions in the DC system when the system is disturbed by a fault. However, the size of its shutdown capability is the main factor that determines its ability to resist commutation failure and verifies the life of core components. According to the design and system requirements, the valve shutdown current capability is much larger than the maximum steady-state current, and the fault is simulated continuously for multiple cycles, generally not less than 3 cycles.

[0006] However, the existing synthetic equivalent test platform developed based on the LCC-HVDC converter valve test has a low high-voltage source voltage and a small output current under the small arc extinction angle equivalent test conditions. It does not have the ability to simulate the output of multiple consecutive cycles to the test valve and the ability to ensure stable, adjustable and controllable fault current under the small arc extinction angle test and other equivalent synthetic test conditions. Therefore, it is not suitable for active shutdown tests on HCC-HVDC converter valves. Summary of the invention

[0007] In view of the above technical problems, the present invention provides an active shut-off test circuit for a hybrid phase-changing valve, wherein the active shut-off test circuit comprises:

[0008] The high voltage source is used to provide a voltage stress with controllable amplitude and polarity for the hybrid commutation valve, i.e., the HCC-HVDC valve, with an equivalent valve test product V t The voltage stress that can be tolerated in the actual DC system with a small arc extinction angle operation condition;

[0009] A high current DC current source is used to provide a rectangular wave current with adjustable amplitude to the HCC-HVDC converter valve, with an equivalent converter valve test product V t In the actual DC system operating condition with small arc extinction angle, the steady-state current stress of conduction;

[0010] Fault current source, used to provide the HCC-HVDC converter valve with adjustable fault current stress to simulate the converter valve test product V t After the rectangular current stress is turned on, the converter valve test product V tIn the natural commutation process, a fault current occurs, resulting in commutation failure. t Verification of the ability to resist active commutation failure.

[0011] Furthermore, the active shutdown test circuit also includes a branch formed by a voltage source isolation valve group, a resonant inductor L1 and a current source isolation valve V2 connected in series in sequence, and the two ends of the branch are respectively connected to a high voltage voltage source and a high current DC current source, wherein:

[0012] The large current DC current source and the current source isolation valve V2 are connected in series with the converter valve test piece V t in parallel;

[0013] Wherein, the voltage source isolation valve group includes anti-parallel voltage source isolation valves V 11 and V 12 .

[0014] Furthermore, the fault current source is connected in parallel to the converter valve test product V t both ends of .

[0015] Further, the fault current source includes a capacitor circuit and a resonant inductor L3 connected in series with the capacitor circuit, wherein:

[0016] The capacitor circuit includes a plurality of capacitor branches connected in parallel, each of which includes capacitors C connected in series. n and isolation control valve V 3n .

[0017] Furthermore, the high voltage source is equivalent to a capacitor whose charging voltage amplitude and voltage polarity can be controllably changed.

[0018] Furthermore, the high-current DC current source is a three-phase six-pulse rectifier.

[0019] Furthermore, the current source isolation valve V2 and the voltage source isolation valve V 11 and V 12 It is a controllable power electronic switch based on a semiconductor device with thyristor as the core.

[0020] Furthermore, the isolation control valve V 3n It is a controllable power electronic switch based on a semiconductor device with thyristor as the core.

[0021] Furthermore, the converter valve test piece V t It includes a reactor L, a metal oxide varistor MOV and a series branch, wherein:

[0022] The metal oxide varistor MOV is connected in parallel at both ends of the series branch, and one end of the series branch is connected to one end of the reactor L, wherein:

[0023] The series branch includes a plurality of valve series modules connected in series, wherein the valve series modules include a damping circuit, a DC voltage balancing circuit and an IGCT device connected in parallel. n , where the damping circuit includes a resistor R dn ;

[0024] The DC voltage balancing circuit includes a series capacitor C N and resistor R n , capacitor C N One end is connected to the resistor R n One end of the capacitor C N The other end is connected to the IGCT n The collector resistor R n The other end is connected to the IGCT n of the emitter.

[0025] On the other hand, the present invention further provides an active shut-off test method for a hybrid phase-changing valve, wherein the active shut-off test method comprises:

[0026] The high voltage source in the active shutdown test circuit is used to provide a voltage stress with controllable amplitude and polarity for the HCC-HVDC converter valve, with an equivalent converter valve test product V t The voltage stress that can be tolerated in the actual DC system with a small arc extinction angle operation condition;

[0027] The high-current DC current source in the active shutdown test circuit is used to provide the HCC-HVDC converter valve with an adjustable amplitude rectangular wave current, with the equivalent converter valve test product V t In the actual DC system operating condition with small arc extinction angle, the steady-state current stress of conduction;

[0028] The fault current source in the active shutdown test circuit is used to provide the HCC-HVDC converter valve with an adjustable amplitude fault current stress to simulate the converter valve test product V t After the rectangular current stress is turned on, a fault current occurs during the natural commutation process of the valve, resulting in commutation failure. t Verification of the ability to resist active commutation failure.

[0029] Furthermore, the active shutdown test circuit further includes a resonant reactor L1, a current source isolation valve V2, a voltage source isolation valve group and a large current DC current source connected in series to form a loop, wherein:

[0030] The large current DC current source and the current source isolation valve V2 are connected in series with the converter valve test piece V t in parallel;

[0031] Wherein, the voltage source isolation valve group includes anti-parallel voltage source isolation valves V 11 and V12 .

[0032] Furthermore, the control strategy of the high voltage source is as follows:

[0033] Current flow control valve test piece V t When the forward voltage is applied, the high voltage power supply is controlled to output the forward voltage. At the same time, the voltage source isolation valve V is turned on when the positive voltage is applied. 11 , when reverse pressure is applied, the voltage source isolation valve V 12 , Converter valve test piece V t In the locked state, the converter valve test product V t The terminals will be subjected to forward voltage stress;

[0034] When the converter valve test product V t When the equivalent opening di / dt is applied, the voltage source isolation valve V is opened at the same time 11 And the converter valve test piece V t , will generate a pulse current with adjustable di / dt, simulating the converter valve test product V t Equivalent di / dt during turn-on or turn-off.

[0035] Furthermore, the control strategy of the high current DC current source is as follows:

[0036] When the converter valve test product V t When the rectangular wave current is applied, the current source isolation valve V2 and the converter valve test piece V t When the current of the bridge arm of the large current source is naturally commutated, it decreases to zero, and the current source isolation valve V2 and the converter valve test piece V t The current naturally crosses zero and turns off.

[0037] Furthermore, the control strategy of the fault current source is as follows:

[0038] Current flow control valve test piece V t When the fault current is applied continuously for multiple cycles during the natural zero-crossing shutdown process, the converter valve test product V t Before the current passes zero, the capacitors C are triggered in sequence for multiple consecutive cycles. n , Isolation control valve V 3n , using the pre-charged standby capacitor C n The resonant current is generated with the resonant inductor L3 and applied to the converter valve test product V t superior;

[0039] The fault current source includes a capacitor circuit and a resonant inductor L3 connected in series with the capacitor circuit; the capacitor circuit includes a plurality of capacitor branches connected in parallel, and the capacitor branches include the capacitors C connected in series. n and the isolation control valve V 3n .

[0040] Compared with the prior art, the present invention provides an active shutdown test circuit and method for a hybrid phase-changing converter valve. By setting up a high-voltage voltage source, a large-current DC current source, and a fault current source, the present invention can equivalently realize the various voltage and current stresses that the converter valve test piece can withstand in a DC system under a small arc extinction angle condition. The test platform construction cost is low and the test equivalence is strong.

[0041] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0043] Figure 1 A topological diagram of an active shut-off test circuit for a hybrid phase-commutation valve according to an embodiment of the present invention is shown;

[0044] Figure 2 A topological diagram of a high current DC current source according to an embodiment of the present invention is shown;

[0045] Figure 3 A topological diagram of a converter valve test product formed by a reactor L in a first manner according to an embodiment of the present invention is shown;

[0046] Figure 4 A topological diagram of a converter valve test product formed by a reactor L in a second manner according to an embodiment of the present invention is shown;

[0047] Figure 5 A flow chart of an active shut-off test method for a hybrid phase-changing valve according to an embodiment of the present invention is shown;

[0048] Figure 6 A schematic diagram of voltage and current stress distribution of each loop according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution 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. 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.

[0050] In view of the fact that the existing synthetic equivalent test platform developed based on LCC-HVDC converter valve test does not have the ability to conduct HCC-HVDC converter valve active shutdown test, such as Figure 1 As shown, the present invention provides an active shutdown test circuit for a hybrid phase-changing converter valve, wherein the active shutdown test circuit includes a high-voltage voltage source 1, a large-current DC current source 2 (exemplarily, an adjustable 120° rectangular wave current source with an amplitude in the range of 0 to 8000A, which meets the current maximum capacity 800kV / 6250A converter valve test requirements) and a fault current source 3, etc., which are explained below.

[0051] The high voltage source 1 is used to provide a voltage stress with controllable amplitude and polarity to the HCC-HVDC converter valve (the converter valve is a hybrid commutation converter valve), and the voltage stress is equivalent to the converter valve test product V t The voltage stress that can be tolerated in the actual DC system operating condition with a small arc extinction angle.

[0052] The high current DC current source 2 is used to provide the HCC-HVDC converter valve with an adjustable amplitude of 120° rectangular wave current, with the equivalent converter valve test product V t The steady-state current stress of conduction in the actual DC system operating condition with small arc extinction angle.

[0053] Fault current source 3 is used to provide the HCC-HVDC converter valve with an adjustable amplitude fault current stress to simulate the converter valve test product V t After the rectangular current stress is turned on, the converter valve test product V t In the natural commutation process, a fault current occurs, resulting in commutation failure. t Active shutdown strategy (when the converter valve test product V t After the commutation failure occurs, active shutdown will be performed to achieve forced commutation) to achieve the commutation valve test product V t Verification of the ability to resist active commutation failure.

[0054] In some embodiments of the present invention, Figure 1In the active shutdown test circuit, the active shutdown test circuit also includes a branch formed by a voltage source isolation valve group, a resonant inductor L1 and a current source isolation valve V2 connected in series in sequence, and the two ends of the branch are respectively connected to a high-voltage voltage source 1 and a high-current DC current source 2, wherein:

[0055] The large current DC current source 2 and the current source isolation valve V2 are connected in series with the converter valve test piece V t wherein the voltage source isolation valve group includes an anti-parallel voltage source isolation valve V 11 and V 12 .

[0056] In some embodiments of the present invention, the current source isolation valve V2 and the voltage source isolation valve V 11 and V 12 It is a controllable power electronic switch based on a semiconductor device with a thyristor as the core, in which the voltage source isolation valve V 11 and V 12 The main function is to control the positive and negative voltage of the high voltage source 1 to be applied to the converter valve test piece V t The main function of the current source isolation valve V2 is to control the large current DC current source 2 to apply the current to the test valve. t During the shutdown period, the high voltage source 1 and the converter valve test product V t The high voltage between the terminals is applied to the high-current DC current source 2 to prevent the high-current DC current source 2 from being damaged by overvoltage.

[0057] In some embodiments of the present invention, Figure 1 As shown, the voltage source isolates the valve V 11 The anode of the valve is isolated from the voltage source V 12 The cathode connection of the voltage source isolating the valve V 11 The cathode of the valve is isolated from the voltage source V 12 Anode connection of the voltage source isolating the valve V 11 The anode of is connected to one end of the high voltage source 1, and the voltage source isolates the valve V 11 The cathode of the resonant reactor L1 is connected to one end of the resonant reactor L1, and the other end of the resonant reactor L1 is connected to the cathode of the current source isolation valve V2 (the cathode of the current source isolation valve V2 is also connected to the converter valve test product V t The anode of the current source isolation valve V2 is connected to one end of the high current DC current source 2, and the other end of the high current DC current source 2 (the other end of the high current DC current source 2 is also connected to the converter valve test piece V t The other end of is connected to the other end of the high voltage voltage source 1.

[0058] In some embodiments of the present invention, the high voltage source 1 is equivalent to a capacitor with a controllable charging voltage amplitude and voltage polarity, and its main functions are: tProvides forward voltage and reverse voltage with adjustable amplitude, and cooperates with resonant inductor L1 to form the converter valve test product V t Provides opening / closing di / dt, simulates the converter valve test product V t Trigger voltage, reverse recovery voltage and turn-on / turn-off di / dt stress in actual DC system transient / steady-state conditions.

[0059] For example, the high current DC current source 2 may be Figure 2 The topology shown includes three bridge arms, each of which is divided into an upper bridge arm and a lower bridge arm. The upper bridge arm and the lower bridge arm of the first bridge arm include a half-controlled device T1 and a half-controlled device T4 respectively, and the cathode of the half-controlled device T1 is connected to the anode of the half-controlled device T4; the upper bridge arm and the lower bridge arm of the second bridge arm include a half-controlled device T3 and a half-controlled device T6 respectively, and the cathode of the half-controlled device T3 is connected to the anode of the half-controlled device T6; the upper bridge arm and the lower bridge arm of the third bridge arm include a half-controlled device T5 and a half-controlled device T2 respectively, and the cathode of the half-controlled device T5 is connected to the anode of the half-controlled device T2.

[0060] The anodes of T1, T3 and T5 are connected to one end of an inductor after being connected to each other, the cathodes of T4, T6 and T2 are connected to the other end of the inductor after being connected to each other, and the midpoints of the three bridge arms are respectively connected to the three phases of the three-phase alternating current, wherein the midpoint of the third bridge arm and the other end of the inductor form two output terminals of the entire high voltage source 1, which are connected as needed. Figure 1 middle.

[0061] The high current DC current source 2 is a three-phase rectifier. Each bridge arm current conducts 120° per cycle, and the bridge arms are naturally commutated and alternately conducted. The main function is to provide a converter valve test product V t Provides 120° rectangular wave current with adjustable amplitude and natural commutation, equivalent to the converter valve test product V t On-current stress in DC systems.

[0062] In some embodiments of the present invention, the fault current source 3 is connected in parallel to the converter valve test product V t The main function of the fault current source 3 is to provide a fault current source for the converter valve test product V t Provides a fault current with flexible adjustment of amplitude and fault cycle number, controllable fault introduction time, and simulates the converter valve test product V t In the actual system, the fault current tolerable after the commutation failure occurs, and the V t Active shutdown capability to protect against commutation failure.

[0063] The fault current source 3 of the present invention is a controllable multi-group LC zero-state second-order oscillation circuit composed of a capacitor group and a resonant inductor with a controllable isolation valve. The fault current of a certain di / dt is generated by the LC oscillation principle and applied to the test valve. Specifically, the fault current source 3 includes a capacitor circuit and a resonant inductor L3 connected in series with the capacitor circuit, wherein the capacitor circuit includes a plurality of capacitor branches connected in parallel, and the capacitor branch includes a capacitor C connected in series. n (like Figure 1 As shown, multiple capacitors are C1, C2, ...C n , n is a positive integer) and isolation control valve V 3n (like Figure 1 As shown, multiple isolation control valves are respectively V 31 、V 32 ,…V 3n ).

[0064] In some embodiments of the present invention, the isolation control valve V 3n It is a controllable power electronic switch based on a semiconductor device with a thyristor as the core. Based on this, the isolation control valve V 31 、V 32 ,…V 3n The cathode of all isolated controlled cathodes is connected to each other and then connected to one end of the resonant inductor L3. The other end of the resonant inductor L3 is connected to the converter valve test product V t One end of the capacitors are connected; C1, C2, ...C n The negative electrode of the converter valve test piece V t The other end of the connection (converter valve test piece V t The other end of the isolation control valve is also grounded), wherein the anode of each isolation control valve is connected to the positive electrode of the corresponding capacitor, for example, the isolation control valve V 3n The anode of the capacitor C is connected n The positive electrode.

[0065] In some embodiments of the present invention, the converter valve test product V t It is a fully controlled power electronic valve string based on IGCT as the core device, including a damping circuit, a DC voltage balancing circuit, MOV (Metal Oxide Varistors), and a saturated reactor L. It has unidirectional conduction, controllable opening, natural zero-crossing shutdown and active shutdown functions. When actively shut down, after the current is shut down, a higher forward voltage will be generated between the terminals. When the voltage reaches a certain value, the parallel MOV protection action is used to suppress the terminal voltage, dissipate the residual energy of the system, and avoid the high voltage between the terminals of the IGCT device, which leads to overvoltage breakdown between the terminals. The following is a test of the converter valve test piece V t Describe the topology.

[0066] like Figure 3 As shown, the converter valve test piece V t There are many structures, for example, Figure 3 As shown, the converter valve test piece V t The invention comprises a reactor L, an MOV and a series branch, wherein the MOV is connected in parallel at both ends of the series branch, and one end of the series branch is connected to one end of the reactor L. The series branch comprises a plurality of valve series modules connected in series, and the valve series modules comprise a damping circuit, a DC voltage balancing circuit and an IGCT connected in parallel. n , specifically:

[0067] The damping circuit, including the resistor R dn The DC voltage equalization circuit includes a series capacitor C N (The multiple capacitors are C1, C2, ...C N , N is a positive integer) and the resistance R n (The multiple resistors are R1, R2, ...R n , n is a positive integer), capacitance C N One end is connected to the resistor R n One end of the capacitor C N The other end is connected to the IGCT n The collector of the device, resistor R n The other end is connected to the IGCT n The emitter of the valve series module is connected in series in the following manner: multiple IGCT devices (IGCT1, IGCT2, ...IGCT n ) are connected in series (i.e., the emitter of the latter IGCT device is connected to the collector of the former IGCT device), and the collector of IGCT1 is connected to one end of the reactor L.

[0068] The anode of IGCT1 can be defined as one end of the series branch. n The cathode of the series branch is the other end of the series branch. In some embodiments of the present invention, there are two ways to connect one end of the series branch to one end of the reactor L. The first way is as follows: Figure 3 As shown, one end of the reactor L is connected to the anode of IGCT1, and the other end of the reactor L is connected to Figure 1 The high voltage side of the IGCT n The cathode is grounded; the second method, such as Figure 4 As shown, one end of the reactor L is connected to the IGCT n The cathode of the IGCT is connected to the ground. n Cathode access Figure 1 The high voltage end.

[0069] Based on the above active shutdown test circuit, the present invention proposes to use a multi-wave fault current source circuit (i.e. a circuit that can generate simulated fault current for multiple consecutive cycles, i.e. Figure 1 The fault current source 3) in the test topology structure using the LC zero-state second-order oscillator circuit principle generates an oscillating current to simulate the valve V t In actual systems, commutation failure occurs for multiple consecutive cycles, and the number of consecutive failure cycles can be flexibly controlled according to hardware settings.

[0070] In some embodiments of the present invention, based on the above-mentioned active shutdown test circuit, the present invention also provides an active shutdown test method for a hybrid commutation converter valve, which is mainly used to test the converter valve test product V t The active shutdown capability test is verified under the minimum arc extinction angle equivalent test condition. The specific solution is: connect the high voltage source 1, the high current DC current source 2, the fault current source 3, the voltage source isolation valve group, the resonant reactor L1, the current source isolation valve V2, and the converter valve test piece V t According to a certain logic control sequence, the converter valve test product V operates under the minimum equivalent arc extinction angle condition. t Before the conduction current naturally crosses zero and turns off, the fault current is introduced for multiple cycles in a timely manner. When the fault current rises to a certain value, the converter valve test product V t The active shut-off strategy implements active shut-off to achieve the purpose of verifying the active shut-off capability of the test valve. Figure 5 As shown, specifically including:

[0071] S1. Use the high voltage source 1 in the active shutdown test circuit to provide the HCC-HVDC converter valve with a voltage stress with controllable amplitude and polarity, and use the equivalent converter valve test product V t The voltage stress that can be tolerated in the actual DC system with a small arc extinction angle operation condition;

[0072] S2. Use the high current DC current source 2 in the active shutdown test circuit to provide the HCC-HVDC converter valve with an adjustable amplitude of 120° rectangular wave current, with the equivalent converter valve test product V t In the actual DC system operating condition with small arc extinction angle, the steady-state current stress of conduction;

[0073] S3. Use the fault current source 3 in the active shutdown test circuit to provide the HCC-HVDC converter valve with an adjustable amplitude fault current stress to simulate the converter valve test product V t After the rectangular current stress is turned on, a fault current occurs during the natural commutation process of the valve, resulting in commutation failure, thereby verifying the valve's ability to resist active commutation failure.

[0074] In some embodiments of the present invention, the control strategy of the high voltage source 1 is as follows:

[0075] Current flow control valve test piece V t When the forward voltage is applied, the high voltage power supply is controlled to output the forward voltage. At the same time, the voltage source isolation valve V is turned on when the positive voltage is applied. 11 , when reverse pressure is applied, the voltage source isolation valve V 12 , Converter valve test piece V t In the locked state, the converter valve test product V t The terminals will be subjected to forward voltage stress.

[0076] When the converter valve test product V t When the equivalent opening di / dt is applied, the voltage source isolation valve V is opened at the same time 11 And the converter valve test piece V t , will generate a pulse current with adjustable di / dt, simulating the converter valve test product V t Equivalent di / dt during turn-on or turn-off.

[0077] In some embodiments of the present invention, the control strategy of the high current DC current source 2 is as follows:

[0078] When the converter valve test product V t When the rectangular wave current is applied, the current source isolation valve V2 and the converter valve test piece V t When the current of the bridge arm of the large current source is naturally commutated, it decreases to zero, and the current source isolation valve V2 and the converter valve test piece V t The current naturally crosses zero and turns off.

[0079] In some embodiments of the present invention, the control strategy of the fault current source 3 is as follows:

[0080] Current flow control valve test piece V t When the fault current is applied continuously for multiple cycles during the natural zero-crossing shutdown process, the converter valve test product V t Before the current passes zero, the capacitors C are triggered in sequence for multiple consecutive cycles. n , controllable isolation valve V 3n (i.e. isolation control valve V 3n ), using the pre-charged standby capacitor C n The resonant current is generated with the resonant inductor L3 and applied to the converter valve test product V t superior.

[0081] In addition, it should be noted that in the present invention: the high-current DC current source 2 is a three-phase six-pulse rectifier bridge circuit. When a conducting DC current is applied to the converter valve specimen, one of the bridge arms is locked, and the conducting current source isolation valve and the converter valve specimen are triggered at the same time, which is equivalent to the conducting current stress of the converter valve specimen in the actual system.

[0082] According to the following Figure 6, showing the schematic diagram of voltage and current stress distribution of each circuit. vt The test product V is the converter valve t Terminal voltage stress, I s Output current stress for large current DC current source 2, I v The output current stress of high voltage source 1, I fc Output current stress of fault current source 3, I vt Converter valve test piece V t Current stress. Combined Figure 1 Circuit topology diagram, specific implementation method (specific operation control strategy for each stage below) is as follows:

[0083] (I) Small arc angle equivalent synthesis normal operation stage

[0084] 0~t1: High voltage source 1 outputs forward voltage, V t In the blocking state, the terminals are subjected to positive voltage stress, and the loop current (through V t The current) stress is zero.

[0085] t1~t4: V is turned on at time t1 11 and V t , high voltage source 1, V 11 , L1 and V t The current loop is formed to generate a current applied to V t In the loop; V2 is turned on at time t2, and the high current DC current source 2, V2, and V t A current loop is formed, and a large current DC current source 2 passes through V2 to V t A 120° rectangular wave current was applied.

[0086] When the current source rectifier (i.e., high voltage source 1) passes through V t The current decreases due to natural commutation, and V is turned on again at t3 during the current decrease process. 11 , high voltage source 1, V 11 , L1 and V t The current loop is formed to generate a current that is superimposed on the large current DC current source and applied to V t Upper analog V t Natural zero-crossing turn-off di / dt stress.

[0087] At t4, V t The current naturally turns off when it passes zero, turning on V 12 , a negative voltage from a high voltage source 1 is applied to V t Both ends, equivalent to analog V t The negative voltage that can be tolerated after shutdown under small arc extinction angle conditions.

[0088] (II) Simulated fault shutdown test phase

[0089] t5~t9: During the t5~t7 period, the circuit working principle is the same as t1~t3. V is turned on at t8. 31 , resonant capacitor C1 through valve V 31 , L3, V t Form an LC oscillation resonant circuit to generate a simulated fault current applied to V t Up; V is sent at time t9 t When the shutdown command is turned off, the on-current drops rapidly to zero and a higher forward voltage is generated between the terminals.

[0090] t 10 ~t 11 The working principle of each cycle of the stage is the same as that of t5 to t9. When the simulated fault current is introduced, a group of capacitor branches is introduced in each cycle, and the corresponding circuit isolation control valve (for example, V 31 ), and then turn on other isolation control valves in sequence (for example, turn on V 32 ,…V 3n ), the number of conducting capacitor branches is determined based on the number of consecutive fault cycles simulated in the test.

[0091] t 11 In the subsequent stage, the lower arc extinction angle test enters the normal operation stage, and the control logic is the same as t1 to t5.

[0092] In summary, the active shut-off test circuit and method for a hybrid phase-changing valve provided by the present invention have the following advantages:

[0093] 1) The active shutdown test circuit topology adopts high-voltage voltage source, high-current DC current source, isolation control valve and each isolation valve is controlled according to a certain logic control sequence, which can equivalently realize the various voltage and current stresses that the converter valve test product can withstand in the DC system under the condition of small arc extinction angle. The test platform construction cost is low and the test equivalence is strong.

[0094] 2) The active shutdown test circuit topology fault current source adopts an LC oscillation circuit formed by an isolation control valve, a capacitor branch and a resonant inductor, which can flexibly control the number of fault current cycles and the simulated fault time;

[0095] 3) The active shutdown test circuit topology fault current source adopts an LC oscillation circuit formed by an isolation control valve, a capacitor and a resonant inductor. The capacitor adopts a pre-charging mode and adjusts the charging voltage to achieve the adjustment of the fault current size and the constant amplitude of the simulated fault current in each cycle.

[0096] 4) The active shutdown test circuit topology adopts an isolation control valve and a capacitor in series as an independent resonant unit. Each resonant unit forms an LC oscillation circuit with the same resonant inductor L3, generating simulated fault currents of equal amplitude in different fault cycles. Each resonant unit shares the same resonant inductor L3, reducing the number of inductors used by n-1, thereby greatly reducing the floor space and investment of the test platform.

[0097] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. An active shut-off test circuit for a hybrid commutation valve, wherein: The active shutdown test circuit comprises: The high voltage source (1) is used to provide a voltage stress with controllable amplitude and polarity to the hybrid commutation converter valve, i.e., the HCC-HVDC converter valve, with an equivalent converter valve test product V t The voltage stress that can be tolerated in the actual DC system with a small arc extinction angle operation condition; A high current DC current source (2) is used to provide a rectangular wave current with adjustable amplitude to the HCC-HVDC converter valve, with an equivalent converter valve test product V t In the actual DC system operating condition with small arc extinction angle, the steady-state current stress of conduction; The fault current source (3) is used to provide the HCC-HVDC converter valve with an adjustable fault current stress to simulate the converter valve test product V t After the rectangular current stress is turned on, the converter valve test product V t In the natural commutation process, a fault current occurs, resulting in commutation failure. t Verification of the ability to resist active commutation failure.

2. An active shut-off test circuit for a hybrid phase-commutation valve according to claim 1, wherein: The active shutdown test circuit also includes a branch formed by a voltage source isolation valve group, a resonant inductor L1 and a current source isolation valve V2 connected in series in sequence, and the two ends of the branch are respectively connected to a high-voltage voltage source (1) and a high-current direct current source (2), wherein: The large current DC current source (2) and the current source isolation valve V2 are connected in series with the converter valve test piece V t in parallel; Wherein, the voltage source isolation valve group includes anti-parallel voltage source isolation valves V 11 and V 12 .

3. An active shut-off test circuit for a hybrid phase-commutation valve according to claim 1 or 2, wherein: The fault current source (3) is connected in parallel to the converter valve test piece V t both ends of .

4. An active shut-off test circuit for a hybrid phase-commutation valve according to claim 3, wherein: The fault current source (3) comprises a capacitor circuit and a resonant inductor L3 connected in series with the capacitor circuit, wherein: The capacitor circuit includes a plurality of capacitor branches connected in parallel, each of which includes capacitors C connected in series. n and isolation control valve V 3n .

5. An active shut-off test circuit for a hybrid phase-commutation valve according to claim 1, wherein: The high voltage source (1) is equivalent to a capacitor whose charging voltage amplitude and voltage polarity can be controllably changed.

6. An active shut-off test circuit for a hybrid phase-commutation valve according to claim 1, wherein: The high-current direct current source (2) is a three-phase six-pulse rectifier.

7. An active shut-off test circuit for a hybrid phase-commutation valve according to claim 2, wherein: The current source isolation valve V2, the voltage source isolation valve V 11 and V 12 It is a controllable power electronic switch based on a semiconductor device with thyristor as the core.

8. An active shut-off test circuit for a hybrid phase-commutation valve according to claim 4, wherein: The isolation control valve V 3n It is a controllable power electronic switch based on a semiconductor device with thyristor as the core.

9. An active shut-off test circuit for a hybrid phase-commutation valve according to any one of claims 1-2 and 4-7, wherein: The converter valve test piece V t It includes a reactor L, a metal oxide varistor MOV and a series branch, wherein: The metal oxide varistor MOV is connected in parallel at both ends of the series branch, and one end of the series branch is connected to one end of the reactor L, wherein: The series branch includes a plurality of valve series modules connected in series, wherein the valve series modules include a damping circuit, a DC voltage balancing circuit and an IGCT device connected in parallel. n , where the damping circuit includes a resistor R dn ; The DC voltage balancing circuit includes a series capacitor C N and resistor R n , capacitor C N One end is connected to the resistor R n One end of the capacitor C N The other end is connected to the IGCT n The collector resistor R n The other end is connected to the IGCT n of the emitter.

10. An active shut-off test method for a hybrid phase-changing valve, wherein: The active shutdown test method comprises: The high voltage source (1) in the active shutdown test circuit is used to provide a voltage stress with controllable amplitude and polarity to the HCC-HVDC converter valve, and the voltage stress is controlled by the equivalent converter valve test product V t The voltage stress that can be tolerated in the actual DC system with a small arc extinction angle operation condition; The high current DC current source (2) in the active shutdown test circuit is used to provide a rectangular wave current with adjustable amplitude to the HCC-HVDC converter valve, with the equivalent converter valve test product V t In the actual DC system operating condition with small arc extinction angle, the steady-state current stress of conduction; The fault current source (3) in the active shutdown test circuit is used to provide the HCC-HVDC converter valve with an adjustable amplitude fault current stress to simulate the converter valve test product V t After the rectangular current stress is turned on, a fault current occurs during the natural commutation process of the valve, resulting in commutation failure. t Verification of the ability to resist active commutation failure.

11. An active shut-off test method for a hybrid phase-commutation valve according to claim 10, wherein: The active shutdown test circuit further comprises a resonant reactor L1, a current source isolation valve V2, a voltage source isolation valve group and a large current DC current source (2) which are connected in series to form a loop, wherein: The large current DC current source (2) and the current source isolation valve V2 are connected in series with the converter valve test piece V t in parallel; Wherein, the voltage source isolation valve group includes anti-parallel voltage source isolation valves V 11 and V 12 .

12. An active shut-off test method for a hybrid phase-changing valve according to claim 11, wherein: The control strategy of the high voltage source (1) is as follows: Current flow control valve test piece V t When the forward voltage is applied, the high voltage power supply is controlled to output the forward voltage. At the same time, the voltage source isolation valve V is turned on when the positive voltage is applied. 11 , when reverse pressure is applied, the voltage source isolation valve V 12 , Converter valve test piece V t In the locked state, the converter valve test product V t The terminals will be subjected to forward voltage stress; When the converter valve test product V t When the equivalent opening di / dt is applied, the voltage source isolation valve V is opened at the same time 11 And the converter valve test piece V t , will generate a pulse current with adjustable di / dt, simulating the converter valve test product V t Equivalent di / dt during turn-on or turn-off.

13. An active shut-off test method for a hybrid phase-changing valve according to claim 11 or 12, wherein: The control strategy of the high current DC current source (2) is as follows: When the converter valve test product V t When the rectangular wave current is applied, the current source isolation valve V2 and the converter valve test piece V t When the current of the bridge arm of the large current source (2) is naturally commutated and reduced to zero, the current source isolation valve V2 and the converter valve test piece V t The current naturally crosses zero and turns off.

14. An active shut-off test method for a hybrid phase-commutation valve according to claim 12, wherein: The control strategy of the fault current source (3) is as follows: Current flow control valve test piece V t When the fault current is applied continuously for multiple cycles during the natural zero-crossing shutdown process, the converter valve test product V t Before the current passes zero, the capacitors C are triggered in sequence for multiple consecutive cycles. n , Isolation control valve V 3n , using the pre-charged standby capacitor C n The resonant current is generated with the resonant inductor L3 and applied to the converter valve test product V t superior; The fault current source (3) comprises a capacitor circuit and a resonant inductor L3 connected in series with the capacitor circuit; the capacitor circuit comprises a plurality of capacitor branches connected in parallel, and the capacitor branches comprise the capacitors C connected in series. n and the isolation control valve V 3n .

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