Converter valve power module overcurrent test system and test method

Abstract

The invention discloses an overcurrent test system and method for a converter valve power module, and belongs to the technical field of direct current transmission. A first charging power supply is connected with an auxiliary control unit and is used for charging the auxiliary control unit; one end of the first current-limiting reactor is connected to the auxiliary control unit, and the other end is connected to the short-circuit simulation branch; the auxiliary control unit is connected with the test object power module and is used for injecting test current into the test object power module; the short-circuit simulation branch is connected with the test object power module and is used for shunting current flowing into the test object power module during a test period; and the second charging power supply is connected with the sample power module and is used for charging the sample power module. The device can be used for simulating that the diode in the converter valve power module is switched off according to the set current change rate under high voltage under the working condition that the bridging lightning arrester of the converter valve is subjected to overvoltage breakdown short circuit, and the safety of the converter valve power module is verified.

Description

Technical Field

[0001] The invention belongs to the field of direct current power transmission, and in particular relates to an overcurrent test system and a test method for a voltage source converter valve power module. Background Art

[0002] Modular Multilevel Converter (MMC) is a widely used converter in flexible DC transmission systems. UHV flexible DC transmission usually adopts true bipolar topology, and each pole converter valve adopts a high-end converter and a low-end converter in series. Under this wiring method, when the converter valve side is grounded, the converter valve submodule capacitor will be overcharged and overvoltage.

[0003] In order to prevent the overvoltage of the converter valve submodule from damaging IGBT, capacitors and other components under fault conditions, an effective way is to configure a valve arrester between the converter valve ends. When an overvoltage appears between the valve ends, the arrester overvoltage protection is activated to prevent the converter valve from overvoltage. After a station fault occurs, the follow-up overvoltage triggers the valve arrester to shunt and absorb energy. During the fault follow-up process, the transient breakdown of the arrester is considered, and a reactor is connected in series in the arrester circuit to limit the overcurrent and overvoltage when the arrester is transiently broken down.

[0004] The converter valve has a high voltage level and large capacity. It is equipped with a large number of parallel large-capacity arresters. The uneven impedance between the columns during the energy absorption process may cause the arrester to break down. When the arrester breaks down, the current flowing through the converter valve power module before the breakdown will quickly transfer to the arrester branch. The reverse recovery of the converter valve power diode under high voltage may cause transient overvoltage in the power module, thereby causing device failure.

[0005] After the arrester short-circuit breakdown, the current amplitude and overvoltage amplitude of the diode current of the converter valve power module when it is turned off depend on the operating conditions of the system. The converter valve voltage level is high and the capacity is large. It is impossible to build the same system as the converter station site in the factory to evaluate the tolerance and equipment safety of the converter valve under fault conditions. Therefore, how to build a test circuit based on the converter valve module to simulate the overvoltage of the converter valve power module and the short-circuit condition of the valve arrester breakdown, verify the safety of the reverse recovery of the diode of the converter valve power module under high voltage and high current, and verify the effectiveness of the design of the valve arrester branch inductance parameters is the key to the converter valve and system design. Summary of the invention

[0006] The purpose of the present invention is to provide a converter valve power module overcurrent test device and method, which can be used to equivalently simulate the overvoltage of the converter valve power module and the valve arrester breakdown short-circuit conditions, evaluate the effectiveness of the parameter design of the converter valve arrester branch reactor and verify the tolerance of the converter valve power component under fault conditions, which is of great significance to ensure the reliable operation of the flexible DC system.

[0007] In order to achieve the above object, the solution of the present invention is:

[0008] A first aspect of the present invention provides a converter valve power module overcurrent test system, comprising: a first charging power supply, an auxiliary control unit, a first current limiting reactor, a short-circuit simulation branch, a second charging power supply and a test power module;

[0009] The first charging power source is connected to the auxiliary control unit and is used to charge the auxiliary control unit;

[0010] One end of the first current limiting reactor L1 is connected to the auxiliary control unit, and the other end is connected to the short-circuit simulation branch;

[0011] The auxiliary control unit is connected to the test power module and is used to inject a test current into the test power module;

[0012] The short-circuit simulation branch is connected to the test power module and is used to shunt the current flowing into the test power module during the test;

[0013] The second charging power source is connected to the test power module and is used to charge the test power module.

[0014] Preferably, the test power module is a full-bridge power module, comprising: a first turn-off semiconductor T1, a second turn-off semiconductor T2, a third turn-off semiconductor T3, a fourth turn-off semiconductor T4, a storage capacitor C1, a first output terminal Y1, a second output terminal Y2 and a bypass switch K;

[0015] The first turn-off semiconductor T1 and the second turn-off semiconductor T2 are connected in series in the same direction, the third turn-off semiconductor T3 and the fourth turn-off semiconductor T4 are connected in series in the same direction, and the above two series branches are connected in parallel. The first to fourth turn-off semiconductors are respectively connected with the first to fourth anti-parallel freewheeling diodes, one end of the energy storage capacitor C1 is connected to the connection point of the first turn-off semiconductor T1 and the third turn-off semiconductor T3, and the other end is connected to the connection point of the second turn-off semiconductor T2 and the fourth turn-off semiconductor T4; the first output terminal Y1 is connected to the connection point of the first turn-off semiconductor T1 and the second turn-off semiconductor T2, and the second output terminal Y2 is connected to the connection point of the third turn-off semiconductor T3 and the fourth turn-off semiconductor T4; the two ends of the bypass switch are respectively connected to the first output terminal Y1 and the second output terminal Y2.

[0016] Preferably, the test power module is a half-bridge power module, comprising: a first turn-off semiconductor T1, a second turn-off semiconductor T2, a storage capacitor C1, a first output terminal Y1, a second output terminal Y2 and a bypass switch K;

[0017] The first turn-off semiconductor T1 and the second turn-off semiconductor T2 are connected in series in the same direction, the first turn-off semiconductor T1 is connected with a first anti-parallel freewheeling diode D1, and the second turn-off semiconductor T2 is connected with a second anti-parallel freewheeling diode D2; the energy storage capacitor C1 is connected in parallel with the series branch formed by the first turn-off semiconductor T1 and the second turn-off semiconductor T2; the first output terminal Y1 and the second output terminal Y2 are respectively connected to the two ends of the second turn-off semiconductor T2, wherein the first output terminal Y1 is connected to the junction of the first turn-off semiconductor T1 and the second turn-off semiconductor T2; the two ends of the bypass switch K are respectively connected to the first output terminal Y1 and the second output terminal Y2.

[0018] Preferably, the first charging power source comprises: a first DC power source U1 , a first current limiting resistor R1 and a first charging control switch K1 connected in series.

[0019] Preferably, the auxiliary control unit comprises N cascaded submodules, wherein N≥2, and the submodules comprise: a first semiconductor unit, a second semiconductor unit, a DC capacitor Cs, a first output terminal X1, and a second output terminal X2;

[0020] The first semiconductor unit and the second semiconductor unit are connected in series in the same direction, and the DC capacitor Cs is connected in parallel with the series branch where the first semiconductor unit and the second semiconductor unit are located; the first output terminal X1 is connected to the connection point between the first semiconductor unit and the second semiconductor unit, and the second output terminal X2 is connected to the connection point between the second semiconductor unit and the DC capacitor.

[0021] Preferably, one end of the first charging power supply is connected to the junction of the DC capacitor Cs of the Nth submodule in the auxiliary control unit and the first semiconductor unit; the other end of the first charging power supply is connected to the junction of the DC capacitor Cs of the 1st submodule in the auxiliary control unit and the second semiconductor unit.

[0022] Preferably, the first semiconductor unit adopts a fully controlled power device and a first power diode connected in reverse parallel thereto;

[0023] The second semiconductor unit adopts a diode device or a fully controlled power device.

[0024] Preferably, the short-circuit simulation branch includes: a controllable switch S1 and a second current-limiting inductor L2 connected in series; a first output terminal Y1 and a second output terminal Y2 of the test power module are connected to both ends of the short-circuit simulation branch.

[0025] Preferably, the controllable switch S1 is an electronic switch or a mechanical switch, which can be closed and turned on after receiving a trigger command.

[0026] Preferably, the second charging power source comprises: a second DC power source U2, a second current limiting resistor R2 and a second charging control switch K2 connected in series;

[0027] Two ends of the second charging power source are connected to two ends of the energy storage capacitor C1 of the test power module.

[0028] Preferably, the positive polarity output terminal and the negative polarity output terminal of the second charging power source are respectively connected to the first output terminal Y1 and the second output terminal Y2 of the converter valve power module.

[0029] A second aspect of the present invention provides a converter valve power module overcurrent test method, based on the converter valve power module overcurrent test system, comprising the following steps:

[0030] Step 1: Use a first charging power source to charge the auxiliary control unit and monitor the voltage across the auxiliary control unit;

[0031] Step 2: After the voltage across the auxiliary control unit reaches the first voltage setting value Uset1, the second charging power source charges the test power module and monitors the voltage of the test power module until it reaches the second voltage setting value Uset2, wherein the first voltage setting value Uset1 is greater than the second voltage setting value Uset2;

[0032] Step 3, after the test power module reaches the second voltage setting value Uset2, control the auxiliary control unit to inject a test current into the test power module until the test current increases to the current setting value Is;

[0033] Step 4: after the current value in the power module of the test product reaches the current setting value Is after time t1, the short-circuit simulation branch is used to shunt the current in the power module of the test product;

[0034] Step 5, lock the auxiliary control unit and the short-circuit simulation branch, the current in the short-circuit simulation branch decays, and the diode of the test power module is turned off at a set current change rate under high voltage.

[0035] Preferably, in step 3, the voltage difference between the first voltage setting value Uset1 and the second voltage setting value Uset2 is controlled to adjust the current rising rate of the diode in the test power module, which is expressed by the following formula:

[0036]

[0037] Where:

[0038] R DIndicates the current rise rate of the diode in the test power module.

[0039] Uset1 and Uset2 represent the first voltage setting value and the second voltage setting value respectively.

[0040] L2 represents the inductance value of the second current limiting inductor.

[0041] Preferably, in step 4, the starting value of the fault current shunting of the test power module can be controlled by controlling the trigger time t1.

[0042] Compared with the prior art, after adopting the above scheme, the present invention has at least the following advantages:

[0043] (1) By adjusting the voltage of the second charging power supply, the starting voltage of the diode turn-off characteristic test of the converter valve power module can be controlled. By controlling the voltage difference between Uset1 and Uset2, the current rise rate of the diode in the converter valve power module can be adjusted. By controlling the trigger time t1, the starting value of the fault current shunting of the converter valve power module can be controlled.

[0044] (2) The controllable switch can be used to simulate the breakdown short-circuit condition of the converter valve arrester, and the starting value of the current flowing into the converter valve power module can be controlled by the triggering time;

[0045] (3) The auxiliary control unit adopts a scheme of connecting multiple sub-modules in series, which can easily realize the controllable opening and closing of the current under high voltage, ensuring the accuracy of the test current;

[0046] (4) The circuit of the present invention is simple and can conveniently simulate the short-circuit fault condition of the converter valve arrester branch. The test method is practical, safe and reliable. It can check the safety of the reverse recovery of the diode of the converter valve power module under high voltage and large current, and verify the effectiveness of the design of the inductance parameters of the valve arrester branch, which is the converter valve and system design. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is an electrical structure diagram of the converter valve full-bridge module targeted by the present invention;

[0048] Figure 2 is an electrical structure diagram of a converter valve half-bridge module targeted by the present invention;

[0049] Figure 3 It is a schematic diagram of the overcurrent test system of the converter valve power module in the test method of the present invention. DETAILED DESCRIPTION

[0050] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0051] The present invention provides a converter valve power module overcurrent test device and method, which are used to equivalently simulate the overvoltage of the converter valve power module and the valve arrester breakdown short-circuit working conditions, evaluate the effectiveness of the parameter design of the converter valve arrester branch reactor and verify the tolerance capacity of the converter valve power components under fault conditions.

[0052] Embodiment 1 of the present invention provides a converter valve power module overcurrent test system, including: a first charging power source, an auxiliary control unit, a first current limiting reactor L1, a short-circuit simulation branch, a second charging power source and a test power module. Figure 3 The figure shows a circuit schematic diagram of an overcurrent test system for a converter valve power module of the present invention.

[0053] The first charging power source is connected to the auxiliary control unit and is used to charge the auxiliary control unit until the voltage across the auxiliary control unit reaches a first voltage setting value Uset1;

[0054] One end of the first current limiting reactor L1 is connected to the auxiliary control unit, and the other end is connected to the short-circuit simulation branch, for limiting the auxiliary control unit;

[0055] The auxiliary control unit is connected to the test power module and is used to inject a test current into the test power module until the current setting value Is is reached;

[0056] The short-circuit simulation branch is connected to the test power module and is used to shunt the current flowing into the test power module during the test;

[0057] The second charging power source is connected to the test power module and is used to charge the test power module until the voltage of the test power module reaches a second voltage setting value Uset2.

[0058] The converter valve is a modular multi-level converter valve, which is composed of a number of cascaded power modules. The test power module can be a full-bridge power module or a half-bridge power module.

[0059] The structure of the full-bridge power module is as follows Figure 1 As shown, it includes: a first turn-off semiconductor T1, a second turn-off semiconductor T2, a third turn-off semiconductor T3, a fourth turn-off semiconductor T4, a storage capacitor C1, a first output terminal Y1, a second output terminal Y2 and a bypass switch K.

[0060] More specifically, the first turn-off semiconductor T1 and the second turn-off semiconductor T2 are connected in series in the same direction, the third turn-off semiconductor T3 and the fourth turn-off semiconductor T4 are connected in series in the same direction, the two series branches are connected in parallel, and the first to fourth turn-off semiconductors are respectively connected with the first to fourth freewheeling diodes connected in anti-parallel. Figure 1The first freewheeling diode D1, the second freewheeling diode D2, the third freewheeling diode D3 and the fourth freewheeling diode D4 in the circuit; one end of the energy storage capacitor C1 is connected to the junction of the first turn-off semiconductor T1 and the third turn-off semiconductor T3, and the other end is connected to the junction of the second turn-off semiconductor T2 and the fourth turn-off semiconductor T4; the first output terminal Y1 is connected to the junction of the first turn-off semiconductor T1 and the second turn-off semiconductor T2, and the second output terminal Y2 is connected to the junction of the third turn-off semiconductor T3 and the fourth turn-off semiconductor T4; the two ends of the bypass switch are respectively connected to the first output terminal Y1 and the second output terminal Y2 of the test power module.

[0061] The structure of the half-bridge power module is as follows Figure 2 As shown, it includes: a first turn-off semiconductor T1, a second turn-off semiconductor T2, an energy storage capacitor C1, a first output terminal Y1, a second output terminal Y2 and a bypass switch K.

[0062] More specifically, the first turn-off semiconductor T1 and the second turn-off semiconductor T2 are connected in series in the same direction, the first turn-off semiconductor T1 is connected to a first anti-parallel freewheeling diode D1, and the second turn-off semiconductor T2 is connected to a second anti-parallel freewheeling diode D2; the energy storage capacitor C1 is connected in parallel to the series branch formed by the first turn-off semiconductor T1 and the second turn-off semiconductor T2; the first output terminal Y1 and the second output terminal Y2 are respectively connected to the two ends of the second turn-off semiconductor T2, wherein the first output terminal Y1 connects the junction of the first turn-off semiconductor T1 and the second turn-off semiconductor T2; the two ends of the bypass switch K are respectively connected to the first output terminal Y1 and the second output terminal Y2 of the test power module.

[0063] The first charging power source includes: a first DC power source U1, a first current limiting resistor R1 and a first charging control switch K1 connected in series.

[0064] The auxiliary control unit includes N cascaded submodules, where N≥2, and the submodules include: a first semiconductor unit, a second semiconductor unit, a DC capacitor Cs, a first output terminal X1 and a second output terminal X2; the first semiconductor unit and the second semiconductor unit are connected in series in the same direction, the first semiconductor unit includes: a first fully-controlled device Ts1 and a first power diode Ds1 connected in reverse parallel thereto, and the second semiconductor unit includes: a second fully-controlled device Ts2 and a second power diode Ds2 connected in reverse parallel thereto; the DC capacitor Cs is connected in parallel to the series branch where the first semiconductor unit and the second semiconductor unit are located; the first output terminal X1 connects the junction of the first semiconductor unit and the second semiconductor unit, and the second output terminal X2 connects the junction of the second semiconductor unit and the DC capacitor; the N submodules are connected in cascade via the first output terminal X1 and the second output terminal X2, and the first output terminal X1 of the i-th submodule is connected to the second output terminal X2 of the i+1-th submodule, where i=1,2,…,N-1.

[0065] One end of the first charging power source is connected to the junction of the DC capacitor Cs of the Nth submodule in the auxiliary control unit and the first semiconductor unit; the other end of the first charging power source is connected to the junction of the DC capacitor Cs of the 1st submodule in the auxiliary control unit and the second semiconductor unit.

[0066] As a prominent substantive feature of the present invention and one of the significant advances brought to the prior art, the auxiliary control unit adopts a solution of connecting multiple sub-modules in series, which can more conveniently realize the controllable opening and closing of the current under high voltage, thereby ensuring the accuracy of the test current.

[0067] The second fully-controlled device Ts2 and the second power diode Ds2 connected in reverse parallel thereto constitute the second semiconductor unit, which may be an IGBT device or other fully-controlled power devices. However, this is only a preferred but non-restrictive implementation. The second semiconductor unit may also be a diode device.

[0068] In an exemplary but non-limiting embodiment, Figure 3As shown, taking N=2 as an example, the auxiliary control unit is composed of two half-bridge sub-modules in cascade, and the half-bridge sub-module includes: a first semiconductor unit, a second semiconductor unit, a DC capacitor Cs, a first output terminal X1 and a second output terminal X2; the first semiconductor unit and the second semiconductor unit are connected in series in the same direction, the first semiconductor unit includes: a first fully-controlled device Ts1 and a first power diode Ds1 connected in reverse parallel thereto, and the second semiconductor unit includes: a second fully-controlled device Ts2 and a second power diode Ds2 connected in reverse parallel thereto; the DC capacitor Cs is connected in parallel to the series branch where the first semiconductor unit and the second semiconductor unit are located; the first output terminal X1 is connected to the junction of the first semiconductor unit and the second semiconductor unit, and the second output terminal X2 is connected to the junction of the second semiconductor unit and the DC capacitor Cs; the first output terminal X1 of the first sub-module is connected to the second output terminal X2 of the second sub-module to realize the cascade of the first sub-module and the second sub-module.

[0069] One end of the first charging power source is connected to the end where the DC capacitor Cs of the second submodule in the auxiliary control unit is connected to the first semiconductor unit; the other end of the first charging power source is connected to the end where the DC capacitor Cs of the first submodule in the auxiliary control unit is connected to the second turn-off semiconductor. Figure 3 In the figure, the lower submodule is the first submodule, and the upper submodule is the second submodule.

[0070] The short-circuit simulation branch includes: a controllable switch S1 and a second current limiting inductor L2 connected in series; the short-circuit simulation branch is connected in parallel with the first charging power supply, for example but not limited to, one end of the controllable switch S1 is connected to the connection point between the first current limiting inductor L1 and the first charging power supply, and the other end is connected to the second current limiting inductor L2, and the other end of the second current limiting inductor L2 is connected to the connection point between the auxiliary control unit and the first charging power supply.

[0071] The first output terminal Y1 and the second output terminal Y2 of the test power module are connected to both ends of the short-circuit simulation branch, for example but not limited to, the first output terminal Y1 is connected to the terminal where the first current limiting inductor L1 is connected to the short-circuit simulation branch; the second output terminal Y2 is connected to the terminal where the second current limiting inductor L2 in the short-circuit simulation branch is connected to the auxiliary control unit.

[0072] In a preferred but non-limiting embodiment of the present invention, the controllable switch S1 adopts an electronic switch, which can be closed and turned on after receiving a trigger command. For example, but not limited to, the electronic switch adopts a fully controlled power device, or the controllable switch S1 adopts a thyristor, the cathode of the thyristor is connected to the second current limiting reactor L2, and the anode of the thyristor is connected to the first current limiting reactor L1; or, the controllable switch S1 adopts a mechanical switch, which can be closed and turned on after receiving a trigger command.

[0073] As a prominent substantive feature of the present invention and one of the significant advances in the prior art, a second current limiting reactor L2 with a set inductance value can be used to adjust the current rise rate of the diode in the test power module to simulate the fault condition more accurately. The rise rate is expressed by the following formula:

[0074]

[0075] Where:

[0076] R D Indicates the current rise rate of the diode in the test power module.

[0077] Uset1 and Uset2 represent the first voltage setting value and the second voltage setting value respectively.

[0078] L2 represents the inductance value of the second current limiting inductor.

[0079] The second charging power supply includes: a second DC power supply U2, a second current limiting resistor R2 and a second charging control switch K2 connected in series, and both ends of the second charging power supply are connected to both ends of the energy storage capacitor C1 of the test power module. For example but not limited to, the positive polarity end of the second DC power supply U2 is connected to the second current limiting resistor R2 and then output through the second charging control switch K2; the output end of the second charging control switch K2 of the second charging power supply and the negative polarity output end of the second DC power supply U2 of the second charging power supply are respectively connected to both ends of the energy storage capacitor C1 of the test power module to be tested.

[0080] In another embodiment, the wiring method is that the positive output terminal and the negative output terminal of the second charging power source are respectively connected to the first output terminal Y1 and the second output terminal Y2 of the test power module.

[0081] It should be noted that in this embodiment, IGBT devices are used as switching devices to realize the switching function. In practical applications, it is not limited to IGBT devices. Fully controlled devices such as triodes and field effect transistors can be applied to the technical solution provided by the present invention. The semiconductor switching unit is defined to include a fully controlled device and a power diode connected in reverse parallel thereto, wherein the positive electrode of the fully controlled device corresponds to the collector in the IGBT device, the collector in the triode, and the drain in the field effect transistor, and the negative electrode of the fully controlled device corresponds to the emitter in the IGBT device, the emitter in the triode, and the source in the field effect transistor.

[0082] Based on the above circuit structure, embodiment 2 of the present invention further provides a test method for a converter valve module test circuit, comprising the following steps:

[0083] Step 1: Use a first charging power source to charge the auxiliary control unit and monitor the voltage across the auxiliary control unit.

[0084] Preferably but not limitatively, in step 1, the first charging control switch K1 of the first charging power source is closed, and the N cascaded submodules of the auxiliary control unit are charged through the first DC power source U1.

[0085] Step 2: After the voltage across the auxiliary control unit reaches the first voltage setting value Uset1, the second charging power supply charges the test power module and monitors the voltage of the test power module until it reaches the second voltage setting value Uset2, wherein the first voltage setting value Uset1 is greater than the second voltage setting value Uset2, and is used to equivalently simulate the overvoltage condition of the test power module.

[0086] Preferably but not restrictively, in step 2, after the voltage sum of the N cascaded sub-modules of the auxiliary control unit reaches the first voltage setting value Uset1, the second charging control switch K2 of the second charging power supply is closed, and the test power module is charged to the second voltage setting value Uset2 through the second DC power supply U2.

[0087] As a prominent substantive feature of the present invention and one of the significant advances brought to the prior art, the voltage at the start of the turn-off characteristic test of the diode of the test power module can be controlled by adjusting the second voltage setting value Uset2.

[0088] Step 3: After the test power module reaches the second voltage setting value Uset2, the auxiliary control unit is controlled to inject a test current into the test power module until the test current increases to the current setting value Is.

[0089] Preferably but not restrictively, in step 3, the second charging control switch K2 of the second charging power source is disconnected, triggering the first fully-controlled device Ts1 in the first semiconductor unit of each submodule of the auxiliary control unit to turn on, and the current in the test power module will gradually increase.

[0090] As a prominent substantive feature of the present invention and one of the significant advances in the prior art, the current rising rate of the diode in the test power module can be adjusted by controlling the voltage difference (Uset1-Uset2) between the first voltage setting value Uset1 and the second voltage setting value Uset2, and the rising rate is expressed by the following formula:

[0091]

[0092] Where:

[0093] R D Indicates the current rise rate of the diode in the test power module.

[0094] Uset1 and Uset2 represent the first voltage setting value and the second voltage setting value respectively.

[0095] L2 represents the inductance value of the second current limiting inductor.

[0096] Step 4: After the current value in the test power module reaches the current setting value Is after time t1, the short-circuit simulation branch shunts the current in the test power module, and the auxiliary control unit charges the test power module through the first semiconductor unit Ts1. The current flowing through the diode of the test power module will decrease from the set value and reversely recover, which is used to simulate the working condition of the converter valve arrester breakdown.

[0097] Preferably but not restrictively, in step 4, after the current value in the test power module reaches the current setting value Is after time t1, the controllable switch S1 of the short-circuit simulation branch is triggered, and the current of the short-circuit simulation branch begins to increase according to the designed change rate, and the short-circuit branch will divert the current flowing into the test power module.

[0098] As a prominent essential feature of the present invention and one of the significant advances brought to the prior art, the starting value of the fault current shunting of the test power module can be controlled by controlling the trigger time t1.

[0099] Step 5, lock the auxiliary control unit and the short-circuit simulation branch, the current in the short-circuit simulation branch decays, and the diode of the test power module is turned off at a set current change rate under high voltage.

[0100] Preferably but not restrictively, in step 5, the trigger pulse of the first fully-controlled device Ts1 in the auxiliary control unit and the controllable switch S1 of the short-circuit simulation branch are locked; the current in the short-circuit simulation branch decays to verify whether the diode of the test power module is turned off at a set current change rate under high voltage.

[0101] During the above steps, the effectiveness of the design of the converter valve arrester branch reactor parameters is evaluated and the tolerance of the converter valve power components under fault conditions is verified, including the safety of the reverse recovery of the diode of the converter valve power module under high voltage and high current.

[0102] The above embodiments are only for illustrating the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. A converter valve power module overcurrent test system, characterized in that: include: A first charging power source, an auxiliary control unit, a first current limiting reactor, a short-circuit simulation branch, a second charging power source and a test product power module; The first charging power source is connected to the auxiliary control unit and is used to charge the auxiliary control unit; One end of the first current limiting reactor L1 is connected to the auxiliary control unit, and the other end is connected to the short-circuit simulation branch; The auxiliary control unit is connected to the test power module and is used to inject a test current into the test power module; The short-circuit simulation branch is connected to the test power module and is used to shunt the current flowing into the test power module during the test; The second charging power source is connected to the test power module and is used to charge the test power module.

2. The converter valve power module overcurrent test system according to claim 1, characterized in that: The test power module is a full-bridge power module, including: a first turn-off semiconductor T1, a second turn-off semiconductor T2, a third turn-off semiconductor T3, a fourth turn-off semiconductor T4, a storage capacitor C1, a first output terminal Y1, a second output terminal Y2 and a bypass switch K; The first turn-off semiconductor T1 and the second turn-off semiconductor T2 are connected in series in the same direction, the third turn-off semiconductor T3 and the fourth turn-off semiconductor T4 are connected in series in the same direction, and the above two series branches are connected in parallel. The first to fourth turn-off semiconductors are respectively connected with the first to fourth anti-parallel freewheeling diodes, one end of the energy storage capacitor C1 is connected to the connection point of the first turn-off semiconductor T1 and the third turn-off semiconductor T3, and the other end is connected to the connection point of the second turn-off semiconductor T2 and the fourth turn-off semiconductor T4; the first output terminal Y1 is connected to the connection point of the first turn-off semiconductor T1 and the second turn-off semiconductor T2, and the second output terminal Y2 is connected to the connection point of the third turn-off semiconductor T3 and the fourth turn-off semiconductor T4; the two ends of the bypass switch are respectively connected to the first output terminal Y1 and the second output terminal Y2.

3. The converter valve power module overcurrent test system according to claim 1, characterized in that: The test power module is a half-bridge power module, comprising: a first turn-off semiconductor T1, a second turn-off semiconductor T2, a storage capacitor C1, a first output terminal Y1, a second output terminal Y2 and a bypass switch K; The first turn-off semiconductor T1 and the second turn-off semiconductor T2 are connected in series in the same direction, the first turn-off semiconductor T1 is connected with a first anti-parallel freewheeling diode D1, and the second turn-off semiconductor T2 is connected with a second anti-parallel freewheeling diode D2; the energy storage capacitor C1 is connected in parallel with the series branch formed by the first turn-off semiconductor T1 and the second turn-off semiconductor T2; the first output terminal Y1 and the second output terminal Y2 are respectively connected to the two ends of the second turn-off semiconductor T2, wherein the first output terminal Y1 is connected to the junction of the first turn-off semiconductor T1 and the second turn-off semiconductor T2; the two ends of the bypass switch K are respectively connected to the first output terminal Y1 and the second output terminal Y2.

4. The converter valve power module overcurrent test system according to claim 1, characterized in that: The first charging power source includes: a first DC power source U1, a first current limiting resistor R1 and a first charging control switch K1 connected in series.

5. The converter valve power module overcurrent test system according to claim 1, characterized in that: The auxiliary control unit includes N cascaded submodules, where N≥2, and the submodules include: a first semiconductor unit, a second semiconductor unit, a DC capacitor Cs, a first output terminal X1, and a second output terminal X2; The first semiconductor unit and the second semiconductor unit are connected in series in the same direction, and the DC capacitor Cs is connected in parallel with the series branch where the first semiconductor unit and the second semiconductor unit are located; the first output terminal X1 is connected to the connection point between the first semiconductor unit and the second semiconductor unit, and the second output terminal X2 is connected to the connection point between the second semiconductor unit and the DC capacitor.

6. The converter valve power module overcurrent test system according to claim 5, characterized in that: One end of the first charging power source is connected to the junction of the DC capacitor Cs of the Nth submodule in the auxiliary control unit and the first semiconductor unit; the other end of the first charging power source is connected to the junction of the DC capacitor Cs of the 1st submodule in the auxiliary control unit and the second semiconductor unit.

7. The converter valve power module overcurrent test system according to claim 5, characterized in that: The first semiconductor unit adopts a fully controlled power device and a first power diode connected in reverse parallel thereto; The second semiconductor unit adopts a diode device or a fully controlled power device.

8. A converter valve power module overcurrent test system according to any one of claims 1 to 5, characterized in that: The short-circuit simulation branch includes: a controllable switch S1 and a second current-limiting inductor L2 connected in series; the first output terminal Y1 and the second output terminal Y2 of the test power module are connected to both ends of the short-circuit simulation branch.

9. The converter valve power module overcurrent test system according to claim 8, characterized in that: The controllable switch S1 is an electronic switch or a mechanical switch, which can be closed and turned on after receiving a trigger command.

10. A converter valve power module overcurrent test system according to any one of claims 1 to 5, characterized in that: The second charging power source comprises: a second DC power source U2, a second current limiting resistor R2 and a second charging control switch K2 connected in series; Two ends of the second charging power source are connected to two ends of the energy storage capacitor C1 of the test power module.

11. A converter valve power module overcurrent test system according to any one of claims 1 to 5, characterized in that: The positive polarity output terminal and the negative polarity output terminal of the second charging power source are respectively connected to the first output terminal Y1 and the second output terminal Y2 of the converter valve power module.

12. A converter valve power module overcurrent test method, based on a converter valve power module overcurrent test system according to any one of claims 1 to 11, characterized in that: The following steps are involved: Step 1: Use a first charging power source to charge the auxiliary control unit and monitor the voltage across the auxiliary control unit; Step 2: After the voltage across the auxiliary control unit reaches the first voltage setting value Uset1, the second charging power source charges the test power module and monitors the voltage of the test power module until it reaches the second voltage setting value Uset2, wherein the first voltage setting value Uset1 is greater than the second voltage setting value Uset2; Step 3, after the test power module reaches the second voltage setting value Uset2, control the auxiliary control unit to inject a test current into the test power module until the test current increases to the current setting value Is; Step 4: after the current value in the power module of the test product reaches the current setting value Is after time t1, the short-circuit simulation branch is used to shunt the current in the power module of the test product; Step 5, lock the auxiliary control unit and the short-circuit simulation branch, the current in the short-circuit simulation branch decays, and the diode of the test power module is turned off at a set current change rate under high voltage.

13. A converter valve power module overcurrent test method according to claim 12, characterized in that: In step 3, the voltage difference between the first voltage setting value Uset1 and the second voltage setting value Uset2 is controlled to adjust the current rising rate of the diode in the test power module, which is expressed by the following formula: Where: R D Indicates the current rise rate of the diode in the test power module. Uset1 and Uset2 represent the first voltage setting value and the second voltage setting value respectively. L2 represents the inductance value of the second current limiting inductor.

14. A converter valve power module overcurrent test method according to claim 12, characterized in that: In step 4, the starting value of the fault current shunting of the test power module can be controlled by controlling the trigger time t1.

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