Converter valve power module overvoltage breakdown test system and test method

Abstract

The invention discloses an overvoltage breakdown test system and method for a converter valve power module, and belongs to the technical field of direct current transmission, and the system comprises an auxiliary control unit and a capacitor energy storage unit which are connected in series, and a series branch where the auxiliary control unit and the capacitor energy storage unit are located is connected in parallel with a follow current branch. The two parallel ends are respectively connected to one end of the current limiting branch and the negative polarity end of the first charging power supply, and the other end of the current limiting branch is connected to the positive polarity end of the first charging power supply; the positive polarity end of the first charging power supply is further connected to a first output terminal Y1 of the sample power module through the change-over switch Ks, and the negative polarity end of the first charging power supply is further connected to a second output terminal Y2 of the sample power module. The device can be used for realizing overvoltage breakdown of the converter valve power module and surge short-circuit discharge of the capacitor, verifying the anti-explosion capability of the converter valve power module, and providing a verification means for the anti-explosion design of the power module.

Description

Technical Field

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

[0002] Modular Multilevel Converter (MMC) is a widely used converter in flexible DC transmission systems. Each bridge arm of the modular multilevel converter uses multiple power modules in series. Each power module is equipped with a bypass switch. When an internal component failure occurs in the power module, a bypass switch closing command will be issued to shut down the faulty power module through the bypass switch. However, when the bypass switch fails, such as the bypass switch refuses to operate, the voltage of the faulty module will further increase, affecting the safety of the converter valve.

[0003] In order to ensure the safety of the power module, one design scheme is to design bypass thyristors in parallel at both ends of the bypass switch of the power module. When the bypass switch of the power module fails to operate and the voltage of the power module increases, the power module is bypassed by overvoltage breakdown of the bypass thyristor. To avoid malfunction of the bypass thyristor, its breakdown voltage is usually set higher, close to the nominal voltage of the power device. The breakdown of the bypass thyristor at a higher voltage may cause surge discharge of the power capacitor and explosion of the power module. When designing the structure of the power module of the converter valve, it should be ensured that the structure of the power module can withstand the impact of capacitor surge discharge at high voltage.

[0004] The voltage level of the converter valve 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 power module after the converter valve overvoltage breakdown under the condition of bypass switch refusal to operate. Therefore, it is of great significance to build an overvoltage breakdown test circuit based on the converter valve module to simulate the overvoltage breakdown and short-circuit condition under a specific charging current during the operation of the converter valve power module, realize the overvoltage breakdown of the power module and the surge short-circuit discharge of the capacitor, verify the explosion-proof ability of the converter valve power module, and provide a verification method for the explosion-proof design of the power module. Summary of the invention

[0005] The purpose of the present invention is to provide a converter valve power module overvoltage breakdown test system and test method, which can be used to simulate the overvoltage breakdown short-circuit condition under a specific charging current during the operation of the converter valve power module, and realize the power module overvoltage breakdown and capacitor surge short-circuit discharge.

[0006] In order to achieve the above object, the solution of the present invention is:

[0007] A first aspect of the present invention provides a converter valve power module overvoltage breakdown test system, comprising: a first charging power supply, an auxiliary control unit, a capacitor energy storage unit, a freewheeling branch, a current limiting branch, a switching switch Ks and a test power module; the auxiliary control unit is connected in series with the capacitor energy storage unit, and the series branch where the auxiliary control unit and the capacitor energy storage unit are located is connected in parallel with the freewheeling branch, and the two ends after parallel connection are respectively connected to one end of the current limiting branch and the negative polarity end of the first charging power supply, and the other end of the current limiting branch is connected to the positive polarity end of the first charging power supply; the positive polarity end of the first charging power supply is also connected to the first output terminal Y1 of the test power module via the switching switch Ks, and the negative polarity end of the first charging power supply is also connected to the second output terminal Y2 of the test power module.

[0008] 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 and a second output terminal Y2, a bypass switch K and a bypass thyristor SCR;

[0009] 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 freewheeling diodes connected in anti-parallel. 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 K are respectively connected to the first output terminal Y1 and the second output terminal Y2; the bypass thyristor SCR is connected in parallel to the two ends of the bypass switch K.

[0010] 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 and a second output terminal Y2, a bypass switch K and a bypass thyristor SCR;

[0011] 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 where the first turn-off semiconductor T1 and the second turn-off semiconductor T2 are located; the first output terminal Y1 and the second output terminal Y2 are connected to the two ends of the second turn-off semiconductor T2 respectively, 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 connected to the first output terminal Y1 and the second output terminal Y2 respectively; the bypass thyristor SCR is connected in parallel with the two ends of the bypass switch K.

[0012] Preferably, the first charging power source comprises: a control switch K1, a charging resistor R1 and a DC power source U1 connected in series in sequence;

[0013] One end of the control switch K1 is connected to one end of the switching switch Ks as the positive polarity end of the first charging power source, and then connected to the first output terminal Y1 of the test converter valve power module through the other end of the switching switch Ks.

[0014] Preferably, the current limiting branch comprises: a current limiting reactance L and a current limiting resistor R connected in series;

[0015] The other end of the current limiting resistor R is connected to the connection point between the switch Ks and the first charging power source, and the other end of the current limiting reactor L is connected to the auxiliary control unit.

[0016] Preferably, the auxiliary control unit comprises a controllable switch, the controllable switch is a mechanical switch, or an electronic switch connected in parallel with a diode, the electronic switch is an IGBT power device or a thyristor device.

[0017] Preferably, the auxiliary control unit uses a fully controlled power device IGBT connected in parallel with a diode;

[0018] The collector of the IGBT is connected to the cathode of the diode, and the emitter of the IGBT is connected to the anode of the diode; the IGBT can be turned on after receiving a trigger command; the collector of the IGBT is connected to the capacitor energy storage unit, and the emitter of the IGBT is also connected to one end of the current limiting branch.

[0019] Preferably, the capacitor energy storage unit comprises: a capacitor branch and a discharge branch connected in parallel;

[0020] The positive polarity end of the capacitor branch voltage is connected to the auxiliary control unit, and the negative polarity end is connected to the negative polarity end of the first charging power source.

[0021] Preferably, the capacitor branch adopts a single capacitor or multiple capacitors, and in the case of multiple capacitors, the capacitor branch is formed by connecting in series, in parallel, in series first and then in parallel, or in parallel first and then in series;

[0022] The discharge branch includes a discharge switch Kc and a discharge resistor Rc connected in series.

[0023] Preferably, the freewheeling branch adopts a diode, the cathode end of the diode is connected to the connection point between the auxiliary control unit and the current limiting branch, and the anode end is connected to the negative polarity end of the first charging power supply; or

[0024] The freewheeling branch adopts a plurality of diodes connected in series, in parallel, in series first and then in parallel, or in parallel first and then in series.

[0025] Preferably, the switch Ks is a mechanical switch, and a current sensor is configured at a connection section between the switch Ks and the first output terminal Y1 of the test power module.

[0026] A second aspect of the present invention provides a converter valve power module overvoltage breakdown test method, based on the converter valve power module overvoltage breakdown test system, comprising the following steps:

[0027] Step 1: close the switch Ks, start the first charging power supply, and use the first charging power supply to charge the test power module;

[0028] Step 2: When the voltage of the energy storage capacitor C1 of the power module to be tested reaches the first voltage setting value Uset1, the switch Ks is switched off to stop charging the power module to be tested;

[0029] Step 3, using the first charging power supply to charge the capacitor energy storage unit to a second voltage setting value Uset2, the second voltage setting value Uset2 being higher than the first voltage setting value Uset1, and turning off the first charging power supply;

[0030] Step 4, close the switching switch Ks, and the capacitor energy storage unit injects current into the test power module, causing the energy storage capacitor C1 of the test power module to undergo surge discharge breakdown, test the explosion-proof capability of the converter valve power module, and verify the safety of the converter valve during operation.

[0031] Preferably, in step 3, the second voltage setting value Uset2 is adjusted to control the current value flowing into the test power module when the test power module breaks down due to overvoltage.

[0032] Preferably, the values ​​of the current-limiting reactance L and the current-limiting resistor R of the current-limiting branch are adjusted to regulate the magnitude and rising rate of the current flowing into the diode in the test product converter valve power module.

[0033] Compared with the prior art, the present invention has the following advantages after adopting the above scheme:

[0034] (1) The overvoltage breakdown test circuit constructed by the present invention can simulate the actual overvoltage breakdown short-circuit condition of the power module under a specific charging current during the operation of the converter valve power module, thereby realizing the overvoltage breakdown of the power module and the surge short-circuit discharge of the capacitor;

[0035] (2) The circuit of the present invention is simple, and only one power supply is required for the entire test, which can conveniently control the charging of the converter valve power module and the test voltage. The test method is practical, safe and reliable, and can test the explosion-proof capability of the converter valve power module and verify the safety of the converter valve during operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is an electrical structure diagram of the converter valve full-bridge module targeted by the present invention;

[0037] Figure 2 is an electrical structure diagram of a converter valve half-bridge module targeted by the present invention;

[0038] Figure 3 The present invention is a schematic diagram of an overvoltage breakdown test system for a converter valve power module. DETAILED DESCRIPTION

[0039] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0040] The present invention provides a converter valve power module overvoltage breakdown test system and test method, which simulate the overvoltage breakdown short-circuit condition under a specific charging current during the operation of the converter valve power module, realize the overvoltage breakdown of the power module and the surge short-circuit discharge of the capacitor, verify the explosion-proof capability of the converter valve power module, and provide a verification means for the explosion-proof design of the power module.

[0041] Embodiment 1 of the present invention provides a converter valve power module overvoltage breakdown test system, including: a first charging power supply, an auxiliary control unit, a capacitor energy storage unit, a current limiting branch, a freewheeling branch, a switch Ks and a test power module. Figure 3 FIG. 1 is a circuit schematic diagram of an overvoltage breakdown test system for a converter valve power module according to the present invention.

[0042] The auxiliary control unit is connected in series with the capacitor energy storage unit, and the series branch where the auxiliary control unit and the capacitor energy storage unit are located is connected in parallel with the freewheeling branch, and the two ends after parallel connection are respectively connected to one end of the current limiting branch and the negative polarity end of the first charging power supply, and the other end of the current limiting branch is connected to the positive polarity end of the first charging power supply; the positive polarity end of the first charging power supply is also connected to the first output terminal Y1 of the test power module through the switching switch Ks, and the negative polarity end of the first charging power supply is also connected to the second output terminal Y2 of the test power module.

[0043] The converter valve is a modular multi-level converter valve, which is composed of a plurality of cascaded power modules, and the power module can be a full-bridge power module or a half-bridge power module. As one of the outstanding substantive features of the present invention and the significant progress brought to the prior art, the test power module in the converter valve power module overvoltage breakdown test system and test method provided by the present invention can be a full-bridge power module or a half-bridge power module; at the same time, it can be applied to the test of power modules equipped with bypass thyristors and the test of power modules not equipped with bypass thyristors, and has a wide range of applications.

[0044] Specifically, 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 and a second output terminal Y2, a bypass switch K and a bypass thyristor SCR.

[0045] 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 1 The 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 K are respectively connected to the first output terminal Y1 and the second output terminal Y2 of the converter valve module; the bypass thyristor SCR is connected in parallel to the two ends of the bypass switch K.

[0046] 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 and a second output terminal Y2, a bypass switch K and a bypass thyristor SCR.

[0047] 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 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 where the first turn-off semiconductor T1 and the second turn-off semiconductor T2 are located; 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 of the converter valve module; the bypass thyristor SCR is connected in parallel to the two ends of the bypass switch K.

[0048] Wherein, the first charging power supply is used to charge the test power module and the capacitor energy storage unit.

[0049] Preferably, but not restrictively, the first charging power source includes: a DC power source U1, a charging resistor R1, and a control switch K1 connected in series; wherein the control switch K1 is used to control the opening and closing of the first charging power source; for example, but not limited to, the control switch K1, the charging resistor R1, and the DC power source U1 are connected in series in sequence, and one end of the control switch K1 is connected to one end of the switching switch Ks as the positive polarity end of the first charging power source, and then connected to the first output terminal Y1 of the test converter valve power module through the other end of the switching switch Ks. Thus, the charging control of the test power module is realized by the opening and closing of the switching switch Ks.

[0050] The current limiting branch is used to adjust the magnitude and rising rate of the diode current value injected by the capacitor energy storage unit into the test product power module.

[0051] Preferably, but not limited to, the current limiting branch includes: a current limiting reactance L and a current limiting resistor R connected in series. For example, but not limited to, the connection point between the control switch K1 of the first charging power source and the switching switch Ks is simultaneously connected to one end of the current limiting resistor R, and the other end of the current limiting reactance L is connected to the auxiliary control unit.

[0052] As a prominent substantive feature of the present invention and one of the significant advances brought to the prior art, the magnitude and rising rate of the current value flowing into the diode in the test product converter valve power module are adjusted by adjusting the values ​​of the current limiting reactance L and the current limiting resistor R of the current limiting branch. For example, but not limited to, the current limiting reactance L and the current limiting resistor R of the current limiting branch are adjusted before the test, and then the test is started, and different current limiting reactance L and current limiting resistor R parameter values ​​are set according to different test requirements.

[0053] The auxiliary control unit includes a controllable switch for switching the capacitor energy storage unit to inject current into the test power module, thereby causing the bypass thyristor of the test power module to break down or the capacitor surge discharge breakdown of the test power module to occur.

[0054] Preferably, but not restrictively, the controllable switch adopts a mechanical switch, or an electronic switch connected in parallel with a diode, which can be closed and turned on after receiving a trigger command; further, the electronic switch adopts an IGBT power device or a thyristor device; preferably, but not limited to, the auxiliary control unit adopts a fully controlled power device IGBT connected in parallel with a diode; the IGBT collector is connected to the cathode of the diode, and the IGBT emitter is connected to the anode of the diode; the IGBT can be turned on after receiving a trigger command; the collector of the auxiliary control unit IGBT is connected to the capacitor energy storage unit, and the IGBT emitter is also connected to one end of the current limiting branch, for example but not limited to, connected to the current limiting reactance L of the current limiting branch.

[0055] The capacitor energy storage unit is used to inject current into the test power module after charging.

[0056] Preferably but not restrictively, the capacitor energy storage unit comprises: a capacitor branch and a discharge branch connected in parallel; the positive polarity end of the capacitor branch voltage is connected to the auxiliary control unit, and the negative polarity end is connected to the negative polarity end of the first charging power supply. The capacitor branch can adopt a single capacitor or multiple capacitors. Further, the capacitor branch can be formed in series, parallel, series first and then parallel, or parallel first and then series; the discharge branch comprises: a discharge switch Kc and a discharge resistor Rc connected in series. After the discharge switch Kc is closed, the capacitor branch and the discharge branch form a loop for discharging the remaining energy in the capacitor after the test.

[0057] like Figure 3 As shown, in an exemplary but non-limiting embodiment, two capacitors are connected in series and then another two capacitors connected in series are connected in parallel to form a capacitor branch, the positive polarity end of the capacitor branch is connected to one end of the discharge switch Kc, and the negative polarity end is connected to the discharge resistor Rc.

[0058] The freewheeling branch is used to provide a freewheeling current flow path for the inductor L in the current limiting branch after the controllable switch of the auxiliary control unit is turned off.

[0059] Preferably, but not restrictively, the freewheeling branch adopts a diode, the cathode end of the diode is connected to the connection point between the auxiliary control unit and the current limiting branch, and the anode end is connected to the negative polarity end of the first charging power supply. Furthermore, the freewheeling branch can also adopt a method of connecting multiple diodes in series, in parallel, in series first and then in parallel, or in parallel first and then in series.

[0060] The switching switch Ks is used to control the input and output of the test power module in the converter valve power module overvoltage breakdown test system by opening and closing the switch.

[0061] Preferably, but not restrictively, the switching switch Ks is a mechanical switch, which can be closed and turned on after receiving a trigger command. Furthermore, a current sensor is configured in the wiring section between the switching switch Ks and the first output terminal Y1 of the test converter valve power module. When the current sensor detects that the current exceeds the set value, the auxiliary control unit is turned off, and the capacitor energy storage unit stops injecting current into the test power module.

[0062] Based on the converter valve power module overvoltage breakdown test system of embodiment 1, embodiment 2 of the present invention provides a converter valve power module overvoltage breakdown test method, including the following steps:

[0063] Step 1: close the switching switch Ks, start the first charging power supply, and use the first charging power supply to charge the test power module.

[0064] Preferably but not restrictively, in step 1, the control switch K1 for charging the first charging power source is closed, the switching switch Ks is closed, and the test power module is charged through the DC power source U1. It is worth noting that, as one of the outstanding essential features of the present invention, if the auxiliary control unit is implemented in a structure in which a controllable switch and a diode are connected in parallel, during the period when the first charging power source is charging the test power module, the controllable switch of the auxiliary control unit is not triggered to turn on, and the diode connected in parallel with the controllable switch can flow the current that charges the capacitor energy storage unit.

[0065] Step 2: When the voltage of the energy storage capacitor C1 of the power module to be tested reaches the first voltage setting value Uset1, the switch Ks is switched off to stop charging the power module to be tested.

[0066] Step 3: Use the first charging power source to charge the capacitor energy storage unit to a second voltage setting value Uset2, where the second voltage setting value Uset2 is higher than the first voltage setting value Uset1, and turn off the first charging power source.

[0067] Preferably but not limitedly, in step 3, the discharge switch Kc is opened to trigger the auxiliary control unit to charge the capacitor in the capacitor branch through the DC power supply U1, for example but not limited to, Figure 3 As shown, a total of four capacitors, which are first connected in series and then in parallel, are charged until a second voltage setting value Uset2 higher than the first voltage setting value Uset1 is reached, and then the first charging power supply charging control switch K1 is disconnected to turn off the first charging power supply.

[0068] As one of the outstanding substantive features of the present invention and a significant improvement over the prior art, when the first voltage setting value Uset1 is fixed, by adjusting the value of the second voltage setting value Uset2 in step 3, the current value flowing into the test power module when the test converter valve power module is over-voltage-broken can be controlled. Furthermore, the magnitude and rising rate of the current value flowing into the diode in the test converter valve power module can be adjusted by adjusting the values ​​of the current limiting reactance L and the current limiting resistor R of the current limiting branch. For example, but not limited to, before the test, the parameters of the current limiting reactance L and the current limiting resistor R of the current limiting branch are adjusted, and then the test is started, and different parameter values ​​of the current limiting reactance L and the current limiting resistor R are set according to different test requirements.

[0069] Step 4, close the switching switch Ks, and the capacitor energy storage unit injects current into the test power module, causing the energy storage capacitor C1 of the test power module to undergo surge discharge breakdown, test the explosion-proof capability of the converter valve power module, and verify the safety of the converter valve during operation.

[0070] Preferably but not restrictively, in step 4, the surge discharge breakdown condition of the energy storage capacitor C1 of the test power module is triggered, including: the surge discharge breakdown condition of the energy storage capacitor C1 when the full-bridge power module or the half-bridge power module is equipped with a bypass thyristor, or the surge discharge breakdown condition of the energy storage capacitor C1 when the full-bridge power module or the half-bridge power module is not equipped with a bypass thyristor.

[0071] Among them, the situation that the full-bridge power module or half-bridge power module is equipped with a bypass thyristor specifically includes: triggering the conduction auxiliary control unit, the current in the test converter valve power module will gradually increase; when the charging voltage exceeds the breakdown voltage value of the bypass thyristor of the test power module (such as 4.4kV), it will cause the bypass thyristor of the test power module to break down. After the bypass thyristor of the power module breaks down, the anti-parallel diode of the first turn-off semiconductor of the power module fails, and the capacitor undergoes surge discharge.

[0072] It can be understood that the switching switch Ks can be closed and then the control unit can be turned on, or the auxiliary unit can be triggered and then the switching switch Ks can be closed.

[0073] It is worth noting that when the charging voltage exceeds the breakdown voltage of the thyristor of the test power module, the thyristor of the test power module will be broken down, and the diode of the test power module will reversely recover under high charging, resulting in device failure. The capacitor of the test power module will form a direct short-circuit discharge loop through the failed diode and thyristor. Therefore, the test method provided by the present invention can be used to achieve overvoltage breakdown of the converter valve power module and surge short-circuit discharge of the capacitor, verify the explosion-proof ability of the converter valve power module, and provide a verification method for the explosion-proof design of the power module.

[0074] Among them, the situation where the full-bridge power module or half-bridge power module is not equipped with a bypass thyristor specifically includes: after the auxiliary control unit is triggered, when the charging voltage exceeds the breakdown voltage value of the test power module (such as 4.4kV), the second turn-off semiconductor of the power module is triggered, causing the capacitor surge discharge breakdown of the test power module.

[0075] When the test system detects that the detection current of the current sensor configured between the switching switch Ks and the first output terminal Y1 of the test valve power module exceeds the set value, the auxiliary control unit is turned off, and the capacitor energy storage unit stops injecting current into the test power module. Alternatively, when the test power module detects that the voltage is lower than the set threshold value, the auxiliary control unit is turned off, and the capacitor energy storage unit stops injecting current into the test power module. It can be understood that as long as one of the detection current exceeding the set value or the voltage being lower than the set threshold value is met, the auxiliary control unit is turned off, and the capacitor energy storage unit stops injecting current into the test power module.

[0076] The switch Kc of the discharge branch in the capacitor energy storage unit is closed to discharge the remaining energy in the capacitor.

[0077] 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 overvoltage breakdown test system, characterized in that: include: A first charging power source, an auxiliary control unit, a capacitor energy storage unit, a freewheeling branch, a current limiting branch, a switching switch Ks and a test power module; The auxiliary control unit is connected in series with the capacitor energy storage unit, and the series branch where the auxiliary control unit and the capacitor energy storage unit are located is connected in parallel with the freewheeling branch, and the two ends after parallel connection are respectively connected to one end of the current limiting branch and the negative polarity end of the first charging power supply, and the other end of the current limiting branch is connected to the positive polarity end of the first charging power supply; the positive polarity end of the first charging power supply is also connected to the first output terminal Y1 of the test power module through the switching switch Ks, and the negative polarity end of the first charging power supply is also connected to the second output terminal Y2 of the test power module.

2. The converter valve power module overvoltage breakdown 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 and a second output terminal Y2, a bypass switch K and a bypass thyristor SCR; 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 freewheeling diodes connected in anti-parallel. 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 K are respectively connected to the first output terminal Y1 and the second output terminal Y2; the bypass thyristor SCR is connected in parallel to the two ends of the bypass switch K.

3. The converter valve power module overvoltage breakdown 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 and a second output terminal Y2, a bypass switch K and a bypass thyristor SCR; 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 where the first turn-off semiconductor T1 and the second turn-off semiconductor T2 are located; the first output terminal Y1 and the second output terminal Y2 are connected to the two ends of the second turn-off semiconductor T2 respectively, 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 connected to the first output terminal Y1 and the second output terminal Y2 respectively; the bypass thyristor SCR is connected in parallel with the two ends of the bypass switch K.

4. The converter valve power module overvoltage breakdown test system according to claim 1, characterized in that: The first charging power supply includes: a control switch K1, a charging resistor R1 and a DC power supply U1 connected in series in sequence; One end of the control switch K1 is connected to one end of the switching switch Ks as the positive polarity end of the first charging power source, and then connected to the first output terminal Y1 of the test converter valve power module through the other end of the switching switch Ks.

5. The converter valve power module overvoltage breakdown test system according to claim 1, characterized in that: The current limiting branch includes: a current limiting reactance L and a current limiting resistor R connected in series; The other end of the current limiting resistor R is connected to the connection point between the switch Ks and the first charging power source, and the other end of the current limiting reactor L is connected to the auxiliary control unit.

6. A converter valve power module overvoltage breakdown test system according to any one of claims 1 to 5, characterized in that: The auxiliary control unit comprises a controllable switch, which adopts a mechanical switch or an electronic switch connected in parallel with a diode, and the electronic switch adopts an IGBT power device or a thyristor device.

7. The converter valve power module overvoltage breakdown test system according to claim 6, characterized in that: The auxiliary control unit uses a fully controlled power device IGBT in parallel with a diode; The collector of the IGBT is connected to the cathode of the diode, and the emitter of the IGBT is connected to the anode of the diode; the IGBT can be turned on after receiving a trigger command; the collector of the IGBT is connected to the capacitor energy storage unit, and the emitter of the IGBT is also connected to one end of the current limiting branch.

8. A converter valve power module overvoltage breakdown test system according to any one of claims 1 to 5, characterized in that: The capacitor energy storage unit comprises: a capacitor branch and a discharge branch connected in parallel; The positive polarity end of the capacitor branch voltage is connected to the auxiliary control unit, and the negative polarity end is connected to the negative polarity end of the first charging power source.

9. The converter valve power module overvoltage breakdown test system according to claim 8, characterized in that: The capacitor branch adopts a single capacitor or multiple capacitors. In the case of multiple capacitors, the capacitor branch is formed by series connection, parallel connection, series connection first and then parallel connection, or parallel connection first and then series connection. The discharge branch includes a discharge switch Kc and a discharge resistor Rc connected in series.

10. A converter valve power module overvoltage breakdown test system according to any one of claims 1 to 5, characterized in that: The freewheeling branch adopts a diode, the cathode end of the diode is connected to the connection point between the auxiliary control unit and the current limiting branch, and the anode end is connected to the negative polarity end of the first charging power supply; or The freewheeling branch adopts a plurality of diodes connected in series, in parallel, in series first and then in parallel, or in parallel first and then in series.

11. A converter valve power module overvoltage breakdown test system according to any one of claims 1 to 5, characterized in that: The switch Ks is a mechanical switch, and a current sensor is configured at a connection section between the switch Ks and the first output terminal Y1 of the test power module.

12. A converter valve power module overvoltage breakdown test method, based on the converter valve power module overvoltage breakdown test system according to any one of claims 1 to 11, characterized in that: The following steps are involved: Step 1: close the switch Ks, start the first charging power supply, and use the first charging power supply to charge the test power module; Step 2: When the voltage of the energy storage capacitor C1 of the power module to be tested reaches the first voltage setting value Uset1, the switch Ks is switched off to stop charging the power module to be tested; Step 3, using the first charging power supply to charge the capacitor energy storage unit to a second voltage setting value Uset2, the second voltage setting value Uset2 being higher than the first voltage setting value Uset1, and turning off the first charging power supply; Step 4, close the switching switch Ks, and the capacitor energy storage unit injects current into the test power module, causing the energy storage capacitor C1 of the test power module to undergo surge discharge breakdown, test the explosion-proof capability of the converter valve power module, and verify the safety of the converter valve during operation.

13. A converter valve power module overvoltage breakdown test method according to claim 12, characterized in that: In step 3, the second voltage setting value Uset2 is adjusted to control the current value flowing into the test power module when the test power module breaks down due to overvoltage.

14. A converter valve power module overvoltage breakdown test method according to claim 12 or 13, characterized in that: The value of the current limiting reactance L and the current limiting resistor R of the current limiting branch is adjusted to regulate the magnitude and rising rate of the current flowing into the diode in the test converter valve power module.

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