Converter valve power module bypass switch operation refusal fault overvoltage bypass device and converter valve power module bypass switch operation refusal fault overvoltage bypass method

Abstract

The invention relates to the technical field of flexible direct-current power transmission, and provides a converter valve power module bypass switch refusal operation fault overvoltage bypass device and method.The converter valve power module bypass switch refusal operation fault overvoltage bypass device comprises a sampling unit, a voltage stabilizing unit, a linear opening unit and a gate capacitor, and the sampling unit is used for obtaining voltage between a collector electrode and a gate electrode of a lower tube IGBT of a converter valve power module; the voltage stabilizing unit is used for being arranged between a collector electrode and a gate electrode of a lower tube IGBT, and the gate electrode capacitor is used for being arranged between the gate electrode and an emitting electrode of the lower tube IGBT and used for stabilizing voltage when a bypass switch of the converter valve power module refuses to operate and the voltage detected by the sampling unit is larger than a first voltage set threshold value. The gate capacitor is charged by the converter valve power module capacitor through the voltage stabilizing unit so as to boost the gate voltage of the lower tube IGBT; and the linear opening unit is used for limiting the gate voltage of the lower tube IGBT when the gate capacitor is charged, so that the lower tube IGBT is opened and enters a linear region, and further the lower tube IGBT of the converter valve power module is subjected to linear thermal failure short circuit to realize breakdown.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible direct current transmission, and in particular to an overvoltage bypass device and method for a bypass switch refusal to operate fault of a converter valve power module. Background Art

[0002] In long-distance, large-capacity HVDC transmission systems, flexible DC converter valves are often used to control DC current and voltage to achieve efficient transmission and stable control of power. Figure 1 As shown, each bridge arm of the flexible converter valve usually includes multiple power modules connected in series, and a bypass switch connected in parallel with the power module is provided at the port of each power module. When a power module fails, the faulty power module can be cut off by closing the corresponding bypass switch, without affecting the normal operation of the flexible direct current converter valve. However, in actual use, when a power module fails, the corresponding bypass switch may fail to operate, resulting in the failure of the power module to exit operation. At this time, the faulty power module is charged, causing the capacitor voltage in the power module to continue to increase, and there is a risk of overvoltage out of control. At this time, the entire high-voltage direct current transmission system needs to be tripped and shut down for maintenance to eliminate the fault.

[0003] In order to improve the reliability of the flexible DC converter valve and avoid the system shutdown caused by the failure of the bypass switch, the existing technology often connects a turning thyristor in parallel at the power module port. When the bypass switch fails to operate and the capacitor voltage in the faulty power module rises to a certain level, the thyristor is broken down by the overvoltage, thus removing the faulty power module. However, using this solution requires additional thyristors for each power module, which is expensive and increases costs. Figure 1 As can be seen, the power module terminals are connected to the C and E terminals of the lower transistor. Therefore, in the prior art, the lower transistor in the power module is broken down to remove the faulty power module without damaging other electronic components in the power module. During operation, different clamping voltages are configured for the upper and lower transistors in the power module. When the clamping circuit is activated, gate current is injected to simultaneously turn on the upper and lower transistors, forming a direct conduction, discharging the power module voltage and bypassing the faulty power module. However, in actual use, when no gate current is injected, the gate voltage is uncontrollable, resulting in an uncontrollable operating state of the lower transistor. If the upper and lower transistors enter the saturation region after turning on, the faulty power module can only be removed by direct conduction damage of the upper and lower transistors. At the same time, when the driver connected to the lower transistor is energized, the driver will control the gate voltage to -10V, turning off the lower transistor. At this time, injecting gate current through the clamping circuit cannot raise the gate voltage, and the lower transistor cannot enter the linear region. Therefore, other auxiliary methods are required to achieve breakdown, which is relatively complicated. Summary of the Invention

[0004] The purpose of the present invention is to provide a device and method for overvoltage bypass of a bypass switch failure of a converter valve power module, so as to solve the problem that the existing scheme for breaking down the lower tube of the power module is complicated to operate and cannot ensure that the upper tube is intact.

[0005] In order to solve the above technical problems, the present invention provides a bypass device for overvoltage in case of failure of bypass switch of converter valve power module to operate, which includes a sampling unit, a voltage stabilizing unit, a linear opening unit and a gate capacitor. The sampling unit is used to obtain the voltage between the collector and gate of the IGBT under the converter valve power module. The voltage stabilizing unit is used to be arranged between the collector and gate of the IGBT under the converter valve power module. The gate capacitor is used to be arranged between the gate and emitter of the IGBT under the converter valve power module. The bypass switch of the converter valve power module fails to operate and the voltage detected by the sampling unit is detected. When the voltage is greater than the first voltage setting threshold, the gate capacitor is charged by the capacitor of the converter valve power module through the voltage stabilizing unit to increase the gate voltage of the IGBT of the lower tube of the converter valve power module; the linear turn-on unit is used to limit the gate voltage of the lower tube IGBT when the gate capacitor is charged, so that the IGBT of the lower tube of the converter valve power module is turned on and enters the linear region, thereby causing the IGBT of the lower tube of the converter valve power module to short-circuit due to linear thermal failure and achieve breakdown. The first voltage setting threshold is greater than the highest level conventional overvoltage protection setting value of the power module and less than the nominal collector-emitter voltage of the IGBT tube.

[0006] Furthermore, it also includes a control unit and a gate drive unit. The control unit realizes switching between the gate drive unit and the linear opening unit and the gate of the IGBT under the converter valve power module through a switching switch. The control unit is used to connect the gate drive unit to the gate of the IGBT under the converter valve power module through the switching switch when the converter valve power module is normal, so that the gate drive unit realizes normal driving of the converter valve power module; and is used to connect the linear opening unit to the gate of the IGBT under the converter valve power module through the switching switch when the bypass switch of the converter valve power module refuses to operate and the voltage detected by the sampling unit is greater than the second voltage setting threshold, and the second voltage setting threshold is less than the first voltage setting threshold.

[0007] Furthermore, the voltage stabilizing unit includes n voltage stabilizing tubes connected in series, each voltage stabilizing tube is connected in parallel with a voltage balancing resistor, and n is determined by the withstand voltage level of the voltage stabilizing tube and the voltage level of the converter valve power module.

[0008] Furthermore, the sampling unit collects voltage from any balancing resistor and calculates the voltage between the collector and gate of the lower IGBT of the converter valve power module according to the number n of stabilizing tubes in the voltage stabilizing unit, the resistance value of the balancing resistor and the collected voltage.

[0009] Furthermore, the gate drive unit includes an IGBT conduction branch and an IGBT turn-off branch arranged in parallel, and each branch is provided with a corresponding control switch.

[0010] Furthermore, the linear turn-on unit includes a Zener diode and a resistor connected in parallel, and the withstand voltage of the Zener diode is determined by the gate voltage when the lower IGBT of the converter valve power module is turned on and enters the linear region.

[0011] A method for bypassing overvoltage in the event of a bypass switch failure in a converter valve power module. When the bypass switch in the converter valve power module fails to operate, the voltage between the collector and emitter of an IGBT on the lower tube of the converter valve power module is detected. When the voltage is greater than a set voltage value, the capacitor in the converter valve power module is charged to a gate capacitor arranged between the gate and emitter of the IGBT on the lower tube of the converter valve power module to raise the gate voltage. The gate voltage is then controlled to turn on the IGBT on the lower tube of the converter valve power module and enter a linear region, thereby causing the IGBT on the lower tube of the converter valve power module to short-circuit due to thermal failure, thereby achieving breakdown.

[0012] Furthermore, the capacitor of the converter valve power module charges the gate capacitor through the voltage stabilizing unit.

[0013] Furthermore, the method controls the gate voltage by a linear turn-on unit arranged between the gate and emitter of the IGBT of the lower tube of the converter valve power module, wherein the linear turn-on unit includes a Zener diode and a resistor connected in parallel, and the gate voltage of the IGBT of the lower tube of the converter valve power module is controlled by the Zener diode of the linear turn-on unit.

[0014] The beneficial effects of the present invention are as follows: As an improved invention, the present invention connects a voltage regulator module between the gate and collector of the lower IGBT of the power module, and disposes a gate capacitor and a linear turn-on unit between the gate and emitter. When the bypass switch of the converter valve power module fails to operate and the voltage detected by the sampling unit is greater than a first voltage setting threshold, the capacitor of the converter valve power module charges the gate capacitor through the voltage regulator unit to increase the gate voltage of the lower IGBT. At the same time, the linear turn-on unit limits the gate voltage of the lower IGBT during the charging of the gate capacitor, causing the lower IGBT to turn on and enter the linear region, thereby causing the lower IGBT to short-circuit due to thermal failure, achieving breakdown, and removing the faulty power module while avoiding damage to the upper IGBT. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a topological diagram of a flexible direct current converter valve in the prior art; Figure 2 This is a schematic diagram of the converter valve power module fault overvoltage bypass device of the present invention; Figure 3 This is a flow chart of the converter valve power module fault overvoltage bypass method of the present invention; Figure 4 This is a waveform diagram of the real-time effect of the solution of the present invention. DETAILED DESCRIPTION

[0016] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0017] The present invention charges the gate capacitor to raise the gate voltage when the power module capacitance exceeds the set voltage threshold. At the same time, the linear turn-on unit is used to limit the gate voltage, so that the lower tube IGBT is turned on and enters the linear region, thereby causing the lower tube IGBT to short-circuit due to linear thermal failure and achieve breakdown.

[0018] Implementation method of overvoltage bypass device for bypass switch refusal to operate fault of converter valve power module The present invention discloses an overvoltage bypass device for a bypass switch failure of a converter valve power module. While ensuring that the upper tube of the converter valve power module is not damaged, the lower tube is broken down when the bypass switch fails to operate, thereby removing the faulty power module. Figure 1 The figure shows the topological structure of a flexible DC converter valve, which consists of six bridge arms, each of which is composed of a power module and a bridge arm reactor in series. The power module includes an upper IGBT T1 and a lower IGBT T2, which are connected in anti-series connection, with a capacitor C connected in parallel between the two IGBTs. The collector, gate, and emitter of the upper IGBT T1 are connected to their corresponding drivers, while the collector, gate, and emitter of the lower IGBT are connected to the overvoltage bypass device proposed in this invention. When the power module is functioning properly, the lower IGBT T2 is driven by the overvoltage bypass device. If the power module fails and the bypass switch fails to operate, the overvoltage bypass device breaks down the lower IGBT T2, thereby disconnecting the power module.

[0019] like Figure 2As shown, the overvoltage bypass device includes a sampling unit, a voltage stabilizing unit, a linear turn-on unit, and a gate capacitor. The sampling unit is used to obtain the voltage between the collector and gate of the lower IGBT T2 of the converter valve power module. The voltage stabilizing unit is provided between the collector and gate of the lower IGBT T2 of the converter valve power module. The gate capacitor is provided between the gate and emitter of the lower IGBT T2 of the converter valve power module. When the bypass switch of the converter valve power module fails to operate and the voltage of the power module capacitor detected by the sampling unit exceeds a first voltage threshold, the gate capacitor is charged from the converter valve power module capacitor via the voltage stabilizing unit to increase the gate voltage of the lower IGBT T2. The linear turn-on unit is used to limit the gate voltage of the lower IGBT T2 during gate capacitor charging, causing the lower IGBT T2 to turn on and enter the linear region, thereby causing the lower IGBT T2 to short-circuit due to thermal failure and breakdown. Among them, the first voltage setting threshold is greater than the highest level of conventional overvoltage protection setting of the power module and less than the nominal collector-emitter voltage of the IGBT tube, so as to ensure that during normal operation of the power module and conventional overvoltage fault, the overvoltage bypass will not operate to break down the lower tube IGBT T2, and the explosion energy will be controlled within a certain range to prevent the power module capacitor voltage from continuing to rise and causing a large explosion.

[0020] The voltage regulator unit includes n series-connected zener diodes, each with a voltage-equalizing resistor connected in parallel. In actual use, the voltage difference between the collector and gate of the IGBT T2 in the converter valve power module is 4200-4500V, but the maximum voltage resistance of commercially available zener diodes is around 350V. Therefore, the voltage regulator module includes multiple bidirectional zener diodes connected in series. To evenly distribute the voltage across the bidirectional zener diodes, a voltage-equalizing resistor is connected in parallel to each bidirectional zener diode to prevent uneven voltage distribution due to slight differences in the voltage distribution between the bidirectional zener diodes.

[0021] The sampling unit acquires the voltage value from the voltage regulator module to obtain the collector-gate voltage of the IGBT T2 on the bottom tube of the converter valve power module. It then adds the collector-gate voltage of the IGBT T2 on the bottom tube of the converter valve power module to the gate-emitter voltage of the IGBT T2 on the bottom tube of the converter valve power module to obtain the collector-emitter voltage of the IGBT T2 on the bottom tube of the converter valve power module. To facilitate data acquisition, the sampling unit can acquire voltage from any voltage-equalizing resistor and calculate the collector-gate voltage of the IGBT T2 on the bottom tube of the converter valve power module based on the number of Zener diodes (n) in the voltage regulator unit, the resistance of the voltage-equalizing resistor, and the acquired voltage. The collector-emitter voltage of the IGBT T2 on the bottom tube of the converter valve power module is obtained by adding the gate-emitter voltage of the IGBT T2 on the bottom tube of the converter valve power module (typically 15V) to the collector-gate voltage of the IGBT T2 on the bottom tube of the converter valve power module. In one embodiment, the sampling unit utilizes an ADC sampling unit to convert the acquired analog voltage value into a digital value for easy transmission.

[0022] The linear turn-on unit limits the gate voltage when charging the gate capacitance of the IGBT T2 on the bottom tube of the converter valve power module. The linear turn-on unit comprises a Zener diode and a resistor connected in parallel. The withstand voltage of the Zener diode is determined based on the gate voltage when the IGBT T2 on the bottom tube of the converter valve power module is turned on and enters the linear region. In one embodiment, the linear turn-on unit is used in the present invention to limit the gate voltage of the IGBT T2 on the bottom tube of the converter valve power module to below 10V. Different Zener diodes can be used depending on the model of the IGBT T2 on the bottom tube of the converter valve power module. The linear turn-on unit can be connected to the gate of the IGBT T2 on the bottom tube of the converter valve power module via a dedicated control switch to limit the gate voltage.

[0023] To ensure normal control of the converter valve power module, a gate drive unit is typically installed. This unit is connected to the gate and controls the on / off switching of the IGBT T2 on the bottom of the converter valve power module according to instructions from the control unit. The gate drive unit typically includes an IGBT on-branch and an IGBT off-branch connected in parallel, each equipped with a corresponding control switch. During operation, when the control switch on the on-branch is closed and the control switch on the off-branch is open, the gate drive unit outputs a turn-on voltage (typically +15V) to the IGBT on the bottom of the converter valve power module, turning it on. When the control switch on the on-branch is closed and the control switch on the off-branch is closed, the gate drive unit outputs a turn-on voltage (typically -10V) to the IGBT on the bottom of the converter valve power module, turning it off.

[0024] To simplify control, the linear switching unit in the present invention can also be controlled by a control unit. The control unit is connected to the sampling unit and determines whether the gate of the lower IGBT T2 is connected to the linear switching unit or the gate drive unit based on the voltage collected by the sampling unit, whether the converter valve power module is faulty, and whether the bypass switch fails to operate. The control unit uses a switching switch to switch between the gate drive unit and the linear switching unit and the gate of the lower IGBT of the converter valve power module, thereby controlling the normal operation of the lower IGBT T2 or causing it to break down, thereby disconnecting the faulty power module. Specifically, the gate switching unit utilizes a relay switch comprising a contact portion and a coil portion, the coil portion being controlled by the control unit. The gate of the lower IGBT T2 of the converter valve power module is connected to the common terminal of the gate switching unit (i.e., the switching switch). The gate drive unit is connected to the gate of the lower IGBT T2 of the converter valve power module via the normally open contact of the gate switching unit, and the linear switching unit is connected to the gate of the lower IGBT T2 of the converter valve power module via the normally closed contact of the gate switching unit. During use, when the converter valve power module is normal, the gate drive unit is connected to the gate of the IGBT T2 tube at the bottom of the converter valve power module through the switching switch, and the normal driving of the converter valve power module is achieved through the gate drive unit. When the bypass switch of the converter valve power module refuses to operate and the voltage detected by the sampling unit is greater than the second voltage setting threshold, the linear opening unit is connected to the gate of the IGBT T2 tube at the bottom of the converter valve power module through the switching switch, and the faulty converter valve power module is cut off through the voltage stabilizing module, the linear opening unit and the gate capacitor.

[0025] In actual use, because the time it takes for the bypass device to charge the gate is unpredictable, if the voltage regulator module is connected to the gate of the lower IGBT T2 after charging the gate, the gate of the lower IGBT T2 will be connected to the gate driver unit before the gate switching unit is connected to the voltage regulator module. At this time, the gate driver unit controls the lower IGBT T2 to be non-conductive via the -10V clamp voltage. Subsequently, connecting the gate of the lower IGBT T2 to the voltage regulator module will not increase the gate voltage. Therefore, the gate of the lower IGBT T2 must be connected to the voltage regulator module before the voltage regulator module charges the gate capacitor.

[0026] like Figure 3As shown, during use, when a bypass switch failure occurs in the power module, the capacitor voltage in the power module continues to rise, and the acquisition unit detects the voltage between the collector and emitter of the lower tube IGBT T2. When the control unit detects that the capacitor voltage value of the power module exceeds the capacitor overvoltage threshold (i.e., the second voltage setting threshold) Uset2, the current state of the gate switching unit is judged. If the coil of the gate switching unit is energized and the gate of the lower tube IGBT T2 is connected to the gate drive unit, the control unit controls the coil of the gate switching unit to de-energize, so that the linear turn-on unit is connected to the gate of the lower tube IGBT T2; if the gate switching unit coil is de-energized, the gate switching unit will directly connect the gate of the lower tube IGBT T2 and the linear turn-on unit. When the voltage exceeds the set voltage value (i.e., the first voltage setting threshold) Uset1, the power module capacitor charges the gate capacitor located between the gate and emitter of the lower IGBT T2, raising the gate voltage. The linear turn-on unit then controls the gate voltage below 10V, turning on the lower IGBT and entering the linear region. This causes the lower IGBT to short-circuit due to thermal failure, leading to breakdown. In one embodiment, the set voltage value Uset1 ranges from 4300-4500V, and the set voltage value Uset2 ranges from 4100-4300V. Uset2 is less than Uset1, and the minimum value of Uset2 is greater than the highest level of conventional overvoltage protection (typically around 4050V).

[0027] The technical solution provided by the present invention does not rely on the power module energy supply and the operation of the central control board, and does not change the original hardware architecture of the power module. Under the premise of not causing direct discharge of the power module, it can achieve precise breakdown of the overvoltage of the IGBT T2 on the lower tube of the power module after the bypass switch refuses to operate, thereby bypassing the power module, thereby improving the reliability of the flexible DC converter valve operation and the safety of the power module overvoltage bypass.

[0028] Implementation method for overvoltage bypass of bypass switch refusal to operate fault of converter valve power module The present invention proposes a method for bypassing overvoltage in a converter valve power module when a bypass switch fails to operate. The method is characterized in that when the bypass switch fails to operate, the voltage between the collector and emitter of the lower IGBT is detected. When the voltage exceeds a set voltage, the power module capacitor is charged to the gate capacitor located between the gate and emitter of the lower IGBT to raise the gate voltage. The gate voltage is then controlled to turn on the lower IGBT and enter the linear region, causing the lower IGBT to short-circuit due to thermal failure, thereby achieving breakdown. The voltage between the collector and emitter of the lower IGBT is detected by a sampling unit, and the gate voltage is controlled by a linear turn-on unit located between the gate and emitter of the lower IGBT.

[0029] In order to verify the effect of IGBT overvoltage breakdown on bypass power module after bypass switch refusal to operate fault, Figure 4The waveforms shown below show the effect of implementing the solution provided by the present invention, showing, from top to bottom, the bridge arm current, the voltage between the collector and emitter of the lower IGBT, and the gate voltage of the lower IGBT. It can be seen that when the voltage between the collector and emitter of the power module's lower IGBT reached 4399V, the gate voltage rose and remained below 10.16V under the control of the overvoltage bypass device. After the IGBT continued operating in the linear region for 3.7799ms, the lower IGBT experienced thermal failure and a voltage-free state. During this entire process, no through-discharge of the power module occurred, and the power module port voltage remained at 0V, effectively bypassing the faulty power module.

[0030] The specific implementation process has been described in detail in the overvoltage bypass device for the bypass switch refusal to operate fault of the converter valve power module, and will not be repeated here.

Claims

1. A converter valve power module bypass switch refusal to operate fault overvoltage bypass device, characterized in that: The device comprises a sampling unit, a voltage stabilizing unit, a linear turn-on unit, and a gate capacitor. The sampling unit is used to obtain the voltage between the collector and gate of the IGBT on the lower tube of the converter valve power module. The voltage stabilizing unit is used to be arranged between the collector and gate of the IGBT on the lower tube of the converter valve power module. The gate capacitor is used to be arranged between the gate and emitter of the IGBT on the lower tube of the converter valve power module. When the bypass switch of the converter valve power module fails to operate and the voltage detected by the sampling unit is greater than a first voltage setting threshold, the gate capacitor is charged by the capacitor of the converter valve power module through the voltage stabilizing unit to increase the gate voltage of the IGBT on the lower tube of the converter valve power module. The linear turn-on unit is used to limit the gate voltage of the IGBT on the lower tube of the converter valve power module when the gate capacitor is charged, so that the IGBT on the lower tube of the converter valve power module is turned on and enters the linear region, thereby causing the IGBT on the lower tube of the converter valve power module to short-circuit due to thermal failure and achieve breakdown. The first voltage setting threshold is greater than the highest level of conventional overvoltage protection set value of the power module and less than the nominal collector-emitter voltage of the IGBT tube.

2. The converter valve power module bypass switch refusal to operate fault overvoltage bypass device according to claim 1, characterized in that: It also includes a control unit and a gate drive unit. The control unit realizes switching between the gate drive unit and the linear opening unit and the gate of the IGBT under the converter valve power module through a switching switch. The control unit is used to connect the gate drive unit to the gate of the IGBT under the converter valve power module through the switching switch when the converter valve power module is normal, so that the gate drive unit realizes normal driving of the converter valve power module; and is used to connect the linear opening unit to the gate of the IGBT under the converter valve power module through the switching switch when the bypass switch of the converter valve power module refuses to operate and the voltage detected by the sampling unit is greater than the second voltage setting threshold, and the second voltage setting threshold is less than the first voltage setting threshold.

3. The converter valve power module bypass switch refusal to operate fault overvoltage bypass device according to claim 1, characterized in that: The voltage stabilizing unit includes n voltage stabilizing tubes connected in series, each of which is connected in parallel with a voltage balancing resistor, and n is determined by the withstand voltage rating of the voltage stabilizing tube and the voltage rating of the converter valve power module.

4. The converter valve power module bypass switch refusal to operate fault overvoltage bypass device according to claim 3, characterized in that: The sampling unit collects voltage from any grading resistor and calculates the voltage between the collector and gate of the lower tube IGBT of the converter valve power module according to the number n of stabilizing tubes in the voltage stabilizing unit, the resistance value of the grading resistor and the collected voltage.

5. The converter valve power module bypass switch refusal to operate fault overvoltage bypass device according to claim 2, characterized in that: The gate drive unit comprises an IGBT conduction branch and an IGBT shutdown branch arranged in parallel, and each branch is provided with a corresponding control switch.

6. The converter valve power module bypass switch refusal to operate fault overvoltage bypass device according to claim 1, characterized in that: The linear turn-on unit includes a voltage-stabilizing diode and a resistor connected in parallel. The withstand voltage of the voltage-stabilizing diode is determined by the gate voltage when the lower IGBT of the converter valve power module is turned on and enters the linear region.

7. A method for bypassing overvoltage caused by a bypass switch failure in a converter valve power module, characterized in that: When the bypass switch of the converter valve power module refuses to operate, the voltage between the collector and emitter of the IGBT of the converter valve power module is detected. When the voltage is greater than the set voltage value, the capacitor of the converter valve power module is charged to the gate capacitor set between the gate and emitter of the IGBT of the converter valve power module to raise the gate voltage, and the gate voltage is controlled to turn on the IGBT of the converter valve power module and enter the linear region, so that the IGBT of the converter valve power module short-circuit due to thermal failure, thereby achieving breakdown.

8. The overvoltage bypass method for a bypass switch failure failure of a converter valve power module according to claim 7, characterized in that: The capacitor of the converter valve power module charges the gate capacitor through the voltage stabilizing unit.

9. The overvoltage bypass method for a bypass switch failure failure of a converter valve power module according to claim 7, characterized in that: The method controls the gate voltage by means of a linear turn-on unit arranged between the gate and emitter of the IGBT of the lower tube of the converter valve power module. The linear turn-on unit includes a voltage-stabilizing diode and a resistor connected in parallel. The gate voltage of the IGBT of the lower tube of the converter valve power module is controlled by the voltage-stabilizing diode of the linear turn-on unit.

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