Grounding device with inductive arc suppression function and hitching operation method

Abstract

The invention discloses a series resonance type grounding device with an induced electric arc extinguishing function and a hitching operation method. The series resonance type grounding device is composed of a series resonance circuit, an overvoltage protection circuit, a capacitor bypass circuit and a direct grounding circuit. The series resonance branch consists of a main branch current-limiting inductor L and a capacitor C which are connected in series; the overvoltage protection circuit enables the capacitor to be bypassed when the voltage at the two ends of the capacitor is overvoltage; a control signal is accessed to the control end of the capacitor bypass circuit, the capacitor bypass circuit is controlled to be conducted at a set moment, and current is transferred to the capacitor bypass circuit; the direct grounding circuit is independently composed of a high-speed switch, and the high-speed switch is closed along with the gradual attenuation of the current in the grounding device to a safety range so as to complete the hooking operation of the grounding device of the whole outage line. According to the invention, overvoltage protection is realized, the safety of the device is enhanced, overheating protection is carried out, energy stored in the capacitor is further released and branch current is attenuated by adopting the inductor and the resistor of the damping device, and the purpose of arc prevention during hooking of the grounding device is better achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a grounding device and method with an induced arc suppression function. Background Art

[0002] With the rapid growth of my country's power load, a large number of 220kV and above grid reinforcement projects have been steadily implemented, and the phenomenon of overhead line crossing has become more prominent. The lines are generally in a high-load operation state, resulting in the traditional adjacent live line accompanying shutdown scheme no longer being applicable when the single-circuit line is shut down for maintenance. During the process of closing the grounding knife switch when the single-circuit line is shut down, the grounding knife switch may fail. At this time, the grounding wire must be manually hung to ensure that the line is effectively grounded. Due to the close arrangement of overhead lines, the operating lines generate induced voltage or induced current on the shut-down lines through electrostatic and electromagnetic coupling. When the grounding wire is manually hung, a large instantaneous arc will be generated at the wire end clamp, causing equipment damage and seriously threatening the personal safety of the operators. Therefore, how to effectively suppress the instantaneous arc of the hook is of great significance to ensuring the safety of the staff and reducing the risk of equipment damage. At the same time, it puts forward higher technical requirements for the equipment, time, angle, etc. of the operators to install the grounding wire.

[0003] The patent with the authorization announcement number CN113224739B discloses a current limiting device for the moment when the synchronous phase condenser grounding wire is grounded, including a signal acquisition module, a current limiting module, a grounding module, and a control module, wherein the current limiting module is mainly composed of an inductor and a capacitor circuit, and can be divided into an instantaneous hook-up state, a transition state, and a normal grounding state according to the working conditions. The instantaneous hook-up state is a resonant circuit composed of an inductor and a capacitor to the power frequency; the transition state is when the capacitor is in an overvoltage state, the arrester is instantly turned on to form an inductive current limiting circuit; the normal grounding state is to switch to a direct grounding state. However, it requires a control module to control the circuit breaker, includes two mutual inductors in parallel, has high requirements on the frequency stability of the current, does not consider the long-term high current conduction of the lightning arrester, and may have the risk of overheating. It uses a single thyristor as a controllable switch unit. Under the conditions of large current and heavy frequency, it may not be able to shut down within the characteristic time. It uses two mutual inductors in parallel, that is, a double-split inductor structure. Compared with ordinary inductors, it has a higher manufacturing cost and a more complex structure, poor operating reliability, difficult maintenance and increased device cost. Summary of the invention

[0004] In order to solve the deficiencies in the prior art and effectively deal with the grounding safety problem caused by induced arc in the out-of-service lines, the present invention proposes a grounding device and method with induced arc suppression function.

[0005] The present invention adopts the following technical solution.

[0006] The first aspect of the present invention provides a series resonant grounding device with an induction arc extinguishing function, which is composed of a series resonant branch, an overvoltage protection branch, a capacitor bypass branch, and a direct grounding branch; One end of the series resonant grounding device is grounded, and the other end is connected to the out-of-service line; The series resonant branch and the direct grounding branch are connected in parallel between the hanging end of the series resonant grounding device hanging the out-of-service line and the grounding body. The series resonant branch has a current limiting inductor. L and capacitor C The direct grounding branch is connected to the hanging end and the grounding body through a fast switch; The overvoltage protection branch and the capacitor bypass branch are connected in parallel to the capacitor C at both ends; The overvoltage protection branch is used to bypass the capacitor when the voltage across the capacitor is overvoltage, thereby suppressing the instantaneous overvoltage generated when the device is connected; The capacitor bypass branch is a controllable branch, and the conduction of the branch is controlled by the control terminal to transfer the conduction current to the overvoltage protection branch and the series resonant branch; The direct grounding branch is composed solely of fast switches.

[0007] Preferably, the overvoltage protection branch is composed of a metal oxide arrester. When the device is connected to the outage line, the capacitor C The voltage value at both ends is equal to the induced voltage value of the line at the connection position. C The voltage at both ends is greater than the starting voltage threshold of the lightning arrester, and the overvoltage protection circuit is turned on.

[0008] Preferably, the starting voltage threshold of the metal oxide arrester is selected to be 1.1 times the capacitance C Rated voltage value.

[0009] Preferably, in the series resonant branch, the inductance value of the current-limiting inductor is set to 2 mH, the capacitance value of the capacitor C is set to 5 mF, and the rated voltage is set to 12 kV.

[0010] Preferably, the capacitor bypass branch is composed of an anti-parallel thyristor valve group, a damping device inductor L b and the resistance of the damping device r b The branch where the anti-parallel thyristor valve group is located is connected to the capacitor C in parallel.

[0011] Preferably, in the capacitor bypass branch, the rated voltage of the anti-parallel thyristor valve group is selected to be 12kV; the inductance of the damping device L b Set to 0.2mH; Damping device resistancer b Set to 40Ω.

[0012] Preferably, the series resonant grounding device is connected to the out-of-service line. t At time 0, the fast switch in the direct grounding branch is in the open state, and the capacitor bypass branch is in the off state.

[0013] Preferably, the series resonant grounding device is connected to the out-of-service line. C When the voltage at both ends is greater than the overvoltage protection branch start voltage threshold, At this moment, the overvoltage protection branch starts, where: .

[0014] Preferably, the series resonant grounding device is connected to the out-of-service line. The capacitor bypass circuit is always controlled to be turned on, where: .

[0015] Preferably, the current flowing through the current limiting inductor is detected in real time L When the current value is less than 1A, the overvoltage protection branch is controlled to be shut down, and the fast switch is closed at the same time to complete the grounding operation of the shutdown line.

[0016] The second aspect of the present invention provides a method for grounding a shut-down line using the series resonant grounding device of the first aspect of the present invention, the method comprising the following steps: Step 1: Adjust the fast switch and capacitor bypass branch in the direct grounding branch of the series resonant grounding device to the disconnected state, and then connect them to the out-of-service line through the connecting point; Step 2: When the capacitor in the device C When the instantaneous overvoltage at both ends is higher than the starting voltage threshold of the overvoltage protection branch, the overvoltage protection branch starts. After the overvoltage protection branch starts for a set time, step 3 is entered; Step 3: Control the capacitor bypass circuit to conduct and detect the current flowing through the current limiting inductor in real time L The current value; Step 4: When the current flows through the current limiting inductor L When the current value drops to a safe current range, the capacitor bypass switch is turned off and the fast switch in the direct grounding branch is closed at the same time, and the grounding hanging operation is completed.

[0017] Preferably, in step 1, the current flowing through the current limiting inductor is detected in real time. L When the current value flows through the current limiting inductor L When the current value is not greater than the safe current range within the set time, the fast switch in the direct grounding branch is directly closed, and the grounding hook operation is completed. The beneficial effect of the present invention is that, compared with the prior art, 1. The present invention mainly breaks the series resonance state by bypassing the capacitor, so that the large inductance acts on the branch circuit, and no external control system is required. The device has a simple structure, is easy to implement, and is convenient to operate. The device has a moderate size and good portability, and the device cost is appropriate and economical. 2. The present invention is provided with an overvoltage protection branch circuit, which utilizes the low resistance characteristic of the metal oxide arrester under overvoltage state to bypass the capacitor bank, limit the voltage at both ends of the capacitor bank, realize overvoltage protection, enhance the safety of the device, and extend the service life of the grounding device; 3. A capacitor bypass circuit is provided to prevent the arrester of the overvoltage protection branch from being turned on for a long time, resulting in excessive energy accumulation and overheating risk. An anti-parallel thyristor valve group is used, which has low voltage and loss during normal operation; it can be quickly closed when the reverse voltage exceeds its withstand voltage; the inductance and resistance of the damping device are used to further release the energy stored in the capacitor, attenuate the branch current, and better achieve the purpose of arc protection when the grounding device is hung. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a topological structure diagram of the device of the present invention; Figure 2 This is the action timing diagram of the main components of the device of the present invention; Figure 3 This is a schematic diagram of the circuit state during the operation of the device of the present invention; Figure 4 It is a circuit principle diagram of the device of the present invention in the series resonance state; Figure 5 It is a circuit principle diagram of the device of the present invention in the current transfer state; Figure 6 The figure is a flow chart of the hooking operation method of the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only embodiments of a part of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0020] Embodiment 1 of the present invention provides a series resonant grounding device with an induction arc extinguishing function, such as Figure 1 As shown, it consists of a series resonant circuit, an overvoltage protection circuit, a capacitor bypass circuit and a direct grounding circuit; specifically: One end of the series resonant grounding device is grounded, and the other end is connected to the out-of-service line; The series resonant branch and the direct grounding branch are connected in parallel between the hanging end of the series resonant grounding device hanging the out-of-service line and the grounding body. The series resonant branch has a current limiting inductor. L and capacitor C The direct grounding branch is connected to the hook terminal and the grounding body through a fast switch; the current limiting inductor L Used to suppress the instantaneous large current caused by the induction electricity of the outage line during the hook-up operation. C Used to store energy; The overvoltage protection branch and the capacitor bypass branch are connected in parallel to the capacitor C at both ends; The overvoltage protection branch is used to bypass the capacitor when the voltage across the capacitor is over-voltage, suppressing the instantaneous overvoltage generated when the device is connected; the overvoltage protection circuit is used to bypass the capacitor when the voltage across the capacitor is over-voltage, suppressing the instantaneous overvoltage generated when the device is connected, preventing the capacitor from C Overvoltage damage; The capacitor bypass branch is a controllable branch, which is controlled by the control end to transfer the conduction current to the overvoltage protection branch and the series resonant branch. The control end of the capacitor bypass circuit is connected to the control signal, and the capacitor bypass circuit is turned on and off within the set time. t 2, it is controlled to be turned on. When it is turned on, if the overvoltage protection circuit has been turned on due to overvoltage, the current in the overvoltage protection circuit is transferred to the capacitor bypass circuit to avoid the overvoltage protection circuit being turned on for a long time and causing the danger of overheating; if the voltage condition at both ends of the capacitor has not reached the overvoltage protection circuit opening condition before, the current flows directly from the capacitor bypass circuit to bypass the capacitor; The direct grounding branch is composed solely of fast switches.

[0021] Preferably, the overvoltage protection circuit is composed of a metal oxide arrester (MOV). When the device is connected to the outage line, the capacitor C The voltage value at both ends is equal to the induced voltage value of the line at the connection position. C The voltage at both ends is greater than the starting voltage threshold of the lightning arrester, and the overvoltage protection circuit is turned on.

[0022] It should be noted that Figure 3 The schematic diagram of the circuit state of the device during the operation of the present invention is shown in Figure 1. The working modes of the grounding device are mainly divided into the resonant working mode and the current limiting working mode. In the instantaneous hook-up state, the device is in the resonant working mode, and the circuit is mainly composed of capacitors. C , Current-limiting inductor L And the equivalent resistance of the circuit in the device R 0 composition.

[0023] Figure 4This is the circuit schematic diagram of the device in the series resonance state. According to Kirchhoff's voltage law: , in, is the current flowing through the current limiting inductor L, is the device input voltage, is the equivalent resistance of the circuit in the device; At this time, the current limiting inductor L With capacitor C In resonance state, when L and C The value meets Capacitance C The voltage at both ends increases. When it reaches the starting voltage of the MOV connected in parallel, the series resonance state is broken and the device enters the overvoltage protection state briefly. The MOV dissipates part of the voltage. C Stored energy.

[0024] Preferably, the capacitor bypass circuit is composed of an anti-parallel thyristor valve group, a damping device inductor L b and the resistance of the damping device r b The anti-parallel thyristor valve group is used to limit the rate of change of the instantaneous grounding current and suppress the arc. The anti-parallel thyristor valve group is also used to transfer the current flowing through the arrester MOV to prevent the MOV from overheating and damage. The damping device resistor r b Used to reduce the ground current peak, damping device inductance L b Used to consume the energy stored in the capacitor and limit the discharge current.

[0025] Preferably, the starting voltage threshold of the metal oxide arrester is selected to be 1.1 times the capacitance C Rated voltage value.

[0026] Preferably, in the series resonant branch, the inductance value of the current-limiting inductor is set to 2 mH, the capacitance value of the capacitor C is set to 5 mF, and the rated voltage is set to 12 kV.

[0027] Preferably, the capacitor bypass branch is composed of an anti-parallel thyristor valve group, a damping device inductor L b and the resistance of the damping device r b The branch where the anti-parallel thyristor valve group is located is connected to the capacitor C in parallel.

[0028] Preferably, in the capacitor bypass branch, the rated voltage of the anti-parallel thyristor valve group is selected to be 12kV; the inductance of the damping deviceL b Set to 0.2mH; Damping device resistance r b Set to 40Ω.

[0029] Preferably, the series resonant grounding device is connected to the out-of-service line. t At time 0, the fast switch in the direct grounding branch is in the open state, and the capacitor bypass branch is in the off state.

[0030] Preferably, the series resonant grounding device is connected to the out-of-service line. C When the voltage at both ends is greater than the overvoltage protection branch start voltage threshold, At this moment, the overvoltage protection branch starts and the protection branch action ends. .

[0031] Preferably, the series resonant grounding device is connected to the out-of-service line. The capacitor bypass circuit is always controlled to be turned on, where: .

[0032] Specifically, this embodiment t 2 is set to 3ms.

[0033] It should be noted that t At time 2, a pulse trigger signal is applied to the anti-parallel thyristor valve group to transfer the current to the capacitor bypass branch. Figure 5 The circuit schematic diagram is shown in the current transfer state. The device enters the current limiting working mode, and the circuit is equivalent to a current limiting inductor. L , Equivalent resistance of the circuit in the device R 0. Inductance of damping device L b and damping device resistance r b The circuit is composed of. According to the circuit theorem: , Current limiting inductor L Inductance of damping device L b This effectively limits the current, but slows down the discharge speed. R 0 and damping device resistance r b It can effectively absorb the energy stored in the capacitor and accelerate the current decay.

[0034] Real-time detection of current flowing through the current limiting inductor L When the current value is less than 1A, the overvoltage protection branch is controlled to be shut down, and the fast switch is closed at the same time to complete the grounding operation of the shutdown line.

[0035] like Figure 6 As shown, embodiment 2 of the present invention provides a method for grounding and hanging an out-of-service line of the series resonant grounding device of embodiment 1 of the present invention, and the method comprises the following steps: Step 1: Adjust the fast switch and capacitor bypass branch in the direct grounding branch of the series resonant grounding device to the disconnected state, and then connect them to the out-of-service line through the connecting point; Step 2: If the instantaneous overvoltage across the capacitor C in the device is higher than the starting voltage threshold of the overvoltage protection branch, the overvoltage protection branch is started, and then the process goes to step 3; if the instantaneous overvoltage across the capacitor C in the device is higher than the starting voltage threshold of the overvoltage protection branch, the process goes directly to step 3; Step 3: Control the capacitor bypass circuit to be turned on, and detect the current value flowing through the current limiting inductor L in real time; Step 4: When the current value flowing through the current limiting inductor L drops to a safe current range, the capacitor bypass switch is turned off and the fast switch in the direct grounding branch is closed at the same time, and the grounding hooking operation is completed.

[0036] Preferably, in step 1, the current value flowing through the current limiting inductor L is detected in real time. When the current value flowing through the current limiting inductor L is not greater than the safe current range within the set time, the fast switch in the direct grounding branch is directly closed, and the grounding hooking operation is completed.

[0037] The beneficial effect of the present invention is that, compared with the prior art, 1. The present invention mainly breaks the series resonance state by bypassing the capacitor, so that the large inductance acts on the branch circuit, and no external control system is required. The device has a simple structure, is easy to implement, and is convenient to operate. The device has a moderate size and good portability, and the device cost is appropriate and economical. 2. The present invention is provided with an overvoltage protection branch circuit, which utilizes the low resistance characteristic of the metal oxide arrester under overvoltage state to bypass the capacitor bank, limit the voltage at both ends of the capacitor bank, realize overvoltage protection, enhance the safety of the device, and extend the service life of the grounding device; 3. A capacitor bypass circuit is provided to prevent the arrester of the overvoltage protection branch from being turned on for a long time, which may lead to excessive energy accumulation and overheating. An anti-parallel thyristor valve group is used, which has low voltage and loss during normal operation; it can be quickly closed when the reverse voltage exceeds its withstand voltage; the inductance and resistance of the damping device are used to further release the energy stored in the capacitor and attenuate the branch current, so as to achieve the purpose of arc protection when the grounding device is connected.

[0038] The present disclosure may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0039] A computer-readable storage medium may be a tangible device that can hold and store instructions used by an instruction execution device. A computer-readable storage medium may be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the above. More specific examples (a non-exhaustive list) of computer-readable storage media include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disk read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which instructions are stored, and any suitable combination of the above. The computer-readable storage medium used herein is not to be interpreted as a transient signal itself, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through a wire.

[0040] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, optical fiber transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in the computer-readable storage medium in each computing / processing device.

[0041] The computer program instructions for performing the operations of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages, such as Smalltalk, C++, etc., and conventional procedural programming languages, such as "C" language or similar programming languages. The computer-readable program instructions may be executed entirely on the user's computer, partially on the user's computer, as a separate software package, partially on the user's computer, partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., using an Internet service provider to connect through the Internet). In some embodiments, by using the state information of the computer-readable program instructions to personalize an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), the electronic circuit may execute the computer-readable program instructions, thereby implementing various aspects of the present disclosure.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A series resonant grounding device with an induction arc extinguishing function, comprising a series resonant branch, an overvoltage protection branch, a capacitor bypass branch and a direct grounding branch; characterized in that: One end of the series resonant grounding device is grounded, and the other end is connected to the out-of-service line; The series resonant branch and the direct grounding branch are connected in parallel between the hanging end of the series resonant grounding device hanging the out-of-service line and the grounding body. The series resonant branch has a current limiting inductor. L and capacitor C The direct grounding branch is connected to the hanging end and the grounding body through a fast switch; The overvoltage protection branch and the capacitor bypass branch are connected in parallel to the capacitor C at both ends; The overvoltage protection branch is used to bypass the capacitor when the voltage across the capacitor is overvoltage, thereby suppressing the instantaneous overvoltage generated when the device is connected; The capacitor bypass branch is a controllable branch, and the conduction of the branch is controlled by the control terminal to transfer the conduction current to the overvoltage protection branch and the series resonant branch; The direct grounding branch is composed solely of fast switches.

2. A series resonant grounding device with an induction arc extinguishing function according to claim 1, characterized in that: The overvoltage protection branch is composed of a metal oxide arrester. When the device is connected to the outage line, the capacitor C The voltage value at both ends is equal to the induced voltage value of the line at the connection position. C The voltage at both ends is greater than the starting voltage threshold of the lightning arrester, and the overvoltage protection circuit is turned on.

3. A series resonant grounding device with an induction arc extinguishing function according to claim 2, characterized in that: The starting voltage threshold of the metal oxide arrester is selected as 1.1 times the capacitance C Rated voltage value.

4. A series resonant grounding device with an induction arc extinguishing function according to claim 3, characterized in that: In the series resonant branch, the inductance value of the current-limiting inductor is set to 2mH, the capacitance value of the capacitor C is set to 5mF, and the rated voltage is set to 12kV.

5. A series resonant grounding device with an induction arc extinguishing function according to claim 1, characterized in that: The capacitor bypass branch is composed of an anti-parallel thyristor valve group, a damping device inductor, L b and the resistance of the damping device r b The branch where the anti-parallel thyristor valve group is located is connected to the capacitor C in parallel.

6. A series resonant grounding device with an induction arc extinguishing function according to claim 1, characterized in that: In the capacitor bypass branch, the rated voltage of the anti-parallel thyristor valve group is selected to be 12kV; the inductance of the damping device L b Set to 0.2mH; Damping device resistance r b Set to 40Ω.

7. A series resonant grounding device with an induction arc extinguishing function according to any one of claims 1 to 6, characterized in that: Connect the series resonant grounding device to the out-of-service line. t At time 0, the fast switch in the direct grounding branch is in the open state, and the capacitor bypass branch is in the off state.

8. A series resonant grounding device with an induction arc extinguishing function according to claim 7, characterized in that: After the series resonant grounding device is connected to the out-of-service line, if the series branch capacitor C When the voltage at both ends is greater than the overvoltage protection branch start voltage threshold, At this moment, the overvoltage protection branch starts, where: .

9. A series resonant grounding device with an induction arc extinguishing function according to claim 8, characterized in that: After the series resonant grounding device is connected to the out-of-service line, The capacitor bypass circuit is always controlled to be turned on, where: .

10. A series resonant grounding device with an induction arc extinguishing function according to claim 9, characterized in that: Real-time detection of current flowing through the current limiting inductor L When the current value is less than 1A, the overvoltage protection branch is controlled to be shut down, and the fast switch is closed at the same time to complete the grounding operation of the shutdown line.

11. A method for grounding a shut-down line using the series resonant grounding device according to any one of claims 1 to 10, characterized in that: The method comprises the following steps: Step 1: Adjust the fast switch and capacitor bypass branch in the direct grounding branch of the series resonant grounding device to the disconnected state, and then connect them to the out-of-service line through the connecting point; Step 2: When the capacitor in the device C When the instantaneous overvoltage at both ends is higher than the starting voltage threshold of the overvoltage protection branch, the overvoltage protection branch starts. After the overvoltage protection branch starts for a set time, step 3 is entered; Step 3: Control the capacitor bypass circuit to conduct and detect the current flowing through the current limiting inductor in real time L The current value; Step 4: When the current flows through the current limiting inductor L When the current value drops to a safe current range, the capacitor bypass switch is turned off and the fast switch in the direct grounding branch is closed at the same time, and the grounding hanging operation is completed.

12. The method for grounding and hanging a shutdown line according to claim 11, characterized in that: In step 1, the current flowing through the current limiting inductor is detected in real time. L When the current value flows through the current limiting inductor L When the current value is not greater than the safe current range within the set time, the fast switch in the direct grounding branch is directly closed and the grounding hanging operation is completed.

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