Integrated arc extinguishing system and method based on hybrid flexible arc extinguishing

Abstract

The application relates to a mixed flexible arc-extinguishing integrated arc-extinguishing system and method, which comprises a power conversion module, two groups of switching switches, an inverter power supply, an isolation transformer, an injection transformer and a switch group. The output end of the power conversion module is connected with the input ends of the two groups of switching switches. The input end of the inverter power supply is connected with the output end of the power conversion module. The input end of the isolation transformer is connected with the output end of the inverter power supply. One port of the output end of the isolation transformer is connected with the output end of one group of switching switches. The input end of the injection transformer is connected with the other port of the output end of the isolation transformer and the output end of the other group of switching switches. The output end of the injection transformer is connected with a neutral point of a power distribution network. The neutral point of the power distribution network is grounded through an arc-extinguishing coil. The switch group is arranged between the output end of the inverter power supply and the input end of the injection transformer, and the switch group is in a normally closed state. The system has the functions of fault arc-extinguishing, injection parameter measurement and neutral point control through switching of the switch.

Description

Technical Field

[0001] This invention relates to the field of relay protection technology for power systems, and in particular to an integrated arc extinguishing system and method based on hybrid flexible arc extinguishing. Background Technology

[0002] In 3-66kV medium and low voltage distribution network systems, single-phase grounding faults account for 70% of all faults and are prone to arcing grounding overvoltages. To prevent the fault from escalating, it is necessary to extinguish the arc at the fault point in a timely manner. Currently, most distribution networks use arc suppression coils to compensate for the distribution network's capacitance current to ground to achieve fault arc suppression. However, with the rapid increase in electricity demand and the continuous changes in the scale and structure of distribution networks, serious accidents such as urban cable trench fires and forest fires caused by single-phase grounding of distribution networks have occurred frequently in recent years. The cause of these fires is often that the arc suppression coils cannot extinguish the arc at the fault point in a timely manner. Therefore, arc suppression coils are gradually becoming unsuitable for the development of distribution networks.

[0003] Since arc suppression coils can only compensate for capacitive current, when the system capacitive current exceeds a certain value, the grounding arc in a single-phase grounding fault system cannot extinguish itself. Therefore, in order to compensate for the active and capacitive components of the single-phase grounding fault current and thus extinguish the grounding arc, active full-compensation arc suppression methods have become widespread. Active full-compensation arc suppression methods are divided into voltage arc suppression and current arc suppression. Active current arc suppression devices require measuring and calculating the distribution network's ground parameters and capacitive current before the fault to accurately compensate for residual fault points. Active voltage arc suppression controls the fault point voltage by adjusting the neutral point voltage, eliminating the need to measure system ground parameters and simplifying control. However, it requires higher capacity power equipment, increasing the device's size and cost. Furthermore, when the three-phase voltage of the distribution network is unbalanced, the arc suppression coil can only compensate for reactive power in the line, reducing voltage deviation on the transmission line, but cannot compensate for neutral point displacement voltage.

[0004] Chinese invention patent CN114024298A proposes a hybrid flexible arc extinguishing system and its usage method. This system injects voltage into the neutral point by combining an inverter power supply and a power source conversion module to reduce the fault point voltage, significantly reducing the inverter power supply capacity and saving costs. However, this method cannot achieve functions such as ground parameter measurement based on the injection method. Therefore, there is an urgent need to propose an integrated arc extinguishing system and method based on hybrid flexible arc extinguishing, aiming to combine fault arc extinguishing, injection parameter measurement, and neutral point control functions. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the problems existing in the prior art and propose an integrated arc extinguishing system and method based on hybrid flexible arc extinguishing, which combines fault arc extinguishing, injection parameter measurement and neutral point control functions through the switching of switches.

[0006] To address the aforementioned technical problems, this invention provides an integrated arc extinguishing system based on hybrid flexible arc extinguishing, comprising:

[0007] A power conversion module, the input of which is connected to the distribution network bus;

[0008] Two sets of switching switches, whose input terminals are connected to the output terminals of the power conversion module.

[0009] An inverter power supply, the input of which is connected to the output of the power conversion module;

[0010] An isolation transformer, the input of which is connected to the output of the inverter power supply, and one port of the output of the isolation transformer is connected to the output of one of the two sets of switching switches;

[0011] An injection transformer is provided, the input of which is connected to another port of the output of the isolation transformer and the output of the other set of two sets of switching switches. The output of the injection transformer is connected to the neutral point of the distribution network, and the neutral point of the distribution network is grounded through an arc suppression coil.

[0012] A switch group is installed between the output terminal of the inverter power supply and the input terminal of the injection transformer. The switch group is normally closed so that the inverter power supply can realize the injection parameter measurement function and neutral point control function when the distribution network is operating normally. When a single-phase ground fault occurs, the switch group switches from the closed state to the open state to realize hybrid arc suppression.

[0013] In one embodiment of the present invention, the switch group includes a pair of switches disposed between the output terminal of the inverter power supply and the input terminal of the injection transformer.

[0014] In one embodiment of the present invention, when the switch is in the closed state, the inverter power supply is directly connected to the input terminal of the injection transformer; when the switch is switched to the open state, the inverter power supply is connected in series with the power conversion module.

[0015] In one embodiment of the present invention, when the switch is in the closed state, the inverter power supply, the injection transformer, and the arc suppression coil constitute an injection parameter measurement and imbalance mitigation module; when the switch is switched to the open state, the inverter power supply, the isolation transformer, the injection transformer, the arc suppression coil, and the power conversion module constitute a flexible arc extinguishing module.

[0016] In one embodiment of the present invention, when the switch is in the closed state, the injection parameter measurement and imbalance management module injects current into the neutral point of the distribution network, and calculates its ground capacitance parameters by measuring the neutral point voltage and three-phase current, thereby realizing real-time online monitoring of the ground capacitance.

[0017] In one embodiment of the present invention, when the switch is switched to the open state, the flexible arc extinguishing module calculates the injected capacitor current based on the ground capacitance parameters measured during normal operation of the power distribution network, so as to compensate for the ground capacitance current during power distribution network faults and realize hybrid arc extinguishing.

[0018] In one embodiment of the present invention, when a single-phase ground fault occurs, the corresponding switching switch is activated according to the faulty phase.

[0019] Furthermore, this invention also provides an integrated arc extinguishing method based on hybrid flexible arc extinguishing. This method is implemented based on an integrated arc extinguishing system based on hybrid flexible arc extinguishing as described above, and includes:

[0020] S1: Real-time monitoring of the power distribution network operating status;

[0021] S2: Determine whether a single-phase ground fault has occurred in the distribution network. If not, the switch is normally closed, enabling the inverter to perform parameter injection measurement and neutral point control functions. If yes, the switch is switched to open, the corresponding switching switch is activated based on the faulty phase, and the current is injected to extinguish the arc according to the parameter measurement results during normal operation of the distribution network. Proceed to S3.

[0022] S3: Use an inverter to adjust the neutral point voltage in real time so that the fault point voltage approaches zero;

[0023] S4: Determine whether the single-phase ground fault has disappeared. If yes, switch the switch to the closed state; if not, go to S2 and continue to inject current to extinguish the arc based on the parameter measurement results during normal operation of the distribution network.

[0024] In one embodiment of the present invention, in S2, after the corresponding switching switch is activated based on the faulty phase, the inverter power supply is activated after a delay.

[0025] In one embodiment of the present invention, in S2, when the switch is in the closed state, the inverter power supply injects current into the neutral point of the distribution network, and calculates its ground capacitance parameters by measuring the neutral point voltage and three-phase current; when the switch is switched to the open state, the injected capacitance current is calculated by using the ground capacitance parameters measured during normal operation of the distribution network, so as to compensate for the ground capacitance current during a distribution network fault.

[0026] The technical solution of the present invention has the following advantages compared with the prior art:

[0027] The present invention proposes an integrated arc extinguishing system and method based on hybrid flexible arc extinguishing. Its inverter power supply can realize the functions of injection parameter measurement and neutral point control when the distribution network is operating normally. In the event of a single-phase ground fault, it can switch to hybrid flexible arc extinguishing through a switch to complete various large-capacity arc extinguishing, thereby reducing the capacity and cost of the inverter power supply. Thus, it has the functions of fault arc extinguishing, injection parameter measurement and neutral point control. Attached Figure Description

[0028] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0029] Figure 1 This is a schematic diagram of an integrated arc extinguishing system based on a hybrid flexible arc extinguishing method proposed in an embodiment of the present invention.

[0030] Figure 2 This is the electrical schematic diagram of the injection parameter measurement and three-phase imbalance mitigation module proposed in this embodiment of the invention.

[0031] Figure 3 This is an equivalent circuit diagram for measuring injection parameters proposed in an embodiment of the present invention.

[0032] Figure 4 This is an equivalent circuit diagram for measuring injection parameters proposed in an embodiment of the present invention.

[0033] Figure 5 This is a schematic diagram of the process of an integrated arc extinguishing method based on hybrid flexible arc extinguishing proposed in an embodiment of the present invention. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0035] Please see Figure 1As shown, this embodiment of the invention provides an integrated arc suppression system based on hybrid flexible arc extinguishing, including a power conversion module, two sets of switching switches, an inverter power supply, an isolation transformer GLB, an injection transformer ZRB, an arc suppression coil, and a switch group. The input terminal of the power conversion module is connected to the distribution network bus; the input terminals of the two sets of switching switches are connected to the output terminal of the power conversion module, and the input terminal of the inverter power supply is connected to the output terminal of the power conversion module; the input terminal of the isolation transformer GLB is connected to the output terminal of the inverter power supply, and one port of the output terminal of the isolation transformer GLB is connected to the output terminal of one of the two sets of switching switches; the injection... The input terminal of transformer ZRB is connected to another port of the output terminal of isolation transformer GLB and the output terminal of the other set of two sets of switching switches. The output terminal of injection transformer ZRB is connected to the neutral point of the distribution network, and the neutral point of the distribution network is grounded through an arc suppression coil. A switch group is set between the output terminal of the inverter power supply and the input terminal of injection transformer ZRB. The switch group is normally closed so that the inverter power supply can realize the injection parameter measurement function and neutral point control function when the distribution network is running normally. When a single-phase ground fault occurs, the switch group switches from the closed state to the open state to realize hybrid arc suppression.

[0036] The present invention proposes an integrated arc extinguishing system based on hybrid flexible arc extinguishing. Its inverter power supply can realize the functions of injection parameter measurement and neutral point control when the distribution network is operating normally. In the event of a single-phase ground fault, it can switch to hybrid flexible arc extinguishing through a switch to complete various large-capacity arc extinguishing, thereby reducing the capacity and cost of the inverter power supply. Thus, it has the functions of fault arc extinguishing, injection parameter measurement and neutral point control.

[0037] Specifically, the input terminals (A1, B1, C1) of the power conversion module are connected to the three phases A, B, and C of the distribution network bus, respectively. The output terminals (a, b, c) of the power conversion module are connected to the input terminals of two sets of switching switches. The output terminals of the first set of switching switches Ka1, Kb1, and Kc1 are connected to one port on the low-voltage side of the isolation transformer GLB. The other port on the low-voltage side of the isolation transformer GLB is connected to one port on the low-voltage side of the injection transformer ZRB. The other port on the low-voltage side of the injection transformer ZRB is connected to the output terminals of the second set of switching switches Ka2, Kb2, and Kc2. Simultaneously, the output terminal of the power conversion module is connected to the input terminal of the inverter power supply, and the output terminal of the inverter power supply is connected to the high-voltage side input terminal of the isolation transformer GLB. The high-voltage side of the injection transformer ZRB is connected to the neutral point N of the distribution network, and the neutral point N of the distribution network is grounded via an arc suppression coil.

[0038] In the event of a single-phase ground fault, the corresponding switching switch is activated according to the faulty phase. Preferably, the switching switches are divided into two groups, each with three switches. The two groups of switches are connected to the output terminals of the power conversion module, and a line voltage that is out of phase with the faulty phase power supply voltage can be obtained through the two groups of switching switches.

[0039] The switch group includes a pair of switches K1 and K2, which are located between the output terminal of the inverter power supply and the input terminal of the injection transformer ZRB. When switches K1 and K2 are closed, the inverter power supply is directly connected to the input terminal of the injection transformer ZRB, i.e., the inverter power supply, the injection transformer ZRB, and the arc suppression coil constitute an injection parameter measurement and imbalance mitigation module. When switches K1 and K2 are switched to the open state, the inverter power supply is connected in series with the power conversion module, i.e., the inverter power supply, the isolation transformer GLB, the injection transformer ZRB, the arc suppression coil, and the power conversion module constitute a flexible arc extinguishing module.

[0040] When switches K1 and K2 are closed, the injection parameter measurement and imbalance mitigation module injects current into the neutral point of the distribution network. By measuring the neutral point voltage and three-phase current, it calculates the ground capacitance parameters, achieving real-time online monitoring of the ground capacitance. When switches K1 and K2 are switched to the open state, the flexible arc extinguishing module calculates the injected capacitance current using the ground capacitance parameters measured during normal operation of the distribution network. This compensates for the ground capacitance current during distribution network faults, achieving hybrid arc extinguishing.

[0041] Please see Figure 2 As shown, the injection parameter measurement and imbalance mitigation module includes the following: (e.g.) Figure 2 As shown, C represents the three-phase power supply voltage of the distribution network. A C B C C For the three-phase-to-ground capacitance of the distribution network, R is the current injected by the inverter power supply into the neutral point of the distribution network, L is the inductance of the arc suppression coil branch, and R is the current injected by the inverter power supply into the neutral point of the distribution network. hThe damping resistor of the arc suppression coil branch is used to periodically inject current into the neutral point of the distribution network. The injection resonance measurement circuit consists of an inverter power supply, an injection transformer ZRB, the arc suppression coil, and the damping resistor. The inverter power supply injects a current signal with a frequency different from the power frequency through the low-voltage side of the injection transformer ZRB. This results in a zero-sequence current with a different turns ratio on the high-voltage side. When the arc suppression coil is in operation, part of the zero-sequence current flows to the ground through the arc suppression coil and the damping resistor, while another part flows through the loop formed by the distributed capacitance to ground and the ground. Simultaneously, the current flowing through the neutral point creates a zero-sequence voltage at the neutral point. When the injected signal frequency is different, the zero-sequence voltage and zero-sequence current are measured. Equations are established according to the equivalent circuit, and the corresponding parameters are obtained by solving the simultaneous equations.

[0042] Because this system needs to measure the distributed capacitance to ground, grounding inductance, and damping resistance, the inductance and damping resistance of the arc suppression coil cannot be ignored when establishing the equivalent measurement model. According to... Figure 2 Obtain its equivalent circuit Figure 3 and Figure 4 Where L is the inductance of the arc suppression coil, R is the damping resistor, and R m This represents the equivalent resistance in the equivalent circuit. Where C... Σ =C A / / C B / / C C .

[0043] The three-phase imbalance mitigation function included in the aforementioned injection parameter measurement and imbalance mitigation module includes the following: when a three-phase imbalance in the distribution network is detected by the injection parameter measurement and imbalance mitigation module, this structure can suppress overvoltage by injecting current into the neutral point of the distribution network through the inverter power supply. The specific implementation method is as follows:

[0044] neutral point voltage The expression is:

[0045]

[0046]

[0047]

[0048] Unbalanced voltage for:

[0049] in This indicates the three-phase power supply voltage of the distribution network. This represents the three-phase bus voltage. Indicates the neutral point voltage. Represents zero-sequence voltage, g A g B g C For the three-phase ground conductance of the distribution network, CA C B C C This refers to the three-phase-to-ground capacitance of the distribution network. ∑ Y represents the ground admittance of the distribution network. ∑ =Y A +Y B +Y C =(g A +g B +g C )+jωC ∑ Y L Indicates the neutral point's earth admittance This indicates the injection of current during imbalance mitigation.

[0050] The aforementioned flexible arc-extinguishing module includes the following: When a single-phase ground fault is detected, i.e., the zero-sequence voltage is greater than 15% of the phase voltage, this topology disconnects switches K1 and K2 to perform the function of a hybrid flexible arc-extinguishing system, which can realize the function of full compensation for residual current in single-phase ground faults. The specific steps are as follows:

[0051] Step 1: Activate the corresponding switching switch according to the faulty phase;

[0052] Step 2: Connect the inverter power supply after a delay of t, which is typically 10ms-30ms;

[0053] Step 3: The inverter power supply adjusts the neutral point voltage in real time to equal the fault phase power supply voltage in the opposite phase;

[0054] Step 4: Determine if the grounding fault has disappeared;

[0055] Step 5: If a grounding fault exists, then according to the user's settings, if it is not necessary to isolate the faulty feeder and the flexible arc extinguishing module has not reached the user-set operating time, then proceed to Step 3; otherwise, proceed to Step 6.

[0056] Step Six: Restore the flexible arc extinguishing module, which means disconnecting the switching switches involved in this fault and disconnecting the inverter power supply.

[0057] When a three-phase imbalance is detected in the distribution network, the voltage source of the inverter power supply can act as a power source to inject zero-sequence current into the distribution network, reducing the three-phase imbalance and suppressing neutral point overvoltage. During normal operation of the distribution network, current is injected into the neutral point, and the ground capacitance parameters are calculated by measuring the neutral point voltage and three-phase current, enabling real-time online monitoring of the line's ground capacitance. In the event of a single-phase ground fault, switches K1 and K2 are disconnected, and the inverter power supply and power conversion module are connected in series. The injected capacitance current is calculated using the ground capacitance parameters measured during normal operation of the distribution network. This accurately compensates for the ground capacitance current during a fault, thus achieving hybrid arc suppression and reducing the inverter power supply capacity. This invention combines the injection and arc suppression functions of a small-capacity inverter power supply.

[0058] Corresponding to the embodiments of the above system, this invention also provides an integrated arc extinguishing method based on hybrid flexible arc extinguishing. This method is implemented based on an integrated arc extinguishing system based on hybrid flexible arc extinguishing as described above. Please refer to... Figure 5 As shown, the method includes:

[0059] S1: Real-time monitoring of the power distribution network operating status;

[0060] S2: Determine whether a single-phase ground fault has occurred in the distribution network. If not, the switch is normally closed, enabling the inverter to perform parameter injection measurement and neutral point control functions. If yes, the switch is switched to open, the corresponding switching switch is activated based on the faulty phase, and the current is injected to extinguish the arc according to the parameter measurement results during normal operation of the distribution network. Proceed to S3.

[0061] S3: Use an inverter to adjust the neutral point voltage in real time so that the fault point voltage approaches zero;

[0062] S4: Determine whether the single-phase ground fault has disappeared. If yes, switch the switch to the closed state; if not, go to S2 and continue to inject current to extinguish the arc based on the parameter measurement results during normal operation of the distribution network.

[0063] The present invention proposes an integrated arc extinguishing method based on hybrid flexible arc extinguishing. Its inverter power supply can realize the functions of injection parameter measurement and neutral point control when the distribution network is operating normally. In the event of a single-phase ground fault, it can switch to hybrid flexible arc extinguishing through a switch to complete various large-capacity arc extinguishing, thereby reducing the capacity and cost of the inverter power supply. Thus, it has the functions of fault arc extinguishing, injection parameter measurement and neutral point control.

[0064] In one embodiment of the present invention, in S2, after the corresponding switching switch is activated based on the faulty phase, the inverter power supply is activated after a delay.

[0065] In one embodiment of the present invention, in S2, when the switch is in the closed state, the inverter power supply injects current into the neutral point of the distribution network, and calculates its ground capacitance parameters by measuring the neutral point voltage and three-phase current; when the switch is switched to the open state, the injected capacitance current is calculated by using the ground capacitance parameters measured during normal operation of the distribution network, so as to compensate for the ground capacitance current during a distribution network fault.

[0066] This embodiment of the integrated arc extinguishing method based on hybrid flexible arc extinguishing is implemented based on the aforementioned integrated arc extinguishing system based on hybrid flexible arc extinguishing. Therefore, the specific implementation method can be found in the embodiment section of the integrated arc extinguishing system based on hybrid flexible arc extinguishing described above. Thus, the specific implementation method can be referred to the description of the corresponding embodiments, and will not be elaborated here.

[0067] Furthermore, since the integrated arc extinguishing method based on hybrid flexible arc extinguishing in this embodiment is implemented based on the aforementioned integrated arc extinguishing system based on hybrid flexible arc extinguishing, its function corresponds to the function of the aforementioned system, and will not be repeated here.

[0068] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An integrated arc extinguishing system based on hybrid flexible arc extinguishing, characterized in that, include: A power conversion module, the input of which is connected to the distribution network bus; Two sets of switching switches, whose input terminals are connected to the output terminals of the power conversion module. An inverter power supply, the input of which is connected to the output of the power conversion module; An isolation transformer, the input of which is connected to the output of the inverter power supply, and one port of the output of the isolation transformer is connected to the output of one of the two sets of switching switches; An injection transformer is provided, the input of which is connected to another port of the output of the isolation transformer and the output of the other set of two sets of switching switches. The output of the injection transformer is connected to the neutral point of the distribution network, and the neutral point of the distribution network is grounded through an arc suppression coil. A switch group is installed between the output terminal of the inverter power supply and the input terminal of the injection transformer. The switch group is normally closed so that the inverter power supply can realize the injection parameter measurement function and neutral point control function when the distribution network is running normally. When a single-phase ground fault occurs, the switch group switches from the closed state to the open state to realize hybrid arc suppression. The switch group includes a pair of switches, which are disposed between the output terminal of the inverter power supply and the input terminal of the injection transformer; When the switch is closed, the inverter power supply is directly connected to the input terminal of the injection transformer; when the switch is switched to open, the inverter power supply is connected in series with the power conversion module.

2. The integrated arc extinguishing system based on hybrid flexible arc extinguishing as described in claim 1, characterized in that: When the switch is in the closed state, the inverter power supply, injection transformer, and arc suppression coil constitute an injection parameter measurement and imbalance mitigation module; when the switch is switched to the open state, the inverter power supply, isolation transformer, injection transformer, arc suppression coil, and power conversion module constitute a flexible arc extinguishing module.

3. The integrated arc extinguishing system based on hybrid flexible arc extinguishing as described in claim 2, characterized in that: When the switch is closed, the injection parameter measurement and imbalance management module injects current into the neutral point of the distribution network, and calculates its ground capacitance parameters by measuring the neutral point voltage and three-phase current, thereby realizing real-time online monitoring of the ground capacitance.

4. The integrated arc extinguishing system based on hybrid flexible arc extinguishing as described in claim 2, characterized in that: When the switch is switched to the open state, the flexible arc extinguishing module calculates the injected capacitor current based on the ground capacitance parameters measured during normal operation of the distribution network, in order to compensate for the ground capacitance current during a distribution network fault and achieve hybrid arc extinguishing.

5. The integrated arc extinguishing system based on hybrid flexible arc extinguishing as described in claim 1, characterized in that: When a single-phase ground fault occurs, the corresponding switching switch is activated according to the faulty phase.

6. An integrated arc extinguishing method based on hybrid flexible arc extinguishing, characterized in that, This method is implemented based on an integrated arc extinguishing system based on a hybrid flexible arc extinguishing method as described in any one of claims 1-5, and the method includes: S1: Real-time monitoring of the power distribution network operating status; S2: Determine whether a single-phase ground fault has occurred in the distribution network. If not, the switch is normally closed, enabling the inverter power supply to perform parameter injection measurement and neutral point control functions. If yes, the switch is switched to open, the corresponding switching switch is activated based on the faulty phase, and the current is injected to extinguish the arc according to the parameter measurement results during normal operation of the distribution network. Proceed to S3. S3: Use an inverter to adjust the neutral point voltage in real time so that the fault point voltage approaches zero; S4: Determine whether the single-phase ground fault has disappeared. If yes, switch the switch to the closed state; if not, go to S2 and continue to inject current to extinguish the arc based on the parameter measurement results during normal operation of the distribution network.

7. The integrated arc extinguishing method based on hybrid flexible arc extinguishing as described in claim 6, characterized in that: In S2, after the corresponding switching switch is activated based on the faulty phase, the inverter power supply is activated after a delay.

8. The integrated arc extinguishing method based on hybrid flexible arc extinguishing as described in claim 6, characterized in that: In S2, when the switch is closed, the inverter injects current into the neutral point of the distribution network, and calculates its ground capacitance parameters by measuring the neutral point voltage and three-phase current. When the switch is switched to the open state, the injected capacitor current is calculated based on the ground capacitance parameters measured during normal operation of the distribution network, in order to compensate for the ground capacitance current during a distribution network fault.

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