Power distribution network ground fault flexible arc extinguishing device control method and system

Abstract

The invention provides a control method and system for a flexible arc extinguishing device for a grounding fault of a power distribution network. The flexible arc extinguishing device serves as a controlled zero-sequence source, provides required power for total zero-sequence ground impedance of the power distribution network, supports required zero-sequence voltage of the power distribution network, and promotes grounding fault current and voltage to be zero. By designing the virtual damping and virtual inertia control of the zero axis, the motion characteristics of the rotor of the synchronous generator are simulated, and by designing the virtual excitation control of the zero axis, the excitation characteristics of the stator of the synchronous generator are simulated. When a distributed power electronic flexible arc-extinguishing device in a power distribution network commonly dominates the zero-sequence voltage of a zero-sequence network circuit of the power distribution network, the droop characteristic of a synchronous generator is simulated, and a droop control equation of active and reactive power output by the flexible arc-extinguishing device and the frequency and amplitude of the zero-sequence voltage of the power distribution network is designed; and virtual impedance control is added to coordinate the output of the flexible arc extinguishing device. And finally, constructing a power distribution network ground fault arc extinguishing device control system to realize arc extinguishing of the power distribution network ground fault.

Description

Technical Field

[0001] This invention proposes a control method and system for a flexible arc suppression device for grounding faults in power distribution networks, which relates to the field of power distribution network safety and protection technology. Background Technology

[0002] The extensive integration of renewable energy and power electronic equipment into active power distribution networks has led to bidirectional power flow, posing a risk of failure for traditional protection measures. The high incidence of single-phase grounding faults is particularly problematic, as the accompanying high-temperature arc can easily cause overvoltage, equipment damage, and even fires, while step voltage threatens personal safety. Although existing arc suppression coils can partially compensate for the fault current (capacitive component), they are ineffective at compensating for resistive and harmonic components, resulting in persistent residual current at the grounding fault point and difficulty in extinguishing the arc.

[0003] Flexible arc suppression devices, with their precise four-quadrant control capabilities, can achieve complete fault current compensation and have broad application prospects. Their deployment is flexible; they can be used in conjunction with arc suppression coils (master-slave mode) or operate independently at the neutral point of the grounding transformer, or be directly connected to any phase of the line. However, because they are in a long-term hot standby state (faults do not occur continuously), the deployment cost-effectiveness of independent power electronic flexible arc suppression devices is not good. At the same time, there is a difficult-to-measure and dynamically changing line impedance voltage drop between the flexible arc suppression device and the grounding fault point, resulting in relatively large residual voltage and current at the grounding fault point, leading to poor arc suppression effect.

[0004] Considering the rapid increase in the types and numbers of power electronic devices in active distribution networks, including direct-connected inverters, energy storage converters, and energy routers for renewable energy grid connection, storage, and consumption, as well as static var compensators, power quality regulators, and unified power flow controllers for auxiliary regulation of distribution network operation, these power electronic devices often have redundant capacity and can be allocated for integration to achieve flexible arc suppression functions. Without changing the functions of existing power electronic devices, by adding power electronic flexible grounding branches, the flexible arc suppression function for distribution network grounding faults can be integrated into devices such as reactive power compensators, power quality regulators, power electronic transformers, and flexible interconnected multi-state switches. This allows for multiple sets of distributed flexible arc suppression devices in active distribution networks, providing the hardware support for distributed flexible arc suppression. Summary of the Invention

[0005] Considering the lack of information exchange between flexible arc-suppression devices, a coordinated and stable control method for these devices should be considered to prevent operational instability from affecting the safe and stable operation of the power distribution network. In view of this, this invention, guided by the goal of solving the aforementioned problems, proposes a specific implementation method.

[0006] To fill the gaps and deficiencies in existing technologies, this invention proposes a control method and system for a flexible arc suppression device for grounding faults in power distribution networks. The method and system proposed in this invention can control the flexible arc suppression device to operate in a virtual zero-sequence synchronous generator mode, thereby achieving coordinated and stable operation of the flexible arc suppression device and ensuring that fault arcs are reliably suppressed.

[0007] This invention proposes a control method for a flexible arc suppression device for grounding faults in a power distribution network, characterized by the following:

[0008] The electrical parameters that the flexible arc suppression device needs to meet are determined by using the zero-sequence network circuit of single-phase grounding fault in the distribution network.

[0009] Based on the electrical parameters that the flexible arc suppression device needs to meet during operation, an algorithm is proposed to control the flexible arc suppression device to operate in a virtual zero-sequence synchronous generator mode, so that the flexible arc suppression device operates in a virtual zero-sequence synchronous generator mode during operation.

[0010] Furthermore, the electrical parameters that the flexible arc-extinguishing device needs to meet also include the following:

[0011] The electrical parameters that the flexible arc suppression device needs to meet include: the flexible arc suppression device, as a controlled zero-sequence source, provides the required active and reactive power to the total zero-sequence impedance of the distribution network; furthermore, the zero-sequence current output by the flexible arc suppression device will be entirely provided to the total zero-sequence impedance of the distribution network, so that the ground fault current and voltage are zero; the rated zero-sequence voltage supported by the total zero-sequence impedance of the distribution network output by the flexible arc suppression device.

[0012] The total zero-sequence impedance to ground of the distribution network includes the total zero-sequence leakage resistance to ground and the total zero-sequence capacitance to ground of the distribution network. The negative value of the fault phase power supply voltage is the rated zero-sequence voltage that the flexible arc suppression device needs to support for the total zero-sequence impedance to ground of the distribution network.

[0013] The relationship between the active and reactive power output of the flexible arc suppression device and the frequency and amplitude of the zero-sequence voltage in the distribution network is as follows:

[0014]

[0015] Among them, P G0 It is the active power output to the distribution network; Q G0 It is the active power output to the distribution network; E G0 It is the amplitude of the output voltage of the flexible arc suppression device; E f The flexible arc suppression device needs to support the rated zero-sequence voltage amplitude for the total zero-sequence impedance of the distribution network; Z G0 It is the output impedance, including the virtual impedance Z. V0 and filter reactance X F0 ;

[0016] θ EG0 It is the phase angle of the output voltage of the flexible arc suppression device.

[0017] Furthermore, the algorithm for controlling the flexible arc-extinguishing device to operate in virtual zero-sequence synchronous generator mode includes the following:

[0018] The use of zero-axis virtual damping and virtual inertia enables the flexible arc suppression device to possess the motion characteristics of a synchronous generator rotor.

[0019] The use of zero-axis virtual excitation control enables the flexible arc suppression device to possess the stator excitation characteristics of a synchronous generator;

[0020] Based on the active and reactive power output of the flexible arc suppression device and the zero-sequence voltage of the distribution network, the flexible arc suppression device is made to have the drooping characteristics of a synchronous generator.

[0021] Add virtual impedance control to coordinate the output of the flexible arc suppression device.

[0022] Furthermore, the use of zero-axis virtual damping and virtual inertia to enable the flexible arc suppression device to possess the motion characteristics of a synchronous generator rotor includes the following:

[0023] The equations for simulating the rotor motion of a synchronous generator using a flexible arc-extinguishing device are designed as follows:

[0024]

[0025] Where J is the virtual moment of inertia; ω G0 ω0 and ω0 are the rated and actual angular velocities of the virtual rotor, respectively; P D and P G0 These represent the active power supplied by the flexible arc suppression device on the DC side and the active power output to the distribution network, respectively; D is the virtual damping coefficient; K J It is the virtual inertia adjustment coefficient.

[0026] Furthermore, the use of zero-axis virtual excitation control enables the flexible arc suppression device to possess the stator excitation characteristics of a synchronous generator, including the following:

[0027] The equations and implementation schemes for simulating stator excitation dynamics using a flexible arc-suppression device are designed as follows:

[0028]

[0029] Among them, E G0 It is the amplitude of the output voltage of the flexible arc suppression device, E G0ref This is its reference value; E f The flexible arc suppression device needs to support the rated zero-sequence voltage amplitude for the total zero-sequence impedance of the distribution network; U G0 It is the voltage amplitude at the grid connection point of the flexible arc suppression device; UD It is the final calculated zero-sequence voltage amplitude; K e It is the excitation gain, T e It is the excitation time constant; K p and K I These are the proportional and integral coefficients of the PI controller that simulates excitation characteristics.

[0030] Furthermore, the use of zero-axis virtual excitation control to enable the flexible arc suppression device to possess the stator excitation characteristics of a synchronous generator also includes the following:

[0031] The implementation scheme for simulating stator excitation dynamics using a flexible arc suppression device can be replaced by a PI controller. The difference between the final calculated zero-sequence voltage amplitude and the voltage amplitude at the grid connection point of the flexible arc suppression device is input into the PI controller. The output of the PI controller is summed with the rated zero-sequence voltage amplitude supported by the total zero-sequence impedance of the distribution network required by the flexible arc suppression device to obtain the reference value of the output voltage amplitude of the flexible arc suppression device.

[0032] Furthermore, based on the active and reactive power output of the flexible arc suppression device and the zero-sequence voltage of the distribution network, enabling the flexible arc suppression device to possess the droop characteristics of a synchronous generator, the following are included:

[0033]

[0034] In the formula, P D P0 is the actual calculated active power output of the flexible arc-extinguishing device, and K is the reference value of the active power output of the flexible arc-extinguishing device. ω It is the frequency regulation coefficient; Q0 is the reference value of the reactive power output of the flexible arc suppression device, Q G0 It is the actual calculated reactive power output of the flexible arc suppression device, K. U It is the voltage amplitude adjustment coefficient.

[0035] Furthermore, adding virtual impedance control to coordinate the output of the flexible arc suppression device includes the following:

[0036]

[0037] in, It is the output voltage of the flexible arc suppression device; It is the grid connection voltage of the flexible arc suppression device; Z G0 It is the output impedance, including the virtual impedance Z. V0 and filter reactance X F0 .

[0038] Furthermore, the output of the enhanced flexible arc suppression device also includes the following:

[0039] When multiple flexible arc suppression devices in a distribution network jointly dominate the zero-sequence voltage of the zero-sequence network circuit, these devices can coordinate and operate stably and communicate with each other.

[0040] This invention proposes a control system for a flexible arc-suppression device for grounding faults in a power distribution network, used in any one of the control methods for a flexible arc-suppression device for grounding faults in a power distribution network described in this invention. The system is characterized by including a flexible arc-suppression device, wherein the flexible arc-suppression device comprises the following:

[0041] The flexible arc extinguishing device includes a sampling module, a fault analysis module, and a control and drive module;

[0042] The sampling module measures the three-phase voltage and zero-sequence voltage at the grid connection point of the arc suppression device, the output current of the flexible arc suppression device, and calculates the amplitude and phase information of each electrical quantity.

[0043] The fault analysis module determines whether a grounding fault has occurred in the distribution network and the type of fault based on the collected electrical quantity information.

[0044] The control and drive module controls and drives the output voltage and current of the arc suppression device based on the collected electrical quantities and the determined fault type, thereby suppressing the current and voltage at the ground fault point to zero.

[0045] The present invention has the following advantages:

[0046] 1. This method improves the zero-sequence voltage frequency stability of the zero-sequence network circuit dominated by the power electronic flexible arc suppression device by designing zero-axis virtual damping and virtual inertia control to simulate the rotor motion characteristics of the synchronous generator.

[0047] 2. This method improves the stability of the zero-sequence voltage amplitude of the distribution network zero-sequence network circuit dominated by the power electronic flexible arc suppression device by simulating the stator excitation characteristics of the synchronous generator through the design of the zero-axis virtual excitation control.

[0048] 3. This method improves the coordinated and stable operation capability and flexible arc suppression effect among multiple flexible arc suppression devices without information interaction by designing droop control and virtual impedance control of the output active and reactive power of the flexible arc suppression device and the frequency and amplitude of the zero-sequence voltage of the distribution network. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the method flow of the present invention.

[0050] Figure 2 The circuit diagram of the flexible arc suppression zero-sequence network for single-phase grounding faults in the power distribution network is shown in the present invention.

[0051] Figure 3This is the overall control block diagram of the distributed arc suppression device for grounding faults in the power distribution network according to the present invention.

[0052] Figure 4 This is a circuit diagram of a distributed flexible arc suppression zero-sequence network for a single-phase ground fault in a power distribution network, as described in this embodiment of the invention.

[0053] Figure 5 This is a schematic diagram of the system device of the present invention.

[0054] Figure 6 This represents the distributed coordinated arc suppression results under low-resistance and high-resistance grounding faults in the power distribution network in this embodiment of the invention. Detailed Implementation

[0055] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings.

[0056] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0057] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention; as used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise; furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0058] like Figure 1 As shown, this invention proposes a control method for a flexible arc suppression device for grounding faults in a power distribution network, characterized by the following:

[0059] The electrical parameters that the flexible arc suppression device needs to meet are determined by using the zero-sequence network circuit of single-phase grounding fault in the distribution network.

[0060] Based on the electrical parameters that the flexible arc suppression device needs to meet during operation, an algorithm is proposed to control the flexible arc suppression device to operate in a virtual zero-sequence synchronous generator mode, so that the flexible arc suppression device operates in a virtual zero-sequence synchronous generator mode during operation.

[0061] In one embodiment of the present invention, the electrical parameters that the flexible arc-extinguishing device needs to meet also include the following:

[0062] The electrical parameters that the flexible arc suppression device needs to meet include: the flexible arc suppression device, as a controlled zero-sequence source, provides the required active and reactive power to the total zero-sequence impedance of the distribution network; furthermore, the zero-sequence current output by the flexible arc suppression device will be entirely provided to the total zero-sequence impedance of the distribution network, so that the ground fault current and voltage are zero; the rated zero-sequence voltage supported by the total zero-sequence impedance of the distribution network output by the flexible arc suppression device.

[0063] The total zero-sequence impedance to ground of the distribution network includes the total zero-sequence leakage resistance to ground and the total zero-sequence capacitance to ground of the distribution network. The negative value of the fault phase power supply voltage is the rated zero-sequence voltage that the flexible arc suppression device needs to support for the total zero-sequence impedance to ground of the distribution network.

[0064] Furthermore, in one embodiment of the present invention, as Figure 2 The zero-sequence network circuit for a single-phase ground fault in the distribution network shown requires the following zero-sequence current output from the flexible arc suppression device to achieve arc suppression of the ground fault in the distribution network:

[0065]

[0066] Where Z0=1 / (3 / R0+j3ωC0) is the total zero-sequence impedance to ground of the distribution network, R0 / 3 is the total zero-sequence leakage resistance to ground of the distribution network, and 3C0 is the total zero-sequence capacitance to ground of the distribution network. It is the rated zero-sequence voltage that the flexible arc suppression device needs to support for the total zero-sequence impedance of the distribution network, that is, the negative value of the fault phase power supply voltage.

[0067] At this time, the single-phase ground fault current of the distribution network is expressed as:

[0068]

[0069] That is, when the ground fault current and voltage are simultaneously suppressed to zero, the ground fault arc will be extinguished. In the formula, This is the zero-sequence voltage of the total zero-sequence impedance to ground in the distribution network. During this period, the rated active and reactive power provided by the flexible arc suppression device to the total zero-sequence impedance to ground in the distribution network is:

[0070]

[0071] Therefore, during the arc suppression process, the flexible arc suppression device acts as a controlled zero-sequence source, providing the required active and reactive power to the total zero-sequence impedance of the distribution network and supporting its required zero-sequence voltage. That is, the zero-sequence current output by the flexible arc suppression device will be entirely provided to the total zero-sequence impedance of the distribution network, making the ground fault current and voltage zero, and the equivalent zero-sequence source of the ground fault branch will fail and no longer output power.

[0072] The relationship between the active and reactive power output of the flexible arc suppression device and the frequency and amplitude of the zero-sequence voltage in the distribution network is as follows:

[0073]

[0074] Among them, P G0 It is the active power output to the distribution network; Q G0 It is the active power output to the distribution network; E G0 It is the amplitude of the output voltage of the flexible arc suppression device; E f The flexible arc suppression device needs to support the rated zero-sequence voltage amplitude for the total zero-sequence impedance of the distribution network; Z G0 It is the output impedance, including the virtual impedance Z. V0 and filter reactance X F0 ;

[0075] θ EG0 It is the phase angle of the output voltage of the flexible arc suppression device.

[0076] like Figure 3 As shown, in one embodiment of the present invention, the algorithm for controlling the flexible arc-extinguishing device to operate in a virtual zero-sequence synchronous generator mode includes the following:

[0077] The use of zero-axis virtual damping and virtual inertia enables the flexible arc suppression device to possess the motion characteristics of a synchronous generator rotor.

[0078] The use of zero-axis virtual excitation control enables the flexible arc suppression device to possess the stator excitation characteristics of a synchronous generator;

[0079] Based on the active and reactive power output of the flexible arc suppression device and the zero-sequence voltage of the distribution network, the flexible arc suppression device is made to have the drooping characteristics of a synchronous generator.

[0080] Add virtual impedance control to coordinate the output of the flexible arc suppression device.

[0081] In one embodiment of the present invention, the use of zero-axis virtual damping and virtual inertia to enable the flexible arc suppression device to possess the motion characteristics of a synchronous generator rotor includes the following:

[0082] The equations for simulating the rotor motion of a synchronous generator using a flexible arc-extinguishing device are designed as follows:

[0083]

[0084] Where j is the virtual moment of inertia; ω G0 ω0 and ω0 are the rated and actual angular velocities of the virtual rotor, respectively; P D and P G0 These represent the active power supplied by the flexible arc suppression device on the DC side and the active power output to the distribution network, respectively; D is the virtual damping coefficient; KJ It is the virtual inertia adjustment coefficient.

[0085] In one embodiment of the present invention, the use of zero-axis virtual excitation control to enable the flexible arc suppression device to possess the stator excitation characteristics of a synchronous generator includes the following:

[0086] The equations and implementation schemes for simulating stator excitation dynamics using a flexible arc-suppression device are designed as follows:

[0087]

[0088] Among them, E G0 It is the amplitude of the output voltage of the flexible arc suppression device, E G0ref This is its reference value; E f The flexible arc suppression device needs to support the rated zero-sequence voltage amplitude for the total zero-sequence impedance of the distribution network; U G0 It is the voltage amplitude at the grid connection point of the flexible arc suppression device; U D It is the final calculated zero-sequence voltage amplitude; K e It is the excitation gain, T e It is the excitation time constant; K p and K I These are the proportional and integral coefficients of the PI controller that simulates excitation characteristics.

[0089] In one embodiment of the present invention, the use of zero-axis virtual excitation control to enable the flexible arc suppression device to possess the stator excitation characteristics of a synchronous generator also includes the following:

[0090] The implementation scheme for simulating stator excitation dynamics using a flexible arc suppression device can be replaced by a PI controller. The difference between the final calculated zero-sequence voltage amplitude and the voltage amplitude at the grid connection point of the flexible arc suppression device is input into the PI controller. The output of the PI controller is summed with the rated zero-sequence voltage amplitude supported by the total zero-sequence impedance of the distribution network required by the flexible arc suppression device to obtain the reference value of the output voltage amplitude of the flexible arc suppression device.

[0091] Furthermore, based on the active and reactive power output of the flexible arc suppression device and the zero-sequence voltage of the distribution network, enabling the flexible arc suppression device to possess the droop characteristics of a synchronous generator, the following are included:

[0092]

[0093] In the formula, P D P0 is the actual calculated active power output of the flexible arc-extinguishing device, and K is the reference value of the active power output of the flexible arc-extinguishing device. ω It is the frequency regulation coefficient; Q0 is the reference value of the reactive power output of the flexible arc suppression device, Q G0 It is the actual calculated reactive power output of the flexible arc suppression device, K. UIt is the voltage amplitude adjustment coefficient.

[0094] In one embodiment of the present invention, adding virtual impedance control to coordinate the output of the flexible arc suppression device includes the following:

[0095]

[0096] in, It is the output voltage of the flexible arc suppression device; It is the grid connection voltage of the flexible arc suppression device; Z G0 It is the output impedance, including the virtual impedance Z. V0 and filter reactance X F0 .

[0097] like Figure 4 As shown, in one embodiment of the present invention, the output of the enhanced flexible arc suppression device further includes the following:

[0098] When multiple flexible arc suppression devices in a distribution network jointly dominate the zero-sequence voltage of the zero-sequence network circuit, these devices can coordinate and operate stably and communicate with each other.

[0099] like Figure 5 As shown, this invention proposes a control system for a flexible arc-suppression device for grounding faults in a power distribution network, used in any one of the control methods for a flexible arc-suppression device for grounding faults in a power distribution network described in this invention. The system is characterized by including a flexible arc-suppression device, wherein the flexible arc-suppression device comprises the following:

[0100] The flexible arc extinguishing device includes a sampling module, a fault analysis module, and a control and drive module;

[0101] The sampling module measures the three-phase voltage and zero-sequence voltage at the grid connection point of the arc suppression device, the output current of the flexible arc suppression device, and calculates the amplitude and phase information of each electrical quantity.

[0102] The fault analysis module determines whether a grounding fault has occurred in the distribution network and the type of fault based on the collected electrical quantity information.

[0103] The control and drive module controls and drives the output voltage and current of the arc suppression device based on the collected electrical quantities and the determined fault type, thereby suppressing the current and voltage at the ground fault point to zero.

[0104] In addition to the above, the present invention also includes the following embodiments:

[0105] like Figure 6As shown, in one embodiment of the present invention, the feasibility and effectiveness of the proposed method are verified through experiments. The total zero-sequence ground leakage resistance R0 of the distribution network is 2280Ω, the total zero-sequence ground capacitance C0 is 34.02μF, and the two flexible arc suppression devices are VZSG1 and VZSG2. A phase-A ground fault occurs in the distribution network at 0.03s. At 0.1s, VZSG1 and VZSG2 start operating simultaneously. At 0.2s, a disturbance occurs in the distribution network, and the ground fault resistance R... f The results are as follows: (The values ​​are 50Ω for low resistance and 5000Ω for high resistance.) Figure 6 As shown in (a) and (b), two flexible arc suppression devices suppress the ground fault current and fault voltage below the arc ignition point, and maintain the zero-sequence impedance voltage to ground at a value negative of the fault phase power supply voltage. Even after a disturbance occurs in the distribution network, the two flexible arc suppression devices can still operate stably and coordinately, keeping the ground fault current and fault voltage below the arc ignition point. Therefore, the feasibility and effectiveness of the proposed method are verified.

[0106] The above are preferred embodiments of the present invention. Any changes made to the technical solution of the present invention that do not exceed the scope of the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims

1. A control method for a flexible arc suppression device for grounding faults in a power distribution network, characterized in that, Includes the following: The electrical parameters that the flexible arc suppression device needs to meet are determined by using the zero-sequence network circuit of single-phase grounding fault in the distribution network. Based on the electrical parameters that the flexible arc suppression device needs to meet during operation, an algorithm is proposed to control the flexible arc suppression device to operate in a virtual zero-sequence synchronous generator mode, so that the flexible arc suppression device operates in a virtual zero-sequence synchronous generator mode during operation.

2. The control method for a flexible arc suppression device for grounding faults in a power distribution network according to claim 1, characterized in that, The electrical parameters that the flexible arc suppression device needs to meet also include the following: The electrical parameters that the flexible arc suppression device needs to meet include: the flexible arc suppression device, as a controlled zero-sequence source, provides the required active and reactive power to the total zero-sequence impedance of the distribution network; furthermore, the zero-sequence current output by the flexible arc suppression device will be entirely provided to the total zero-sequence impedance of the distribution network, so that the ground fault current and voltage are zero; the rated zero-sequence voltage supported by the total zero-sequence impedance of the distribution network output by the flexible arc suppression device. The total zero-sequence impedance to ground of the distribution network includes the total zero-sequence leakage resistance to ground and the total zero-sequence capacitance to ground of the distribution network. The negative value of the fault phase power supply voltage is the rated zero-sequence voltage that the flexible arc suppression device needs to support for the total zero-sequence impedance to ground of the distribution network. The relationship between the active and reactive power output of the flexible arc suppression device and the frequency and amplitude of the zero-sequence voltage in the distribution network is as follows: Among them, P G0 It is the active power output to the distribution network; Q G0 It is the active power output to the distribution network; E G0 It is the amplitude of the output voltage of the flexible arc suppression device; E f The rated zero-sequence voltage amplitude that the flexible arc-suppression device needs to support for the total zero-sequence impedance to ground of the distribution network; Z G0 It is the output impedance, including the virtual impedance Z. V0 and filter reactance X F0 ; θ EG0 It is the phase angle of the output voltage of the flexible arc suppression device.

3. The control method for a flexible arc suppression device for grounding faults in a power distribution network according to claim 2, characterized in that, The algorithm for controlling the flexible arc suppression device to operate in virtual zero-sequence synchronous generator mode includes the following: The use of zero-axis virtual damping and virtual inertia enables the flexible arc suppression device to possess the motion characteristics of a synchronous generator rotor. The use of zero-axis virtual excitation control enables the flexible arc suppression device to possess the stator excitation characteristics of a synchronous generator; Based on the active and reactive power output of the flexible arc suppression device and the zero-sequence voltage of the distribution network, the flexible arc suppression device is made to have the drooping characteristics of a synchronous generator. Add virtual impedance control to coordinate the output of the flexible arc suppression device.

4. The control method for a flexible arc suppression device for grounding faults in a power distribution network according to claim 3, characterized in that, The use of zero-axis virtual damping and virtual inertia to enable the flexible arc suppression device to possess the motion characteristics of a synchronous generator rotor includes the following: The equations for simulating the rotor motion of a synchronous generator using a flexible arc-extinguishing device are designed as follows: Where J is the virtual moment of inertia; ω G0 ω0 and ω0 are the rated and actual angular velocities of the virtual rotor, respectively; P D and P G0 These represent the active power supplied by the flexible arc suppression device on the DC side and the active power output to the distribution network, respectively; D is the virtual damping coefficient; K J It is the virtual inertia adjustment coefficient.

5. The control method for a flexible arc suppression device for grounding faults in a power distribution network according to claim 3, characterized in that, Employing zero-axis virtual excitation control enables the flexible arc suppression device to possess the stator excitation characteristics of a synchronous generator, including the following: The equations and implementation schemes for simulating stator excitation dynamics using a flexible arc-suppression device are designed as follows: Among them, E G0 It is the amplitude of the output voltage of the flexible arc suppression device, E G0ref This is its reference value; E f The flexible arc suppression device needs to support the rated zero-sequence voltage amplitude for the total zero-sequence impedance of the distribution network; U G0 It is the voltage amplitude at the grid connection point of the flexible arc suppression device; U D It is the final calculated zero-sequence voltage amplitude; K e It is the excitation gain, T e It is the excitation time constant; K p and K I These are the proportional and integral coefficients of the PI controller that simulates excitation characteristics.

6. The control method for a flexible arc suppression device for grounding faults in a power distribution network according to claim 5, characterized in that, Employing zero-axis virtual excitation control to give the flexible arc suppression device the stator excitation characteristics of a synchronous generator also includes the following: The implementation scheme for simulating stator excitation dynamics using a flexible arc suppression device can be replaced by a PI controller. The difference between the final calculated zero-sequence voltage amplitude and the voltage amplitude at the grid connection point of the flexible arc suppression device is input into the PI controller. The output of the PI controller is summed with the rated zero-sequence voltage amplitude supported by the total zero-sequence impedance of the distribution network required by the flexible arc suppression device to obtain the reference value of the output voltage amplitude of the flexible arc suppression device.

7. The control method for a flexible arc suppression device for grounding faults in a power distribution network according to claim 3, characterized in that, Based on the relationship between the active and reactive power output of the flexible arc suppression device and the zero-sequence voltage of the distribution network, enabling the flexible arc suppression device to possess the droop characteristics of a synchronous generator, the following are included: In the formula, P D P0 is the actual calculated active power output of the flexible arc-extinguishing device, and K is the reference value of the active power output of the flexible arc-extinguishing device. ω It is the frequency regulation coefficient; Q0 is the reference value of the reactive power output of the flexible arc suppression device, Q G0 It is the actual calculated reactive power output of the flexible arc suppression device, K. U It is the voltage amplitude adjustment coefficient.

8. The control method for a flexible arc suppression device for grounding faults in a power distribution network according to claim 3, characterized in that, Adding virtual impedance control to coordinate the output of the flexible arc suppression device includes the following: in, It is the output voltage of the flexible arc suppression device; It is the grid connection voltage of the flexible arc suppression device; Z G0 It is the output impedance, including the virtual impedance Z. V0 and filter reactance X F0 .

9. The control method for a flexible arc suppression device for grounding faults in a power distribution network according to claim 8, characterized in that, The output of the enhanced flexible arc suppression device also includes the following: When multiple flexible arc suppression devices in a distribution network jointly dominate the zero-sequence voltage of the zero-sequence network circuit, these devices can coordinate and operate stably and communicate with each other.

10. A control system for a flexible arc-suppression device for grounding faults in a power distribution network, used to execute the control method for a flexible arc-suppression device for grounding faults in a power distribution network as described in any one of claims 1 to 9, characterized in that, The invention includes a flexible arc-extinguishing device, wherein the flexible arc-extinguishing device comprises the following: The flexible arc extinguishing device includes a sampling module, a fault analysis module, and a control drive module; The sampling module measures the three-phase voltage and zero-sequence voltage at the grid connection point of the arc suppression device, the output current of the flexible arc suppression device, and calculates the amplitude and phase information of each electrical quantity. The fault analysis module determines whether a grounding fault has occurred in the distribution network and the type of fault based on the collected electrical quantity information. The control and drive module controls and drives the output voltage and current of the arc suppression device based on the collected electrical quantities and the determined fault type, thereby suppressing the current and voltage at the ground fault point to zero.

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