High-resistance grounding fault detection method and device for inverter grid-connected system

Abstract

The invention discloses a high-resistance grounding fault detection method and device for an inverter grid-connected system, and belongs to the technical field of power system control. The high-resistance grounding fault detection method comprises the steps that in the first regulation and control stage, the maximum current constraint of a converter and the reactive power support requirement of a power grid are met; enabling first positive and negative sequence current amplitudes currently output by the inverter to be equal, and enabling the phase difference to be 180 degrees; in the second regulation and control stage, positive-sequence reactive current is injected for supporting voltage recovery, the amplitudes of first positive and negative sequence current currently output by the inverter are made to be equal to the positive-sequence reactive current, and the phase difference is 180 degrees; according to the invention, through controllable injection of inverter sequence components in different stages, an electrical quantity increment fault loop equation is constructed to realize protection discrimination, the influence of transition resistance and system parameter uncertainty on impedance distance measurement is reduced, the quickness and reliability of a line high-resistance grounding fault are improved, and the method is suitable for line protection of an inverter grid-connected scene.

Description

Technical Field

[0001] This invention belongs to the field of power system control technology, and more specifically, relates to a method and device for detecting high-resistance grounding faults in inverter grid-connected systems. Background Technology

[0002] Existing renewable energy sources are typically connected to the AC grid via inverters to achieve efficient energy conversion and injection. However, in inverter-connected systems, high-resistance ground faults are a common and insidious type of fault. Their fault resistance often reaches hundreds of ohms, resulting in small fault current amplitudes, large phase shifts, and significant nonlinear harmonic components. Traditional ground fault protection based on amplitude thresholds is difficult to reliably identify, and is prone to failure to operate or false operation, seriously threatening the stability of the power grid and the continuous operation of renewable energy equipment.

[0003] Currently, fault detection in inverter grid-connected systems mainly relies on independent protection devices. However, due to the current-limiting characteristics of the inverter's output current and the dynamic response of the control strategy, existing methods are not sensitive enough in high-impedance fault scenarios and cannot quickly locate the fault point, which may trigger a chain reaction, such as voltage collapse or system disconnection.

[0004] Therefore, there is an urgent need for an innovative detection method based on the synergy of control and protection to achieve accurate identification and rapid isolation of high-resistance grounding faults, so as to improve the overall reliability and grid adaptability of inverter grid-connected systems. Summary of the Invention

[0005] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention provides a method and device for detecting high-resistance grounding faults in inverter grid-connected systems. The purpose is to solve the technical problem that the existing methods are not sensitive enough in high-resistance fault scenarios, and cannot quickly locate the fault point, which may lead to a chain reaction.

[0006] To achieve the above objectives, according to one aspect of the present invention, a method for detecting high-resistance grounding faults in an inverter grid-connected system is provided, comprising:

[0007] When a ground fault is detected in any phase of the inverter grid-connected system, the first control phase is initiated. During this first control phase, while satisfying the inverter's maximum current constraint and the grid's reactive power support requirements, the inverter's current output first positive sequence current is controlled. With the first negative sequence current The amplitude is adjusted to be equal, and the sequence phase difference is set. ; When the first regulation phase continues After sampling points, the second control phase begins; in the second control phase: positive sequence reactive current is injected. Perform a support voltage recovery to restore the second positive sequence current of the inverter's current output. , the amplitude of the second negative sequence current is regulated again to be equal to the amplitude of the second positive sequence current and the phase difference ; The voltage and current at the protection installation under the two regulation stages are incrementally operated to obtain the line voltage drop increments corresponding to the two regulation stages respectively, and the fault loop equation is constructed by using the line voltage drop increments of the two groups of multiple sampling points to solve the fault distance of the fault loop equation. If the fault distance is less than the preset setting range, it is determined as an internal fault.

[0008] Further, the maximum current constraint of the converter includes: the rated current in a preset range, which is used to ensure the hardware safety margin and avoid thermal overload.

[0009] Further, the power grid reactive power support demand includes: injecting reactive current according to a preset reactive power injection ratio, which is used to improve the voltage recovery capability.

[0010] Further, the injected positive sequence reactive current supports voltage recovery, including: the injected positive sequence reactive current ; wherein, is the reactive current, is the rated current, is the voltage base value.

[0011] Further, the increment operation of the voltage and current at the protection installation under the two regulation stages to obtain the line voltage drop increments of multiple sampling points corresponding to the two regulation stages includes: The line voltage drop increment of the first regulation stage is calculated by using the following formula:

[0012] The line voltage drop increment of the second regulation stage is calculated by using the following formula: ; wherein, and respectively represent the line voltage drop increments of the fault phase in the first regulation stage and the second regulation stage, , and are the current measurement values of the A, B, and C phases under the first regulation stage, , and are the current measurement values of the A, B, and C phases under the second regulation stage, is the line unit length self-resistance, a line per unit length mutual resistance, a line per unit length self-inductance, a line per unit length mutual inductance.

[0013] Further, the line pressure drop increment of the two groups of multiple sampling points is used to construct a fault loop equation, comprising: For the measurement values of the multiple sampling points of the first regulation stage and the multiple sampling points of the second regulation stage, the expression is: ; ; The fault loop equation is obtained by performing a differential operation on the measurement values of the two-stage corresponding sampling points: ; Solving the fault loop equation obtains a fault distance of a fault phase ; ; Wherein, n is the number of sampling points of each stage, and are voltage measurement values of the sampling point i of the first regulation stage and the second regulation stage respectively, and are line pressure drop increments of the sampling point i of the first regulation stage and the second regulation stage respectively, is a zero sequence current of the sampling point i of the two stages, is a grounding resistance.

[0014] Further, it also includes: collecting voltage and current electrical quantity parameters of the line protection installation in real time to determine whether a grounding fault exists.

[0015] According to another aspect of the present application, a high-resistance grounding fault detection device of an inverter grid-connected system is provided, comprising: A first regulation module is configured to enter a first regulation stage when detecting that a grounding fault occurs in any phase of the inverter grid-connected system; in the first regulation stage, the amplitude of a first positive sequence current output by the inverter is regulated to be equal to the amplitude of a first negative sequence current while meeting the maximum current constraint of the converter and the reactive power support requirement of the power grid, and a sequence phase difference ; A second regulation module is configured to enter a second regulation stage when the first regulation stage lasts for a sampling point; in the second regulation stage, a positive sequence reactive current is injected to support voltage recovery, so that a second positive sequence current output by the inverter is regulated again to make the amplitude of a second negative sequence current equal to the amplitude of the second positive sequence current have equal amplitudes and a phase difference ; The solving module is configured to perform incremental operation on the voltage and the current at the protection installation in the two regulation stages to obtain line voltage drop increments corresponding to the two regulation stages respectively, and construct a fault loop equation by using the line voltage drop increments of the two groups of multiple sampling points, and solve the fault distance of the fault loop equation. The determining module is configured to determine that the fault is an internal fault if the fault distance is less than a preset setting range.

[0016] According to another aspect of the present application, an electronic device is provided, which comprises a memory and a processor, the memory stores a computer program, and the processor implements the steps of the high-resistance ground fault detection method of the inverter grid-connected system when executing the computer program.

[0017] According to another aspect of the present application, a computer readable storage medium is provided, which stores a computer program, and the processor implements the steps of the high-resistance ground fault detection method of the inverter grid-connected system when executing the computer program.

[0018] Overall, compared with the prior art, the above technical solutions conceived by the present application can achieve the following beneficial effects: (1) The present application provides a high-resistance ground fault detection method of an inverter grid-connected system, which constructs an electrical quantity increment fault loop equation by controllable injection of inverter sequence components in different stages to realize protection discrimination, reduces the influence of transition resistance and system parameter uncertainty on impedance distance measurement, improves the speed and reliability of line high-resistance ground fault, and is suitable for line protection in an inverter grid-connected scenario. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a flowchart of the high-resistance ground fault detection method provided by an embodiment of the present application; Figure 2 is a schematic diagram of a typical new energy field station sending-out system structure provided by an embodiment of the present application; Figure 3 is a fault distance calculated by a traditional differential equation distance protection element when a single-phase ground 100 high-resistance fault occurs at the new energy field station sending-out line F1 (a line midpoint position) in an embodiment of the present application; Figure 4 is a fault distance calculated by the high-resistance ground fault detection method of the inverter grid-connected system based on control and protection collaboration when a single-phase ground 100 high-resistance fault occurs at the new energy field station sending-out line F1 (a line midpoint position) in an embodiment of the present application; Figure 5The fault distance calculated by the high-resistance grounding fault detection method of the inverter grid-connected system based on control and protection cooperation when a single-phase grounding 100 high-resistance fault occurs at the new energy station sending-out line F2 (line end position) in an embodiment of the application. DETAILED DESCRIPTION

[0020] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0021] Embodiment 1 The embodiment provides a high-resistance grounding fault detection method of an inverter grid-connected system, comprising S1-S5.

[0022] S1: Real-time acquisition of voltage and current electrical quantity parameters at the line protection installation position to determine whether there is a grounding fault.

[0023] S2: When detecting that a grounding fault occurs in any phase of the inverter grid-connected system, enter the first control stage; in the first control stage: while meeting the maximum current constraint of the converter and the reactive power support demand of the power grid, the amplitudes of the first positive sequence current and the first negative sequence current output by the inverter are controlled to be equal, and the phase difference is set.

[0024] S3: When the first control stage lasts for sampling points, enter the second control stage; in the second control stage: the positive sequence reactive current is injected to support voltage recovery, so that the second positive sequence current output by the inverter is re-controlled, and the amplitude of the second negative sequence current is controlled to be equal to the amplitude of the second positive sequence current and the phase difference .

[0025] S4: Incremental operation is performed on the voltage and current at the protection installation position in the two control stages to obtain the line voltage drop increments corresponding to the two control stages respectively, and the fault loop equation is constructed by using the line voltage drop increments of the two groups of multiple sampling points, and the fault distance of the fault loop equation is solved.

[0026] S5: If the fault distance is less than the preset setting range, it is determined as an internal fault.

[0027] In one embodiment, S1 includes: using a data acquisition device to collect in real time the voltage and current electrical parameters at the installation location of the line protection, including the three-phase voltages U of phases A, B, and C. A U B U C and current I A I B I C After high-frequency noise interference is removed by digital low-pass filtering, the signal enters the low-voltage ride-through (LVRT) component discrimination logic. This is achieved by calculating the voltage amplitude of each phase. ( It consists of phases A, B, and C, among which , (dq axis components), and compare them with a preset low voltage threshold. ,in It can be set to 0.9 pu, if This indicates a voltage drop in that phase, and the corresponding phase is the faulty phase. The positive sequence voltage component is calculated based on the symmetrical component method. Negative sequence voltage component and zero-sequence voltage component (in (where is a complex twitch factor), analyzing asymmetry. ,like If so, it is determined to be an asymmetric fault, where It can be set to 0.1. Furthermore, if the zero-order component... (Set voltage) (Set to 0.05pu) to determine if there is a grounding fault in the corresponding fault phase (A, B, C phases), thereby triggering the subsequent fault response mechanism.

[0028] Optionally, the maximum current constraint of the converter in S2 includes: rated current. Within a preset range, this is used to ensure hardware safety margins and avoid thermal overload. Furthermore, the grid's reactive power support requirements include: injecting reactive current according to a preset reactive power injection ratio to improve voltage recovery capability.

[0029] Specifically, S2 includes: After detecting a grid connection fault by monitoring the voltage dip and sequence component anomalies at the grid connection point, the inverter control device immediately switches to the first control stage of the low voltage ride-through (LVRT) control strategy. In this stage, the maximum current capacity constraint of the converter (typically the rated current I) is comprehensively considered. N 1.1 to 1.5 times, that is Where k is the overload factor, and k is set to 1.5 to ensure hardware safety margin and avoid thermal overload) and the reactive power support requirements of the power grid (according to power grid specifications such as GB / T 19964 or IEEE 1547 standards, reactive current is injected first to improve voltage recovery capability, for example, by dynamically calculating the reactive power injection ratio). ,in For reference reactive power, To control the apparent power limit of the inverter, adjust the amplitude of the positive sequence current output of the inverter. With negative sequence current amplitude Equal. Specifically, to balance the positive and negative sequence components and maximize the reactive power support effect, while satisfying the constraint that the total current vector does not exceed the limit, i.e., the total current amplitude... (exist Simplified to ),set up (in (The maximum allowable current of the converter), and set the sequence phase difference. .

[0030] Furthermore, inject positive-sequence reactive current. Support voltage restoration includes: injected positive-sequence reactive current. ;in, It is reactive current. Rated current, This is the per-unit voltage value.

[0031] Specifically, S3 includes: after the first control phase lasts for T1 sampling points, switching to the second control phase of the low voltage ride-through (LVRT) control strategy. In this phase, firstly, based on the voltage drop level and the reactive current injection specifications in the national standard GB / T 19964-2012, when... Reactive current needs to be injected to support voltage recovery. The specific formula is the positive sequence reactive current injected. That is, positive sequence current equal ,in It is reactive current. Rated current, Voltage per unit value; positive sequence current After confirmation, adjust the negative sequence current amplitude. Make it consistent with the positive sequence current amplitude Equal, that is And the phases are opposite (phase difference) ).

[0032] Furthermore, in S4, incremental calculations are performed on the voltage and current at the protection installation point under the two control stages to obtain the line voltage drop increments at multiple sampling points corresponding to each of the two control stages, including: The line voltage drop increment during the first control phase is calculated using the following formula:

[0033] The line voltage drop increment during the second control phase is calculated using the following formula: ; in, and These represent the faulty phases. The increase in line voltage drop during the first and second control phases. , and These are the current measurement values ​​for phases A, B, and C during the first control phase, respectively. , and These are the current measurement values ​​for phases A, B, and C during the second control stage, respectively. The self-resistance per unit length of the line. The mutual resistance per unit length of the line. The self-inductance per unit length of the line. The mutual inductance per unit length of the line.

[0034] Furthermore, a fault loop equation is constructed using the line voltage drop increments from two sets of multi-sampling points, including: for the measured values ​​of multiple sampling points in the first control phase and multiple sampling points in the second control phase, the expression is: ; ; The fault loop equation is obtained by performing differential calculations on the measured values ​​of the corresponding sampling points in the two stages: ; Solving the fault loop equations yields the fault phase. Fault distance ;in, n is the number of sampling points in each stage. and These are the voltage measurements at sampling point i in the first and second control phases, respectively. and These represent the line voltage drop increments at sampling point i in the first and second control phases, respectively. The zero-sequence current at sampling point i in the two stages. This is the grounding resistance.

[0035] In one embodiment, S4 includes: performing incremental calculations based on the current voltage and current measurements at the protection installation location (corresponding to the values ​​under the control strategy of the second control stage) and the memory values ​​before T1 sampling points (corresponding to the values ​​under the control strategy of the first control stage), where T1 is a value of one cycle sampling point (80 points). The fault loop equation is constructed using the voltage and current increments, and the fault distance is solved. Specifically, assuming the fault is a high-resistance ground fault in phase A, the line voltage drop increment for each stage is first calculated: for the first control stage, Similar calculations for the second phase of regulation Then, a set of fault loop equations is constructed for multiple sampling points in the first control phase: The second phase of regulation is similar: By performing differential calculations on the measured values ​​from the corresponding sampling points in two stages, the unknown grounding resistance can be eliminated. The item (due to the coordinated design of control and protection, the two-stage zero-sequence current) (If they are equal, the difference term will be 0), resulting in the simplified equation: Thus, the fault distance can be calculated. (Accuracy and robustness can be improved by using the least squares method).

[0036] In one embodiment, S5 includes: if the calculated fault distance (Based on incremental calculation in S4) Less than the preset tuning range , If the value is 80% of the total length of the protected area line, it is determined to be a fault within the area and the protection action is triggered; otherwise, if If the fault is outside the designated area, the protection system will remain inactive.

[0037] This will be illustrated using a typical new energy wind farm transmission system as an example, such as... Figure 2 As shown, a wind farm mainly includes doubly-fed induction generators, transformer substations, collector lines, and the main transformer at the wind farm. The wind farm is connected to external systems via transmission lines. s This is the equivalent voltage source for the external system; N and M are the protection installation points at both ends of the line. Figure 3 In one embodiment of the present invention, a single-phase ground fault occurred at point F1 (midpoint of the line) on the power transmission line of the new energy power station. In the case of a high-resistance fault, the fault distance is calculated by solving the differential equation and the distance to the protection element in the traditional method. Figure 4 In one embodiment of the present invention, a single-phase ground fault occurred at point F1 (midpoint of the line) on the power transmission line of the new energy power station. The fault distance is calculated by the high-resistance grounding fault detection method of inverter grid-connected system based on control and protection coordination during high-resistance faults. Figure 5 In one embodiment of the present invention, a single-phase ground fault occurred at point F2 (the end of the line) of the new energy power station transmission line. The fault distance is calculated by the high-resistance grounding fault detection method of inverter grid-connected system based on control and protection coordination during high-resistance faults.

[0038] Example 2 This embodiment provides a high-resistance grounding fault detection device for an inverter grid-connected system, including: a first control module, a second control module, a solution module, and a judgment module.

[0039] The first control module is used to enter the first control phase when a ground fault is detected in any phase of the inverter grid-connected system. During the first control phase, while meeting the maximum current constraint of the inverter and the reactive power support requirements of the grid, the first positive sequence current currently output by the inverter is controlled. With the first negative sequence current The amplitude is adjusted to be equal, and the sequence phase difference is set. .

[0040] The second control module is used when the first control phase continues... After sampling points, the second control phase begins; in the second control phase: positive sequence reactive current is injected. Perform a support voltage recovery to restore the second positive sequence current of the inverter's current output. Then regulate the second negative sequence current. The amplitude makes it similar to the second positive sequence current. The amplitudes are equal and the phase difference is equal. .

[0041] The solution module is used to perform incremental calculations on the voltage and current at the protection installation point under two control stages to obtain the line voltage drop increment corresponding to each of the two control stages. The fault loop equation is constructed using the line voltage drop increments of two sets of multi-sampling points, and the fault distance is solved by solving the fault loop equation.

[0042] The judgment module is used to determine that if the fault distance is less than the preset setting range, it is a fault within the zone.

[0043] Example 3 The present invention also relates to an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the high-resistance grounding fault detection method for the inverter grid-connected system described above.

[0044] The electronic device can be a desktop computer, laptop, handheld computer, or cloud server, etc. The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The memory can be used to store computer programs and / or modules. The processor implements various functions of the electronic device by running or executing the computer programs and / or modules stored in the memory, and by accessing data stored in the memory.

[0045] Example 4 The present invention also relates to a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the high-resistance grounding fault detection method for the inverter grid-connected system described above.

[0046] Specifically, the memory may include high-speed random access memory, as well as non-volatile memory, such as hard disks, RAM, plug-in hard disks, smart media cards (SMC), secure digital (SD) cards, flash cards, at least one disk storage device, flash memory device, or other volatile solid-state storage devices.

[0047] Example 5 This invention provides a computer program product or computer program that includes computer instructions stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the computer device to perform the steps of the method described in the above embodiments of this invention.

[0048] The technical features of the embodiments described above can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. It should be noted that the terms "in one embodiment," "for example," and "again" in this invention are intended to illustrate the invention and are not intended to limit the invention.

[0049] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for detecting high-resistance grounding faults in an inverter grid-connected system, characterized in that, include: When a ground fault is detected in any phase of the inverter grid-connected system, the first control phase is entered; During the first control phase: while meeting the maximum current constraint of the inverter and the reactive power support requirements of the grid, the first positive sequence current currently output by the inverter will be... With the first negative sequence current The amplitude is adjusted to be equal, and the sequence phase difference is set. ; When the first regulation phase continues After sampling points, the second control phase begins; in the second control phase: positive sequence reactive current is injected. Perform a support voltage recovery to restore the second positive sequence current of the inverter's current output. Then regulate the second negative sequence current. The amplitude makes it similar to the second positive sequence current. The amplitudes are equal and the phase difference is equal. ; Incremental calculations are performed on the voltage and current at the protection installation point under the two control stages to obtain the line voltage drop increment corresponding to each of the two control stages. The fault loop equation is constructed using the line voltage drop increments of two sets of multi-sampling points, and the fault distance is solved by solving the fault loop equation. If the fault distance is less than the preset setting range, it is determined to be a fault within the zone.

2. The high-resistance grounding fault detection method for inverter grid-connected systems as described in claim 1, characterized in that, The maximum current constraint of the converter includes: rated current. Within a preset range, it is used to ensure hardware safety margins and avoid thermal overload.

3. The high-resistance grounding fault detection method for inverter grid-connected systems as described in claim 1, characterized in that, The power grid reactive power support requirements include: injecting reactive current according to a preset reactive power injection ratio to improve voltage recovery capability.

4. The high-resistance grounding fault detection method for inverter grid-connected systems as described in claim 1, characterized in that, The injected positive sequence reactive current Support voltage restoration includes: injected positive-sequence reactive current. ;in, It is reactive current. Rated current, This is the per-unit voltage value.

5. The high-resistance grounding fault detection method for inverter grid-connected systems as described in claim 1, characterized in that, The incremental calculation of the voltage and current at the protection installation point under the two control stages to obtain the line voltage drop increment at multiple sampling points corresponding to each of the two control stages includes: The line voltage drop increment during the first control phase is calculated using the following formula: The line voltage drop increment during the second control phase is calculated using the following formula: ； in, and These represent the faulty phases. The increase in line voltage drop during the first and second control phases. , and These are the current measurement values ​​for phases A, B, and C during the first control phase, respectively. , and These are the current measurement values ​​for phases A, B, and C during the second control stage, respectively. The self-resistance per unit length of the line. The mutual resistance per unit length of the line. The self-inductance per unit length of the line. The mutual inductance per unit length of the line.

6. The high-resistance grounding fault detection method for an inverter grid-connected system as described in claim 5, characterized in that, The method of constructing fault loop equations using the line voltage drop increments from two sets of multi-sampling points includes: For the measured values ​​of multiple sampling points in the first control phase and multiple sampling points in the second control phase, the expression is: ; ; The fault loop equation is obtained by performing differential calculations on the measured values ​​of the corresponding sampling points in the two stages: ； Solving the fault loop equations yields the fault phase. Fault distance ; in, n is the number of sampling points in each stage. and These are the voltage measurements at sampling point i in the first and second control phases, respectively. and These represent the line voltage drop increments at sampling point i in the first and second control phases, respectively. The zero-sequence current at sampling point i in the two stages. This is the grounding resistance.

7. The high-resistance grounding fault detection method for inverter grid-connected systems as described in claim 1, characterized in that, Also includes: Real-time acquisition of voltage and current electrical parameters at the installation location of line protection devices is used to determine whether a grounding fault exists.

8. A high-resistance grounding fault detection device for an inverter grid-connected system, characterized in that, include: The first control module is used to enter the first control stage when a ground fault is detected in any phase of the inverter grid-connected system; During the first control phase: while meeting the maximum current constraint of the inverter and the reactive power support requirements of the grid, the first positive sequence current currently output by the inverter will be... With the first negative sequence current The amplitude is adjusted to be equal, and the sequence phase difference is set. ; The second control module is used when the first control phase continues After sampling points, the second control phase begins; in the second control phase: positive sequence reactive current is injected. Perform a support voltage recovery to restore the second positive sequence current of the inverter's current output. Then regulate the second negative sequence current. The amplitude makes it similar to the second positive sequence current. The amplitudes are equal and the phase difference is equal. ; The solution module is used to perform incremental calculations on the voltage and current at the protection installation point under two control stages to obtain the line voltage drop increment corresponding to each of the two control stages. The fault loop equation is constructed using the line voltage drop increments of two sets of multi-sampling points, and the fault distance of the fault loop equation is solved. The determination module is used to determine that if the fault distance is less than a preset setting range, it is a fault within the zone.

9. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 7.

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