Single-phase earth fault line selection method, system and device, equipment and storage medium

Abstract

The embodiment of the invention discloses a single-phase earth fault line selection method, system and device, equipment and a storage medium, and the method comprises the steps: calculating a first ratio of the zero-sequence current of each feeder line of a power system before and after the input of a parallel small resistor when a permanent single-phase earth fault occurs in the power system; any feeder line is used as a reference feeder line, the first ratio of the reference feeder line is used as a reference ratio, a second ratio of the first ratio of the other feeder lines relative to the reference ratio is compared, and the other feeder lines are feeder lines except the reference feeder line; and according to the second ratio and a preset fault line selection rule, distinguishing a fault feeder line and a non-fault feeder line to obtain a line selection result. The method is simple, high in line selection accuracy and good in transition resistance tolerance.

Description

Technical Field

[0001] The present invention relates to the field of power protection technology, and in particular to a single-phase grounding fault line selection method, system and device, equipment and storage medium. Background Art

[0002] Distributed energy is increasing its share in distribution networks year by year due to its advantages of cleanliness, environmental friendliness, and sustainable development. This also makes the fault evolution mechanism of active distribution networks more and more complicated after a single-phase grounding fault occurs. Rapid and accurate fault line selection helps to minimize the adverse effects of the fault on the distribution network. There is a relative lack of research on line selection methods for flexible grounding active distribution networks containing distributed power sources, and it is of practical significance to propose a reliable single-phase grounding fault line selection method. Summary of the invention

[0003] The main purpose of the present invention is to provide a single-phase grounding fault line selection method, system and device, equipment and storage medium, which can solve the problem of lack of reliable single-phase grounding fault line selection method in the prior art.

[0004] To achieve the above object, the present invention provides a single-phase ground fault line selection method in a first aspect, the method comprising:

[0005] When a permanent single-phase grounding fault occurs in the power system, a first ratio of zero-sequence currents of feeders in the power system before and after a small parallel resistor is connected is calculated;

[0006] Taking any feeder as a reference feeder, the first ratio of the reference feeder is the reference ratio, and comparing the second ratios of the first ratios of the remaining feeders relative to the reference ratio, the remaining feeders are feeders other than the reference feeder;

[0007] The faulty feeder and the non-faulty feeder are distinguished according to the second ratio and a preset faulty line selection rule to obtain a line selection result.

[0008] In a feasible implementation, the line selection result includes at least a faulty feeder, and the faulty line selection rule includes a first rule and a second rule, and the faulty feeder and the non-faulty feeder are distinguished according to the second ratio and the preset faulty line selection rule to obtain the line selection result, including:

[0009] If there is a first feeder whose second ratio satisfies a preset first rule, determining that the first feeder is a faulty feeder, the first rule being that the amplitude of the second ratio is not less than a first threshold value and the phase is within a first phase interval;

[0010] If there is a second feeder whose second ratio satisfies a preset second rule, determining that the reference feeder is a faulty feeder, the second rule being that the amplitude of the second ratio is not higher than a second threshold value and the phase is within a second phase interval;

[0011] If the first feeder or the second feeder does not exist, it is determined that the busbar of the power system is a faulty feeder.

[0012] In a feasible implementation, the power system is an active distribution network, and the first ratio of zero-sequence current of each feeder of the power system before and after the parallel small resistance is put into operation is calculated, and the above also includes:

[0013] When the active power distribution network is in a normal operating state, the switch at the flexible grounding point of the active power distribution network is disconnected, and the active power distribution network is in a grounding state through an arc suppression coil;

[0014] When a single-phase grounding fault occurs in the active distribution network, the switch is kept disconnected, and the first zero-sequence current of each feeder connected in parallel with a small resistor in the previous power frequency cycle is obtained by sampling;

[0015] When the single-phase grounding fault is determined to be a permanent grounding fault, the switch is controlled to close to input a small parallel resistor, and the second zero-sequence current of each feeder after a delay of a preset time length and one power frequency cycle is obtained by sampling.

[0016] In a feasible implementation, the second ratio includes the following mathematical expression:

[0017]

[0018] In the formula, Feeder L i The first ratio of The reference feeder L p The first ratio of Feeder L i The second ratio of 0i Feeder L i The first zero sequence current, I' 0i Feeder L i The second zero-sequence current; I 0p The reference feeder L p The first zero sequence current, I' 0p The reference feeder L p The second zero-sequence current; M i-p Feeder L i The second ratio The amplitude of Feeder L i The second ratio phase.

[0019] To achieve the above-mentioned purpose, the second aspect of the present invention provides a single-phase grounding fault line selection system, which is used to execute the steps shown in the first aspect and any feasible implementation method. There is a communication connection between the single-phase grounding fault line selection system and the power system. The power system includes a plurality of feeders and a main transformer. The main transformer is used to transmit power to each feeder. The neutral point of the main transformer adopts a flexible grounding method, and the small parallel resistor is flexibly grounded after a permanent single-phase grounding fault occurs in the system through the closure of the switch.

[0020] In a feasible implementation, the power system further includes a distributed power source, at least one of the feeders is connected to the distributed power source, and a grid-connected transformer of the distributed power source connected to any of the feeders is connected in a neutral point ungrounded manner.

[0021] To achieve the above object, the third aspect of the present invention provides a single-phase ground fault line selection device, the device comprising:

[0022] The first ratio module is used to calculate the first ratio of the zero-sequence current of each feeder of the power system before and after the parallel small resistance is put into use when a permanent single-phase grounding fault occurs in the power system;

[0023] A second ratio module: used for taking any feeder as a reference feeder, wherein the first ratio of the reference feeder is the reference ratio, and comparing the second ratios of the first ratios of the remaining feeders relative to the reference ratio, wherein the remaining feeders are feeders other than the reference feeder;

[0024] Line selection module: used to distinguish faulty feeders from non-faulty feeders according to the second ratio and a preset faulty line selection rule to obtain a line selection result.

[0025] In a feasible implementation, the line selection result includes at least a faulty feeder, and the faulty line selection rule includes a preset first rule and a preset second rule. The line selection module has a function for determining that if there is a first feeder whose second ratio satisfies the preset first rule, the first feeder is determined to be a faulty feeder, and the first rule is that the amplitude of the second ratio is not lower than a first threshold value, and the phase is within a first phase interval; if there is a second feeder whose second ratio satisfies the preset second rule, the reference feeder is determined to be a faulty feeder, and the second rule is that the amplitude of the second ratio is not higher than a second threshold value, and the phase is within a second phase interval; if the first feeder or the second feeder does not exist, the busbar of the power system is determined to be a faulty feeder.

[0026] To achieve the above-mentioned purpose, the fourth aspect of the present invention provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the processor executes the steps of the first aspect and any feasible implementation method.

[0027] To achieve the above-mentioned purpose, the fifth aspect of the present invention provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the first aspect and any feasible implementation method.

[0028] The embodiments of the present invention have the following beneficial effects:

[0029] The present invention provides a single-phase grounding fault line selection method, the method comprising: when a permanent single-phase grounding fault occurs in a power system, calculating the first ratio of zero-sequence current of each feeder of the power system before and after a small parallel resistor is put into operation; taking any feeder as a reference feeder, the first ratio of the reference feeder is the reference ratio, comparing the second ratio of the first ratio of the remaining feeders relative to the reference ratio, the remaining feeders are feeders other than the reference feeder; distinguishing the fault feeder from the non-fault feeder according to the second ratio and a preset fault line selection rule, and obtaining a line selection result. The method of the present invention is simple, has a high line selection accuracy, and has a good ability to tolerate transition resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] in:

[0032] Figure 1 This is a flow chart of a single-phase ground fault line selection method according to an embodiment of the present invention;

[0033] Figure 2 A 10kV distribution network topology diagram in an embodiment of the present invention;

[0034] Figure 3 Another flow chart of a single-phase ground fault line selection method according to an embodiment of the present invention;

[0035] Figure 4 A zero-sequence current diagram in an embodiment of the present invention;

[0036] Figure 5 It is a structural block diagram of a single-phase ground fault line selection device in an embodiment of the present invention;

[0037] Figure 6 4 is a structural block diagram of a computer device in an embodiment of the present invention. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] See also Figure 1 , Figure 1 The present invention is a flowchart of a single-phase ground fault line selection method in an embodiment of the present invention, wherein the method is applied to a single-phase ground fault line selection system, the single-phase ground fault line selection system is used to execute the single-phase ground fault line selection method shown in the present application, the single-phase ground fault line selection system can be a terminal or a server, the terminal can be a desktop terminal or a mobile terminal, the mobile terminal can be at least one of a mobile phone, a tablet computer, a laptop computer, etc., and the server can be implemented by an independent server or a server cluster composed of multiple servers. The single-phase ground fault line selection system has a communication connection with the power system, wherein the power system includes a plurality of feeders and a main transformer, the main transformer is used to transmit power to each feeder, the neutral point of the main transformer adopts a flexible grounding method, and the parallel small resistor is put into flexible grounding after a permanent single-phase ground fault occurs in the system. Further, the power system also includes a distributed power supply, at least one of the feeders is connected to the distributed power supply, and the grid-connected transformer of the distributed power supply connected to any feeder adopts a neutral point ungrounded method, and the distributed power supply can be an inverter-type distributed power supply.

[0040] Further, such as Figure 1 The methods shown include:

[0041] 101. When a permanent single-phase grounding fault occurs in the power system, a first ratio of zero-sequence currents of feeders in the power system before and after a small parallel resistor is connected is calculated;

[0042] It should be noted that the power system may be an active distribution network. The present invention provides a single-phase ground fault line selection method for a flexible grounding active distribution network. For ease of understanding, the present invention adopts a 10kV distribution network, and the topology is shown in FIG. Figure 2 . Single-phase ground fault line selection method for flexible grounding active distribution network, active distribution network system flexible grounding - before S is closed, the neutral point is the arc suppression coil L s Grounding; after S is closed, the neutral point is the arc extinguishing coil L s Parallel small resistor R NGrounding. The L4 outgoing line is connected to a distributed power source DG, and the dedicated transformer of the distributed power source adopts the neutral point ungrounded operation mode. Set the system to have a metallic single-phase grounding fault at t = 0.5s. After a certain delay, the nature of the fault is judged. When it is determined that the fault is a permanent grounding fault, a small resistor R is connected in parallel at t = 1.5s. N (10Ω) input.

[0043] The first ratio of the zero-sequence current of each feeder of the power system before and after the parallel small resistor is put into operation is calculated, and steps A01 to A03 are also included to collect the zero-sequence current before and after the input:

[0044] A01. When the active distribution network is in a normal operating state, the switch at the flexible grounding point of the active distribution network is disconnected, and the active distribution network is in a grounding state through an arc suppression coil;

[0045] A02. When a single-phase grounding fault occurs in the active distribution network, the switch is kept disconnected, and the first zero-sequence current of each feeder connected in parallel with a small resistor in the previous power frequency cycle is obtained by sampling;

[0046] A03. When it is determined that the single-phase grounding fault is a permanent grounding fault, the switch is controlled to close to input a small parallel resistor, and the second zero-sequence current of each feeder after a preset delay time and one power frequency cycle is obtained by sampling.

[0047] It should be noted that continuing Figure 2 For example, when the system is operating normally, the switch S at the flexible grounding is disconnected, and the active distribution network is in the state of arc suppression coil L. s Ground state.

[0048] After a single-phase grounding fault occurs in the system, for the distribution network system with flexible grounding mode, the zero-sequence current passes through the arc suppression coil L s A loop is formed, at this time the switch S remains open and a small resistor R is connected in parallel N Not put into use. At the same time, the small parallel resistance R N Zero-sequence current I of each outgoing line in the previous power frequency cycle 0i (i=1,2,3…p…), that is, the first zero-sequence current.

[0049] When the fault is determined to be a permanent ground fault, close the switch S and connect a small parallel resistor R N . Obtain the zero-sequence current I' of each outgoing line after a delay of 0.05s and one power frequency cycle 0i (i=1,2,3…p…), that is, the second zero-sequence current.

[0050] 102. Taking any feeder as a reference feeder, the first ratio of the reference feeder is a reference ratio, and comparing second ratios of the first ratios of other feeders relative to the reference ratio, the other feeders being feeders other than the reference feeder;

[0051] In a feasible implementation, the second ratio includes the following mathematical expression:

[0052]

[0053] In the formula, Feeder L i The first ratio of The reference feeder L p The first ratio of Feeder L i The second ratio of 0i Feeder L i The first zero sequence current, I' 0i Feeder L i The second zero-sequence current; I 0p The reference feeder L p The first zero sequence current, The reference feeder L p The second zero-sequence current; M i-p Feeder L i The second ratio The amplitude of Feeder L i The second ratio phase.

[0054] 103. Distinguish the faulty feeder from the non-faulty feeder according to the second ratio and a preset faulty line selection rule to obtain a line selection result.

[0055] In a feasible implementation, the line selection result includes at least a faulty feeder, and the faulty line selection rule includes a first rule and a second rule, then step 103 includes: if there is a first feeder whose second ratio satisfies a preset first rule, then the first feeder is determined to be a faulty feeder, and the first rule is that the amplitude of the second ratio is not lower than a first threshold, and the phase is within a first phase interval; if there is a second feeder whose second ratio satisfies a preset second rule, then the reference feeder is determined to be a faulty feeder, and the second rule is that the amplitude of the second ratio is not higher than a second threshold, and the phase is within a second phase interval; if the first feeder or the second feeder does not exist, then the busbar of the power system is determined to be a faulty feeder.

[0056] It should be noted that, for the ratio of the zero-sequence current ratio of all feeders to the reference ratio, if there is a feeder whose amplitude of the zero-sequence current ratio ratio to the reference feeder is not lower than the first threshold and the phase is within the first phase interval, then the feeder is determined to be a fault line; if there is a feeder whose amplitude of the zero-sequence current ratio ratio to the reference feeder is not higher than the second threshold and the phase is within the second phase interval, then the reference feeder is determined to be a fault line.

[0057] For example, any feeder line is selected as the reference line L p ,calculate If there is M i-p ≥ the first threshold and Then determine line L i is a fault line; if there is M i-p ≤ the second threshold and Then the reference line L is determined p Otherwise, the busbar is determined to be a faulty line. It can be understood that the first phase interval is a first phase angle interval, and the second phase interval is a second phase angle interval.

[0058] by Figure 2 For example, consider the condition that the maximum ground capacitance current of a single line of a 10kV distribution system does not exceed 50A, and the condition that the ground capacitance current of the system is generally not greater than 200A. It can be calculated that the first and second thresholds are 8.271 and 0.121 respectively, and the first and second phase intervals are (83.06°, 90°) and (-90°, -83.06°) respectively. In other words, if there is M i-p ≥8.271 and Then determine line L i is a fault line; if there is M i-p ≤0.121 and Then the reference line L is determined p It is a fault line; otherwise, the bus is determined to be a fault line.

[0059] When the reference line is selected as L1, the zero-sequence current ratio of lines L1, L2, and L3 to the reference line L1 is considered to be equal to 1∠0 within the acceptable error range, and the amplitude of the zero-sequence current ratio of line L4 to the reference line L1 is greater than 8.21, and the phase angle is between (83.06°, 90°), so L4 is accurately determined as the fault line according to the line selection criterion; when the reference line is selected as L4, the zero-sequence current ratio of line L4 to the reference line L4 is equal to 1∠0, and the amplitude of the zero-sequence current ratio of lines L1, L2, and L3 to the reference line L4 is less than 0.021, and the phase angle is between (-90°, -83.06°), so L4 is accurately determined as the fault line according to the line selection criterion. In summary, whether the reference line is selected as a sound line or the fault line itself, the line selection method proposed in this paper can correctly identify the fault line.

[0060] The present invention provides a single-phase grounding fault line selection method, the method comprising: when a permanent single-phase grounding fault occurs in a power system, calculating the first ratio of zero-sequence current of each feeder of the power system before and after a small parallel resistor is put into operation; taking any feeder as a reference feeder, the first ratio of the reference feeder is the reference ratio, comparing the second ratio of the first ratio of the remaining feeders relative to the reference ratio, the remaining feeders are feeders other than the reference feeder; distinguishing the fault feeder from the non-fault feeder according to the second ratio and a preset fault line selection rule, and obtaining a line selection result. The method of the present invention is simple, has a high line selection accuracy, and has a good ability to tolerate transition resistance.

[0061] See also Figure 3 , Figure 3 Another flow chart of a single-phase ground fault line selection method according to an embodiment of the present invention is shown below in conjunction with Figure 3 Specific description of the method implementation process:

[0062] Step 1: Check if the neutral point zero-sequence current I0 is greater than the starting value I set When the protection starts, the small parallel resistance R N Zero-sequence current I of each outgoing line in the previous power frequency cycle 0i (i=1,2,3…p…) and neutral point zero sequence current I 0N .

[0063] Step 2: Connect a small resistor R in parallel N Before input, if the detected neutral point zero sequence current I 0N If it returns to normal, the fault disappears and the line selection process ends; otherwise, continue with step 3.

[0064] Step 3: Connect a small resistor R in parallel N After being put into operation, the zero-sequence current I' of each outgoing line of one power frequency cycle after a delay of 0.05s is obtained. 0i(i=1,2,3…p…).

[0065] Step 4: According to the formula If there is M i-p ≥8.271 and Then determine line L i is a fault line; if there is M i-p ≤0.121 and Then the reference line L is determined p It is a fault line; otherwise, the bus is determined to be a fault line.

[0066] Figure 4 is a zero-sequence current diagram in an embodiment of the present invention, Figure 4 Shows Figure 2 Zero-sequence current diagram of the starting ends of each outgoing line when a single-phase grounding fault occurs at point f through a 100Ω transition resistance.

[0067] The present invention discloses a single-phase grounding fault line selection method for a flexible grounding active distribution network. The line selection method calculates the zero-sequence current ratio of each feeder before and after a small parallel resistor is put into operation when a permanent single-phase grounding fault occurs in the system, and uses the zero-sequence current ratio of a certain feeder as a reference zero-sequence current ratio, compares the ratio of the zero-sequence current ratio of all feeders to the reference zero-sequence current ratio, and distinguishes the fault feeder from the non-fault feeder according to the value, that is, fault line selection. The method of the present invention is simple, has a high line selection accuracy, and has a good ability to tolerate transition resistance.

[0068] See also Figure 5 , Figure 5 FIG. 1 is a structural block diagram of a single-phase ground fault line selection device according to an embodiment of the present invention. Figure 5 The single-phase ground fault line selection device shown comprises:

[0069] The first ratio module 501 is used to calculate the first ratio of the zero-sequence current of each feeder of the power system before and after the parallel small resistance is put into operation when a permanent single-phase grounding fault occurs in the power system;

[0070] A second ratio module 502 is used to take any feeder as a reference feeder, wherein the first ratio of the reference feeder is the reference ratio, and compare the second ratios of the first ratios of the remaining feeders relative to the reference ratio, wherein the remaining feeders are feeders other than the reference feeder;

[0071] The line selection module 503 is used to distinguish the faulty feeder from the non-faulty feeder according to the second ratio and the preset faulty line selection rule to obtain a line selection result.

[0072] In a feasible implementation, the line selection result includes at least a faulty feeder, and the faulty line selection rule includes a preset first rule and a preset second rule. The line selection module has a function for determining that if there is a first feeder whose second ratio satisfies the preset first rule, the first feeder is determined to be a faulty feeder, and the first rule is that the amplitude of the second ratio is not lower than a first threshold value, and the phase is within a first phase interval; if there is a second feeder whose second ratio satisfies the preset second rule, the reference feeder is determined to be a faulty feeder, and the second rule is that the amplitude of the second ratio is not higher than a second threshold value, and the phase is within a second phase interval; if the first feeder or the second feeder does not exist, the busbar of the power system is determined to be a faulty feeder.

[0073] The present invention provides a single-phase grounding fault line selection device, the device comprising: a first ratio module: used for calculating the first ratio of zero-sequence current of each feeder of the power system before and after a small parallel resistor is put into operation when a permanent single-phase grounding fault occurs in the power system; a second ratio module: used for taking any feeder as a reference feeder, the first ratio of the reference feeder is the reference ratio, and comparing the second ratio of the first ratio of the remaining feeders relative to the reference ratio, the remaining feeders are feeders other than the reference feeder; a line selection module: used for distinguishing a fault feeder from a non-fault feeder according to the second ratio and a preset fault line selection rule, and obtaining a line selection result. The present invention is simple, has a high line selection accuracy, and has a good ability to tolerate transition resistance.

[0074] Figure 6 FIG. 1 shows an internal structure diagram of a computer device in an embodiment. The computer device may be a terminal or a server. Figure 6 As shown, the computer device includes a processor, a memory and a network interface connected via a system bus. The memory includes a non-volatile storage medium and an internal memory. The non-volatile storage medium of the computer device stores an operating system and may also store a computer program. When the computer program is executed by the processor, the processor can implement the above method. The internal memory may also store a computer program. When the computer program is executed by the processor, the processor can implement the above method. Those skilled in the art can understand that Figure 6 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0075] In one embodiment, a computer device is provided, comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the following steps: Figure 1 or Figure 3Steps shown.

[0076] In one embodiment, a computer-readable storage medium is provided, which stores a computer program. When the computer program is executed by a processor, the processor performs the following steps: Figure 1 or Figure 3 Steps shown.

[0077] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the program can be stored in a non-volatile computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0078] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0079] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A single-phase ground fault line selection method, characterized in that: The method comprises: When a permanent single-phase grounding fault occurs in the power system, a first ratio of zero-sequence currents of feeders in the power system before and after a small parallel resistor is connected is calculated; Taking any feeder as a reference feeder, the first ratio of the reference feeder is the reference ratio, and comparing the second ratios of the first ratios of the remaining feeders relative to the reference ratio, the remaining feeders are feeders other than the reference feeder; The faulty feeder and the non-faulty feeder are distinguished according to the second ratio and a preset faulty line selection rule to obtain a line selection result.

2. The method according to claim 1, characterized in that: The line selection result includes at least a faulty feeder, and the faulty line selection rule includes a first rule and a second rule. Then, the faulty feeder and the non-faulty feeder are distinguished according to the second ratio and the preset faulty line selection rule to obtain the line selection result, including: If there is a first feeder whose second ratio satisfies a preset first rule, determining that the first feeder is a faulty feeder, the first rule being that the amplitude of the second ratio is not less than a first threshold value and the phase is within a first phase interval; If there is a second feeder whose second ratio satisfies a preset second rule, determining that the reference feeder is a faulty feeder, the second rule being that the amplitude of the second ratio is not higher than a second threshold value and the phase is within a second phase interval; If the first feeder or the second feeder does not exist, it is determined that the busbar of the power system is a faulty feeder.

3. The method according to claim 1, characterized in that: The power system is an active distribution network, and the first ratio of zero-sequence current of each feeder of the power system before and after the parallel small resistor is put into operation is calculated, and the above also includes: When the active power distribution network is in a normal operating state, the switch at the flexible grounding point of the active power distribution network is disconnected, and the active power distribution network is in a grounding state through an arc suppression coil; When a single-phase grounding fault occurs in the active distribution network, the switch is kept disconnected, and the first zero-sequence current of each feeder connected in parallel with a small resistor in the previous power frequency cycle is obtained by sampling; When the single-phase grounding fault is determined to be a permanent grounding fault, the switch is controlled to close to input a small parallel resistor, and the second zero-sequence current of each feeder after a delay of a preset time length and one power frequency cycle is obtained by sampling.

4. The method according to claim 3, characterized in that: The second ratio includes the following mathematical expression: In the formula, is the first ratio of feeder Li, is the first ratio of the reference feeder Lp; is the second ratio of feeder line Li; 0i is the first zero-sequence current of feeder Li, I' 0i is the second zero-sequence current of feeder Li; I 0p is the first zero-sequence current of the reference feeder Lp, I' 0p is the second zero-sequence current of the reference feeder Lp; M i-p is the second ratio of feeder line Li The amplitude of is the second ratio of feeder line Li phase.

5. A single-phase ground fault line selection system, characterized in that: The single-phase grounding fault line selection system is used to execute the steps of the method as described in any one of claims 1 to 4. There is a communication connection between the single-phase grounding fault line selection system and the power system. The power system includes a plurality of feeders and a main transformer. The main transformer is used to transmit power to each feeder. The neutral point of the main transformer adopts a flexible grounding method, and a small parallel resistor is put into flexible grounding after a permanent single-phase grounding fault occurs in the system through the closure of the switch.

6. The single-phase ground fault line selection system according to claim 5, characterized in that: The power system further includes a distributed power source, at least one of the feeders is connected to the distributed power source, and a grid-connected transformer of the distributed power source connected to any of the feeders is connected in a neutral point ungrounded manner.

7. A single-phase ground fault line selection device, characterized in that: The device comprises: The first ratio module is used to calculate the first ratio of the zero-sequence current of each feeder of the power system before and after the parallel small resistance is put into operation when a permanent single-phase grounding fault occurs in the power system; A second ratio module: used for taking any feeder as a reference feeder, wherein the first ratio of the reference feeder is the reference ratio, and comparing the second ratios of the first ratios of the remaining feeders relative to the reference ratio, wherein the remaining feeders are feeders other than the reference feeder; Line selection module: used to distinguish faulty feeders from non-faulty feeders according to the second ratio and a preset faulty line selection rule to obtain a line selection result.

8. The device according to claim 7, characterized in that: The line selection result includes at least a faulty feeder, and the faulty line selection rule includes a preset first rule and a preset second rule. The line selection module is configured to determine that the first feeder is a faulty feeder if there is a first feeder whose second ratio satisfies the preset first rule, and the first rule is that the amplitude of the second ratio is not less than a first threshold value, and the phase is within a first phase interval; If there is a second feeder whose second ratio satisfies a preset second rule, determining that the reference feeder is a faulty feeder, the second rule being that the amplitude of the second ratio is not higher than a second threshold value and the phase is within a second phase interval; If the first feeder or the second feeder does not exist, it is determined that the busbar of the power system is a faulty feeder.

9. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the processor is caused to perform the steps of the method according to any one of claims 1 to 4.

10. A computer device comprising a memory and a processor, characterized in that: The memory stores a computer program, and when the computer program is executed by the processor, the processor is caused to perform the steps of the method according to any one of claims 1 to 4.

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