Single-phase earth fault positioning method and system based on cooperation of main network and distribution network

Abstract

The invention discloses a main network and distribution network coordinated single-phase earth fault positioning method and system, and the method comprises the steps: analyzing a network topology architecture file of a power distribution network, and obtaining all power supply paths and the lengths of the power supply paths; if the bus voltage collected in real time and the zero-sequence current of each outgoing line meet a preset condition, calculating the single-phase earth fault probability of each outgoing line by adopting a comprehensive criterion of combining a transient state quantity and a steady state quantity, and selecting the outgoing line meeting the requirement as an initial line selection result; correcting the initial line selection result based on transient fault direction discrimination results, all power supply paths and power supply path lengths sent by the power distribution terminals configured at the switches to obtain a final line selection result; and for each outgoing line in the final line selection result, fault section positioning is carried out respectively, and a section with a single-phase earth fault is found out. According to the method, through accurate section positioning, fault point isolation instead of whole line removal is realized, the fault transfer risk caused by blind tripping is avoided, and accident expansion is restrained from the mechanism.

Description

Technical Field

[0001] This invention belongs to the field of power system relay protection technology, specifically relating to a method and system for locating single-phase grounding faults in coordination between the main and distribution networks. Background Technology

[0002] Single-phase grounding faults are the most common type of fault in distribution networks, with a high probability of occurrence. If the fault cannot be located and isolated in a timely manner, it may expand the fault range, even causing equipment damage and large-scale power outages, seriously affecting the reliability of power supply and the safety of electricity use. Current single-phase grounding fault location technology mainly consists of two aspects: in-station line selection and section location. Existing low-current grounding line selection devices in substations can only disconnect the entire faulty line and cannot accurately locate the faulty section, making it difficult to effectively coordinate with the detection results of external distribution lines. In terms of section location, existing technologies mostly rely on steady-state quantities or fault indicator action information collected by distribution terminals, and achieve location by comparing the current amplitude or direction of adjacent nodes. However, due to the large number of branches in the distribution network, large load fluctuations, and problems such as insufficient sampling accuracy and clock asynchronization of terminals, the location error is large, especially in branch lines or high-resistance grounding scenarios, where location failure often occurs. If the fault is downstream, after the in-station line selection trips, the automatic transfer switch of the next-level switching station may transfer the fault to other lines, leading to the expansion of the accident.

[0003] Furthermore, the lack of data interaction and coordination mechanisms between substations and distribution terminals, coupled with the absence of closed-loop verification between line selection results and terminal detection data, leads to low processing efficiency. Additionally, issues such as reversed polarity of current transformers (CTs) and errors in line parameters can cause direction criteria to fail, affecting positioning accuracy. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes a method and system for locating single-phase grounding faults in a coordinated manner between the main and distribution networks. By accurately locating the fault section, it achieves fault isolation rather than complete line disconnection, avoiding the risk of fault transfer caused by blind tripping and curbing the escalation of the accident from a mechanism perspective.

[0005] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0006] In a first aspect, the present invention provides a method for locating single-phase grounding faults in a coordinated manner between the main and distribution networks, applied to a centralized protection and control device. The centralized protection and control device is connected to the busbar and each outgoing line. The method for locating single-phase grounding faults includes:

[0007] Parse the power distribution network topology file to obtain all power supply paths and the length of each power supply path;

[0008] If the real-time collected bus zero-sequence voltage and zero-sequence current of each outgoing line meet the preset conditions, the single-phase grounding fault selection process is started. A comprehensive criterion combining transient and steady-state quantities is used to calculate the single-phase grounding fault probability of each outgoing line, and the outgoing lines with the highest single-phase grounding fault probability L are selected as the initial selection result.

[0009] Based on the received transient fault direction discrimination results sent by the power distribution terminals at each switch, all power supply paths, and the length of each power supply path, the initial line selection result is corrected to obtain the final line selection result.

[0010] For each outgoing line in the final line selection result, the fault section is located to find the section where a single-phase ground fault occurred.

[0011] In conjunction with the first aspect, optionally, the distribution network topology file includes several nodes connected according to the distribution network topology, parent node information and child node information of each node, and spacing parameters of each node. Each node is a bus node, an outgoing switch node, or a switch node on each distribution network line connected to each outgoing switch node.

[0012] The methods for obtaining each power supply path include:

[0013] The bus node is set as the first node in the distribution network topology, serving as the starting reference for power supply path search.

[0014] For each switching node, a preset power supply path search step is performed to determine the complete power supply path from the switching node itself to the bus node. The preset power supply path search step includes:

[0015] Identify the parent node information of the switch node;

[0016] Starting from the parent node of the switch node, and combining the distribution network topology, the related nodes are searched upstream one by one until the bus node is reached, thus determining the complete power supply path from the switch node to the bus node.

[0017] Methods for obtaining the length of the power supply path include:

[0018] Based on the spacing parameters of each node in the power supply path, the length of the power supply path corresponding to each switching node is calculated.

[0019] In conjunction with the first aspect, optionally, if the real-time acquired bus zero-sequence voltage and zero-sequence current of each outgoing line meet preset conditions, then the single-phase grounding fault selection process is initiated, including:

[0020] Real-time acquisition of bus zero-sequence voltage and zero-sequence current of each outgoing line, and calculation. and ,in, For the current sampling time and The bus zero-sequence voltage difference at the sampling time before the cycle, For the current sampling time and Zhoubo pre-sampling time line The zero-sequence current difference, ;

[0021] When satisfied ,or When the mutation initiation process is triggered, the bus zero-sequence voltage amplitude reaches a certain value within a set time after the mutation initiation process begins. If this occurs, the single-phase ground fault selection process will be initiated, in which... The zero-sequence voltage changeover setpoint, To qualify The zero-sequence current sudden change setpoint, The zero-sequence voltage threshold setting for single-phase grounding protection.

[0022] In conjunction with the first aspect, optionally, the method for generating the initial route selection result includes the following steps:

[0023] Step 1: At the first set time after the single-phase ground fault selection process is officially started, the fault correlation characteristic value of the line is calculated using four criteria, specifically including:

[0024] Based on the transient differential line selection method, the differential characteristic value of the transient zero-sequence current of each outgoing line after the fault is calculated.

[0025] Based on the transient zero-sequence current amplitude and phase ratio method, the transient current amplitude and phase of each outgoing line after the fault are calculated;

[0026] Based on the steady-state zero-sequence current amplitude and phase ratio method, the amplitude and phase of the steady-state zero-sequence current of each outgoing line after the fault are calculated.

[0027] Based on the zero-sequence active power method, the zero-sequence active power components of each outgoing line are calculated after the fault.

[0028] Step 2: Normalize the fault correlation feature values ​​of the line calculated using the four criteria to obtain normalized output values ​​X1, X2, X3, and X4;

[0029] X1, X2, X3, and X4 are mapped to the [0,1] interval according to a preset rule. The interval endpoint 1 indicates the highest confidence level of the criterion in determining that the line is a faulty line, and the interval endpoint 0 indicates the lowest confidence level of the criterion in determining that the line is a faulty line. The preset rule is: the higher the fault correlation, the closer the normalized value is to 1.

[0030] Step 3: Calculate the line using weighted fusion. grounding fault probability Qualifying grounding fault probability The calculation formula is:

[0031] ,

[0032] in, , , , The weights of the fault-related feature values ​​of the line are calculated for each of the four criteria, and the following conditions are met: , , , , They are the ones who qualify The normalized values ​​of the fault-related characteristic values ​​of the line are calculated using four criteria.

[0033] Step 4: Press The values ​​are sorted from high to low, and the top three lines are selected as the first choice and the alternative lines, respectively, to obtain the initial line selection results.

[0034] In conjunction with the first aspect, optionally, the method for generating the transient fault direction determination result includes:

[0035] After a ground fault occurs, each distribution terminal configured at the switching node collects and extracts the transient zero-sequence voltage signal within a second set time period following a sudden change in zero-sequence voltage or zero-sequence current. and transient zero-sequence current signal ,in, N is the number of sampling points within the second set time period;

[0036] Calculate the transient zero-sequence voltage signal With transient zero-sequence current signal The sum of the products of the sampled values ​​S and the sum of the absolute values ​​S abs The sum of the products of the sampled values, S, and the sum of the absolute values, S abs The calculation formulas are as follows:

[0037] ,

[0038] ,

[0039] when When the transient zero-sequence voltage and transient zero-sequence current are not in the same direction, the transient fault direction is positive.

[0040] when When the transient zero-sequence voltage and transient zero-sequence current are in the same direction, the transient fault direction is in the opposite direction.

[0041] In conjunction with the first aspect, optionally, all switches located outside the substation and equipped with distribution terminals are defined as fault detection points; the initial line selection result includes the preferred outgoing line and the alternative outgoing line; the method for generating the final line selection result includes:

[0042] Based on preset correction rules, the initial route selection result is corrected to obtain the final route selection result; the correction rules are:

[0043] 1) If the number of valid positive direction detection points for the first selected line L1 is the largest among all selected lines in the initial line selection results, then the first selected line L1 is determined to be correct, and the initial line selection results remain unchanged; the method for determining the number of valid positive direction detection points for the selected line includes:

[0044] The power supply path and its length between each switch in the preferred or alternative outgoing lines are selected. The longest power supply path is identified as the fault path. Switches whose transient fault direction is identified as positive are defined as valid positive direction detection points. The number of switches whose transient fault direction is identified as positive on the longest power supply path is counted as the number of valid positive direction detection points for that outgoing line.

[0045] 2) If any candidate qualifying spot meets the following conditions simultaneously, then that candidate qualifying spot will be adjusted to the first qualifying spot:

[0046] 2.1) The number of its effective positive direction detection points is the highest among all the lines that emerge in the initial line selection results;

[0047] 2.2) The difference in zero-sequence current amplitude at all valid positive direction detection points is less than a set threshold, and the transient energy coefficient is greater than the first transient energy coefficient threshold. ;

[0048] 2.3) The difference in zero-sequence current amplitude between the effective positive direction detection point switch of the last stage and its sub-switches is greater than a set threshold, and the transient energy coefficient is less than the second transient energy coefficient threshold. , .

[0049] In conjunction with the first aspect, optionally, the step of locating the fault section for each outgoing line in the final line selection result to find the section where a single-phase ground fault occurred includes:

[0050] For each outgoing line in the final line selection result, a predetermined fault section location step is executed to identify the section where a single-phase ground fault occurs. The predetermined fault section location step includes:

[0051] Locate the moment of zero-sequence voltage change in the electrical quantity data sent by each distribution terminal in the outgoing line, and align the electrical quantity data.

[0052] Calculate the transient energy and transient energy coefficient of each switch equipped with a power distribution terminal;

[0053] Using the branch switches on the outgoing line as boundaries, the outgoing line is divided into several protection zones. Based on the transient energy and transient energy coefficient of each switch equipped with a distribution terminal, fault determination is performed on each protection zone to identify the section where a single-phase ground fault occurs.

[0054] In conjunction with the first aspect, optionally, the step of finding the zero-sequence voltage abrupt change time in the electrical quantity data sent by each distribution terminal and aligning the electrical quantity data includes:

[0055] Search for zero-sequence voltage data in the electrical quantity data sent by each distribution terminal configured on each outgoing line in the final line selection result, and perform abrupt change detection;

[0056] When a zero-sequence voltage mutation value of a power distribution terminal is detected to be greater than a preset threshold value, the sampling time is marked as the zero-sequence voltage mutation time of the power distribution terminal.

[0057] The first peak voltage that appears after the zero-sequence voltage abrupt change is retrieved, and the sampling time at which the peak voltage occurs is determined as the fault initiation time of the distribution terminal.

[0058] Based on the initial fault time of each power distribution terminal, the electrical quantity data of all power distribution terminals on the same outgoing line are aligned on the time axis.

[0059] If the zero-sequence voltage change moment cannot be identified in the electrical quantity data of a certain power distribution terminal, then the electrical quantity data of that power distribution terminal will not be included in the calculation of transient energy and transient energy coefficient.

[0060] In conjunction with the first aspect, optionally, the outgoing line is divided into several protection zones, with the branch switches on the outgoing line as boundaries. Based on the transient energy coefficient of each switch equipped with a distribution terminal, a fault determination step is performed for each protection zone. The fault determination step includes:

[0061] When only one switch within the protected area has a transient energy coefficient greater than the first transient energy coefficient threshold Furthermore, the transient energy coefficients of all other switches within the protection zone are less than the second transient energy coefficient threshold. If the fault is within the zone, it is determined to be an internal fault; otherwise, it is determined to be an external fault. The formula for calculating the transient energy coefficient is:

[0062] ,

[0063] In the formula, For the first The transient energy coefficient of a switch, For the first A switch transient energy, For the first The transient energy of the outgoing switch corresponding to each switch. ;

[0064] If multiple protection zones meet the fault determination criteria within the zone, they are sorted according to the transient energy magnitude of the switches that meet the fault criteria in each protection zone. The switch with the larger transient energy is output first as the fault location result. The formula for calculating transient energy is:

[0065] ,

[0066] In the formula, For the first The first of the waveform recordings of the power distribution terminal on the first switch One transient zero-sequence current sampling point.

[0067] In conjunction with the first aspect, the method for locating single-phase grounding faults in coordinated main and distribution network operations may optionally include:

[0068] For the preferred outgoing line and the alternative outgoing line in the final line selection result, the adjacent switch pairs connected to them located outside the substation are searched. If the transient fault direction determination results of the two adjacent switches are opposite, and the difference between their zero-sequence current amplitudes is less than the set threshold, then the switch with the opposite transient direction has a CT polarity reversal problem.

[0069] For any outgoing line other than the primary outgoing line and the alternative outgoing line, if there is a switch outside the station connected to the outgoing line that is determined to be in transient positive direction, and the difference between the zero-sequence current amplitude of the switch and the zero-sequence current amplitude of the corresponding outgoing line switch is less than a set threshold, then it is determined that the switch outside the station has a CT polarity reverse connection problem.

[0070] Secondly, the present invention provides a single-phase grounding fault location system for main and distribution network coordination, which is applied to a centralized protection and control device, including a storage medium and a processor;

[0071] The storage medium is used to store instructions;

[0072] The processor is configured to operate according to the instructions to perform the method according to any one of the first aspects.

[0073] Thirdly, the present invention provides a single-phase grounding fault location system for main and distribution network coordination, including a centralized protection and control device and a distribution terminal;

[0074] The centralized protection and control device is installed in the substation and configured to perform the method according to any one of the first aspects;

[0075] The power distribution terminal is installed at a designated switch on the power distribution network line outside the substation and is communicatively connected to the centralized protection and control device.

[0076] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0077] This invention proposes a method and system for locating single-phase grounding faults in a coordinated manner between the main and distribution networks. By accurately locating the fault section, it achieves fault isolation rather than complete line disconnection, avoiding the risk of fault transfer caused by blind tripping and curbing the expansion of accidents from a mechanism perspective.

[0078] Furthermore, in the on-site line selection process, a comprehensive criterion combining transient and steady-state quantities is adopted. The grounding fault probability is calculated and ranked by weighted fusion of multiple criteria, and dynamic correction is performed by combining the transient fault direction detection results of the off-site power distribution terminal, forming a closed-loop verification mechanism, which greatly improves the accuracy of on-site line selection.

[0079] Furthermore, in terms of section location, the zero-sequence voltage mutation and first peak time alignment technology are adopted. The true effective value of the zero-sequence current within a preset time (e.g., 10ms) is used as the transient energy parameter. By comparing the transient energy coefficients, the fault section is accurately divided, which overcomes the location interference caused by the large number of branches and load fluctuations in the distribution network and improves the location accuracy in complex scenarios.

[0080] Furthermore, by using communication methods such as fiber optics, 5G / 4G, and carrier waves, real-time data interaction between the centralized protection and control devices of the substation and the distribution terminal is achieved, forming a global fault analysis perspective. The CT polarity verification function can automatically identify and correct directional misjudgments caused by wiring errors, enhancing on-site adaptability. Attached Figure Description

[0081] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0082] Figure 1 This is an architecture diagram of a single-phase grounding fault location system with main and distribution network coordination in one embodiment of the present invention;

[0083] Figure 2 This is a schematic diagram of power supply path search in one embodiment of the present invention;

[0084] Figure 3 This is an embodiment of the in-station route selection correction process of the present invention;

[0085] Figure 4 This is a flowchart of segment positioning in one embodiment of the present invention. Detailed Implementation

[0086] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0087] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0088] Example 1

[0089] This invention provides a method for locating single-phase grounding faults in a coordinated manner between the main and distribution networks. This method is applied to a centralized protection and control device, which is connected to both the busbar and each outgoing line. The single-phase grounding fault location method includes:

[0090] (1) Parse the power distribution network topology file to obtain all power supply paths and the length of each power supply path;

[0091] (2) If the zero-sequence voltage of the bus and the zero-sequence current of each outgoing line collected in real time meet the preset conditions, the single-phase grounding fault selection process is started. The comprehensive criterion combining transient and steady-state quantities is used to calculate the single-phase grounding fault probability of each outgoing line, and the outgoing lines with the highest single-phase grounding fault probability L are selected as the initial selection result. In the specific implementation process, L can be 3 or other suitable values, which can be set according to the actual situation.

[0092] (3) Based on the received transient fault direction discrimination results sent by the power distribution terminal configured at each switch, all power supply paths, and the length of each power supply path, the initial line selection results are corrected to obtain the final line selection results;

[0093] (4) For each outgoing line in the final line selection result, locate the fault section and find the section where the single-phase grounding fault occurred.

[0094] Based on the above solution, by accurately locating the fault section, the fault point is isolated instead of the entire line is cut off, thus avoiding the risk of fault transfer caused by blind tripping and curbing the expansion of the accident from a mechanism perspective.

[0095] In one specific embodiment of the present invention, the power distribution network topology file includes several nodes connected according to the power distribution network topology, parent node information and child node information of each node, and spacing parameters of each node. Each node is a bus node, an outgoing switch node, or a switch node on each power distribution line connected to each outgoing switch node.

[0096] The methods for obtaining each power supply path include:

[0097] The bus node is set as the first node in the distribution network topology, serving as the starting reference for power supply path search.

[0098] For each switching node, a preset power supply path search step is performed to determine the complete power supply path from the switching node itself to the bus node. The preset power supply path search step includes:

[0099] Identify the parent node information of the switch node;

[0100] Starting from the parent node of the switch node, and combining the distribution network topology, the related nodes are searched upstream one by one until the bus node is reached, thus determining the complete power supply path from the switch node to the bus node.

[0101] Methods for obtaining the length of the power supply path include:

[0102] Based on the spacing parameters of each node in the power supply path, the length of the power supply path corresponding to each switching node is calculated.

[0103] The above scheme provides a specific method for obtaining the power supply path and the length of each power supply path. This method is used to cooperate with the transient fault direction discrimination results sent by the power distribution terminals at each switch on the power distribution network line to correct the initial line selection result, obtain the final line selection result, and improve the accuracy of line selection within the station.

[0104] In one specific embodiment of the present invention, if the real-time acquired bus zero-sequence voltage and zero-sequence current of each outgoing line meet preset conditions, then the single-phase grounding fault selection process is initiated, including:

[0105] Real-time acquisition of bus zero-sequence voltage and zero-sequence current of each outgoing line, and calculation. and ,in, For the current sampling time and The bus zero-sequence voltage difference at the sampling time before the cycle, For the current sampling time and Zhoubo pre-sampling time line The zero-sequence current difference, ;

[0106] When satisfied ,or When the mutation initiation process is triggered, the bus zero-sequence voltage amplitude reaches a certain value within a set time after the mutation initiation process begins. If this occurs, the single-phase ground fault selection process will be initiated, in which... The zero-sequence voltage changeover setpoint, To qualify The zero-sequence current sudden change setpoint, The zero-sequence voltage threshold setting for single-phase grounding protection.

[0107] In one specific embodiment of the present invention, the method for generating the initial line selection result includes:

[0108] Step 1: At the first set time after the single-phase ground fault selection process is officially started, the fault correlation characteristic value of the line is calculated using four criteria, specifically including:

[0109] Based on the transient differential line selection method, the differential characteristic value of the transient zero-sequence current of each outgoing line after the fault is calculated.

[0110] Based on the transient zero-sequence current amplitude and phase ratio method, the transient current amplitude and phase of each outgoing line after the fault are calculated;

[0111] Based on the steady-state zero-sequence current amplitude and phase ratio method, the amplitude and phase of the steady-state zero-sequence current of each outgoing line after the fault are calculated.

[0112] Based on the zero-sequence active power method, the zero-sequence active power components of each outgoing line are calculated after the fault.

[0113] Step 2: Normalize the fault correlation feature values ​​of the line calculated using the four criteria to obtain normalized output values ​​X1, X2, X3, and X4;

[0114] X1, X2, X3, and X4 are mapped to the [0,1] interval according to a preset rule. The interval endpoint 1 indicates the highest confidence level of the criterion in determining that the line is a faulty line, and the interval endpoint 0 indicates the lowest confidence level of the criterion in determining that the line is a faulty line. The preset rule is: the higher the fault correlation, the closer the normalized value is to 1.

[0115] Step 3: Calculate the line using weighted fusion. grounding fault probability Qualifying grounding fault probability The calculation formula is:

[0116] ,

[0117] in, , , , The weights of the fault-related feature values ​​of the line are calculated for each of the four criteria, and the following conditions are met: , , , , They are the ones who qualify The normalized values ​​of the fault-related characteristic values ​​of the line are calculated using four criteria.

[0118] Step 4: Press The values ​​are sorted from high to low, and the top three lines are selected as the first choice and the alternative lines, respectively, to obtain the initial line selection results.

[0119] The above scheme adopts a comprehensive criterion that combines transient and steady-state quantities. By weighted fusion of multiple criteria to calculate and sort the fault probability, the accuracy of route selection within the station can be improved.

[0120] In one specific embodiment of the present invention, the method for generating the transient fault direction discrimination result includes:

[0121] After a ground fault occurs, each distribution terminal configured at the switching node collects and extracts the transient zero-sequence voltage signal within a second set time period following a sudden change in zero-sequence voltage or zero-sequence current. and transient zero-sequence current signal ,in, N is the number of sampling points within the second set time period;

[0122] Calculate the transient zero-sequence voltage signal With transient zero-sequence current signal The sum of the products of the sampled values ​​S and the sum of the absolute values ​​S abs The sum of the products of the sampled values, S, and the sum of the absolute values, S abs The calculation formulas are as follows:

[0123] ,

[0124] ,

[0125] when When the transient zero-sequence voltage and transient zero-sequence current are not in the same direction, the transient fault direction is positive.

[0126] when When the transient zero-sequence voltage and transient zero-sequence current are in the same direction, the transient fault direction is in the opposite direction.

[0127] In one specific embodiment of the present invention, all switches located outside the substation and equipped with distribution terminals are defined as fault detection points; the initial line selection result includes a preferred outgoing line and a backup outgoing line; the method for generating the final line selection result includes:

[0128] Based on preset correction rules, the initial route selection result is corrected to obtain the final route selection result; the correction rules are:

[0129] 1) If the number of valid positive direction detection points for the first selected line L1 is the largest among all selected lines in the initial line selection results, then the first selected line L1 is determined to be correct, and the initial line selection results remain unchanged; the method for determining the number of valid positive direction detection points for the selected line includes:

[0130] The power supply path and its length between each switch in the preferred or alternative outgoing lines are selected. The longest power supply path is identified as the fault path. Switches whose transient fault direction is identified as positive are defined as valid positive direction detection points. The number of switches whose transient fault direction is identified as positive on the longest power supply path is counted as the number of valid positive direction detection points for that outgoing line.

[0131] 2) If any candidate qualifying spot meets the following conditions simultaneously, then that candidate qualifying spot will be adjusted to the first qualifying spot:

[0132] 2.1) The number of its effective positive direction detection points is the highest among all the lines that emerge in the initial line selection results;

[0133] 2.2) The difference in zero-sequence current amplitude at all valid positive direction detection points is less than a set threshold, and the transient energy coefficient is greater than the first transient energy coefficient threshold. ;

[0134] 2.3) The difference in zero-sequence current amplitude between the effective positive direction detection point switch of the last stage and its sub-switches is greater than a set threshold, and the transient energy coefficient is less than the second transient energy coefficient threshold. , .

[0135] In the above scheme, the initial route selection result is dynamically corrected by combining the transient fault direction detection results of the external power distribution terminal, forming a closed-loop verification mechanism, which greatly improves the accuracy of route selection within the station.

[0136] In one specific embodiment of the present invention, the step of locating the fault section for each outgoing line in the final line selection result and identifying the section where a single-phase ground fault occurred includes:

[0137] For each outgoing line in the final line selection result, a predetermined fault section location step is executed to identify the section where a single-phase ground fault occurs. The predetermined fault section location step includes:

[0138] Locate the moment of zero-sequence voltage change in the electrical quantity data sent by each distribution terminal in the outgoing line, and align the electrical quantity data.

[0139] Calculate the transient energy and transient energy coefficient of each switch equipped with a power distribution terminal;

[0140] Using the branch switches on the outgoing line as boundaries, the outgoing line is divided into several protection zones. Based on the transient energy and transient energy coefficient of each switch equipped with a distribution terminal, fault determination is performed on each protection zone to identify the section where a single-phase ground fault occurs.

[0141] In one specific embodiment of the present invention, the step of finding the zero-sequence voltage change moment in the electrical quantity data sent by each power distribution terminal and aligning the electrical quantity data includes:

[0142] Search for zero-sequence voltage data in the electrical quantity data sent by each distribution terminal configured on each outgoing line in the final line selection result, and perform abrupt change detection;

[0143] When a zero-sequence voltage mutation value of a power distribution terminal is detected to be greater than a preset threshold value, the sampling time is marked as the zero-sequence voltage mutation time of the power distribution terminal.

[0144] The first peak voltage that appears after the zero-sequence voltage abrupt change is retrieved, and the sampling time at which the peak voltage occurs is determined as the fault initiation time of the distribution terminal.

[0145] Based on the initial fault time of each power distribution terminal, the electrical quantity data of all power distribution terminals on the same outgoing line are aligned on the time axis.

[0146] If the zero-sequence voltage change moment cannot be identified in the electrical quantity data of a certain power distribution terminal, then the electrical quantity data of that power distribution terminal will not be included in the calculation of transient energy and transient energy coefficient.

[0147] In one specific embodiment of the present invention, the outgoing line is divided into several protection zones by the branch switches on the outgoing line. Based on the transient energy coefficient of each switch equipped with a distribution terminal, a fault determination step is performed for each protection zone. The fault determination step includes:

[0148] When only one switch within the protected area has a transient energy coefficient greater than the first transient energy coefficient threshold Furthermore, the transient energy coefficients of all other switches within the protection zone are less than the second transient energy coefficient threshold. If the fault is within the zone, it is determined to be an internal fault; otherwise, it is determined to be an external fault. The formula for calculating the transient energy coefficient is:

[0149] ,

[0150] In the formula, For the first The transient energy coefficient of a switch, For the first A switch transient energy, For the first The transient energy of the outgoing switch corresponding to each switch. ;

[0151] If multiple protection zones meet the fault determination criteria within the zone, they are sorted according to the transient energy magnitude of the switches that meet the fault criteria in each protection zone. The switch with the larger transient energy is output first as the fault location result. The formula for calculating transient energy is:

[0152] ,

[0153] In the formula, For the first The first of the waveform recordings of the power distribution terminal on the first switch One transient zero-sequence current sampling point.

[0154] In terms of section location, the zero-sequence voltage mutation and first peak time alignment technology are adopted. The true effective value of transient zero-sequence current within a set time (e.g., within 10ms) is used as the transient energy parameter. By comparing the transient energy coefficient, the fault section is accurately divided, which overcomes the location interference caused by the large number of branches and large load fluctuations in the distribution network and improves the location accuracy in complex scenarios.

[0155] In one specific embodiment of the present invention, the single-phase grounding fault location method of main and distribution network coordination further includes:

[0156] For the preferred outgoing line and the alternative outgoing line in the final line selection result, the adjacent switch pairs connected to them located outside the substation are searched. If the transient fault direction determination results of the two adjacent switches are opposite, and the difference between their zero-sequence current amplitudes is less than the set threshold, then the switch with the opposite transient direction has a CT polarity reversal problem.

[0157] For any outgoing line other than the primary outgoing line and the alternative outgoing line, if there is a switch outside the station connected to the outgoing line that is determined to be in transient positive direction, and the difference between the zero-sequence current amplitude of the switch and the zero-sequence current amplitude of the corresponding outgoing line switch is less than a set threshold, then it is determined that the switch outside the station has a CT polarity reverse connection problem.

[0158] The method for locating single-phase grounding faults in the main distribution network coordination of the present invention will be described in detail below with reference to a specific implementation method.

[0159] The single-phase grounding fault location method system for main and distribution network coordination includes a centralized protection and control device installed in the substation, and distribution terminals installed at selected switches on the distribution network lines. Preferably, a distribution terminal is installed at each switch. The centralized protection and control device and the distribution terminals establish a communication connection via optical fiber, 5G / 4G, or carrier wave. The centralized protection and control device is equipped with network topology analysis, single-phase grounding line selection, and fault section location functions. The centralized protection and control device is connected to the busbar and several outgoing lines, and each outgoing line is equipped with several switches and distribution terminals; each distribution terminal is equipped with transient grounding protection function. The single-phase grounding fault location method specifically includes the following steps:

[0160] S1. The centralized protection and control device starts the network architecture topology analysis function, parses the distribution network topology architecture file, calculates the power supply path and path length from each switch node to the substation head node (i.e., bus node), and obtains all power supply paths and the length of each power supply path.

[0161] S2. A single-phase ground fault occurs in the distribution network line;

[0162] S3. Substation fault location: The centralized protection and control device collects the bus zero-sequence voltage and the zero-sequence current of each outgoing line in real time. When a sudden change in the bus zero-sequence voltage or the zero-sequence current of any outgoing line is detected, the single-phase ground fault location function is automatically activated. 20ms after activation, a comprehensive fault location method combining transient and steady-state quantities is used to generate initial fault location results. This comprehensive method involves using conventional transient differential fault location, transient zero-sequence current amplitude and phase comparison, steady-state zero-sequence current amplitude and phase comparison, and zero-sequence active power methods to calculate the fault-related characteristic values ​​of the line, and then using weighted fusion to calculate the fault location. grounding fault probability Based on the probability of a single-phase ground fault, the top 3 outgoing lines are selected and marked as the primary outgoing line L1, the alternative outgoing lines L2 and L3, respectively.

[0163] S4. When a single-phase ground fault occurs, the distribution terminal of each switching node calculates the transient fault direction, that is, the direction of the transient zero-sequence voltage and the transient zero-sequence current 10ms after the fault occurs. If the two directions are inconsistent, the transient fault direction is determined to be the positive direction; if they are consistent, it is determined to be the reverse direction.

[0164] S5, after the single-phase grounding fault location function is activated, the centralized protection and control device sends a record electrical quantity data identifier to the distribution terminal. After receiving the instruction, the distribution terminal records the electrical quantity data 40ms before and after the identifier.

[0165] S6. After the centralized protection and control device completes the line selection within the substation, it generates the initial line selection result, receives the transient fault direction judgment result from the distribution terminal, and corrects the initial line selection result. The line selection result is dynamically adjusted based on the number of positive direction detection points outside the station for the primary outgoing line L1, alternative outgoing line L2 and alternative outgoing line L3, the difference in zero-sequence current amplitude of the positive direction detection points, and the difference in amplitude between the last positive direction detection point switch and its sub-switch (i.e., the downstream switch).

[0166] S7. After the centralized protection and control device identifies the faulty line, it activates the fault section location function. First, it retrieves the electrical quantity data stored in all distribution terminals in the distribution network lines connected to L1, L2, and L3, searches for the zero-sequence voltage change moment in the electrical quantity data sent by each distribution terminal, further aligns the electrical quantity data, and calculates the true effective value of the zero-sequence current within 10ms as the transient energy. , ,in For the first The first of the waveform recordings of the power distribution terminal on the first switch There are N transient zero-sequence current sampling points, where N is the number of sampling points within 10 ms. The transient energy coefficient is further calculated. , , For the outside of the station The transient energy coefficient of a switch, For the outside of the station The transient energy of electrical quantity data transmitted by a switch. For the first The transient energy of the outgoing switches corresponding to each switch; comparing the transient energy coefficients of upstream and downstream switches, only a single switch in the area satisfies the condition. > If the other conditions are not met, the fault is determined to be within the region; when there are multiple candidate regions, the results are sorted and output according to the size of the transient energy.

[0167] Specifically, step S1, parsing the distribution network topology file, includes the following steps:

[0168] The distribution network topology file is generated based on the actual distribution network architecture, including bus nodes, outgoing switch nodes, or switch nodes on each distribution network line connected to each outgoing switch node, parent node information and child node information of each node, and spacing parameters of each node; the bus is set as the first node of the distribution network (i.e., the first node of the substation) as the starting reference for searching the power supply path of the distribution network; for each switch node, the upstream node information (i.e., parent node information) and downstream node information (i.e., child node information) of the switch are first identified; combined with the radial power supply characteristics of the distribution network, starting from the upstream node of a certain switch, the related nodes and corresponding switches are searched upstream one by one until the 10kV bus node is reached; through the above successive tracing search process, the complete power supply path from the location of each switch node to the 10kV bus node is determined; based on the line segment length or node spacing parameters included in the power supply path, the power supply path length corresponding to each switch node is calculated; for example Figure 2 The diagram shows the power supply path search. Node 110 has upstream nodes Node 103, Node 102, and Node 101. Node 101's upstream node is Node 5, which is a bus node. After the power supply path search is completed, the length of the path segment is calculated from Node 110 to Node 5. The line segment length is 3, so the power supply path length is 3. Similarly, the power supply path and its length for all switches can be calculated using this method.

[0169] Furthermore, the single-phase grounding selection function of the centralized protection and control device in step S3 specifically includes the following steps:

[0170] The centralized protection and control device collects the zero-sequence voltage of the busbar and the zero-sequence current of each outgoing line in real time and calculates... and ,in This represents the difference between the bus zero-sequence voltage at the current sampling time and the sampling time two cycles prior. To qualify The difference in zero-sequence current between the current sampling time and the sampling time 2 cycles prior; when satisfying ( (Set value for zero-sequence voltage change) or ( To qualify When the zero-sequence current changes abruptly (to its set value), the sudden change is triggered. After the sudden change is triggered, the zero-sequence voltage amplitude reaches a certain value within a set time. ( When the zero-sequence voltage threshold setting for single-phase grounding protection is set, the protection is activated, and the single-phase grounding fault selection function is officially activated.

[0171] Furthermore, the on-site line selection process in step S3 is as follows: 20ms after the single-phase ground fault line selection function is officially activated, a comprehensive criterion combining transient and steady-state quantities is used to perform the line selection operation. This comprehensive criterion specifically includes the transient differential line selection method, the transient zero-sequence current amplitude-phase comparison method, the steady-state zero-sequence current amplitude-phase comparison method, and the zero-sequence active power method; the probability of ground fault for each outgoing line is calculated through weighted fusion. , ,in To qualify The probability of grounding faults, These are the weights of the transient differential line selection method, the transient zero-sequence current amplitude and phase comparison method, the steady-state zero-sequence current amplitude and phase comparison method, and the zero-sequence active power method, respectively, and satisfy the following conditions: , To qualify The four criteria are used to normalize the output values. (According to...) The values ​​are sorted from high to low, and the top three are selected as the primary qualifying candidate L1 and the alternative qualifying candidates L2 and L3.

[0172] Furthermore, the calculation process for the transient fault direction in step S4 is as follows: After a ground fault occurs, the distribution terminals of each switching node in the distribution network line collect and extract the transient zero-sequence voltage signal within 10ms after the sudden change in zero-sequence voltage or zero-sequence current. and transient zero-sequence current signal Where k = 1, 2, ..., N, and N is the number of sampling points within 10 ms; calculate the sum of the products S of the sampled values ​​of transient zero-sequence voltage and transient zero-sequence current and the sum of their absolute values ​​Ss. abs ,

[0173] ;

[0174] The directional relationship is determined by the ratio of the two values. When the transient zero-sequence voltage and transient zero-sequence current are not in the same direction, the transient fault direction is positive; when When the transient zero-sequence voltage and transient zero-sequence current are in the same direction, the transient fault direction is in the opposite direction.

[0175] Furthermore, the specific process of the centralized protection and control device correcting the route selection results within the station in step S6 is as follows: Figure 3 As shown, in the distribution network lines, all switches with distribution terminals configured outside the station serve as fault detection points. The initial line selection result includes the preferred outgoing line and the alternative outgoing line. The method for generating the final line selection result includes:

[0176] Based on preset correction rules, the initial route selection result is corrected to obtain the final route selection result;

[0177] The revised rules are as follows:

[0178] 1) If the number of valid positive direction detection points for the first selected line L1 is the largest among all selected lines in the initial line selection results, then the first selected line L1 is determined to be correct, and the initial line selection results remain unchanged; the method for determining the number of valid positive direction detection points for the selected line includes:

[0179] The power supply path and its length between each switch in the preferred or alternative outgoing lines are selected. The longest power supply path is identified as the fault path. Switches whose transient fault direction is identified as positive are defined as valid positive direction detection points. The number of switches whose transient fault direction is identified as positive on the longest power supply path is counted as the number of valid positive direction detection points for that outgoing line.

[0180] 2) If any candidate qualifying spot meets the following conditions simultaneously, then that candidate qualifying spot will be adjusted to the first qualifying spot:

[0181] 2.1) The number of its effective positive direction detection points is the highest among all the lines that emerge in the initial line selection results;

[0182] 2.2) The difference in zero-sequence current amplitude at all valid positive direction detection points is less than a set threshold, and the transient energy coefficient is greater than the first transient energy coefficient threshold. ;

[0183] 2.3) The difference in zero-sequence current amplitude between the effective positive direction detection point switch of the last stage and its sub-switches is greater than a set threshold, and the transient energy coefficient is less than the second transient energy coefficient threshold. , .

[0184] After correction, the three outgoing lines L1, L2, and L3 with the highest probability of unidirectional grounding faults were obtained.

[0185] Further, the method for aligning distribution terminal data in step S7 is as follows: After the centralized protection and control device determines the faulty line, it summons the stored electrical quantity data of all distribution terminals connected to outgoing lines L1, L2, and L3, extracts the electrical quantity data sent by the distribution terminals, and performs abrupt change detection on the zero-sequence voltage data of each distribution terminal; when the abrupt change value of the zero-sequence voltage of a distribution terminal is detected to be greater than a preset threshold value, the sampling time is marked as the abrupt change time of the zero-sequence voltage; the first peak voltage that appears after the abrupt change time of the zero-sequence voltage is retrieved, and the sampling time where the peak voltage is located is determined as the initial fault time of the distribution terminal; based on the initial fault time of each distribution terminal, the electrical quantity data of all distribution terminals on the same outgoing line are aligned on the time axis to ensure the consistency of the data in the time dimension; if the abrupt change time of the zero-sequence voltage cannot be identified in the electrical quantity data of a distribution terminal (including no detection of the abrupt change of the zero-sequence voltage or the change value not reaching the threshold value), then the electrical quantity data of the distribution terminal will not participate in the subsequent calculation of transient energy and transient energy coefficient.

[0186] Furthermore, the ground fault section location method in step S7 is as follows: After aligning the electrical quantity data of the distribution terminal, the true effective value of the zero-sequence current (converted to the primary value according to the CT ratio) within 10ms after the fault is calculated as the transient energy. , ,in For the first The first of the waveform recordings of the power distribution terminal on the first switch There are 10 transient zero-sequence current sampling points, where N is the number of sampling points within 10ms; the transient energy coefficient is further calculated. , ,in, For the first The transient energy coefficient of a switch, For the first A switch transient energy, For the first The transient energy of the outgoing switches corresponding to each switch is measured; the magnitude of the transient energy coefficients upstream and downstream of each switch is compared to locate the fault: for the switch upstream of the fault point on the faulty line, the transient energy coefficient is close to 1; for the switch downstream of the fault point, the transient energy coefficient is much less than 1.

[0187] Furthermore, such as Figure 4 As shown, ground fault location analysis was performed on outgoing lines L1, L2, and L3 respectively. Each outgoing line was divided into several protection zones, with the branch switches on the outgoing lines as boundaries. Fault determination was performed on each protection zone: when only one switch in the protection zone had a transient energy coefficient greater than the first transient energy coefficient threshold... Furthermore, the transient energy coefficients of all other switches within the protection zone are less than the second transient energy coefficient threshold. If the fault is within the zone, it is determined to be a fault within the zone; otherwise, it is determined to be a fault outside the zone. If multiple protection zones meet the conditions for determining a fault within the zone, they are sorted according to the transient energy of the switches that meet the fault conditions in each protection zone, and the switches with larger transient energy are output as the fault location results.

[0188] Furthermore, for the preferred outgoing line and alternative outgoing lines L1, L2, and L3 in the final line selection results, the adjacent switch pairs located outside the substation connected to them are searched. If the transient fault direction determination results of two adjacent switches are opposite, and the difference between their zero-sequence current amplitudes is less than a set threshold (i.e., basically the same), then the switch with the reverse transient direction is determined to have a CT polarity reversed problem. For any outgoing line other than the preferred outgoing line and alternative outgoing line, if the off-site switch connected to the outgoing line is determined to be in the positive transient direction, and the difference between the zero-sequence current amplitude of the switch and the zero-sequence current amplitude of the corresponding outgoing line switch is less than a set threshold (i.e., basically the same), then the off-site switch is determined to have a CT polarity reversed problem.

[0189] Example 2

[0190] This invention provides a single-phase grounding fault location system for main and distribution network coordination, applied to a centralized protection and control device, including a storage medium and a processor;

[0191] The storage medium is used to store instructions;

[0192] The processor is configured to operate according to the instructions to execute the method according to any one of Embodiment 1.

[0193] Example 3

[0194] This invention provides a single-phase grounding fault location system that coordinates the main and distribution networks, such as... Figure 1 As shown, it includes centralized protection and control devices and power distribution terminals;

[0195] The centralized protection and control device is installed in the substation and configured to perform the method according to any one of Embodiments 1;

[0196] The power distribution terminal is installed at a designated switch on the power distribution network line outside the substation and is communicatively connected to the centralized protection and control device.

[0197] In practice, the power distribution terminal and the centralized protection and control device establish a communication connection through optical fiber, 5G / 4G or carrier wave.

[0198] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0199] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0200] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0201] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0202] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

[0203] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for locating single-phase grounding faults in a coordinated manner between the main and distribution networks, characterized in that, Applied to centralized protection and control devices, which are connected to the busbar and each outgoing line, the single-phase grounding fault location method includes: Parse the power distribution network topology file to obtain all power supply paths and the length of each power supply path; If the real-time collected bus zero-sequence voltage and zero-sequence current of each outgoing line meet the preset conditions, the single-phase grounding fault selection process is started. A comprehensive criterion combining transient and steady-state quantities is used to calculate the single-phase grounding fault probability of each outgoing line, and the outgoing lines with the highest single-phase grounding fault probability L are selected as the initial selection result. Based on the received transient fault direction discrimination results sent by the power distribution terminals at each switch, all power supply paths, and the length of each power supply path, the initial line selection result is corrected to obtain the final line selection result. For each outgoing line in the final line selection result, the fault section is located to find the section where a single-phase ground fault occurred.

2. The method for locating a single-phase grounding fault in a coordinated main and distribution network according to claim 1, characterized in that: The distribution network topology file includes several nodes connected according to the distribution network topology, parent node information and child node information of each node, and spacing parameters of each node. Each node is a bus node, an outgoing switch node, or a switch node on each distribution network line connected to each outgoing switch node. The methods for obtaining each power supply path include: The bus node is set as the first node in the distribution network topology, serving as the starting reference for power supply path search. For each switching node, a preset power supply path search step is performed to determine the complete power supply path from the switching node itself to the bus node. The preset power supply path search step includes: Identify the parent node information of the switch node; Starting from the parent node of the switch node, and combining the distribution network topology, the related nodes are searched upstream one by one until the bus node is reached, thus determining the complete power supply path from the switch node to the bus node. Methods for obtaining the length of the power supply path include: Based on the spacing parameters of each node in the power supply path, the length of the power supply path corresponding to each switch node is calculated.

3. The method for locating a single-phase grounding fault in a coordinated main and distribution network according to claim 1, characterized in that: If the real-time acquired bus zero-sequence voltage and zero-sequence current of each outgoing line meet the preset conditions, the single-phase grounding fault selection process is initiated, including: Real-time acquisition of bus zero-sequence voltage and zero-sequence current of each outgoing line, and calculation. and ,in, For the current sampling time and The bus zero-sequence voltage difference at the sampling time before the cycle, For the current sampling time and Zhoubo pre-sampling time line The zero-sequence current difference, ; When satisfied ,or When the mutation initiation process is triggered, the bus zero-sequence voltage amplitude reaches a certain value within a set time after the mutation initiation process begins. If this occurs, the single-phase ground fault selection process will be initiated, in which... The zero-sequence voltage changeover setting is used. To qualify The zero-sequence current sudden change setpoint, The zero-sequence voltage threshold setting for single-phase grounding protection.

4. The method for locating a single-phase grounding fault in a coordinated main and distribution network according to claim 3, characterized in that: The method for generating the initial route selection result includes the following steps: Step 1: At the first set time after the single-phase ground fault selection process is officially started, the fault correlation characteristic value of the line is calculated using four criteria, specifically including: Based on the transient differential line selection method, the differential characteristic value of the transient zero-sequence current of each outgoing line after the fault is calculated. Based on the transient zero-sequence current amplitude and phase ratio method, the transient current amplitude and phase of each outgoing line after the fault are calculated; Based on the steady-state zero-sequence current amplitude and phase ratio method, the amplitude and phase of the steady-state zero-sequence current of each outgoing line after the fault are calculated. Based on the zero-sequence active power method, the zero-sequence active power components of each outgoing line are calculated after the fault. Step 2: Normalize the fault correlation feature values ​​of the line calculated using the four criteria to obtain normalized output values ​​X1, X2, X3, and X4; X1, X2, X3, and X4 are mapped to the [0,1] interval according to a preset rule. The interval endpoint 1 indicates the highest confidence level of the criterion in determining that the line is a faulty line, and the interval endpoint 0 indicates the lowest confidence level of the criterion in determining that the line is a faulty line. The preset rule is: the higher the fault correlation, the closer the normalized value is to 1. Step 3: Calculate the line using weighted fusion. grounding fault probability Qualifying grounding fault probability The calculation formula is: ， in, , , , The weights of the fault-related feature values ​​of the line are calculated for each of the four criteria, and the following conditions are met: , , , , They are the ones who qualify The normalized values ​​of the fault-related characteristic values ​​of the line are calculated using four criteria. Step 4: Press The values ​​are sorted from high to low, and the top three lines are selected as the first choice and the alternative lines, respectively, to obtain the initial line selection results.

5. A method for locating single-phase grounding faults in a coordinated manner between the main and distribution networks according to claim 1, characterized in that: The method for generating the transient fault direction determination result includes: After a ground fault occurs, each distribution terminal configured at the switching node collects and extracts the transient zero-sequence voltage signal within a second set time period following a sudden change in zero-sequence voltage or zero-sequence current. and transient zero-sequence current signal ,in, N is the number of sampling points within the second set time period; Calculate the transient zero-sequence voltage signal With transient zero-sequence current signal The sum of the products of the sampled values ​​S and the sum of the absolute values ​​S abs The sum of the products of the sampled values, S, and the sum of the absolute values, S abs The calculation formulas are as follows: ， ， when When the transient zero-sequence voltage and transient zero-sequence current are not in the same direction, the transient fault direction is positive. when When the transient zero-sequence voltage and transient zero-sequence current are in the same direction, the transient fault direction is in the opposite direction.

6. The method for locating a single-phase grounding fault in a coordinated main and distribution network according to claim 1, characterized in that: All switches located outside the substation and equipped with distribution terminals are defined as fault detection points; The initial route selection results include the preferred route and the alternative route; The method for generating the final route selection result includes: Based on preset correction rules, the initial route selection result is corrected to obtain the final route selection result; the correction rules are: 1) If the number of valid positive direction detection points for the first selected line L1 is the largest among all selected lines in the initial line selection results, then the first selected line L1 is determined to be correct, and the initial line selection results remain unchanged; the method for determining the number of valid positive direction detection points for the selected line includes: The power supply path and its length between each switch in the preferred or alternative outgoing lines are selected. The longest power supply path is identified as the fault path. Switches whose transient fault direction is identified as positive are defined as valid positive direction detection points. The number of switches whose transient fault direction is identified as positive on the longest power supply path is counted as the number of valid positive direction detection points for that outgoing line. 2) If any candidate qualifying spot meets the following conditions simultaneously, then that candidate qualifying spot will be adjusted to the first qualifying spot: 1) The number of its effective positive direction detection points is the highest among all the lines that emerge in the initial line selection results; 2) The difference in zero-sequence current amplitude at all valid positive direction detection points is less than the set threshold, and the transient energy coefficients are all greater than the first transient energy coefficient threshold. ; 3) The difference in zero-sequence current amplitude between the last-stage effective positive direction detection point switch and its sub-switches is greater than a set threshold, and the transient energy coefficient is less than the second transient energy coefficient threshold. , .

7. A method for locating single-phase grounding faults in a coordinated manner between the main and distribution networks according to claim 1, characterized in that: For each outgoing line in the final line selection result, the fault section is located to find the section where a single-phase ground fault occurred, including: For each outgoing line in the final line selection result, a predetermined fault section location step is executed to identify the section where a single-phase ground fault occurs. The predetermined fault section location step includes: Locate the moment of zero-sequence voltage change in the electrical quantity data sent by each distribution terminal in the outgoing line, and align the electrical quantity data. Calculate the transient energy and transient energy coefficient of each switch equipped with a power distribution terminal; Using the branch switches on the outgoing line as boundaries, the outgoing line is divided into several protection zones. Based on the transient energy and transient energy coefficient of each switch equipped with a distribution terminal, fault determination is performed on each protection zone to identify the section where a single-phase ground fault occurs.

8. A method for locating a single-phase grounding fault in a coordinated main and distribution network according to claim 7, characterized in that: The step of finding the zero-sequence voltage abrupt change time in the electrical quantity data sent by each power distribution terminal and aligning the electrical quantity data includes: Search for zero-sequence voltage data in the electrical quantity data sent by each distribution terminal configured on each outgoing line in the final line selection result, and perform abrupt change detection; When a zero-sequence voltage mutation value of a power distribution terminal is detected to be greater than a preset threshold value, the sampling time is marked as the zero-sequence voltage mutation time of the power distribution terminal. The first peak voltage that appears after the zero-sequence voltage abrupt change is retrieved, and the sampling time at which the peak voltage occurs is determined as the fault initiation time of the distribution terminal. Based on the initial fault time of each power distribution terminal, the electrical quantity data of all power distribution terminals on the same outgoing line are aligned on the time axis. If the zero-sequence voltage change moment cannot be identified in the electrical quantity data of a certain power distribution terminal, then the electrical quantity data of that power distribution terminal will not be included in the calculation of transient energy and transient energy coefficient.

9. A method for locating a single-phase grounding fault in a coordinated main and distribution network according to claim 8, characterized in that: The outgoing line is divided into several protection zones, with the branch switches on the outgoing line as boundaries. Based on the transient energy coefficient of each switch equipped with a distribution terminal, a fault determination step is performed for each protection zone. The fault determination step includes: When only one switch within the protected area has a transient energy coefficient greater than the first transient energy coefficient threshold Furthermore, the transient energy coefficients of all other switches within the protection zone are less than the second transient energy coefficient threshold. If the fault is within the zone, it is determined to be an internal fault; otherwise, it is determined to be an external fault. The formula for calculating the transient energy coefficient is: ， In the formula, For the first The transient energy coefficient of a switch, For the first A switch transient energy, For the first The transient energy of the outgoing switch corresponding to each switch. ; If multiple protection zones meet the fault determination criteria within the zone, they are sorted according to the transient energy magnitude of the switches that meet the fault criteria in each protection zone. The switch with the larger transient energy is output first as the fault location result. The formula for calculating transient energy is: ， In the formula, For the first The first of the waveform recordings of the power distribution terminal on the first switch One transient zero-sequence current sampling point.

10. A method for locating single-phase grounding faults in a coordinated manner between the main and distribution networks according to claim 1, characterized in that: The single-phase grounding fault location method for main and distribution network coordination also includes: For the preferred outgoing line and the alternative outgoing line in the final line selection result, the adjacent switch pairs connected to them located outside the substation are searched. If the transient fault direction determination results of the two adjacent switches are opposite, and the difference between their zero-sequence current amplitudes is less than the set threshold, then the switch with the opposite transient direction has a CT polarity reversal problem. For any outgoing line other than the primary outgoing line and the alternative outgoing line, if there is a switch outside the station connected to the outgoing line that is determined to be in transient positive direction, and the difference between the zero-sequence current amplitude of the switch and the zero-sequence current amplitude of the corresponding outgoing line switch is less than a set threshold, then it is determined that the switch outside the station has a CT polarity reverse connection problem.

11. A single-phase grounding fault location system for coordinated main and distribution network operation, characterized in that, It is used in centralized protection and control devices, including storage media and processors; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the method according to any one of claims 1-10.

12. A single-phase grounding fault location system for coordinated main and distribution network operation, characterized in that, This includes centralized protection and control devices and power distribution terminals; The centralized protection and control device is installed in the substation and configured to perform the method according to any one of claims 1-10; The power distribution terminal is installed at a designated switch on the power distribution network line outside the substation and is communicatively connected to the centralized protection and control device.

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