Method and system for studying, judging and handling single-phase earth fault of power distribution network

Abstract

The invention discloses a method and a system for studying, judging and handling a single-phase grounding fault of a power distribution network. The method comprises the following steps: acquiring a line selection alarm signal and a line selection result of a low-current grounding line selection device in a station; according to the line selection result, calculating the zero-sequence current variation of all the off-station terminals of the corresponding line; if the line topological structure passes the verification, replacing a specified terminal in the line topological structure with a lead to obtain a new line topological structure; hierarchical clustering is carried out on the out-of-station terminals according to the zero-sequence current variable quantity, the class with the large arithmetic mean value in the clustering result is a fault class, and the class with the small arithmetic mean value in the clustering result is a normal class; marking a fault point in the new line topological structure according to the out-of-station terminal corresponding to the fault class and the normal class; and isolating the fault points, and if the line selection alarm signal is not reset after all the fault points are isolated, iteratively executing the steps until the line selection alarm signal is reset. According to the method, iterative clustering is carried out in combination with the fault reset condition, and the single-phase earth fault can be accurately handled.

Description

Technical Field

[0001] The present invention relates to the technical field of distribution network, and in particular to a method and system for analyzing and handling single-phase grounding faults in a distribution network. Background Art

[0002] The 10kV outgoing line of the distribution network is an ungrounded system. When a single-phase grounding fault occurs, it generally will not cause the line to trip in order not to affect the power supply reliability of users. However, single-phase grounding not only affects the normal power supply of users, but also may generate overvoltage, damage equipment, cause wildfires, and even develop into a phase-to-phase short circuit fault, thereby causing the outgoing line to trip and affecting the economy of the power grid operation.

[0003] In the analysis and treatment of 10kV outgoing line grounding faults, it is necessary to complete the positioning of the outgoing line of the grounding fault and the positioning of the fault between the outgoing line sections. At present, the transient method of small current grounding line selection device in the station can achieve an accuracy rate of more than 97.4%, and the problem of inaccurate line selection in the station has been well solved. For the selection of outgoing line fault sections, the dispatcher usually receives the fault information by phone or checks the small current grounding alarm signal in the alarm window of the distribution automation master station, enters the zero-sequence current display interface or the busbar grounding fault auxiliary treatment interface to view the zero-sequence current change sorting, and then manually performs a switch test to locate the fault, and then arranges maintenance personnel to patrol the line.

[0004] The current handling methods have the following problems: the small current grounding line selection device in the station is not coordinated with the terminal outside the station, which makes it difficult to locate the fault; fault handling mainly relies on manual work and experience, with low fault judgment accuracy, long handling time, and low automation level; and it is impossible to respond to faults in a timely manner. Summary of the invention

[0005] Technical problem to be solved by the present invention: In view of the above-mentioned problems in the prior art, a method and system for analyzing and handling single-phase grounding faults in a distribution network are provided. The method collects the alarm signal of the transient small current grounding line selection device in the station, the zero-sequence current and the grounding alarm signal of the terminal outside the station, and collects them to the distribution automation master station to realize the coordination of information inside and outside the station, complete the small current grounding line selection and the section selection outside the station, and perform fault location and fault isolation through the distribution automation master station.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A method for analyzing and handling a single-phase grounding fault in a distribution network comprises the following steps:

[0008] Obtain the line selection alarm signal and line selection result of the small current grounding line selection device in the station;

[0009] According to the line selection results, calculate the zero-sequence current variation of all the off-station terminals of the corresponding line;

[0010] The line topology structure is checked. If the check passes, the designated terminals in the line topology structure are replaced with wires to obtain a new line topology structure.

[0011] The off-station terminals are hierarchically clustered according to the zero-sequence current variation, and the classes whose arithmetic mean of the zero-sequence current variation is greater than the preset threshold are classified as fault classes, and the classes whose arithmetic mean of the zero-sequence current variation is less than the preset threshold are classified as normal classes;

[0012] Mark the fault point in the new line topology structure according to the off-station terminals corresponding to the fault class and the normal class;

[0013] The fault points are isolated. If the line selection alarm signal is not restored after all fault points are isolated, the above steps are iterated until the line selection alarm signal is restored.

[0014] Further, after obtaining the line selection alarm signal and line selection result of the small current grounding line selection device in the station, it includes:

[0015] Get the grounding type information. If it is instantaneous grounding, end and exit. If it is not instantaneous grounding, execute the step of calculating the zero-sequence current change of all off-station terminals of the corresponding line according to the line selection results.

[0016] Furthermore, the designated terminals include non-automatic switches, offline terminals, faulty terminals and abnormal terminals.

[0017] Furthermore, when the off-station terminals are hierarchically clustered according to the zero-sequence current variation, it includes:

[0018] Sort the zero-sequence current changes and calculate the difference between adjacent elements in the sequence;

[0019] The off-station terminals corresponding to the minimum difference of zero-sequence current variation are classified into the same category;

[0020] Eliminating the zero-sequence current variation of the clustered off-site terminals from the sequence, calculating the arithmetic mean of the zero-sequence current variation of the clustered off-site terminals and adding the arithmetic mean to the sequence;

[0021] If the number of elements in the sequence is greater than the specified number, repeat the above steps until the number of elements in the sequence is less than or equal to the specified number.

[0022] Furthermore, after obtaining the new line topology structure, the method includes: if the new line topology structure does not include any branches, generating a virtual terminal at the end of the line, and the virtual zero-sequence current value of the virtual terminal is 0.

[0023] Furthermore, before performing hierarchical clustering on the zero-sequence current variation, the method includes: if the number of terminals in the new line topology is less than the target number, marking the line ends where all the terminals are located as fault points, and performing the step of isolating the fault points.

[0024] Further, when marking the fault point in the new line topology structure according to the off-station terminals corresponding to the fault class and the normal class, it includes:

[0025] If there are no normal terminals between faulty terminals, the faulty terminals are considered to be adjacent, and the lines of each adjacent faulty terminal are colored with the fault color;

[0026] If there is a normal terminal between the faulty lines, the line of the normal terminal is colored with a faulty color;

[0027] If there are two normal terminals between the faulty lines, the lines of the normal terminals will not be marked with faulty colors;

[0028] Mark the end of each colored section as a failure point.

[0029] Furthermore, isolating the fault point includes:

[0030] Starting from the end of the topology in the line topology structure, the fault points are isolated from the branch line to the middle section in sequence. When isolating the fault point at the end of the topology, open the switch in front of the fault point. When isolating the fault point in the middle section of the line, open all the switches at the rear end of the fault point and then open the switch at the front end of the fault point.

[0031] Furthermore, when isolating the fault points from the outside to the inside in sequence starting from the topological end in the line topological structure, it includes:

[0032] If the fault point in the line topology is single, after isolating the fault point, check whether the line selection alarm signal is restored. If so, end and exit. Otherwise, re-execute the step of obtaining the line selection alarm signal and line selection result of the small current grounding line selection device in the station and its subsequent steps;

[0033] If there are multiple fault points in the line topology, after isolating each fault point, check whether the line selection alarm signal is restored. If it is, end and exit, otherwise continue to isolate subsequent fault points. If the line selection alarm signal has not been restored after all fault points are isolated, re-execute the steps of obtaining the line selection alarm signal and line selection result of the small current grounding line selection device in the station and its subsequent steps.

[0034] The present invention also proposes a single-phase grounding fault analysis and treatment system for a distribution network, including a small current grounding line selection device in a station and a distribution automation master station, wherein:

[0035] The small current grounding line selection device in the station is used to trigger an alarm, and send the line selection alarm signal and the line selection result to the distribution automation master station through the data gateway machine;

[0036] The distribution automation master station is used for:

[0037] Obtain the line selection alarm signal and line selection result of the small current grounding line selection device in the station;

[0038] According to the line selection results, calculate the zero-sequence current variation of all the off-station terminals of the corresponding line;

[0039] The line topology structure is checked. If the check passes, the designated terminals in the line topology structure are replaced with wires to obtain a new line topology structure.

[0040] The off-station terminals are hierarchically clustered according to the zero-sequence current variation, and the classes whose arithmetic mean of the zero-sequence current variation is greater than the preset threshold are classified as fault classes, and the classes whose arithmetic mean of the zero-sequence current variation is less than the preset threshold are classified as normal classes;

[0041] Mark the fault point in the new line topology structure according to the off-station terminals corresponding to the fault class and the normal class;

[0042] The fault points are isolated. If the line selection alarm signal is not restored after all fault points are isolated, the above steps are iterated until the line selection alarm signal is restored.

[0043] Compared with the prior art, the advantages of the present invention are:

[0044] After obtaining the line selection results of the small current grounding line selection device in the station, the present invention collects the zero-sequence current of the distribution automation terminal outside the station to locate the specific fault position, thereby realizing the coordination of devices inside and outside the station. At the same time, the terminals outside the station are hierarchically clustered according to the change in zero-sequence current, without setting a threshold, and can adapt to different line parameters.

[0045] The present invention combines hierarchical clustering with automatic topology generation, can filter out abnormal data, and has certain fault tolerance. In addition, the hierarchical clustering algorithm provided by the present invention performs multiple iterations according to the situation of fault isolation to achieve accurate positioning of the fault point. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 The figure is a brief flow chart of ground fault analysis and judgment in an embodiment of the present invention.

[0047] Figure 2 The figure is a detailed flow chart of ground fault analysis and judgment in an embodiment of the present invention.

[0048] Figure 3 This is a topological diagram of a 110 / 10kV outgoing line simulation model provided in an embodiment of the present invention.

[0049] Figure 4 Schematic diagram of zero-sequence current distribution in single-phase grounding fault simulation in an embodiment of the present invention.

[0050] Figure 5 It is a schematic diagram of hierarchical clustering according to the zero-sequence current variation in an embodiment of the present invention.

[0051] Figure 6 This is a coloring schematic diagram of a single-phase grounding fault simulation fault line determined for the first time in an embodiment of the present invention.

[0052] Figure 7 The figure is a brief flowchart of the ground fault handling in the embodiment of the present invention.

[0053] Figure 8 This is a coloring schematic diagram of a single-phase grounding fault simulation fault line for the second determination in an embodiment of the present invention. DETAILED DESCRIPTION

[0054] The present invention is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

[0055] Embodiment 1

[0056] This embodiment proposes a method for analyzing and handling single-phase grounding faults in a distribution network, which is applied to a distribution network equipped with a small current grounding line selection device in a station and a distribution automation master station, such as Figure 1 and Figure 2 As shown, the following steps are included:

[0057] Fault analysis, including:

[0058] S1, the low current grounding line selection device in the station triggers an alarm, and sends the line selection alarm signal and line selection result to the distribution automation master station through the data gateway;

[0059] S2, the distribution automation master station obtains the line selection alarm signal and line selection result of the small current grounding line selection device in the station; according to the line selection result, the zero-sequence current change of all the external terminals of the corresponding line is calculated;

[0060] S3, the distribution automation master station checks the line topology structure, and ends and exits if the check is wrong;

[0061] S4, if the verification is passed, the distribution automation master station replaces the designated terminal in the line topology with the wire to obtain a new line topology;

[0062] S5, the distribution automation master station performs hierarchical clustering on the off-station terminals according to the zero-sequence current variation, classifies the class with a larger arithmetic mean value of the zero-sequence current variation in the clustering result into a fault class, and classifies the class with a smaller arithmetic mean value of the zero-sequence current variation in the clustering result into a normal class;

[0063] S6, the distribution automation master station marks the fault point in the new line topology structure according to the off-station terminals corresponding to the fault class and the normal class, so as to locate the fault;

[0064] Troubleshooting, including:

[0065] S7, isolate the fault point by trying to pull. If the line selection alarm signal has not been restored after all fault points are isolated, jump to step S1 for the next iteration until the line selection alarm signal is restored, so that the fault self-healing after isolation is achieved.

[0066] Each step is described in detail below with reference to specific examples.

[0067] according to Figure 3 The system shown in the figure builds a simulation model, and the system parameter values ​​are shown in Table 1:

[0068] Table 1 Simulation model parameter values

[0069]

[0070]

[0071] Figure 4 The zero-sequence current distribution when single-phase grounding faults occur simultaneously at nodes 2 and 5 in the simulation model is given.

[0072] In step S2 of this embodiment, after obtaining the line selection alarm signal and line selection result of the low current grounding line selection device in the station, the following steps are included:

[0073] Get the grounding type information. If it is instantaneous grounding, end and exit. If it is not instantaneous grounding, execute the step of calculating the zero-sequence current change of all the off-station terminals of the corresponding line according to the line selection result. After the distribution automation master station obtains the line selection alarm signal and line selection result of the small current grounding line selection device in the station, how to continue to obtain the grounding type information is well known to those skilled in the art. For example, the current and voltage waveforms when the fault occurs can be recorded, and the nature of the fault can be inferred by analyzing these waveforms, or hardware equipment can be used to analyze the fault type, or the characteristics of the grounding fault can be analyzed in real time by continuously monitoring the relevant parameters. This embodiment is not limited here and will not be repeated.

[0074] In step S2 of this embodiment, when calculating the zero-sequence current variation of all the off-station terminals of the corresponding line according to the line selection result, specifically, the zero-sequence current telemetry and grounding alarm signals of all the switches of the corresponding line are collected, and the zero-sequence current telemetry and grounding alarm signals before the fault are recorded. The zero-sequence current variation is obtained by calculating the difference between the zero-sequence current telemetry before and after the fault. Figure 4 As shown, the changes in zero-sequence current of all terminals outside the station are: line 1 is 5.83, 301 is 4, 302 is 1.81, 303 is 0.07, 304 is 1.83, 305 is 0.06, and 306 is 0.07.

[0075] In step S3 of this embodiment, the distribution automation master station verifies the line topology and coloring. The specific implementation process of the verification is well known to those skilled in the art and is not the focus of this solution. This embodiment will not be repeated. If the verification is wrong, the line topology is automatically refreshed and then verified again. If the verification is still wrong, the judgment is terminated.

[0076] In step S4 of this embodiment, when the distribution automation master station replaces the designated terminals in the line topology structure with wires, the designated terminals include non-automatic switches, offline terminals, faulty terminals and abnormal terminals. The non-automatic switches, offline terminals, faulty terminals and abnormal terminals can be obtained by analyzing the relevant information when measuring the zero-sequence current telemetry and grounding alarm signals of all switches on the corresponding line. The specific data analysis process is well known to those skilled in the art and is not the focus of this solution, so it will not be repeated in this embodiment.

[0077] After obtaining the new line topology, the number of terminals in the new line topology is counted. If it is less than the target number, the line ends where all terminals are located are marked as fault points, and the process jumps to step S7 for fault handling. In this embodiment, the target number is 3, that is, when the number of terminals in the new line topology is 2, the process directly enters the fault handling step.

[0078] Furthermore, when the number of terminals in the new line topology is greater than or equal to the target number, it is determined whether the new line topology contains any branches. If it does not contain any branches, a virtual terminal is generated at the end of the line, and the virtual zero-sequence current value of the virtual terminal is 0.

[0079] In step S5 of this embodiment, a hierarchical clustering method is used to cluster the off-site terminals into two classes, without setting a threshold, and can adapt to various line parameter scenarios. Specifically, when the off-site terminals are hierarchically clustered according to the zero-sequence current variation, it includes:

[0080] S51, sorting the zero-sequence current variation and calculating the difference between adjacent elements in the sequence;

[0081] S52, selecting the minimum difference, and classifying the out-of-station terminals corresponding to the zero-sequence current variation forming the minimum difference into one category;

[0082] S53, removing the zero-sequence current changes of the clustered out-of-station terminals from the sequence, calculating the arithmetic mean of the clustered zero-sequence current changes of the out-of-station terminals and adding the arithmetic mean to the sequence;

[0083] S54, if the elements in the sequence are greater than the specified number, repeat steps S51 to S53 until the elements in the sequence are less than or equal to the specified number.

[0084] The specified number in this embodiment is 2. According to the above, the zero-sequence current changes of each terminal outside the station are: outgoing line 1 is 5.83, 301 is 4, 302 is 1.81, 303 is 0.07, 304 is 1.83, 305 is 0.06, and 306 is 0.07. The specific clustering process is as follows: Figure 5 As shown, the process is as follows:

[0085] First round of clustering:

[0086] The zero-sequence current variation is sorted in ascending order, and the results are: 0.06(305), 0.07(306), 0.07(303), 1.81(302), 1.83(304), 4(301), 5.83(outgoing line 1), where the brackets indicate the off-station terminals corresponding to the zero-sequence current variation;

[0087] Calculate the difference between adjacent elements in the sequence and get: 0.01, 0, 1.74, 0.02, 2.17, 1.83;

[0088] The off-station terminals corresponding to the zero-sequence current variation forming the minimum difference are classified into one category, that is, the off-station terminals 306 and 303 corresponding to the difference 0 are classified into one category;

[0089] The zero-sequence currents 0.07(306) and 0.07(303) of the clustered off-site terminals are removed from the sequence, and the arithmetic mean of the zero-sequence current changes of the clustered off-site terminals 306 and 303 is calculated to obtain 0.07 and added to the sequence to obtain: 0.06(305), 1.81(302), 1.83(304), 4(301), 5.83(outgoing line 1), 0.07(306, 303). At this time, the number of elements in the sequence is 6, so the second round of clustering is performed;

[0090] Second round of clustering:

[0091] The zero-sequence current changes are sorted from small to large, and the results are: 0.06 (305), 0.07 (306, 303), 1.81 (302), 1.83 (304), 4 (301), 5.83 (outgoing line 1);

[0092] Calculate the difference between adjacent elements in the sequence and get: 0.01, 1.74, 0.02, 2.17, 1.83;

[0093] The off-station terminals corresponding to the zero-sequence current variation forming the minimum difference are classified into one category, that is, the off-station terminals 305, 306, and 303 corresponding to the difference of 0.01 are classified into one category;

[0094] The zero-sequence currents 0.06 (305) and 0.07 (306, 303) of the clustered off-site terminals are removed from the sequence, and the arithmetic mean of the zero-sequence current changes of the clustered off-site terminals 305, 306, and 303 is calculated to be 0.068 and added to the sequence to obtain: 1.81 (302), 1.83 (304), 4 (301), 5.83 (outgoing line 1), 0.068 (305, 306, 303). At this time, the number of elements in the sequence is 5, so the third round of clustering is performed;

[0095] The third round of clustering:

[0096] The zero-sequence current changes are sorted in ascending order, and the results are: 0.068 (305, 306, 303), 1.81 (302), 1.83 (304), 4 (301), 5.83 (outgoing line 1);

[0097] Calculate the difference between adjacent elements in the sequence and get: 1.74, 0.02, 2.17, 1.83;

[0098] The off-station terminals corresponding to the zero-sequence current variation forming the minimum difference are classified into one category, that is, the off-station terminals 302 and 304 corresponding to the difference of 0.02 are classified into one category;

[0099] The zero-sequence currents 1.81 (302) and 1.83 (304) of the clustered off-site terminals are removed from the sequence, and the arithmetic mean of the zero-sequence current changes of the clustered off-site terminals 302 and 304 is calculated to obtain 1.82 and added to the sequence, and the following results are obtained: 0.068 (305, 306, 303), 4 (301), 5.83 (outgoing line 1), 1.82 (302, 304). At this time, the number of elements in the sequence is 4, so the fourth round of clustering is performed;

[0100] Fourth round of clustering:

[0101] The zero-sequence current changes are sorted in ascending order, and the results are: 0.068 (305, 306, 303), 1.82 (302, 304), 4 (301), 5.83 (outgoing line 1);

[0102] Calculate the difference between adjacent elements in the sequence and get: 1.75, 2.18, 1.83;

[0103] The off-station terminals corresponding to the zero-sequence current variation forming the minimum difference are classified into one category, that is, the off-station terminals 305, 306, 303, 302, and 304 corresponding to the difference of 1.75 are classified into one category;

[0104] The zero-sequence currents 0.067 (305, 306, 303) and 1.82 (302, 304) of the clustered off-site terminals are removed from the sequence, and the arithmetic mean of the zero-sequence current changes of the clustered off-site terminals 305, 306, 303, 302, 304 is calculated to obtain 0.932 and added to the sequence to obtain: 4 (301), 5.83 (outgoing line 1), 0.932 (305, 306, 303, 302, 304). At this time, the number of elements in the sequence is 3, so the fifth round of clustering is performed;

[0105] Fifth round of clustering:

[0106] The zero-sequence current changes are sorted in ascending order, and the results are: 0.932 (305, 306, 303, 302, 304), 4 (301), 5.83 (outgoing line 1);

[0107] Calculate the difference between adjacent elements in the sequence and get: 3.068, 1.83;

[0108] The off-station terminals corresponding to the zero-sequence current variation that forms the minimum difference are classified into one category, that is, the off-station terminals 301 and outgoing line 1 corresponding to the difference of 1.83 are classified into one category;

[0109] The zero-sequence current 4 (301) and 5.83 (outgoing line 1) of the clustered off-site terminals are removed from the sequence, and the arithmetic mean of the zero-sequence current changes of the clustered off-site terminals 301 and outgoing line 1 is calculated to obtain 4.915 and added to the sequence to obtain: 0.932 (305, 306, 303, 302, 304), 4.915 (301, outgoing line 1). At this time, the number of elements in the sequence is 2, and the clustering is completed.

[0110] Since the arithmetic mean of the zero-sequence current changes of the off-station terminals 305, 306, 303, 302, and 304 is a smaller value of 0.932, and the arithmetic mean of the zero-sequence current changes of the off-station terminals 301 and the outgoing line 1 is a larger value of 4.915, through the above steps, the fault-type terminals are obtained as the outgoing lines 1 and 301.

[0111] In step S6 of this embodiment, when marking the fault point in the new line topology structure according to the off-station terminal corresponding to the fault class and the normal class, it includes:

[0112] S61, if there is no normal terminal between the faulty terminals, the faulty terminals are considered to be adjacent, and the lines of the adjacent faulty terminals are colored with fault colors;

[0113] S62, if there is a normal terminal between the faulty colored lines, the data of the terminal is considered abnormal, and the line of the normal terminal is colored with a faulty color, thereby coloring the line between the colored parts at both ends with a faulty color;

[0114] S63, if there are two normal terminals between the fault colored lines, the data of the two terminals are considered normal, and the lines of the two normal terminals are not colored with fault colors, so that the middle part is not colored;

[0115] S64, marking the end of each colored portion as a fault point.

[0116] Through the above steps, the coloring result is as follows Figure 6 As shown, it can be seen that the fault is located at the end of 301, that is, node 2.

[0117] In step S7 of this embodiment, when isolating the fault point, the branch line fault is handled first, and then the mid-section fault is handled, which specifically includes:

[0118] Starting from the end of the topology in the line topology structure, the fault points are isolated from the branch line to the middle section in sequence. When isolating the fault point at the end of the topology, open the switch in front of the fault point. When isolating the fault point in the middle section of the line, open all the switches at the rear end of the fault point and then open the switch at the front end of the fault point.

[0119] Furthermore, when isolating the fault points from the outside to the inside in sequence starting from the topological end in the line topological structure, it includes:

[0120] If the fault point in the line topology is single, after isolating the fault point, check whether the line selection alarm signal is restored. If so, end and exit. Otherwise, re-execute the step of obtaining the line selection alarm signal and line selection result of the small current grounding line selection device in the station and its subsequent steps;

[0121] If there are multiple fault points in the line topology, after isolating each fault point, check whether the line selection alarm signal is restored. If it is, end and exit, otherwise continue to isolate subsequent fault points. If the line selection alarm signal has not been restored after all fault points are isolated, re-execute the steps of obtaining the line selection alarm signal and line selection result of the small current grounding line selection device in the station and its subsequent steps.

[0122] like Figure 7As shown, the specific steps of step S7 in this embodiment are as follows:

[0123] Step 1: Isolate the fault point at the end of the topology first, and open the switch in front of the fault point; that is, open 301. If the fault line selection alarm signal is not restored, exclude 301 and re-execute S1 to S6. When re-executing S1 to S6, remove the relevant data of 301 in steps S2 and S4. The result after execution is: outgoing lines 1, 302, and 304 are faulty, and the topology is colored as follows: Figure 8 As shown, there is no fault point in the branch line;

[0124] Step 2: Since there is no fault point in the branch line of the new line topology, the fault point in the middle of the line is directly isolated. After opening all switches at the rear end of the fault point, the switch at the front end of the fault point is opened, that is, 306, 305, and 304 are opened in sequence;

[0125] Step 3: If the ground fault signal is restored after all faults are isolated, the line will enter self-healing mode.

[0126] Embodiment 2

[0127] This embodiment proposes a single-phase grounding fault analysis and handling system for a distribution network, including a small current grounding line selection device in a station and a distribution automation master station, wherein:

[0128] The small current grounding line selection device in the station is used to trigger an alarm, and send the line selection alarm signal and the line selection result to the distribution automation master station through the data gateway machine;

[0129] The distribution automation master station is used for:

[0130] Obtain the line selection alarm signal and line selection result of the small current grounding line selection device in the station;

[0131] According to the line selection results, calculate the zero-sequence current variation of all the off-station terminals of the corresponding line;

[0132] The line topology structure is checked. If the check passes, the designated terminals in the line topology structure are replaced with wires to obtain a new line topology structure.

[0133] The off-station terminals are hierarchically clustered according to the zero-sequence current variation, and the class whose arithmetic mean value of the zero-sequence current variation in the clustering result is greater than the preset threshold is classified as the fault class, and the class whose arithmetic mean value of the zero-sequence current variation in the clustering result is less than the preset threshold is classified as the normal class;

[0134] Mark the fault point in the new line topology structure according to the off-station terminals corresponding to the fault class and the normal class;

[0135] The fault points are isolated. If the line selection alarm signal is not restored after all fault points are isolated, the above steps are iterated until the line selection alarm signal is restored.

[0136] In summary, the present invention proposes a method and system for analyzing and handling single-phase grounding faults in distribution networks. When analyzing faults, the terminal conditions and abnormal data are identified, the topology is updated, and the zero-sequence current at the time of the fault is collected to calculate the zero-sequence current change. The zero-sequence current change is quickly clustered using a hierarchical clustering algorithm, and then verified according to the topological structure to locate the fault point. When handling faults, branch line faults are handled first, followed by mid-section faults. Combined with the fault recovery situation, iterative clustering is performed to accurately handle single-phase grounding faults. In general, it has the following advantages:

[0137] (1) The present invention uses a hierarchical clustering algorithm to cluster zero-sequence currents without setting a threshold, and can adapt to various line parameter scenarios;

[0138] (2) The present invention timely updates the topology according to the terminal offline, abnormal and other situations, and combines the topological structure and zero-sequence current clustering results to make fault determination more accurate;

[0139] (3) The present invention performs iterative clustering according to the fault handling results, can handle multi-point single-phase grounding faults, and has a certain fault tolerance capability.

[0140] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may take the form of a computer program product implemented on one or more computer-readable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes. The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, may be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the functions in the process. Figure 1 A process or multiple processes and / or boxes Figure 1These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing device to work in a specific way, so that the instructions stored in the computer-readable memory produce a product including an instruction device, which implements the functions specified in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide for implementing the process in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0141] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for analyzing and handling single-phase grounding faults in a distribution network, characterized in that: The following steps are involved: Obtain the line selection alarm signal and line selection result of the small current grounding line selection device in the station; According to the line selection results, calculate the zero-sequence current variation of all the off-station terminals of the corresponding line; The line topology structure is checked. If the check passes, the designated terminals in the line topology structure are replaced with wires to obtain a new line topology structure. According to the variation of zero-sequence current, the off-station terminals are hierarchically clustered. The class with a larger arithmetic mean of zero-sequence current variation in the clustering result is classified as a fault class, and the class with a smaller arithmetic mean of zero-sequence current variation is classified as a normal class. Mark the fault point in the new line topology structure according to the off-station terminals corresponding to the fault class and the normal class; The fault points are isolated. If the line selection alarm signal is not restored after all fault points are isolated, the above steps are iterated until the line selection alarm signal is restored.

2. The method for analyzing and handling single-phase grounding faults in a distribution network according to claim 1 is characterized in that: After obtaining the line selection alarm signal and line selection result of the small current grounding line selection device in the station, it includes: Get the grounding type information. If it is instantaneous grounding, end and exit. If it is not instantaneous grounding, execute the step of calculating the zero-sequence current change of all off-station terminals of the corresponding line according to the line selection results.

3. The method for analyzing and handling single-phase grounding faults in a distribution network according to claim 1 is characterized in that: The designated terminals include non-automatic switches, offline terminals, fault terminals and abnormal terminals.

4. The method for analyzing and handling single-phase grounding faults in a distribution network according to claim 1 is characterized in that: When the off-station terminals are hierarchically clustered according to the change in zero-sequence current, it includes: Sort the zero-sequence current changes and calculate the difference between adjacent elements in the sequence; The off-station terminals corresponding to the minimum difference of zero-sequence current variation are classified into the same category; Eliminating the zero-sequence current variation of the clustered off-site terminals from the sequence, calculating the arithmetic mean of the zero-sequence current variation of the clustered off-site terminals and adding the arithmetic mean to the sequence; If the number of elements in the sequence is greater than the specified number, repeat the above steps until the number of elements in the sequence is less than or equal to the specified number.

5. The method for analyzing and handling single-phase grounding faults in a distribution network according to claim 1 is characterized in that: After the new line topology structure is obtained, the method includes: if the new line topology structure does not include any branches, a virtual terminal is generated at the end of the line, and the virtual zero-sequence current value of the virtual terminal is 0.

6. The method for analyzing and handling single-phase grounding faults in a distribution network according to claim 1 is characterized in that: Before performing hierarchical clustering on the zero-sequence current variation, the method includes: if the number of terminals in the new line topology is less than the target number, marking the line ends where all the terminals are located as fault points, and performing the step of isolating the fault points.

7. The method for analyzing and handling single-phase grounding faults in a distribution network according to claim 1 is characterized in that: When marking the fault point in the new line topology structure according to the off-station terminals corresponding to the fault class and the normal class, it includes: If there are no normal terminals between faulty terminals, the faulty terminals are considered to be adjacent, and the lines of each adjacent faulty terminal are colored with the fault color; If there is a normal terminal between the faulty lines, the line of the normal terminal is colored with a faulty color; If there are two normal terminals between the faulty lines, the lines of the normal terminals will not be marked with faulty colors; Mark the end of each colored section as a failure point.

8. The method for analyzing and handling single-phase grounding faults in a distribution network according to claim 1 is characterized in that: Isolating the fault point includes: Starting from the end of the topology in the line topology structure, the fault points are isolated from the branch line to the middle section in sequence. When isolating the fault point at the end of the topology, open the switch in front of the fault point. When isolating the fault point in the middle section of the line, open all the switches at the rear end of the fault point and then open the switch at the front end of the fault point.

9. The method for analyzing and handling single-phase grounding faults in a distribution network according to claim 8, characterized in that: When isolating the fault point from the outside to the inside in sequence starting from the topology end of the line topology structure, it includes: If the fault point in the line topology is single, after isolating the fault point, check whether the line selection alarm signal is restored. If so, end and exit. Otherwise, re-execute the step of obtaining the line selection alarm signal and line selection result of the small current grounding line selection device in the station and its subsequent steps; If there are multiple fault points in the line topology, after isolating each fault point, check whether the line selection alarm signal is restored. If it is, end and exit, otherwise continue to isolate subsequent fault points. If the line selection alarm signal has not been restored after all fault points are isolated, re-execute the steps of obtaining the line selection alarm signal and line selection result of the small current grounding line selection device in the station and its subsequent steps.

10. A single-phase grounding fault analysis and treatment system for a distribution network, characterized in that: It includes the small current grounding line selection device in the station and the distribution automation master station, including: The small current grounding line selection device in the station is used to trigger an alarm, and send the line selection alarm signal and the line selection result to the distribution automation master station through the data gateway machine; The distribution automation master station is used for: Obtain the line selection alarm signal and line selection result of the small current grounding line selection device in the station; According to the line selection results, calculate the zero-sequence current variation of all the off-station terminals of the corresponding line; The line topology structure is checked. If the check passes, the designated terminals in the line topology structure are replaced with wires to obtain a new line topology structure. The off-station terminals are hierarchically clustered according to the zero-sequence current variation, and the classes whose arithmetic mean of the zero-sequence current variation is greater than the preset threshold are classified as fault classes, and the classes whose arithmetic mean of the zero-sequence current variation is less than the preset threshold are classified as normal classes; Mark the fault point in the new line topology structure according to the off-station terminals corresponding to the fault class and the normal class; The fault points are isolated. If the line selection alarm signal is not restored after all fault points are isolated, the above steps are iterated until the line selection alarm signal is restored.

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