Power distribution network single-phase earth fault section positioning method based on multi-source data fusion

Abstract

The invention discloses a power distribution network single-phase earth fault section positioning method based on multi-source data fusion, and the method comprises the steps: obtaining a power distribution cloud master station, dispatching remote signaling data, obtaining power distribution terminal grounding, bus grounding, small-current grounding line selection, arc suppression coil and bus voltage information through data cleaning, and carrying out the positioning of a single-phase earth fault section. Any information of a power distribution terminal grounding alarm signal, bus grounding and small current grounding line selection is used as a grounding research and judgment trigger condition; and after any information of a power distribution terminal grounding alarm signal, bus grounding and small current grounding line selection triggers grounding fault section research and judgment, the power distribution cloud master station respectively researches and judges a grounding fault section by adopting three kinds of information of grounding fault alarm information, a zero-sequence current remote measurement value and grounding fault recording. According to the method, the in-station line selection result, the relation between the neutral point grounding mode and the zero-sequence current, the terminal wave recording file and the terminal alarm information are considered at the same time, and the grounding fault section positioning method which is high in reliability, practicability and accuracy is comprehensively obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of distribution network, and in particular to a method for locating a single-phase grounding fault section of a distribution network based on multi-source data fusion. Background Art

[0002] With the development of energy globalization, the construction and safe operation of distribution networks have attracted more and more attention. In 10kV power systems, single-phase grounding faults are one of the common fault types, and their occurrence rate accounts for more than 70% of the total system fault rate. Single-phase grounding faults not only affect the stable operation of the power system, but may also cause more serious electrical accidents, such as phase-to-phase short circuits and fires. The electrical quantity information of single-phase grounding faults mainly depends on zero-sequence voltage and zero-sequence current. The signal is much weaker than that of short-circuit faults, and is affected by equipment performance, equipment operating status, etc., making it difficult to accurately identify the fault. After a single-phase grounding fault occurs, the fault is still commonly handled by the test pull. There are different degrees of problems caused by inaccurate fault identification and untimely isolation, such as large-scale power outages, fires, electric shock casualties, and equipment damage. Therefore, it is of great significance to carry out in-depth research on single-phase grounding fault protection technology, improve the accuracy of positioning the single-phase grounding fault section of the distribution network, and quickly isolate the fault section to improve the safety and reliability of the power system.

[0003] The existing single-phase grounding fault analysis and judgment of the distribution network mainly relies on the grounding line selection device in the station and the feeder terminal on the 10kV feeder. The current common grounding fault section positioning method is based on the grounding alarm information of the line selection device in the station and the grounding alarm information sent to the main station by the feeder terminal. By combining the alarm information of the two and comparing the line topology diagram, the fault location section is obtained. However, due to the limited line selection accuracy of the grounding line selection device in the station, the line selection accuracy of the early equipment is not high, and due to the progress of the transformation, the station line selection device is still not installed in some substations. In addition, due to the large number of feeder terminal equipment manufacturers put into operation, the grounding fault analysis and judgment algorithms of each unit are different, and the terminal grounding protection setting value configuration is unreasonable, and the upper and lower switches are mismatched, resulting in different credibility of the grounding alarm signal sent from the terminal to the main station. At present, the main grid and distribution automation systems operate separately, and the information is not integrated, which reduces the efficiency of ground fault handling. The dispatcher mainly selects and pulls the results of the main grid line selection device or tries to pull the sequence list, which takes a long time to find the fault. Grassroots personnel need to understand and grasp the grounding information through telephone notifications or check the system interface. The information acquisition is fragmented, which is not conducive to the rapid handling of ground faults. Therefore, there is still no set of highly reliable and practical methods for locating the single-phase grounding fault section of the distribution network.

[0004] In order to improve the accuracy of locating the single-phase grounding fault section of the distribution network and overcome the problem of insufficient accuracy and reliability of the line selection device in the station and the single-phase grounding fault judgment of the feeder terminal, the fault section location method of the distribution network needs to comprehensively consider the line selection results of the line selection device in the station, the zero-sequence current telemetry value of the switch, the grounding alarm information of the feeder terminal, and the grounding fault recording of the feeder terminal. The invention patent publication CN 118275820 A mentions that the single-phase grounding fault section information is obtained by comprehensive comparison of four types of information: terminal grounding alarm information, switch zero-sequence current, feeder zero-sequence voltage, and terminal recording file. However, the invention patent publication CN 118275820 A does not consider the neutral point grounding mode of the main transformer when comparing the zero-sequence current size to determine the fault section. It only sorts the real-time zero-sequence current value of the switch and the historical steady-state current value change, and determines that the grounding fault point is at the rear end of the switch with the largest zero-sequence current change. In a neutral point ungrounded system, when a single-phase grounding fault occurs, if the zero-sequence current is collected correctly, it can be determined that the grounding fault point is at the rear end of the switch with the largest zero-sequence current change. However, in the neutral point grounding system through the arc suppression coil, due to the over-compensation effect of the arc suppression coil, the zero-sequence current of the compensated switch decreases successively to the subsequent switch, so the fault point is not necessarily located at the rear end of the switch where the zero-sequence current change is the largest.

[0005] In addition, the invention patent publication CN 118275820 A determines the ground fault section by comparing the similarity of the switch recording files. However, when an arc grounding occurs, a terminal will record multiple sets of waveforms in a short period of time. Comparing the similarity of the recorded waveforms of multiple terminals at the same time may be limited by the timing accuracy, resulting in misjudgment of the fault section. Summary of the invention

[0006] In view of the shortcomings of the existing single-phase grounding fault section locating technology in distribution network, the purpose of the present invention is to provide a single-phase grounding fault section locating method for distribution network based on multi-source data fusion, aiming to solve the problems in the prior art that the neutral point grounding mode and the size of the switch zero-sequence current are not fully considered and the terminal fault recording is not fully utilized.

[0007] In order to achieve the above object, the present invention provides the following technical solution: a method for locating a single-phase grounding fault section in a distribution network based on multi-source data fusion, the locating method comprising the following steps: Obtain the distribution cloud master station and dispatch telesignal data, and through data cleaning, obtain the distribution terminal grounding, busbar grounding, low current grounding line selection, arc suppression coil, and busbar voltage information respectively, and use the distribution terminal grounding alarm signal, busbar grounding, and low current grounding line selection as the grounding judgment trigger condition; After the grounding alarm signal of the distribution terminal, bus grounding, and low-current grounding line selection trigger the grounding fault section analysis, the distribution cloud master station uses the grounding fault alarm information, zero-sequence current telemetry value, and grounding fault recording information to respectively analyze the grounding fault section; for the neutral point arc suppression coil grounding system, the grounding fault alarm information and grounding fault recording are used to locate the grounding fault section, and the distribution cloud master station uses the grounding fault recording analysis result as the main basis, and the distribution terminal grounding alarm information as an auxiliary criterion; if the grounding fault If there is a conflict between the fault information and the judgment result of the distribution cloud master station, the waveform analysis result of the distribution cloud master station shall prevail; for the system with ungrounded neutral point, the three kinds of information, namely ground fault alarm information, zero-sequence current telemetry value and ground fault recording, are used simultaneously to locate the section; the low-resistance grounding system relies on the ground fault alarm and zero-sequence current telemetry value to locate the section; among them, the system with ungrounded neutral point is mainly based on the zero-sequence current telemetry value method and ground fault recording judgment, and the confidence of the zero-sequence current telemetry value method is higher than that of the ground fault recording method.

[0008] In a preferred embodiment, the use of zero-sequence current telemetry value to judge the ground fault section includes the following steps: when the ground fault section is triggered, the distribution cloud master station deploys an algorithm to extract the relationship between the bus and the outgoing line, the switch topology, the line type, the line diameter and the line length information, and calculates the zero-sequence current setting value when the ground fault occurs in the switch area. I set_n , n is the switch number, and is the zero-sequence current value recorded on the distribution terminal I 0n to compare; when I set_n Less than I 0n When , it is marked that a ground fault occurs in this switch area; when I set_n Greater than I 0n When a ground fault occurs outside this switch area, it is marked; after the ground fault section is triggered, the distribution cloud master station also uses the substation as a container to collect the zero-sequence current telemetry values ​​of all switches, and obtains the ground fault section by comparing the size of the zero-sequence current telemetry value at the time of the fault and the size of the change value of the zero-sequence current telemetry value.

[0009] In a preferred embodiment, the calculation of the zero-sequence current setting value includes the following steps: After obtaining the relationship between the busbar and the outgoing line, the switch topology, the line type, and the line diameter and length information, the zero-sequence current setting value of the zero-sequence current protection of the automatic switch of each line is calculated. The zero-sequence current setting value of the zero-sequence current protection is set to be less than the sum of the capacitive currents of all lines on the same busbar on the power supply side of the switch and greater than the sum of the capacitive currents of the lines on the load side of the switch. The zero-sequence current setting value of each automatic switch on the line is set to be less than the sum of the capacitive currents of all lines on the same busbar on the power supply side of the switch and greater than the sum of the capacitive currents of the lines on the load side of the switch when a fault occurs.I set The calculation expression is: , in, L JK1 The total length of overhead lines of other 10kV feeder lines on the same busbar, L JK2 is the total length of the overhead line from the switch to the busbar, L JK is the total length of overhead lines on the switching power supply side and other feeder lines on the same busbar, L 1 is the total length of overhead lines on the switch load side, in kilometers. S 1 is the capacitance current value per kilometer of overhead line; L DL1 The total length of other 10kV feeder cables on the same busbar, L DL2 is the total length of the cable from the switch to the busbar, L DL is the total length of the switch power supply side and other feeder cables on the same busbar, L 2 is the total length of the cable on the load side of the switch, in kilometers. S 2 is the capacitance current value per kilometer of the cable line; M is the margin coefficient; the capacitance current value of all lines on the same busbar on the switch power supply side of each automatic switch on the line when a fault occurs is calculated I set1 and the line capacitance current value on the load side of the switch I set2 , zero sequence current setting value I set Between I set1 and I set2 between.

[0010] In a preferred embodiment, the use of ground fault recording to determine the ground fault section includes the following steps: first, by comparing the correlation of the first half-wave waveform of the zero-sequence current of each feeder outgoing switch, the line with the larger correlation deviation is the fault line where the grounding occurs, and then according to the switch topology information, comparing the deviation of the first half-wave waveform of the zero-sequence current of two adjacent switches, the ground fault section is located between the two switches with the largest deviation.

[0011] In a preferred embodiment, after the ground fault section is triggered, the substation is used as a container to collect the switch ground fault recording file, and the fault time is recorded as t 0, intercept tThe first half-wave waveform of the zero-sequence current after time 0 is fitted nonlinearly at the discrete points of the first half-wave waveform of the zero-sequence current at each time. The fitting adopts the Levenberg-Marquardt algorithm, and the fitting formula is as follows: , In the formula, is the fitting curve of the first half-wave waveform of zero-sequence current, I 0_max is the maximum amplitude of the first half-wave waveform of the zero-sequence current, t It's time ，t max is the time value corresponding to the maximum amplitude moment, α , β is the fitting constant parameter; After obtaining the fitting curve of the first half-wave waveform of the zero-sequence current, calculate the derivative of the fitting curve with time , as shown below: , In the formula 、 are the fitted zero-sequence current values ​​at time t2 and t1 respectively; The Euclidean distance between the time derivatives of the first half-wave of the zero-sequence current of two switches is calculated by using the time derivative of the fitting curve of the first half-wave of the zero-sequence current of the switch, as shown in the following formula: , In the formula, It represents the time derivative of the first half-wave of zero-sequence current of switch n and switch m and The Euclidean distance at time t, T represents the duration of the first half wave; is the sum of the Euclidean distances of the time derivatives of the first half-wave of the zero-sequence current of the two switches at each moment, which is taken as the correlation coefficient of the first half-wave of the zero-sequence current of the two switches; The larger it is, the lower the correlation; The smaller the value, the higher the correlation. When a ground fault occurs, the correlation coefficient of the first half-wave of the zero-sequence current of each feeder outgoing switch or the first switch on the line is first calculated. Through pairwise comparison and cluster analysis, the feeder with the largest correlation coefficient with the first half-wave of the zero-sequence current waveform of other switches is the fault line; after determining the fault line, the correlation coefficient of the first half-wave of the zero-sequence current of the switch is compared through the switch topology relationship. , a small correlation coefficient indicates that the first half-wave waveforms of the zero-sequence current of the two switches are similar; if the fault point is located between the two switches, the correlation coefficient of the first half-wave of the zero-sequence current of the two switches is much larger than the correlation coefficient of the first half-wave of the zero-sequence current of other adjacent switches; if the fault point is located at the rear end of the last-stage switch and there is no branch line between the switch and the busbar, the correlation coefficients of the first half-wave of the zero-sequence current of the switches are close, and it is judged that the grounding fault section is at the last stage.

[0012] In a preferred embodiment, using the ground fault alarm information to determine the ground fault section includes the following steps: When the grounding alarm information of the distribution terminal is received, the substation is first used as a container to collect the grounding alarm information of the distribution terminal, and the distribution terminal that sends the grounding fault alarm corresponds to the 10kV feeder, and it is verified whether the distribution terminal that reports the grounding fault telesignal is on the same feeder; if the distribution terminal that reports the grounding fault telesignal is on the same line, and only one distribution terminal reports the grounding fault alarm information, it is judged that the grounding fault section is located between the switch that reports the grounding fault alarm and the switch at the next level; if more than one distribution terminal reports the grounding fault alarm information, it is judged that the grounding fault section is located between the switch at the last level that reports the grounding fault alarm and the switch at the next level.

[0013] In the above technical solution, the technical effects and advantages provided by the present invention are: 1. The present invention obtains the distribution cloud master station and dispatching telesignal data through KAFKA, and obtains the distribution terminal grounding, bus grounding, small current grounding line selection, arc suppression coil, and bus voltage information through data cleaning. The distribution terminal grounding alarm signal, bus grounding, and small current grounding line selection are used as the grounding judgment trigger condition to avoid the problems of grounding fault omission caused by inconsistent main and distribution network related equipment or fixed value settings.

[0014] 2. After the present invention obtains the busbar and outgoing line relationship, switch topology relationship, line type, line diameter and line length information through the business middle station, the power distribution cloud master station uniformly calculates the zero-sequence current setting value of each line automatic switch of the neutral point ungrounded system when a fault occurs I set ,Will I set By comparing with the zero-sequence current value at the time of the fault, the grounding fault section is determined, avoiding problems such as false alarm and missed alarm of grounding fault information caused by incorrect setting of the operating set values, and greatly reducing the work pressure at the grassroots level to modify the set values ​​of the operating distribution terminals in large quantities.

[0015] 3. The present invention deploys a ground fault section positioning algorithm based on the correlation of the first half-wave waveform of the zero-sequence current of the ground fault recording at the distribution cloud master station. By analyzing the similarity of the first half-wave waveform of the zero-sequence current, the fault line and the fault section are determined, and the credibility of the fault section of the ground fault recording analysis is unified, avoiding the problem of inconsistent credibility of grounding analysis due to different terminal devices and different program versions.

[0016] 4. The present invention uses the grounding alarm signal of the distribution terminal, the zero-sequence current telemetry value, and the grounding fault recording as the basis for the grounding fault section analysis. According to the neutral point grounding method of the system, the appropriate section positioning method is selected, and the priority of using multiple information for analysis is clarified. Taking full account of factors such as failure and loss of information upload, the substation is used as a container, and the grounding fault section after comprehensive analysis is pushed through the enterprise-level message platform. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0018] Figure 1 A schematic diagram of a circuit topology of an embodiment of the present invention; Figure 2 A schematic diagram of calculating the zero-sequence current setting value of a switch in a system with an ungrounded neutral point according to the present invention; Figure 3 Schematic diagram for locating ground fault section using ground alarm information from power distribution terminals; Figure 4 Schematic diagram of locating ground fault section using zero-sequence current telemetry value; Figure 5 A schematic diagram of locating the ground fault section using ground fault recording; Figure 6 This is a logical diagram of pushing the ground fault section location information proposed by the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] This embodiment provides a method for locating a single-phase ground fault section in a distribution network based on multi-source data fusion, and the locating method needs to be applied to feeder switches, distribution terminals (FTU, DTU) and distribution cloud master stations. The distribution terminal in this embodiment has the function of recording and uploading zero-sequence current and ground fault waveforms, as well as a ground fault analysis algorithm, which can generate and upload a ground fault alarm signal according to a preset value. The distribution cloud master station has the functions of accessing substation information, busbar information, switch information, distribution terminal ground fault recording, and homologous graphics, and can obtain real-time telemetry and telesignaling information of the distribution terminal, and access the distribution terminal to upload the ground fault recording.

[0021] The implementation of the present invention requires obtaining the single-line diagram of the business middle station line and the thematic diagram within the substation through the data interface, and analyzing the switch topology relationship, the length of the cable and the overhead line, the relationship between the bus and the 10kV feeder line, and the relationship between the bus and the bus. The distribution cloud master station and the dispatching telesignal data are obtained through KAFKA, and the distribution terminal grounding, bus grounding, small current grounding line selection, arc suppression coil, and bus voltage information are obtained through data cleaning, and any information of the distribution terminal grounding alarm signal, bus grounding, and small current grounding line selection is used as the grounding judgment trigger condition.

[0022] In order to reduce the pressure of basic operation and maintenance, the present invention uses the grounding alarm information of the distribution terminal as a supplement, and deploys a single-phase grounding fault section judgment method based on the line and switch topology relationship and the correlation of the zero-sequence current waveform at the distribution cloud master station. Figure 4 As shown, the specific implementation method is as follows: After obtaining the bus and outgoing line relationship, switch topology, line type, line diameter and line length information through the business middle station, the zero-sequence current setting value of the zero-sequence current protection of each line automatic switch is calculated. The zero-sequence current setting value of the zero-sequence current protection is set to be less than the sum of the line capacitance currents of all lines on the same bus on the switch power supply side and greater than the sum of the line capacitance currents on the switch load side. Figure 2 The figure shows the schematic diagram of calculating the zero-sequence current setting value of the switch in the system with ungrounded neutral point. The zero-sequence current setting value of each automatic switch on the line when a fault occurs I set The calculation expression is: , in, L JK1 The total length of overhead lines of other 10kV feeder lines on the same busbar, L JK2 is the total length of the overhead line from the switch to the busbar, L JK is the total length of overhead lines on the switching power supply side and other feeder lines on the same busbar, L 1 is the total length of overhead lines on the switch load side, in kilometers. S1 is the capacitance current value per kilometer of overhead line; L DL1 The total length of other 10kV feeder cables on the same busbar, L DL2 is the total length of the cable from the switch to the busbar, L DL is the total length of the switch power supply side and other feeder cables on the same busbar, L 2 is the total length of the cable on the load side of the switch, in kilometers. S 2 is the capacitance current value per kilometer of the cable line; M is the margin factor, which is 1.2~1.5. Through the above formula, the capacitance current value of all lines on the same busbar on the switch power supply side of each automatic switch on the line can be calculated when a fault occurs. I set1 and the line capacitance current value on the load side of the switch I set2 . Zero sequence current setting value I set Between I set1 and I set2 If the neutral point is not grounded, after the ground fault section is triggered, the distribution cloud master station deploys an algorithm to extract the line type, wire diameter, switch topology and location information of the bus feeder, and calculates the zero-sequence current setting value when a ground fault occurs in the switch area. I set_n (n is the switch number) and is recorded with the zero-sequence current value sent to the distribution terminal I 0n For comparison. I set_n Less than I 0n When , it is marked that a ground fault occurs in this switch area; when I set_n Greater than I 0n When , it is marked that a ground fault occurs outside this switch area. Thus, the position relationship between the ground fault point and the switch can be obtained. In addition, after the ground fault section is triggered, the distribution cloud master station can also use the substation as a container to collect the zero-sequence current telemetry values ​​of all switches, and obtain the ground fault section by comparing the magnitude of the zero-sequence current telemetry value at that moment. Figure 1 As shown in the figure, when a ground fault occurs between switch 2 and switch 3 on feeder 3, the zero-sequence current setting values ​​of switch 1 and switch 2 are I set_1 , I set_2 Less than I 01 and I 02 , other switch zero sequence current setting valueI set_n Both greater than I 0n , the zero-sequence current telemetry values ​​of switch 1 and switch 2 are much larger than those of other switches, and the zero-sequence current telemetry value change value of other switches before and after the ground fault occurs is Δ I It is much smaller than switch 1 and switch 2. Combined with the switch topology, it can be concluded that the grounding fault section is between switch 2 and switch 3. Due to the compensation effect of the arc suppression coil on the grounding zero-sequence current, it is impossible to distinguish whether the switch is in the grounding fault area based on the magnitude of the zero-sequence current telemetry value of the distribution terminal. Therefore, the neutral point grounding system through the arc suppression coil does not use the method based on the magnitude of the zero-sequence current to judge the grounding fault section. By comparing the zero-sequence current recorded online I 0 and zero-sequence current setting value when ground fault occurs in the switch area I set The size of the zero-sequence current telemetry value and the change value Δ I , the grounding fault section of the system with ungrounded neutral point can be obtained, which greatly reduces the work pressure of grassroots operation and maintenance personnel in modifying the set values ​​of the in-service distribution terminals.

[0023] If the neutral point is grounded through an arc suppression coil, first compare the correlation of the first half-wave waveform of the zero-sequence current of each feeder outgoing switch. The line with the largest correlation deviation is the fault line with grounding. Then, based on the switch topology information, compare the deviation of the first half-wave waveform of the zero-sequence current of two adjacent switches. The grounding fault section is located between the two switches with the largest deviation. Figure 5 As shown, the specific implementation method is as follows: After the ground fault section is triggered, the substation is used as a container to collect the switch ground fault recording file and record the time of the fault as t 0, intercept t The first half-wave waveform of the zero-sequence current after time 0. In order to avoid the influence of sampling mutation points or jitter errors, nonlinear fitting is performed on the discrete points of the first half-wave waveform of the zero-sequence current at each time. The fitting adopts the Levenberg-Marquardt algorithm, and the fitting formula is as follows: , In the formula, is the fitting curve of the first half-wave waveform of zero-sequence current, I 0_max is the maximum amplitude of the first half-wave waveform of the zero-sequence current, t It's time ，t max is the time value corresponding to the maximum amplitude moment, α , β is the fitting constant parameter; After obtaining the fitting curve of the first half-wave waveform of the zero-sequence current, calculate the derivative of the fitting curve with time , as shown below: , In the formula 、 are the fitted zero-sequence current values ​​at time t2 and t1 respectively; The Euclidean distance between the time derivatives of the first half-wave of the zero-sequence current of two switches is calculated by using the time derivative of the fitting curve of the first half-wave of the zero-sequence current of the switch, as shown in the following formula: , In the formula, It represents the time derivative of the first half-wave of zero-sequence current of switch n and switch m and The Euclidean distance at time t, T represents the duration of the first half wave; is the sum of the Euclidean distances of the time derivatives of the first half-wave of the zero-sequence current of the two switches at each moment, which is taken as the correlation coefficient of the first half-wave of the zero-sequence current of the two switches; The larger it is, the lower the correlation; The smaller the value, the higher the correlation. When a ground fault occurs, the correlation coefficient of the first half-wave of the zero-sequence current of each feeder outgoing switch or the first switch on the line is first calculated. Through pairwise comparison and cluster analysis, the feeder with the largest correlation coefficient with the first half-wave of the zero-sequence current waveform of other switches is the fault line; after determining the fault line, the correlation coefficient of the first half-wave of the zero-sequence current of the switch is compared through the switch topology relationship. , a small correlation coefficient indicates that the first half-wave waveforms of the zero-sequence currents of the two switches are similar; if the fault point is between the two switches, the correlation coefficient of the first half-wave of the zero-sequence currents of the two switches is much greater than the correlation coefficient of the first half-wave of the zero-sequence currents of other adjacent switches; if the fault point is located at the rear end of the last switch, and there is no branch line between the switch and the bus, the correlation coefficients of the first half-wave of the zero-sequence currents of the switches are close, and it is judged that the grounding fault section is at the last stage. Figure 1 As shown in Figure 2, if a ground fault occurs between switch 2 and switch 3 on feeder 2, then and Much greater than , the similarity of the first half-wave waveforms of zero-sequence currents of switch 2 and switch 3 is low, and the ground fault is judged to be between switch 2 and switch 3; if a ground fault occurs at the rear end of switch 3 on feeder 2, the correlation coefficient between the switches is small and close to 0, and the ground fault point is judged to be at the last section, that is, the rear side of switch 3. By comparing the correlation coefficient of the first half-wave of zero-sequence current, the ground fault section of the neutral point grounding system through the arc suppression coil can be determined, avoiding the problem of insufficient judgment accuracy caused by the traditional algorithm that considers the magnitude and phase of zero-sequence voltage and zero-sequence current at the same time.

[0024] Figure 3The figure shows the relevant logic flow diagram for locating the fault section by the grounding alarm information of the distribution terminal. When the grounding alarm information of the distribution terminal is received, the grounding alarm information of the distribution terminal is first collected with the substation as the container, and the distribution terminal that sends the grounding fault alarm corresponds to the 10kV feeder, and the distribution terminal that reports the grounding fault remote signal is verified whether it is on the same feeder. If the distribution terminal that reports the grounding fault remote signal is on the same line, and only one distribution terminal reports the grounding fault information, then this method is used to determine that the grounding fault section is located between this switch and the next level switch; if more than one distribution terminal reports the grounding fault information, then this method is used to determine that the grounding fault section is located between the last level switch that reports the grounding fault alarm and the next level switch. For example, if the distribution terminal of switch 3 on feeder 1 sends the grounding fault alarm information, then the grounding fault section is determined to be located at the rear end of switch 3; if the distribution terminals of switch 1 and switch 2 send the grounding fault alarm information, and the distribution terminal of switch 3 does not send it, then the grounding fault section is located in the section between switch 2 and switch 3. If the distribution terminal for sending grounding alarm is not on the same 10kV feeder, the grounding fault section of each line shall be analyzed separately according to the above method to avoid the risk of missing multiple grounding faults.

[0025] After the grounding alarm signal of the distribution terminal, bus grounding, and low-current grounding line selection trigger the grounding fault section analysis, the distribution cloud master station uses the grounding fault alarm information, zero-sequence current telemetry value, and grounding fault recording to respectively analyze the grounding fault section. For the neutral point grounding system through the arc suppression coil, the grounding fault alarm information and grounding fault recording are used to locate and judge the grounding fault section, and the grounding fault recording analysis result of the distribution cloud master station is used as the main basis, and the grounding alarm information of the distribution terminal is used as an auxiliary judgment criterion. When the analysis algorithm deployed by the distribution cloud master station can accurately locate the minimum fault section by relying on the grounding fault recording, the final analysis is based on this result; when the grounding fault recording file fails to be uploaded or is missing, the grounding fault alarm information is used as an auxiliary judgment criterion to help decide the location of the grounding fault section; if the grounding fault information conflicts with the analysis result of the distribution cloud master station, the waveform analysis result of the distribution cloud master station shall prevail. For a neutral point ungrounded system, the ground fault alarm information, zero sequence current telemetry value, and ground fault recording can be used to locate the section at the same time; for a low resistance grounded system, the ground fault alarm and zero sequence current telemetry value can be used to locate the section. Among them, the neutral point ungrounded system mainly relies on the zero sequence current telemetry value method and the ground fault recording method, and the confidence of the zero sequence current value method is higher than that of the ground fault recording method. For example, when Figure 1When a ground fault occurs in feeder 1, the zero-sequence current value of the distribution terminals of switch 1 and switch 3 is used to analyze that the ground fault section is between switches 1-3. If the distribution cloud master station judges that the rear end of switch 2 is grounded through the ground fault recording of the distribution terminal of switch 2, the ground fault section is given as between switch 2 and switch 3; if the rear end of switch 4 is grounded through the ground fault recording of the distribution terminal of switch 4, the zero-sequence current value judgment result is used as the basis to locate the ground fault section between switch 1 and switch 3, and the minimum fault section positioning algorithm is skipped. When the ground fault recording file fails to be uploaded or is missing, the ground alarm information is used as an auxiliary basis, which is consistent with the above-mentioned neutral point grounding system through arc suppression coil. If the ground fault information can help locate the minimum fault section, and does not conflict with the judgment results of the ground fault recording and zero-sequence current telemetry value, the ground fault information is valid and can assist in locating the fault section; if there is a conflict, the ground fault information is invalid and there is no need to give the minimum ground fault section.

[0026] In summary, the three grounding fault section analysis methods can be used to locate the minimum grounding fault section. If there is a conflict in information, the above method with higher confidence shall prevail, and the minimum fault section location result can be abandoned to prevent section location errors and increase the work pressure of grassroots operation and maintenance personnel. Figure 6 As shown in the figure, after the distribution cloud master station locates the grounding fault section, the substation can be used as a container to push information to the designated group through the enterprise-level message push platform to assist grassroots operation and maintenance personnel to find the fault point more quickly and efficiently, isolate the faulty section and restore power supply.

[0027] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0028] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for locating single-phase grounding fault sections in a distribution network based on multi-source data fusion, characterized in that: The positioning method comprises the following steps: Obtain the distribution cloud master station and dispatch telesignal data, and through data cleaning, obtain the distribution terminal grounding, busbar grounding, low current grounding line selection, arc suppression coil, and busbar voltage information respectively, and use the distribution terminal grounding alarm signal, busbar grounding, and low current grounding line selection as the grounding judgment trigger condition; After the grounding alarm signal of the distribution terminal, bus grounding, and low-current grounding line selection trigger the grounding fault section analysis, the distribution cloud master station uses the grounding fault alarm information, zero-sequence current telemetry value, and grounding fault recording information to respectively analyze the grounding fault section; for the neutral point arc suppression coil grounding system, the grounding fault alarm information and grounding fault recording are used to locate the grounding fault section, and the distribution cloud master station uses the grounding fault recording analysis result as the main basis, and the distribution terminal grounding alarm information as an auxiliary criterion; if the grounding fault If there is a conflict between the fault information and the judgment result of the distribution cloud master station, the waveform analysis result of the distribution cloud master station shall prevail; for the system with ungrounded neutral point, the three kinds of information, namely ground fault alarm information, zero-sequence current telemetry value and ground fault recording, are used simultaneously to locate the section; the low-resistance grounding system relies on the ground fault alarm and zero-sequence current telemetry value to locate the section; among them, the system with ungrounded neutral point is mainly based on the zero-sequence current telemetry value method and ground fault recording judgment, and the confidence of the zero-sequence current telemetry value method is higher than that of the ground fault recording method.

2. The method for locating a single-phase grounding fault section in a distribution network based on multi-source data fusion according to claim 1 is characterized in that: The use of zero-sequence current telemetry to determine the ground fault section includes the following steps: When the ground fault section is triggered, the distribution cloud master station deploys an algorithm to extract the relationship between the bus and the outgoing line, the switch topology, the line type, the line diameter and line length information, and calculates the zero-sequence current setting value when a ground fault occurs in the switch area. I set_n , n is the switch number, and is the zero-sequence current value recorded on the distribution terminal I 0n to compare; when I set_n Less than I 0n When , it is marked that a ground fault occurs in this switch area; when I set_n Greater than I 0n When a ground fault occurs outside this switch area, it is marked; after the ground fault section is triggered, the distribution cloud master station also uses the substation as a container to collect the zero-sequence current telemetry values ​​of all switches, and obtains the ground fault section by comparing the size of the zero-sequence current telemetry value at the time of the fault and the size of the change value of the zero-sequence current telemetry value.

3. The method for locating a single-phase grounding fault section in a distribution network based on multi-source data fusion according to claim 2 is characterized in that: The calculation of the zero-sequence current setting value comprises the following steps: After obtaining the relationship between the busbar and the outgoing line, the switch topology, the line type, and the line diameter and length information, the zero-sequence current setting value of the zero-sequence current protection of the automatic switch of each line is calculated. The zero-sequence current setting value of the zero-sequence current protection is set to be less than the sum of the capacitive currents of all lines on the same busbar on the power supply side of the switch and greater than the sum of the capacitive currents of the lines on the load side of the switch. The zero-sequence current setting value of each automatic switch on the line is set to be less than the sum of the capacitive currents of all lines on the same busbar on the power supply side of the switch and greater than the sum of the capacitive currents of the lines on the load side of the switch when a fault occurs. I set The calculation expression is: ， in, L JK1 The total length of overhead lines of other 10kV feeder lines on the same busbar, L JK2 is the total length of the overhead line from the switch to the busbar, L JK is the total length of overhead lines on the switching power supply side and other feeder lines on the same busbar, L 1 is the total length of overhead lines on the switch load side, in kilometers. S 1 is the capacitance current value per kilometer of overhead line; L DL1 The total length of other 10kV feeder cables on the same busbar, L DL2 is the total length of the cable from the switch to the busbar, L DL is the total length of the switch power supply side and other feeder cables on the same busbar, L 2 is the total length of the cable on the load side of the switch, in kilometers. S 2 is the capacitance current value per kilometer of the cable line; M is the margin coefficient; the capacitance current value of all lines on the same busbar on the switch power supply side of each automatic switch on the line when a fault occurs is calculated I set1 and the line capacitance current value on the load side of the switch I set2 , zero sequence current setting value I set Between I set1 and I set2 between.

4. The method for locating a single-phase grounding fault section in a distribution network based on multi-source data fusion according to claim 1 is characterized in that: The following steps are included in the analysis of the grounding fault section using grounding fault recording: first, by comparing the correlation of the first half-wave waveform of the zero-sequence current of each feeder outgoing switch, the line with the larger correlation deviation is the fault line where the grounding occurs. Then, based on the switch topology information, the deviation of the first half-wave waveform of the zero-sequence current of the two adjacent switches is compared. The grounding fault section is located between the two switches with the largest deviation.

5. The method for locating a single-phase grounding fault section in a distribution network based on multi-source data fusion according to claim 4 is characterized in that: After the ground fault section is triggered, the substation is used as a container to collect the switch ground fault recording file and record the time of the fault as t 0, intercept t The first half-wave waveform of the zero-sequence current after time 0 is fitted nonlinearly at the discrete points of the first half-wave waveform of the zero-sequence current at each time. The fitting adopts the Levenberg-Marquardt algorithm, and the fitting formula is as follows: , In the formula, is the fitting curve of the first half-wave waveform of zero-sequence current, I 0_max is the maximum amplitude of the first half-wave waveform of the zero-sequence current, t It's time ，t max is the time value corresponding to the maximum amplitude moment, α , β is the fitting constant parameter; After obtaining the fitting curve of the first half-wave waveform of the zero-sequence current, calculate the derivative of the fitting curve with time , as shown below: ， In the formula 、 are the fitted zero-sequence current values ​​at time t2 and t1 respectively; The Euclidean distance between the time derivatives of the first half-wave of the zero-sequence current of two switches is calculated by using the time derivative of the fitting curve of the first half-wave of the zero-sequence current of the switch, as shown in the following formula: ， In the formula, It represents the time derivative of the first half-wave of zero-sequence current of switch n and switch m and The Euclidean distance at time t, T represents the duration of the first half wave; is the sum of the Euclidean distances of the time derivatives of the first half-wave of the zero-sequence current of the two switches at each moment, which is taken as the correlation coefficient of the first half-wave of the zero-sequence current of the two switches; The larger it is, the lower the correlation; The smaller it is, the higher the correlation is; When a ground fault occurs, first calculate the correlation coefficient of the first half-wave of the zero-sequence current of each feeder outgoing switch or the first switch on the line Through pairwise comparison and cluster analysis, the feeder with the largest correlation coefficient with the first half-wave of the zero-sequence current waveform of other switches is the fault line; after determining the fault line, the correlation coefficient of the first half-wave of the zero-sequence current of the switch is compared through the switch topology relationship. ,The small correlation coefficient indicates that the first half wave waveforms of the two switch zero sequence currents are similar; If the fault point is located between two switches, the correlation coefficient of the first half-wave of the zero-sequence current of these two switches is much greater than the correlation coefficient of the first half-wave of the zero-sequence current of other adjacent switches; If the fault point is located at the rear end of the last-stage switch and there is no branch line between the switch and the busbar, the correlation coefficients of the first half-wave of the switch zero-sequence current are close, and it is judged that the grounding fault section is at the last stage.

6. The method for locating a single-phase grounding fault section in a distribution network based on multi-source data fusion according to claim 1 is characterized in that: The following steps are used to determine the ground fault section using the ground fault alarm information: When the grounding alarm information of the distribution terminal is received, the substation is first used as a container to collect the grounding alarm information of the distribution terminal, and the distribution terminal that sends the grounding fault alarm corresponds to the 10kV feeder, and it is verified whether the distribution terminal that reports the grounding fault telesignal is on the same feeder; if the distribution terminal that reports the grounding fault telesignal is on the same line, and only one distribution terminal reports the grounding fault alarm information, it is judged that the grounding fault section is located between the switch that reports the grounding fault alarm and the switch at the next level; if more than one distribution terminal reports the grounding fault alarm information, it is judged that the grounding fault section is located between the switch at the last level that reports the grounding fault alarm and the switch at the next level.

Images