Overhead line grounding fault section selection method and system

Abstract

The invention provides an overhead line grounding fault segment selection method and system, and the method comprises the steps: obtaining the grounding fault time of an alarm line, and the information of a fault indicator and an intelligent switch, and analyzing the collected data of the fault indicator and the intelligent switch 15 minutes before and after the grounding fault time; the last abnormal point and the first normal point of the fault indicator and the intelligent switch are found, the grounding fault interval is shortened between the two fault indicators or the intelligent switches, after the 10kV overhead line is grounded, grounding operation is kept for a period of time, overhead line grounding fault section selection can be completed, the fault occurrence position is rapidly determined, and the fault occurrence time is shortened. The fault inspection range is greatly reduced, and the troubleshooting time is shortened.

Description

Technical Field

[0001] The present application relates to the technical field of distribution line fault identification, and in particular to a method and system for selecting a ground fault section of an overhead line. Background Art

[0002] The grounding fault of 10kV distribution network line is the most common type of fault. Grounding faults present a dilemma between power supply reliability and personal and equipment safety. In a system where the neutral point is not directly grounded, the grounding of the 10kV side will lead to an increase in the voltage of the non-fault phase. The longer the grounding fault lasts, the greater the test on the equipment. There is a risk of breakdown of weak equipment in the substation, and even the main transformer may be shut down. In addition, if the line is broken and grounded, there may be a risk of electric shock accidents.

[0003] The distribution automation coverage rate of 10kV cable lines is relatively high. After a ground fault occurs, the master station can conduct analysis and judgment through the collection of zero-sequence current, which can better meet the requirements of fault handling and command. The main difficulty of the current distribution network grounding lies in the overhead line. The grounding fault point of the overhead line is hidden. At the same time, in order to protect the main network equipment, the neutral point of the substation is generally grounded through an arc suppression coil. Affected by the compensation current, the accuracy of grounding analysis and judgment of the traditional protection line selection method is very low. Although the master station in Zone IV supports batch query of fault indicators and intelligent switch collection data according to 10kV feeders, it currently does not have the function of ground fault interval analysis and judgment, and cannot achieve accurate section selection. Summary of the invention

[0004] The purpose of the present invention is to solve the problems in the background technology and to provide a method and system for selecting a section for a ground fault in an overhead line.

[0005] The first aspect of the present application provides a method for selecting a section of an overhead line grounding fault, comprising the following steps:

[0006] S1, obtain the substation alarm information, if there is grounding alarm information, enter S2;

[0007] S2, obtaining the ground fault time, fault indicator and intelligent switch information of the alarm line, analyzing the collected data, and finding the last abnormal point and the first normal point of the fault indicator and the intelligent switch, including the following steps:

[0008] S2-1, obtaining the data of the fault indicator and the intelligent switch 15 minutes before the ground fault time, and obtaining the fault indicator reference data Stan1 and the intelligent switch reference data Stan2;

[0009] S2-2, obtaining data of each fault indicator and intelligent switch 15 minutes after the grounding fault occurs, and obtaining fault indicator comparison data con1 and intelligent switch comparison data con2;

[0010] S2-3, set the current variation range, compare and analyze Stan1, con1 and Stan2, con2 respectively according to the current variation range, and obtain abnormal points and normal points;

[0011] S2-4, determine the last abnormal point according to the pole number information of each abnormal point, determine the first normal point according to the pole number information of each normal point, and the area between the last abnormal point and the first normal point is the fault selection interval.

[0012] S3, visualize and output the fault selected section information.

[0013] Furthermore, the current variation amplitude is a current mutation of 100%, and the Stan1 and con1 comparison analysis method of S2-3 is:

[0014] a. Determine whether Stan1 is an abnormal point. If not, determine whether the grounding current reference of any phase in con1 is greater than twice that of Stan1 and greater than 10. At the same time, the ground electric field of the corresponding phase in con1 decreases by more than 20% compared with that in Stan1. If so, it is an abnormal point;

[0015] b. If Stan1 is an abnormal point, determine whether the ground current reference of any phase in con1 is reduced by more than 2 times compared with Stan1. If it is reduced by more than 2 times, it is a normal point. If it is not reduced by more than 2 times, it is an abnormal point.

[0016] Furthermore, the Stan2 and con2 comparison analysis methods of S2-3 are:

[0017] a. Determine whether Stan2 is an abnormal point. If not, determine whether the zero-sequence current in con2 is more than twice that of Stan2 and greater than 0.01, and whether the zero-sequence voltage in con2 is more than 20 times that of Stan2. If so, it is an abnormal point;

[0018] b. If Stan2 is an abnormal point, determine whether the zero-sequence current of con2 is more than twice lower than that of Stan2. If it is, it is a normal point. If it is not, it is an abnormal point.

[0019] Furthermore, the method further comprises the step: S4, recording and comparing the actual fault point and the fault selection interval, and calculating the correctness rate of the fault selection interval.

[0020] Furthermore, the visual output includes PC-side output and mobile-side output, wherein the PC-side output intuitively displays the faulty segment interval, and the mobile-side output displays the faulty segment interval at a relevant personnel port.

[0021] The second aspect of the present application also provides an overhead line ground fault section selection system, comprising: a data acquisition unit, an input unit, a data storage unit, a data query unit, a data processing unit, a display unit and a communication unit;

[0022] The data acquisition unit is electrically connected to the fault indicator and the intelligent switch, and is used to convert the collected signals and transmit them to the data storage unit;

[0023] The input unit is used to input the ground fault time and line name, and transmit the input information to the data query unit;

[0024] The data query unit extracts the data information corresponding to the data storage unit according to the data transmitted by the input unit, and transmits the extracted data to the data processing unit;

[0025] The data processing unit analyzes the data obtained by the data query unit, performs fault analysis on the line, and obtains the ground fault section interval;

[0026] The display unit is used to display the ground fault information on the PC side to achieve visual output;

[0027] The communication unit is used to exchange ground fault information and transmit the ground fault information to a relevant personnel port.

[0028] Furthermore, it also includes an alarm module, which issues an alarm after obtaining the substation alarm information.

[0029] Furthermore, the communication unit includes a communication interface and a debugging interface, the communication interface is remotely connected to the relevant personnel port, and the debugging interface is used to connect to a computer so that an operator can set the current variation amplitude.

[0030] In the technical solution provided in the present application, by comparing and analyzing the data of the fault indicator and the intelligent switch 15 minutes before and after the grounding fault, the last abnormal point and the first normal point are determined. After the 10kV overhead line is grounded, it is only necessary to maintain the grounding operation for a period of time to complete the overhead line grounding fault section selection, and narrow the grounding fault interval to between two fault indicators or intelligent switches, so as to quickly determine the location of the fault, greatly reduce the fault inspection range, and speed up the fault investigation time. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of a flow chart of a method for selecting a section for an overhead line ground fault in one embodiment of the present application;

[0032] Figure 2 This is an architecture diagram of an overhead line ground fault section selection system in one embodiment of the present application. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] Reference Figure 1 As shown, a method for selecting a section of an overhead line ground fault includes the following steps:

[0035] S1, obtain the substation alarm information, if there is grounding alarm information, enter S2;

[0036] S2, obtaining the ground fault time, fault indicator and intelligent switch information of the alarm line, analyzing the collected data, and finding the last abnormal point and the first normal point of the fault indicator and the intelligent switch, including the following steps:

[0037] S2-1, obtaining the data of the fault indicator and the intelligent switch 15 minutes before the ground fault time, and obtaining the fault indicator reference data Stan1 and the intelligent switch reference data Stan2;

[0038] S2-2, obtaining data of each fault indicator and intelligent switch 15 minutes after the grounding fault occurs, and obtaining fault indicator comparison data con1 and intelligent switch comparison data con2;

[0039] S2-3, set the current variation range, compare and analyze Stan1, con1 and Stan2, con2 respectively according to the current variation range, and obtain abnormal points and normal points;

[0040] S2-4, determine the last abnormal point according to the pole number information of each abnormal point, determine the first normal point according to the pole number information of each normal point, and the area between the last abnormal point and the first normal point is the fault selection interval.

[0041] S3, visualize and output the fault selected section information.

[0042] In a specific embodiment, the current variation amplitude is a current mutation of 100%, and the Stan1 and con1 comparison analysis method of S2-3 is:

[0043] a. Determine whether Stan1 is an abnormal point. If not, determine whether the grounding current reference of any phase in con1 is greater than twice that of Stan1 and greater than 10. At the same time, the ground electric field of the corresponding phase in con1 decreases by more than 20% compared with that in Stan1. If so, it is an abnormal point;

[0044] b. If Stan1 is an abnormal point, determine whether the ground current reference of any phase in con1 is reduced by more than 2 times compared with Stan1. If it is reduced by more than 2 times, it is a normal point. If it is not reduced by more than 2 times, it is an abnormal point.

[0045] In a specific embodiment, the Stan2 and con2 comparison analysis methods of S2-3 are:

[0046] a. Determine whether Stan2 is an abnormal point. If not, determine whether the zero-sequence current in con2 is more than twice that of Stan2 and greater than 0.01, and whether the zero-sequence voltage in con2 is more than 20 times that of Stan2. If so, it is an abnormal point;

[0047] b. If Stan2 is an abnormal point, determine whether the zero-sequence current of con2 is more than twice lower than that of Stan2. If it is, it is a normal point. If it is not, it is an abnormal point.

[0048] In a specific embodiment, the method further includes step: S4, recording and comparing the actual fault point and the fault selection interval, and calculating the correctness of the fault selection. Fault data can be collected, analyzed and recorded to provide data support for subsequent fault prevention and processing.

[0049] In a specific embodiment, the visualization output includes PC-side output and mobile-side output. The PC-side output intuitively displays the fault selection interval, and the mobile-side output displays the fault selection interval at the relevant personnel port.

[0050] The second aspect of the present application also provides an overhead line ground fault section selection system, comprising: a data acquisition unit, an input unit, a data storage unit, a data query unit, a data processing unit, a display unit and a communication unit;

[0051] The data acquisition unit is electrically connected to the fault indicator and the intelligent switch, and is used to convert the acquired signals and transmit them to the data storage unit;

[0052] The input unit is used to input the ground fault time and line name, and transmit the input information to the data query unit;

[0053] The data query unit extracts the corresponding data information of the data storage unit according to the data transmitted by the input unit, and transmits the extracted data to the data processing unit;

[0054] The data processing unit analyzes the data obtained by the data query unit, performs fault analysis on the line, and obtains the ground fault section interval;

[0055] The display unit is used to display the ground fault information on the PC side to achieve visual output;

[0056] The communication unit is used to exchange ground fault information and transmit the ground fault information to the relevant personnel port. In actual use, a clear fault indication alarm SMS can be sent to the maintenance personnel via SMS.

[0057] In a specific embodiment, an alarm module is also included, and the alarm module issues an alarm after obtaining the substation alarm information.

[0058] In a specific embodiment, the communication unit includes a communication interface and a debugging interface. The communication interface is remotely connected to a relevant personnel port, and the debugging interface is used to connect to a computer so that an operator can set the current variation amplitude. In actual use, the current variation amplitude can be continuously set and tested in practical tests to obtain a more accurate and smaller fault selection interval, so that a more accurate current variation amplitude can be obtained, which is highly practical.

[0059] Taking a municipal 10kV overhead line F575 as an example, an inversion calculation is performed on it. The line includes 3 fault indicators. The segment selection method is used to obtain data 15 minutes after the ground fault time of the fault indicator, as shown in Table 1:

[0060] Table 1 Fault indicator test data

[0061]

[0062] As can be seen from Table 1, the grounding reference current of pole 3 and pole 15 faults both have mutations (the mutation of pole 15 is large, and pole 3 has compensatory attenuation), while the reference current of pole 30 fault has no mutation. The application of this segment selection method can determine that pole 15 is the last abnormal point and pole 30 is the first normal point, so the fault point is between poles 15 and 30. According to the fault analysis, the phases indicated by the pole 3 fault and pole 15 fault are different. According to the ground electric field data, one indicates phase A and the other indicates phase C. It can be obviously determined that the A and C phases of the fault indicator are connected in reverse.

[0063] The fault range obtained by this selection method is between poles 15 and 30, with only 15 base poles. After field inspection, the actual fault situation was found to be metallic grounding of phase C of F575 line. After inspection, the fault point was pole 25 of F575 line, and the fault inspection range was reduced exponentially.

[0064] By using the segment selection method of the present invention, after the 10kV overhead line is grounded, it is only necessary to keep the grounding running for a period of time (no longer than 15 minutes) to complete the overhead line grounding fault segment selection, and reduce the grounding fault interval to between two fault indicators or intelligent switches, greatly reducing the fault inspection range and speeding up the fault troubleshooting time. Reduce grounding test pulls, avoid short-term frequent power outages caused by test pulls, and avoid complaints from some users who are sensitive to instantaneous power outages.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for selecting a section for an overhead line ground fault, characterized in that: The following steps are involved: S1, obtain the substation alarm information, if there is grounding alarm information, enter S2; S2, obtaining the ground fault time, fault indicator and intelligent switch information of the alarm line, analyzing the collected data, and finding the last abnormal point and the first normal point of the fault indicator and the intelligent switch, including the following steps: S21, acquiring data of the fault indicator and the intelligent switch 15 minutes before the ground fault time, and obtaining fault indicator reference data Stan1 and intelligent switch reference data Stan2; S22, acquiring data of each fault indicator and intelligent switch 15 minutes after the occurrence of the grounding fault, and obtaining the fault indicator comparison data con1 and the intelligent switch comparison data con2; S2-3, set the current variation range, compare and analyze Stan1, con1 and Stan2, con2 respectively according to the current variation range, and obtain abnormal points and normal points; S2-4, determine the last abnormal point according to the pole number information of each abnormal point, determine the first normal point according to the pole number information of each normal point, and the area between the last abnormal point and the first normal point is the fault selection interval. S3, visualize and output the fault selected section information.

2. A method for selecting a section of an overhead line ground fault according to claim 1, characterized in that: The current variation amplitude is a 100% current mutation. The Stan1 and con1 comparison analysis method of S23 is: a. Determine whether Stan1 is an abnormal point. If not, determine whether the grounding current reference of any phase in con1 is greater than twice that of Stan1 and greater than 10. At the same time, the ground electric field of the corresponding phase in con1 decreases by more than 20% compared with that in Stan1. If so, it is an abnormal point; b. If Stan1 is an abnormal point, determine whether the ground current reference of any phase in con1 is reduced by more than 2 times compared with Stan1. If it is reduced by more than 2 times, it is a normal point. If it is not reduced by more than 2 times, it is an abnormal point.

3. A method for selecting a section of an overhead line ground fault according to claim 2, characterized in that: The Stan2 and con2 comparison analysis methods of S2-3 are: a. Determine whether Stan2 is an abnormal point. If not, determine whether the zero-sequence current in con2 is more than twice that of Stan2 and greater than 0.01, and whether the zero-sequence voltage in con2 is more than 20 times that of Stan2. If so, it is an abnormal point; b. If Stan2 is an abnormal point, determine whether the zero-sequence current of con2 is more than twice lower than that of Stan2. If it is, it is a normal point. If it is not, it is an abnormal point.

4. A method for selecting a section for an overhead line ground fault according to claim 3, characterized in that The method further includes the step: S4, recording and comparing the actual fault point and the fault selection interval, and calculating the correct rate of the fault selection interval.

5. The method for selecting a section of an overhead line ground fault according to claim 4, characterized in that: The visual output includes PC-side output and mobile-side output. The PC-side output intuitively displays the fault selection interval, and the mobile-side output displays the fault selection interval at the relevant personnel port.

6. An overhead line grounding fault section selection system, based on the overhead line grounding fault section selection method according to claim 1, characterized in that: include: Data acquisition unit, input unit, data storage unit, data query unit, data processing unit, display unit and communication unit; The data acquisition unit is electrically connected to the fault indicator and the intelligent switch, and is used to convert the collected signals and transmit them to the data storage unit; The input unit is used to input the ground fault time and line name, and transmit the input information to the data query unit; The data query unit extracts the data information corresponding to the data storage unit according to the data transmitted by the input unit, and transmits the extracted data to the data processing unit; The data processing unit analyzes the data obtained by the data query unit, performs fault analysis on the line, and obtains the ground fault section interval; The display unit is used to display the ground fault information on the PC side to achieve visual output; The communication unit is used to exchange ground fault information and transmit the ground fault information to a relevant personnel port.

7. The overhead line ground fault section selection system according to claim 6, characterized in that: It also includes an alarm module, which issues an alarm after obtaining the substation alarm information.

8. The overhead line ground fault section selection system according to claim 7, characterized in that: The communication unit includes a communication interface and a debugging interface. The communication interface is remotely connected to the relevant personnel port. The debugging interface is used to connect to a computer so that an operator can set the current variation amplitude.

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