Ground fault monitoring device and ground fault point studying and judging method thereof

Abstract

The invention relates to the technical field of power monitoring, in particular to a ground fault monitoring device and a ground fault point studying and judging method thereof, and the ground fault monitoring device comprises a data analysis module, a monitoring module and a reading control module. The data analysis module is respectively connected with the monitoring module and the reading control module, the monitoring module acquires current data of a grounding wire by connecting the low-voltage transformer area grounding wire, and the reading control module acquires 96-point data of a user ammeter in the low-voltage transformer area and related power consumption data by connecting a power line in the low-voltage transformer area. And the data analysis module performs data analysis and calculation according to the data of the monitoring module and the reading control module and gives out a suspected user with a grounding fault. According to the ground fault monitoring device and the ground fault point studying and judging method thereof, low-voltage transformer area ground fault troubleshooting can be rapidly and accurately completed, the troubleshooting range is narrowed, the field ground fault troubleshooting workload is reduced, and real-time early warning of the low-voltage transformer area ground problem and rapid ground fault troubleshooting are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of electric power monitoring, and in particular to a ground fault monitoring device and a ground fault point analysis method thereof. Background Art

[0002] Traditional ground fault detection methods often rely on manual inspection tools, which consumes a lot of manpower and time. For complex low-voltage power grids, the line environment is complex, the number of users is large, the manual inspection cycle is long, and the ground fault occurs intermittently, resulting in the ground fault cannot be discovered in time, thus affecting the stable operation of the power system.

[0003] At present, low-voltage substations, especially rural low-voltage substations, often adopt a three-level protection form. Power supply companies are increasingly strict in assessing the total protection operation rate and the number of households during power outages. However, when the total protection trips and the user's power outage occurs, the power supply company employees are unable to promptly discover the cause of the grounding fault and eliminate the hidden danger. In order to ensure power supply, the total protection is often returned, which will cause great safety hazards. Therefore, being able to promptly discover grounding fault problems and make accurate judgments is a necessary means to ensure the safe operation of low-voltage power systems.

[0004] With the widespread application of HPLC communication technology in low-voltage substations, the present invention is provided with necessary data acquisition convenience and improved usability. The grounding fault monitoring device of the present invention is installed in the low-voltage substation, which can realize real-time monitoring of grounding faults and real-time analysis of the causes of grounding faults. When a grounding fault occurs, it notifies the power supply company employees as soon as possible to carry out early operation and maintenance. There is no need for power supply company employees to patrol the lines and check each household, which greatly saves the manpower investment in inspection, improves the efficiency of operation and maintenance, and protects people’s lives and property. Summary of the invention

[0005] The purpose of the present invention is to provide a ground fault monitoring device and a ground fault point analysis method, which can realize ground fault monitoring in low-voltage substations and give early warning notification in the first time when a ground fault occurs in the low-voltage substation. At the same time, the ground fault can be quickly located through the ground fault analysis method, saving manpower and material resources caused by line patrol and household inspection, and ensuring the safe and reliable operation of the low-voltage power system.

[0006] To achieve the above object, the present invention adopts the following technical solutions: The invention provides a ground fault monitoring device, comprising a ground fault monitoring module, a copy control module and a data analysis module.

[0007] The data analysis module is connected to the ground monitoring module and the copy control module, and performs data analysis based on the received data; The ground monitoring module is connected to the substation ground wire and monitors the ground wire current; The reading control module is connected to the power line of the substation area and is used to monitor and read the data of the low-voltage substation meter; The grounding fault monitoring device detects the grounding wire current in the low-voltage substation through the grounding monitoring module and monitors 96 points of data of the low-voltage substation user meters through the reading and control module. The data analysis module performs data analysis based on the data reported by the grounding monitoring module and the grounding wire monitoring module, and removes non-fault related meters; at the same time, the data analysis module can also control the reading and control module to perform intensive data reading when receiving the grounding current mutation provided by the grounding monitoring module, so as to accurately locate the grounding fault point.

[0008] Furthermore, the grounding monitoring module of the grounding fault monitoring device monitors the grounding wire current through a current transformer. The current transformer types include common open-type current transformers, flexible coils, etc. After the grounding fault monitoring module monitors the grounding wire current, it reports it to the data analysis module. The data analysis module determines the grounding fault based on the set grounding wire current threshold and reports it.

[0009] Furthermore, the reading and control module of the ground fault monitoring device is used to connect the low-voltage substation power line, and obtain the low-voltage substation meter file list and substation meter data through power line carrier (HPLC) monitoring and reading. After the reading and control module is connected to the power line, all power line data of the low-voltage substation can be monitored, and the power line data can be analyzed to obtain the substation meter list and 96 points of data reported regularly by the low-voltage substation meter.

[0010] Furthermore, the data analysis module can control the data collection density of the monitoring module and the reading and control module, and perform data analysis on the data reported by the two modules, screen out user data that causes grounding faults in the low-voltage substation, and control the monitoring module to read the designated meter data according to data analysis requirements. When a large mutation occurs in the grounding current, high-frequency collection is performed, and the collected meter data is compared with the grounding current and calculated using a correlation algorithm to screen out meters with currents less than the grounding wire current, and obtain meters with current changes consistent with the grounding wire current.

[0011] In a second aspect, the present invention provides a method for determining a ground fault point, comprising the following steps: S1. The monitoring module of the ground fault monitoring device monitors the ground wire current and freezes the ground wire current at each 96 points. In this way, the ground wire current data and the meter current data are collected at the same frequency, thereby ensuring that the correlation calculation between the ground wire current and the meter current data is as accurate as possible; S2. When the ground fault monitoring device ground monitoring module detects that the ground current is greater than the set trigger threshold, the data analysis module controls the reading and control module to synchronously monitor the 96-point data of the area meter, and reports the 96-point data to the data analysis module. The 96-point data of the low-voltage area meter is a fixed collection task of the current power supply company. The meter freezes the data and actively reports it. The reading and control module can obtain the corresponding 96-point data by connecting the power line; S3. The data analysis module of the ground fault monitoring device analyzes the ground wire current and 96 points of the meter data. First, users with a current of 0 are eliminated. Then, the meters of users with current fluctuations significantly smaller than the ground wire current fluctuations are eliminated. When comparing three-phase meters, the comparison is performed according to the current of each phase. S4, the ground fault monitoring device data analysis module calculates the correlation between the 96-point data of the eliminated electric meter and the 96-point data of the low-voltage area grounding line, and selects the electric meter with the largest correlation for key monitoring; S5. After the data analysis module of the ground fault detection device calculates the meter with the maximum range of ground fault correlation, the control reading module and the monitoring module are controlled to perform high-density collection of the meter and the ground wire current. When the monitoring module detects a sudden change in the ground wire current, the ground fault user is further confirmed by calculation through the correlation algorithm. The correlation algorithm is used to screen the meter with high and consistent correlation between the meter current change and the ground wire current change; S6. The suspected ground fault user is locked through the correlation algorithm and the correlation ranking user is given for rapid ground fault investigation. The suspected users are investigated one by one and the final ground fault user is locked.

[0012] S7. After the suspected users are screened out and the grounding fault is controlled, the grounding fault monitoring device continues to monitor the substation to further screen for grounding fault problems of other users in the low-voltage substation.

[0013] The beneficial effects of the present invention compared with the prior art are: When troubleshooting a ground fault, the present invention requires operators to only install a ground fault monitoring device on the side of the substation to identify suspected users and conduct targeted troubleshooting, thus avoiding the problems of traditional household-by-household inspection and heavy workload, improving troubleshooting efficiency and saving labor costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0015] Figure 1 A schematic diagram of a ground fault monitoring device in the present invention for mounting in a station area Figure 2 A schematic diagram of each module of a bypass meter changing device in the present invention DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are 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.

[0017] like Figure 1-2 As shown, the present invention provides a ground fault monitoring device, including a ground monitoring module, a copy control module, and a data analysis module.

[0018] The data analysis module is connected to the ground monitoring module and the copy control module, and performs data analysis based on the received data.

[0019] The ground monitoring module is connected to the current transformer and installed on the ground wire in the substation to monitor the ground wire current.

[0020] The reading control module is connected to the power line of the substation, supplies power to the ground fault monitoring device and is used to monitor and read the low-voltage substation meter data.

[0021] The grounding fault monitoring device detects the grounding wire current in the substation through the grounding monitoring module and monitors and reads the low-voltage substation HPLC data through the reading and control module to obtain 96 points of user meter data. The data analysis module performs data analysis based on the data reported by the grounding monitoring module and the grounding wire monitoring module to remove non-fault related meters; at the same time, the data analysis module can also control the reading and control module to perform intensive data reading when receiving the grounding current mutation provided by the grounding monitoring module, so as to accurately locate the grounding fault point.

[0022] The grounding monitoring module of the grounding fault monitoring device monitors the grounding wire current through a current transformer. The current transformer forms include common open-type current transformers, flexible coils, etc. After the grounding fault monitoring module monitors the grounding wire current, it reports to the data analysis module. The data analysis module determines the grounding fault and reports it according to the set grounding wire current threshold. For example, when the grounding current threshold is set to 300ma, when the grounding current is detected to exceed 300ma, the grounding monitoring module reports to the data analysis module.

[0023] The reading and control module of the ground fault monitoring device is used to connect the low-voltage power line in the substation, and obtain the low-voltage substation meter file list and substation meter data through power line carrier (HPLC) monitoring and reading. After the reading and control module is connected to the power line, all power line data of the low-voltage substation can be monitored and the meter data can be read in a targeted manner, and the power line data can be analyzed to obtain the low-voltage substation meter list and 96 points of data reported regularly by the low-voltage substation meter.

[0024] The data analysis module of the grounding monitoring device can control the data collection density of the monitoring module and the reading and control module, and perform data analysis on the data reported by the two modules, screen the user data that causes the grounding fault in the low-voltage substation, and control the monitoring module to read the designated meter data according to the data analysis requirements. When the grounding current undergoes a large mutation, high-frequency collection is performed, and the meters that need to be intensively read are selected from the acquired low-voltage substation meter file list, and reading parameters are formulated, such as obtaining the minute-level and second-level current data of a certain meter for comparison with the grounding current data and current fluctuation correlation analysis. Synchronously, the data analysis module is required to control the grounding monitoring module to report the grounding current data at the corresponding time, so as to facilitate the correlation comparison of the two data.

[0025] Based on the above-mentioned ground fault monitoring device, such as Figure 2 As shown, the present invention also provides a ground fault point analysis method, comprising the following steps: S1. After the ground fault monitoring device ground monitoring module transformer is installed, the wire is connected to the low-voltage power line, the equipment is powered on, and the ground monitoring module monitors the ground wire current. By monitoring the low-voltage data, the clock is synchronized with the data in the data center, and the ground wire current data at 96 points in the low-voltage data center is collected and frozen at the same time, so that the ground wire current data and the meter current data can be collected at the same frequency. The significance of achieving the same frequency collection is to compare the data at the same time to ensure the accuracy of the algorithm. S2. The ground fault monitoring device sets the ground current reporting trigger threshold in advance. When the ground monitoring module detects that the ground current is greater than the set trigger threshold, the data analysis module controls the reading and control module to synchronously monitor the 96-point data of the low-voltage area meter, and reports the 96-point data to the data analysis module. The 96-point data of the low-voltage area meter is a fixed collection task of the current power supply company. The meter freezes the data and actively reports it. The reading and control module can obtain the corresponding 96-point data by connecting the power line. The significance of obtaining the 96-point data of the meter is to compare it with the ground current value monitored by the ground monitoring module. S3. The data analysis module of the ground fault monitoring device analyzes the ground wire current and 96 points of the meter data. First, users with a current of 0 are eliminated, and then the meters of users with current fluctuations significantly smaller than the ground wire current fluctuations are eliminated. When comparing three-phase meters, the current of each phase is compared. By comparing, the scope of ground fault investigation for users in the low-voltage area is narrowed, and it is beneficial to the subsequent correlation calculation. S4. The data analysis module of the ground fault monitoring device calculates the correlation between the 96 data points of the eliminated electric meter and the 96 data points of the ground wire in the substation, and selects the electric meter with the greatest correlation for key monitoring. The electric meter with the greatest correlation with the ground fault in the low-voltage substation is the most likely to have a ground fault, and the scope of investigation is minimized; S5. After the data analysis module of the ground fault detection device calculates the meter with the maximum range of ground fault correlation, the control reading module and the monitoring module perform high-density data collection on the meter and the ground wire current. When the monitoring module detects a sudden change in the ground wire current, the data analysis module compares and analyzes the ground fault occurrence time with the meter collection time, and uses the meter closest to the time before the ground fault occurs as the target meter for high-density data collection, and accurately locates the ground fault user through the correlation algorithm before, during and after the ground fault occurs.

[0026] Because the time of ground fault occurrence is random, the analysis module cannot determine when a certain meter is read. Through this high-density random acquisition method, the target analysis meter when the ground fault occurs can be effectively locked, and non-suspicious meters can be gradually eliminated to locate the suspected meters.

[0027] S6. Use the correlation algorithm to lock the suspected ground fault user and give the correlation ranking user for rapid ground fault investigation. Check the suspected users one by one, lock the final ground fault user, and check the users according to the correlation ranking to achieve rapid investigation. S7. After the suspected users are screened and the grounding fault is treated, the grounding fault monitoring device continues to monitor the substation to further screen the grounding fault problems of other users in the substation. There may be more than one user with a grounding fault problem in the low-voltage substation. By continuously screening the user's grounding fault problem, the grounding fault on the user side of the low-voltage substation can be cleared.

[0028] In order to more clearly illustrate the above technical solution, the following example is given: After receiving the ground fault troubleshooting task, the staff went to the designated low-voltage substation address to install the ground fault monitoring device, completed the power supply of the ground fault monitoring device and the installation of the grounding bus current transformer on site. After the installation was completed, the ground fault monitoring device powered on the equipment by connecting the low-voltage substation power line (1011) and automatically obtained the power line HPLC data. Since the equipment was installed on the transformer side of the low-voltage substation, it is the center point of the low-voltage substation, and the HPLC data can be fully monitored. The HPLC data is monitored by the copy control module, and the clock of the ground fault monitoring device is first synchronized with the low-voltage substation; Since there are fixed hourly freeze and 96-point freeze collection tasks for electricity meters in low-voltage areas, the reading and control module can realize the analysis of low-voltage area meter files and 96-point meter data by monitoring the data. The 96-point data includes the frozen current data and power data of the meter.

[0029] When the grounding current monitored by the grounding monitoring module exceeds the preset threshold, the data analysis module performs preliminary data screening through the meter freezing data uploaded by the reading and control module and the grounding current data reported by the grounding monitoring module. First, the meter current data of 0 is eliminated, because this meter does not contribute to the grounding current. After the screening is completed, all meter data and grounding current data are analyzed. First, when the grounding current fluctuates, the meter current data is less than the grounding current and the data does not fluctuate. In the remaining meters, the meter current data and the grounding current data are analyzed for data fluctuation correlation, and the meters with large correlation are screened to form a list of suspect meters. Synchronously, the suspect meters are read through the reading and control module. The reading can be set to minute or second level. When the grounding current fluctuates in real time, whether there is a corresponding fluctuation in the suspect meter current is further locked in the faulty meter. After screening, the staff can be given the suspected meter number, and the staff can confirm it on site; after the staff checks the suspected meter, if there is leakage, on-site processing can be carried out to eliminate the leakage. After the leakage is eliminated, the grounding fault monitoring device continues to collect data. When the grounding current exceeds the threshold, data analysis is triggered, and the fault point in the substation is continued to be analyzed and judged, which greatly improves the inspection efficiency and saves labor costs.

[0030] Working status 1 During the continuous grounding current analysis, correlation analysis is performed between the 96-point current data of the electric energy meter and the 96-point current data of the grounding wire of the monitoring device, and the zero-current meters and the meters with overload current less than the grounding current during the continuous grounding current are eliminated. The remaining meters are suspected meters.

[0031] Working status 2 If the grounding current ends after a period of time, based on the suspected meters left in working state 1, when a breakpoint occurs in the continuous grounding current, the monitoring device starts intensive data collection to obtain the real-time load of these meters, and analyzes which meters' load current disappears synchronously when the grounding current disappears, and marks these meters as suspected meters.

[0032] Working status 3 If the grounding current is intermittent, segmented or fluctuates greatly, the working state 1 and 2 marking protocol meters are used first. At this time, since the grounding current does not last very long, there are more suspicious meters left. The monitoring device intensively collects the load data of the suspected electric energy meters, and when the grounding current occurs, the load meter closest to the time of the grounding current is selected as the target meter, and the current data of these meters after the grounding current occurs and after the grounding current disappears are collected, so as to perform the correlation analysis of the closest time before, during and after the grounding current occurs to ensure the accuracy of the analysis. Because in the actual environment, the load changes at any time, so the closer the comparison time is, the higher the accuracy.

[0033] As mentioned above, after another intermittent, continuous or fluctuating grounding current, some irrelevant meters are eliminated from the suspected meters. If there are relevant meters, they are marked as suspected meters. The same method is used to eliminate irrelevant meters and mark suspected meters for multiple intermittent, segmented and fluctuating currents. After all the suspected meters have been subjected to a round of intensive reading and correlation analysis, a few suspected meters are finally left. They can be screened and located through multiple rounds. The more rounds, the more accurate the results.

[0034] In the process of troubleshooting grounding faults in low-voltage substations, there are common problems such as the investigation relying on manpower to conduct a dragnet-style household-by-household investigation, difficulty in troubleshooting intermittent leakage, inability to put the substation into operation due to grounding faults, and complaints against the power supply company. The present invention provides a grounding fault monitoring device and a method for determining a grounding fault point thereof. The staff only needs to simply install the grounding fault monitoring device without the need to conduct household-by-household investigation, thereby simplifying the grounding fault troubleshooting process, avoiding user complaints, and protecting the safety of user life and property.

[0035] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A ground fault monitoring device and a ground fault point determination method thereof, characterized in that: Contains grounding monitoring module, copy control module, and data analysis module; The data analysis module is connected to the ground monitoring module and the copy control module; The ground monitoring module is connected to the low voltage area ground wire and monitors the ground wire current; The reading control module is connected to the power line of the substation area and is used to monitor and read the data of the low-voltage substation meter; The ground fault monitoring device detects the grounding wire current in the low-voltage substation through the grounding monitoring module and monitors 96 points of data of the low-voltage substation user meters through the reading and control module. The data analysis module performs data analysis based on the data reported by the grounding monitoring module and the grounding wire monitoring module, and removes non-fault related meters; at the same time, the data analysis module can also control the reading and control module to perform intensive data reading when receiving the grounding current mutation provided by the grounding monitoring module, so as to accurately locate the grounding fault point.

2. The grounding monitoring module of the grounding fault monitoring device according to claim 1 is characterized in that the grounding monitoring module monitors the grounding wire current through a current transformer.

3. The ground fault monitoring device reading and control module according to claim 1 is characterized in that it is used to connect to the low-voltage area power line and obtain the low-voltage area meter file list and low-voltage area meter data through the power line carrier.

4. The ground fault monitoring device according to claim 1 is characterized in that the data analysis module can control the data collection density of the monitoring module and the copy control module, and perform correlation analysis on the data reported by the two modules.

5. A method for determining a ground fault point, characterized in that The following steps are involved: S1. The monitoring module of the ground fault monitoring device monitors the ground wire current and freezes the ground wire current at each 96 points; S2. When the grounding monitoring module of the ground fault monitoring device detects that the grounding current is greater than the set trigger threshold, the data analysis module controls the copy control module to synchronously monitor the 96-point data of the area meter and report the 96-point data to the data analysis module; S3, the data analysis module of the ground fault monitoring device analyzes the ground wire current and 96 points of the electric meter data, first eliminating users with a current of 0, and then eliminating the electric meters of users whose current fluctuation is obviously smaller than the ground wire current fluctuation; S4, the ground fault monitoring device data analysis module calculates the correlation between the 96-point data of the eliminated electric meter and the 96-point data of the low-voltage area grounding line, and selects the electric meter with the largest correlation for key monitoring; S5. After the data analysis module of the ground fault monitoring device calculates the meter with the maximum range of ground fault correlation, the control reading module and the monitoring module are controlled to perform high-density collection of the meter and the ground wire current. When the monitoring module detects a sudden change in the ground wire current, the ground fault user is further confirmed by calculation through the correlation algorithm. The correlation algorithm is used to screen the meter with high and consistent correlation between the meter current change and the ground wire current change; S6. Use the correlation algorithm to identify suspected ground fault users and give correlation ranking users for rapid ground fault troubleshooting; S7. After the suspected users are screened out and the grounding fault is controlled, the grounding fault monitoring device continues to monitor the substation to further screen for grounding fault problems of other users in the low-voltage substation.

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