A low-voltage distribution line leakage discrimination method and system
By adaptively calculating the line loss rate and the standard deviation of air humidity to screen suspected leakage areas, and combining the power fluctuation rate and change rate to determine the leakage type and phase, the accuracy and timeliness of leakage detection in low-voltage distribution lines are solved, providing accurate leakage location support.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- STATE GRID JIANGSU ELECTRIC POWER CO LTD MARKETING SERVICE CENT
- Filing Date
- 2026-04-03
- Publication Date
- 2026-06-09
AI Technical Summary
Existing technologies are not accurate enough in detecting leakage current in low-voltage distribution lines, cannot accurately locate the leakage range, and rely on human experience, resulting in poor timeliness.
By adaptively calculating the line loss rate and the standard deviation of air humidity, suspected leakage areas are screened out. The leakage type is determined by combining the fluctuation rate and change rate of power loss, and the leakage phase is further determined by the change in the proportion of the three-phase average current.
It improved the accuracy and timeliness of leakage current investigation, clarified the specific scope of leakage current, provided data support for on-site investigation, and improved the accuracy of abnormal line loss analysis in transformer areas.
Smart Images
Figure CN121978583B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of transformer substation line loss technology, and more specifically, relates to a method and system for detecting leakage current in low-voltage transformer substation power distribution lines. Background Technology
[0002] Leakage current is one of the most direct factors affecting the economic operation, power supply reliability, and power supply safety of low-voltage distribution lines. In the daily operation and maintenance of low-voltage distribution areas, leakage current investigation is usually carried out after checking for abnormal line losses such as abnormal data collection, metering, and record-keeping, resulting in a significant lag in anomaly localization. Traditional leakage current investigation relies on the experience of maintenance personnel and simple tools. The vast topology and complex spatial layout of low-voltage distribution areas greatly limit the timeliness of leakage current detection, leading to continuous power loss.
[0003] Existing technology discloses a method, device, medium, and equipment for monitoring leakage current in low-voltage power distribution lines (CN117786440A). It establishes a time-series dataset using the neutral current, live current, and power of the low-voltage power distribution user as influencing factors. A granularity-based clustering method is used to cluster the time-series dataset, obtaining the nonlinear functional relationship between the influencing factor of each cluster and the leakage current. Finally, the cluster category of the low-voltage power distribution line to be monitored is determined, and the leakage current is estimated using the corresponding nonlinear functional relationship. The shortcomings of this technology are: in real-world scenarios, many low-voltage power distribution users use a common neutral wiring method for metering equipment, leading to distortion of the neutral current data and affecting the accuracy of clustering; and the final result of this technology can only determine whether leakage current exists in the low-voltage power distribution line under test, but cannot specify the exact range of the leakage current. Summary of the Invention
[0004] To address the shortcomings of existing technologies, this invention provides a method and system for detecting leakage current in low-voltage distribution lines.
[0005] The present invention adopts the following technical solution.
[0006] The first aspect of the present invention is a method for detecting leakage current in low-voltage distribution lines, characterized in that it includes:
[0007] The second period is adaptively calculated based on the standard deviation of the line loss rate and the standard deviation of the air humidity within the previously set base period for the current number of days.
[0008] Based on the daily power loss and line loss rate of all low-voltage distribution areas within the first cycle set before the current number of days, suspected leakage distribution areas of Class I are initially screened out from all low-voltage distribution areas; the leakage type of the suspected leakage distribution areas of Class I is continuous leakage.
[0009] Based on the line loss rate and air humidity of all transformer substations in the second period prior to the current number of days, suspected leakage substations of Class II were initially screened out from all low-voltage transformer substations; the leakage type of the suspected leakage substations of Class II is intermittent leakage.
[0010] Obtain the indicator curves of the gate table and user table for each moment of each day within the set third cycle before the current number of days for all suspected leakage areas, and calculate the power loss at each corresponding moment; for Class I suspected leakage areas, determine whether there is leakage based on the fluctuation rate of power loss; for Class II suspected leakage areas, determine whether there is leakage based on the rate of change of power loss.
[0011] For transformer substations identified as having leakage, the data collection period is selected based on the leakage type. The average current of the three phases is obtained for each day within the selected period prior to the current day. The change in the percentage of the average current of the three phases is calculated to determine which phase has experienced leakage.
[0012] Preferably, the adaptive calculation of the second period based on the standard deviation of the line loss rate and the standard deviation of the air humidity within the base period set before the current number of days specifically involves:
[0013] Calculate the standard deviation of the line loss rate and the standard deviation of the air humidity within the base period set before the current number of days, and normalize them to obtain the normalized standard deviation of the line loss rate and the normalized standard deviation of the air humidity. Select the larger of the normalized standard deviations of the line loss rate and the normalized standard deviations of the air humidity and multiply it by a set coefficient. The negative number of the product is used as the exponent, and the natural logarithm e is used as the base for exponential operation. If the product of the exponential operation result and the base period is rounded up and is greater than the first period, then the second period is the product of the exponential operation result and the base period rounded up; otherwise, the second period is equal to the first period.
[0014] The set base period is greater than the first period, and the first period is greater than the third period.
[0015] Preferably, the preliminary screening of suspected leaky transformer areas of Class I among all low-voltage transformer areas specifically involves:
[0016] Calculate the difference in power loss and line loss rate for each day of the first set period for all transformer areas, excluding the first day, compared to the first day. If any transformer area has a power loss difference exceeding a set power loss difference threshold for each day of the first set period, and a line loss rate difference exceeding a set first line loss rate difference threshold for each day of the first set period, then the corresponding transformer area is identified as a Class I suspected leaky transformer area.
[0017] Preferably, the preliminary screening of suspected leaky transformer areas of type II among all low-voltage transformer areas specifically involves:
[0018] Based on the line loss rate and air humidity of all days in the second period prior to the current number of days for all transformer substations, calculate the Pearson correlation coefficient between the line loss rate and air humidity. If the Pearson correlation coefficient exceeds the set correlation coefficient threshold, and the air humidity of the day before the current number of days exceeds the set air humidity threshold, and the line loss rate of the day before the current number of days minus the line loss rate of the two days prior to the current number of days exceeds the set second line loss rate difference threshold, then the corresponding transformer substation is judged as a suspected leaky transformer substation of Class II.
[0019] Preferably, the calculation of the power loss at each corresponding moment is specifically as follows:
[0020] The value displayed on the gate meter at each time point is the power supply at that time point; the value displayed on the user meter at each time point is the power sales at that time point; the power loss at that time point is obtained by subtracting the power sales at the corresponding time point from the power supply at each time point.
[0021] Preferably, for suspected leakage areas of type I, the presence of leakage is determined based on the fluctuation rate of the lost power, specifically as follows:
[0022] For each day within the third cycle prior to the current number of days, calculate the standard deviation of the power loss at all times for the corresponding number of days as the volatility of the power loss for the corresponding number of days.
[0023] If the daily power loss fluctuation rate of a suspected Class I leakage power distribution area is less than the set fluctuation rate threshold for the third cycle prior to the current number of days, then the suspected Class I leakage power distribution area is determined to have leakage.
[0024] Preferably, for suspected leakage areas of type II, the existence of leakage is determined based on the rate of change of power loss, specifically as follows:
[0025] Calculate the growth rate of power loss at each moment of the day before the current day compared to the corresponding moment of the day before the current day. If the growth rate of power loss at any moment exceeds the set growth rate threshold, then the corresponding moment is a growth moment. If the total number of growth moments of suspected Class II leakage areas exceeds the set quantity threshold, then it is determined that there is leakage in the corresponding Class II suspected leakage area.
[0026] Preferably, for transformer substations determined to have leakage current, the data collection period is selected based on the type of leakage current, specifically as follows:
[0027] When the leakage current type is continuous leakage current, select the first set period for data collection.
[0028] When the leakage current type is intermittent leakage current, the data acquisition period is selected as the third set period.
[0029] Preferably, the step of determining the phase where leakage occurred by calculating the change in the average current ratio of the three phases specifically involves:
[0030] Obtain the average three-phase current for each day within the selected period prior to the current day, and calculate the average three-phase current for each day by dividing it by the sum of the average three-phase currents to obtain the average three-phase current percentage.
[0031] The difference between the average current percentage of the three phases for each day of the selected period (excluding the first day) and the average current percentage of the three phases for the first day is calculated as the change in the average current percentage of the three phases for the corresponding days. If the change in the average current percentage of any phase exceeds the set threshold for the change in percentage for each day, it is determined that the corresponding phase has leakage.
[0032] The second aspect of this invention proposes a low-voltage distribution line leakage current detection system based on the method described in the first aspect of this invention, comprising a distribution line loss data acquisition module, a preliminary leakage distribution line screening module, a distribution line loss meter and user meter data acquisition module, a leakage distribution line determination module, a current curve data acquisition module, a leakage phase determination module, and an anomaly output module, specifically:
[0033] Transformer Area Line Loss Data Acquisition Module: Used to adaptively calculate the second cycle based on the standard deviation of the line loss rate and the standard deviation of the air humidity within the base cycle set before the current number of days, to acquire the power loss and line loss rate of all low-voltage transformer areas within the first cycle set before the current number of days, and to acquire the line loss rate and air humidity of all transformer areas within the second cycle before the current number of days;
[0034] The preliminary screening module for leakage areas is used to initially screen all low-voltage distribution areas for suspected leakage areas of type I based on the power loss and line loss rate of all distribution areas within the first cycle prior to the current number of days. The leakage type of the suspected leakage areas of type I is continuous leakage. Based on the line loss rate and air humidity of all distribution areas within the second cycle prior to the current number of days, the module initially screens all low-voltage distribution areas for suspected leakage areas of type II. The leakage type of the suspected leakage areas of type II is intermittent leakage.
[0035] The data acquisition module for the gate meter and user meter of all suspected leaky transformer areas is used to acquire the indicator curves of the gate meter and user meter at each moment within the set third cycle before the current number of days; and to calculate the lost power at each moment within the set third cycle before the current number of days.
[0036] Leakage Circuit Determination Module: For suspected leakage circuits of type I, it determines whether leakage exists based on the fluctuation rate of power loss; for suspected leakage circuits of type II, it determines whether leakage exists based on the rate of change of power loss.
[0037] Current curve data acquisition module: For transformer areas identified as having leakage, it selects the data acquisition period based on the leakage type and obtains the average three-phase current of each day within the selected period up to the current day.
[0038] Leakage current phase identification module: used to calculate the change in the average current ratio of the three phases to determine the phase in which leakage current has occurred;
[0039] Abnormal output module: Used to output the leakage type and determine the area and phase where the leakage occurred.
[0040] A third aspect of the invention provides an apparatus comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, the processor performing steps of the low-voltage distribution line leakage detection method described in the first aspect of the invention.
[0041] A fourth aspect of the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, uses the steps of the low-voltage distribution line leakage detection method described in the first aspect of the present invention.
[0042] The beneficial effects of this invention are compared with those of the prior art:
[0043] 1. This invention uses operational data such as power loss and line loss rate in the transformer area as triggering conditions to promptly capture leakage signals, make judgments based on the type of leakage, solve the problem of difficult-to-determine leakage in the transformer area, and thus improve the priority of leakage investigation.
[0044] 2. In terms of the selection of technical parameters, this invention introduces the air humidity parameter of the area where the transformer substation is located, which increases the realism and reliability of the algorithm's simulation of leakage scenarios; it adopts a classification and typology approach according to different fault types, covering a variety of leakage characteristics discrimination methods;
[0045] 3. The results of this invention clearly identify the phase of leakage in the transformer substation, providing accurate data support for on-site troubleshooting and management, and improving the accuracy of abnormal line loss analysis in the transformer substation. Attached Figure Description
[0046] Figure 1 This is a flowchart of the method of the present invention;
[0047] Figure 2 This is a block diagram of the system of the present invention. Detailed Implementation
[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.
[0049] like Figure 1 As shown, Embodiment 1 of the present invention proposes a method for detecting leakage current in low-voltage distribution lines, including:
[0050] The second period is adaptively calculated based on the standard deviation of the line loss rate and the standard deviation of the air humidity within the previously set base period for the current number of days.
[0051] In this preferred embodiment, the standard deviation of the line loss rate and the standard deviation of the air humidity within the base period set before the current number of days are calculated, and both are normalized to obtain the normalized standard deviation of the line loss rate and the normalized standard deviation of the air humidity. The larger value of the normalized standard deviation of the line loss rate and the normalized standard deviation of the air humidity is selected and multiplied by a set coefficient. The negative number of the multiplication result is used as the exponent, and the natural logarithm e is used as the base for exponential operation. If the product of the exponential operation result and the base period is rounded up and is greater than the first period, then the second period is the same as the first period.
[0052] The set base period is greater than the first period, and the first period is greater than the third period.
[0053] The formula is:
[0054]
[0055] in, , These are the standard deviations of the line loss rate and the air humidity, respectively, within the baseline period set before the current number of days. The set coefficient; For the first cycle, As the set base period, This is the second cycle.
[0056] Specifically, the first set cycle is 3 days, and the third set cycle is 2 days.
[0057] Based on the daily power loss and line loss rate of all low-voltage distribution areas within the first cycle set before the current number of days, suspected leakage distribution areas of Class I are initially screened out from all low-voltage distribution areas; the leakage type of the suspected leakage distribution areas of Class I is continuous leakage.
[0058] In this preferred embodiment, the preliminary screening of suspected leaky power stations of Class I among all low-voltage power stations specifically involves:
[0059] Calculate the difference in power loss and line loss rate for each day of the first set period for all transformer areas, excluding the first day, compared to the first day. If any transformer area has a power loss difference exceeding a set threshold for both the first and second days, and a line loss rate difference exceeding a set threshold for both the first and second days, then the corresponding transformer area is classified as a suspected Class I leaky transformer area. Specifically, a transformer area is classified as a suspected Class I leaky transformer area if it meets all of the following conditions:
[0060]
[0061] in, , , Each represents the current number of days. The day before (i.e. The day before (i.e.) Days), the first three days (i.e. The amount of electricity lost (days); , , Each represents the current number of days. The day before (i.e. The day before (i.e.) Days), the first three days (i.e. The line loss rate (days); This is the threshold for the difference in power loss. The threshold for the first line loss rate difference;
[0062] Based on experience summarizing on-site transformer operation conditions, the threshold for power loss difference is set to 30 in this embodiment. The threshold for the first line loss rate difference is set to 1%.
[0063] Based on the line loss rate and air humidity of all transformer substations in the second period prior to the current number of days, suspected leakage substations of Class II were initially screened out from all low-voltage transformer substations; the leakage type of the suspected leakage substations of Class II is intermittent leakage.
[0064] In this preferred embodiment, the preliminary screening of suspected leaky low-voltage transformer areas of type II specifically involves:
[0065] Based on the line loss rate and air humidity of all days within the second period prior to the current day for all transformer substations, the Pearson correlation coefficient between the line loss rate and air humidity is calculated. If the Pearson correlation coefficient exceeds a set correlation coefficient threshold, and the air humidity of the day before the current day exceeds a set air humidity threshold, and the line loss rate of the day before the current day minus the line loss rate of the two days prior to the current day exceeds a set second line loss rate difference threshold, then the corresponding transformer substation is judged as a suspected leaky transformer substation of type II. Specifically, the second period calculated in this embodiment is 7 days.
[0066] The formula is:
[0067]
[0068] in, This is the threshold for the second line loss rate difference; The air humidity of the day before the current day; The set air humidity threshold; Pearson correlation coefficient between line loss rate and air humidity; The threshold value for the set correlation coefficient;
[0069] In this embodiment, based on experience summarizing the operation of the transformer substations, the second line loss rate difference threshold is also set to 1%, and the air humidity threshold is also set to 1%. Take 80%, correlation coefficient threshold Take 0.8.
[0070] Obtain the indicator curves of the gate table and user table for each moment of each day within the set third cycle before the current number of days for all suspected leaky radio stations, and calculate the corresponding power loss at each moment.
[0071] In this preferred embodiment, the calculation of the power loss at each corresponding moment specifically involves:
[0072] The value displayed on the gate meter at each time point is the power supply at that time point; the value displayed on the user meter at each time point is the power sales at that time point; the power loss at that time point is obtained by subtracting the power sales at the corresponding time point from the power supply at each time point.
[0073] Specifically, each moment is 1 hour, and the indicator curves of the gate meter and user meter for each moment of the day are the 24-hour hourly indicator curves of the gate meter and user meter for each day. It should be noted that when calculating the power loss at each moment, if the gate meter and user meter fail to collect data at any moment, the relevant data for the corresponding moment will be removed, the power loss at the corresponding moment will not be calculated, and the corresponding moment will not be involved in the subsequent judgment of whether there is leakage.
[0074] For Class I suspected leakage areas, the presence of leakage is determined based on the fluctuation rate of power loss; for Class II suspected leakage areas, the presence of leakage is determined based on the rate of change of power loss.
[0075] In this preferred embodiment, for suspected leakage areas of type I, determining whether leakage exists based on the fluctuation rate of lost power specifically involves:
[0076] For each day within the third cycle prior to the current number of days, calculate the standard deviation of the power loss at all times for the corresponding number of days as the volatility of the power loss for the corresponding number of days.
[0077] If the daily power loss fluctuation rate within the set third cycle prior to the current number of days for a suspected Class I leakage area is less than the set fluctuation rate threshold, then it is determined that the corresponding Class I suspected leakage area has a leakage. Specifically, for this embodiment, when... , All are less than the set volatility threshold. If so, it is determined that there is a leakage current in the suspected leakage area corresponding to Class I. , These are the volatility of the lost electricity on the day before the current day and the day before the current day, respectively. The volatility threshold set in this embodiment... The value is 3.
[0078] In this preferred embodiment, for suspected leakage areas of type II, the presence of leakage is determined based on the rate of change of power loss, specifically as follows:
[0079] Calculate the growth rate of power loss at each moment of the day before the current day compared to the corresponding moment of the day before the current day. If the growth rate of power loss at any moment exceeds the set growth rate threshold, then the corresponding moment is a growth moment. If the total number of growth moments of suspected Class II leakage areas exceeds the set quantity threshold, then it is determined that there is leakage in the corresponding Class II suspected leakage area.
[0080] Specifically, the growth rate threshold is set at 100%, and the quantity threshold is set at 10.
[0081] For transformer substations identified as having leakage, the data collection period is selected based on the leakage type. The average current of the three phases is obtained for each day within the selected period prior to the current day. The change in the percentage of the average current of the three phases is calculated to determine which phase has experienced leakage.
[0082] In this preferred embodiment, for the transformer area determined to have leakage current, the data collection period is selected according to the type of leakage current, specifically as follows:
[0083] When the leakage current type is continuous leakage current, select the first set period for data collection.
[0084] When the leakage current type is intermittent leakage current, the data acquisition period is selected as the third set period.
[0085] In this preferred embodiment, the step of determining the phase where leakage occurred by calculating the change in the average current ratio of the three phases specifically involves:
[0086] Obtain the average three-phase current for each day within the selected period prior to the current day, and calculate the average three-phase current for each day by dividing it by the sum of the average three-phase currents to obtain the average three-phase current percentage.
[0087] The difference between the average current percentage of the three phases for each day of the selected period (excluding the first day) and the average current percentage of the three phases for the first day is calculated as the change in the average current percentage of the three phases for the corresponding days. If the change in the average current percentage of any phase exceeds the set threshold for the change in percentage for each day, it is determined that the corresponding phase has leakage.
[0088] It should be noted that the current curves obtained are based on 96 sampling points per day, and the average current for the corresponding number of days is calculated.
[0089] Specifically, for suspected leakage areas of type I (i.e., leakage type is continuous leakage), the average current of the three phases over the previous 3 days is collected, i.e.:
[0090]
[0091] in, , , These are the average currents of phases A, B, and C on the day preceding the current day; , , These are the average currents of phases A, B, and C for the two days preceding the current day; , , These are the average currents of phases A, B, and C for the first three days of the current day, respectively. for , and sum; for , and sum; for , and sum.
[0092] Calculate the corresponding average current percentages of the three phases, as follows:
[0093]
[0094] in, , , The average current percentages of phases A, B, and C on the day before the current number of days are respectively equal to , , and ratio; , , The average current percentages of phases A, B, and C for the first two days of the current day are respectively equal to , , and ratio; , , The average current percentages of phases A, B, and C for the first three days of the current day are respectively equal to , , and ratio;
[0095] The difference between the average three-phase current percentage for each day within the selected period (excluding the first day) and the first day is used as the change in the average three-phase current percentage for that corresponding number of days. The formula is:
[0096]
[0097] in, , , These are the average current percentages of phases A, B, and C on the day preceding the current day, and the average current percentages of phases A, B, and C on the first day (for the first cycle). , , ) difference; , , These are the average current percentages of phases A, B, and C for the first two days of the current period, and the average current percentages of phases A, B, and C for the first few days (for the first cycle). , , ) difference;
[0098] like and If so, it is determined that a leakage has occurred in the A-phase branch line;
[0099] like and If so, it is determined that a leakage has occurred in the B-phase branch line;
[0100] like and If so, it is determined that a leakage has occurred in the C-phase branch line;
[0101] For suspected Class II leakage circuits (i.e., intermittent leakage), the average three-phase current of the previous two days is collected. The difference between the percentage of the average three-phase current for each day within the selected period (excluding the very first day) and the percentage for the very first day is calculated as the change in the percentage of the average three-phase current for that corresponding number of days. The formula is:
[0102]
[0103] in, , , These are the average current percentages of phases A, B, and C on the day preceding the current day, and the average current percentages of phases A, B, and C on the first day (for the third cycle). , , ) difference;
[0104] like If so, it is determined that a leakage has occurred in the A-phase branch line;
[0105] like If so, it is determined that a leakage has occurred in the B-phase branch line;
[0106] like If so, it is determined that a leakage has occurred in the C-phase branch line.
[0107] like Figure 2 As shown, Embodiment 2 of the present invention proposes a low-voltage distribution line leakage current detection system based on the method described in Embodiment 1 of the present invention, including a distribution line loss data acquisition module, a leakage distribution area preliminary screening module, a distribution area gate meter and user meter data acquisition module, a leakage distribution area determination module, a current curve data acquisition module, a leakage phase determination module, and an abnormal output module, specifically:
[0108] Transformer Area Line Loss Data Acquisition Module: Used to adaptively calculate the second cycle based on the standard deviation of the line loss rate and the standard deviation of the air humidity within the base cycle set before the current number of days; acquire the power loss and line loss rate of all low-voltage transformer areas within the first cycle set before the current number of days, and acquire the line loss rate and air humidity of all transformer areas within the second cycle before the current number of days;
[0109] The preliminary screening module for leakage areas is used to initially screen all low-voltage distribution areas for suspected leakage areas of type I based on the power loss and line loss rate of all distribution areas within the first cycle prior to the current number of days. The leakage type of the suspected leakage areas of type I is continuous leakage. Based on the line loss rate and air humidity of all distribution areas within the second cycle prior to the current number of days, the module initially screens all low-voltage distribution areas for suspected leakage areas of type II. The leakage type of the suspected leakage areas of type II is intermittent leakage.
[0110] The data acquisition module for the gate meter and user meter of all suspected leaky transformer areas is used to acquire the indicator curves of the gate meter and user meter at each moment within the set third cycle before the current number of days; and to calculate the lost power at each moment within the set third cycle before the current number of days.
[0111] Leakage Circuit Determination Module: For suspected leakage circuits of type I, it determines whether leakage exists based on the fluctuation rate of power loss; for suspected leakage circuits of type II, it determines whether leakage exists based on the rate of change of power loss.
[0112] Current curve data acquisition module: For transformer areas identified as having leakage, it selects the data acquisition period based on the leakage type and obtains the average three-phase current of each day within the selected period up to the current day.
[0113] Leakage current phase identification module: used to calculate the change in the average current ratio of the three phases to determine the phase in which leakage current has occurred;
[0114] Abnormal output module: Used to output the leakage type and determine the area and phase where the leakage occurred.
[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.
Claims
1. A method for detecting leakage current in low-voltage distribution lines, characterized in that, include: The second period is adaptively calculated based on the standard deviation of the line loss rate and the standard deviation of the air humidity within the previously set base period for the current number of days. Based on the daily power loss and line loss rate of all low-voltage distribution areas within the first cycle prior to the current number of days, suspected leakage distribution areas of Class I are initially screened out from all low-voltage distribution areas; the leakage type of the suspected leakage distribution areas of Class I is continuous leakage. Based on the daily line loss rate and air humidity of all distribution areas within the second cycle prior to the current number of days, suspected leakage distribution areas of Class II are initially screened out from all low-voltage distribution areas; the leakage type of the suspected leakage distribution areas of Class II is intermittent leakage. Obtain the indicator curves of the gate table and user table for each moment of each day within the set third cycle before the current number of days for all suspected leakage areas, and calculate the power loss at each corresponding moment; for Class I suspected leakage areas, determine whether there is leakage based on the fluctuation rate of power loss; for Class II suspected leakage areas, determine whether there is leakage based on the rate of change of power loss. For transformer substations identified as having leakage, the data collection period is selected based on the leakage type. The average current of the three phases is obtained for each day within the selected period prior to the current day. The change in the percentage of the average current of the three phases is calculated to determine which phase has experienced leakage.
2. The method for determining leakage current in low-voltage distribution lines according to claim 1, characterized in that: The second period is adaptively calculated based on the standard deviation of the line loss rate and the standard deviation of the air humidity within the previous base period, as set by the current number of days. Calculate the standard deviation of the line loss rate and the standard deviation of the air humidity within the base period set before the current number of days, and normalize them to obtain the normalized standard deviation of the line loss rate and the normalized standard deviation of the air humidity. Select the larger of the normalized standard deviations of the line loss rate and the normalized standard deviations of the air humidity and multiply it by a set coefficient. The negative number of the product is used as the exponent, and the natural logarithm e is used as the base for exponential operation. If the product of the exponential operation result and the base period is rounded up and is greater than the first period, then the second period is the product of the exponential operation result and the base period rounded up; otherwise, the second period is equal to the first period. The set base period is greater than the first period, and the first period is greater than the third period.
3. The method for determining leakage current in low-voltage distribution lines according to claim 1, characterized in that: The preliminary screening identified Class I suspected leaky transformer areas among all low-voltage transformer areas, specifically: Calculate the difference in power loss and line loss rate for each day of the first set period for all transformer areas, excluding the first day, compared to the first day. If any transformer area has a power loss difference exceeding a set power loss difference threshold for each day of the first set period, and a line loss rate difference exceeding a set first line loss rate difference threshold for each day of the first set period, then the corresponding transformer area is identified as a Class I suspected leaky transformer area.
4. The method for determining leakage current in low-voltage distribution lines according to claim 2, characterized in that: The preliminary screening identified Class II suspected leaky transformer areas among all low-voltage transformer areas, specifically: Based on the line loss rate and air humidity of all days in the second period prior to the current number of days for all transformer substations, calculate the Pearson correlation coefficient between the line loss rate and air humidity. If the Pearson correlation coefficient exceeds the set correlation coefficient threshold, and the air humidity of the day before the current number of days exceeds the set air humidity threshold, and the line loss rate of the day before the current number of days minus the line loss rate of the two days before the current number of days exceeds the set second line loss rate difference threshold, then the corresponding transformer substation is judged as a suspected leaky transformer substation of Class II.
5. The method for determining leakage current in low-voltage distribution lines according to claim 1, characterized in that: The calculation of the power loss at each corresponding moment is specifically as follows: The value displayed on the gate meter at each time point is the power supply at that time point; the value displayed on the user meter at each time point is the power sales at that time point; the power loss at that time point is obtained by subtracting the power sales at the corresponding time point from the power supply at each time point.
6. The method for determining leakage current in low-voltage distribution lines according to claim 4, characterized in that: For suspected leakage areas of type I, the presence of leakage is determined based on the fluctuation rate of the lost power, specifically as follows: For each day within the third cycle prior to the current number of days, calculate the standard deviation of the power loss at all times for the corresponding number of days as the volatility of the power loss for the corresponding number of days. If the daily power loss fluctuation rate of a suspected Class I leakage power distribution area is less than the set fluctuation rate threshold for the third cycle prior to the current number of days, then the suspected Class I leakage power distribution area is determined to have leakage.
7. The method for determining leakage current in low-voltage distribution lines according to claim 4, characterized in that: For suspected leakage areas of Class II, the existence of leakage is determined based on the rate of change of power loss, specifically as follows: Calculate the growth rate of power loss at each moment of the day before the current day compared to the corresponding moment of the day before the current day. If the growth rate of power loss at any moment exceeds the set growth rate threshold, then the corresponding moment is a growth moment. If the total number of growth moments of suspected Class II leakage areas exceeds the set quantity threshold, then it is determined that there is leakage in the corresponding Class II suspected leakage area.
8. The method for determining leakage current in low-voltage distribution lines according to claim 5, characterized in that: For transformer substations identified as having leakage current, the data collection period is selected based on the type of leakage current, specifically as follows: When the leakage current type is continuous leakage current, select the first set period for data collection. When the leakage current type is intermittent leakage current, the data acquisition period is selected as the third set period.
9. The method for determining leakage current in low-voltage distribution lines according to claim 8, characterized in that: The method of determining the phase where leakage occurred by calculating the change in the average current ratio of the three phases is as follows: Obtain the average three-phase current for each day within the selected period prior to the current day, and calculate the average three-phase current for each day by dividing it by the sum of the average three-phase currents to obtain the average three-phase current percentage. The difference between the average current percentage of the three phases for each day of the selected period (excluding the first day) and the average current percentage of the three phases for the first day is calculated as the change in the average current percentage of the three phases for the corresponding days. If the change in the average current percentage of any phase exceeds the set threshold for the change in percentage for each day, it is determined that the corresponding phase has leakage.
10. A low-voltage distribution line leakage current detection system based on the method of any one of claims 1-9, comprising a distribution line loss data acquisition module, a preliminary leakage distribution line screening module, a distribution line loss meter and user meter data acquisition module, a leakage distribution line judgment module, a current curve data acquisition module, a leakage phase judgment module, and an abnormal output module, characterized in that: Transformer Area Line Loss Data Acquisition Module: Used to adaptively calculate the second cycle based on the standard deviation of the line loss rate and the standard deviation of the air humidity within the base cycle set before the current number of days, to acquire the power loss and line loss rate of all low-voltage transformer areas within the first cycle set before the current number of days, and to acquire the line loss rate and air humidity of all transformer areas within the second cycle before the current number of days; The preliminary screening module for leakage areas is used to initially screen all low-voltage distribution areas for suspected leakage areas of type I based on the power loss and line loss rate of all distribution areas within the first cycle prior to the current number of days. The leakage type of the suspected leakage areas of type I is continuous leakage. Based on the line loss rate and air humidity of all distribution areas within the second cycle prior to the current number of days, the module initially screens all low-voltage distribution areas for suspected leakage areas of type II. The leakage type of the suspected leakage areas of type II is intermittent leakage. The data acquisition module for the gate meter and user meter of all suspected leaky transformer areas is used to acquire the indicator curves of the gate meter and user meter at each moment within the set third cycle before the current number of days; and to calculate the lost power at each moment within the set third cycle before the current number of days. Leakage Circuit Determination Module: For suspected leakage circuits of type I, it determines whether leakage exists based on the fluctuation rate of power loss; for suspected leakage circuits of type II, it determines whether leakage exists based on the rate of change of power loss. Current curve data acquisition module: For transformer areas identified as having leakage, it selects the data acquisition period based on the leakage type and obtains the average three-phase current of each day within the selected period up to the current day. Leakage current phase identification module: used to calculate the change in the average current ratio of the three phases to determine the phase in which leakage current has occurred; Abnormal output module: Used to output the leakage type and determine the area and phase where the leakage occurred.
11. A device, characterized in that: The system includes a memory, a processor, and a computer program stored in the memory and executable on the processor, the processor performing the steps of the low-voltage distribution line leakage detection method according to any one of claims 1 to 9.
12. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program that, when executed by a processor, uses the steps of the low-voltage distribution line leakage detection method according to any one of claims 1 to 9.