A distribution box with self-checking function and self-checking method

Abstract

The present application relates to the field of distribution box detection technology, and specifically to a distribution box with a self-detection function and a self-detection method, the method comprising: obtaining the current at each moment of each phase circuit, the current at each moment on the neutral circuit, and the average voltage of each detection point of each phase circuit; determining the current abnormality of each phase circuit; determining the relative difference of the current of each phase circuit; determining the suspected leakage coefficient of each phase circuit; determining the forward monotonic trend and backward monotonic trend of each detection point of each phase circuit; determining the front and back voltage difference of each detection point of each phase circuit; determining the leakage index of each detection point of each phase circuit; based on the leakage index, judging whether there is a leakage fault in the distribution box, and troubleshooting the leakage fault of the circuit in the distribution box. The present application reduces the risk of false operation of triggering the overcurrent protection of the distribution box, and improves the accuracy of judging the leakage fault.

Description

Technical Field

[0001] The present application relates to the technical field of distribution box detection, and in particular to a distribution box with a self-detection function and a self-detection method. Background Art

[0002] As one of the basic facilities to ensure social development and technological advancement, the stability and safety of the power system are of vital importance. As the main electrical device in the power supply and distribution lines, the distribution box is crucial to ensure the safety and stability of power supply. Therefore, fault detection of the distribution box becomes an important part of ensuring the normal operation of the distribution box. In actual use, leakage faults may occur due to loose wiring, aging of insulation materials, etc. Leakage faults have become one of the most common and harmful faults in distribution boxes, which may cause damage to equipment and even cause serious risks such as fire.

[0003] In the existing technology, leakage protectors, current clamp meters and other devices are used to detect leakage faults. These devices judge leakage faults based on the residual current overcurrent protection method. Although this method is more convenient, it has a relatively large risk of false operation due to the relatively single data used, and is not sensitive enough to smaller leakage currents, which can cause unnecessary power outages, or ignore tiny leakage currents and cause safety hazards. Summary of the invention

[0004] In order to solve the above technical problems, a distribution box with a self-checking function and a self-checking method are provided to solve the existing problems.

[0005] The solution to the technical problem of the present application is to provide a distribution box with a self-checking function and a self-checking method, comprising the following steps:

[0006] In a first aspect, an embodiment of the present application provides a self-checking method for a distribution box with a self-checking function, the method comprising the following steps:

[0007] Obtain the current of each phase circuit at each moment, the current of the neutral line circuit at each moment, and the average voltage of each detection point of each phase circuit;

[0008] Determine the current anomaly of each phase circuit according to the difference in the current waveform deviation in different time periods of each phase circuit; determine the relative difference in the current of each phase circuit according to the difference in the current of different phase circuits at the same time; analyze the correlation between the current of each phase circuit and the current change on the neutral line circuit, and determine the suspected leakage coefficient of each phase circuit in combination with the current anomaly and the current relative difference;

[0009] Determine the forward monotonic trend and the backward monotonic trend of each detection point of each phase circuit according to the monotonic change trend of the average voltage of the front and rear detection points of each detection point of each phase circuit; determine the front and rear voltage difference of each detection point of each phase circuit according to the difference of the average voltage of the front and rear detection points of each detection point of each phase circuit; analyze the difference of the forward monotonic trend and the backward monotonic trend, and determine the leakage index of each detection point of each phase circuit in combination with the suspected leakage coefficient and the front and rear voltage difference;

[0010] Based on the leakage index, it is determined whether there is a leakage fault in the distribution box.

[0011] Preferably, the determining of the current abnormality of each phase circuit includes:

[0012] The current of each phase circuit at all times is divided into each time period; each time in each time period of each phase circuit and its corresponding current are formed into a two-dimensional array;

[0013] Perform curve fitting on all two-dimensional arrays of each phase circuit in each time period to obtain a sinusoidal curve of each phase circuit in each time period;

[0014] Calculate the integral area between the sinusoidal curve and the horizontal axis in each period of each phase circuit;

[0015] The average value of the difference between the integrated areas of all two arbitrary time periods of each phase circuit is taken as the current abnormality degree of each phase circuit.

[0016] Preferably, determining the relative difference in current of each phase circuit includes:

[0017] Calculate the ratio between the current at each moment of any phase circuit other than each phase circuit and the current at the same moment of each phase circuit;

[0018] The average of the ratios of each phase circuit to all other phase circuits at all times is taken as the relative current difference of each phase circuit.

[0019] Preferably, the determining of the suspected leakage coefficient of each phase circuit includes:

[0020] Calculate the correlation between the current of each phase circuit at all times and the current of the neutral circuit at all times;

[0021] The product of the current abnormality and the correlation degree is calculated, and the ratio of the product to the current relative difference is used as the suspected leakage coefficient of each phase circuit.

[0022] Preferably, the determining of the forward monotonic trend of each detection point of each phase circuit comprises:

[0023] Obtain the peak value of the average voltage of all detection points of each phase circuit; in the order in which the current passes through the detection points, record all the peak values ​​of the detection points before each detection point of each phase circuit as the forward peak voltage of each detection point of each phase circuit; record all the peak values ​​of the detection points after each detection point of each phase circuit as the backward peak voltage of each detection point of each phase circuit;

[0024] For each detection point, calculating the difference between each average voltage in the forward peak voltage and its previous average voltage, and recording it as a first difference;

[0025] The ratio of the number of the first differences in the forward peak voltage that are negative numbers to the number of all average voltages in the forward peak voltage is used as the forward monotonic trend of each detection point in each phase circuit.

[0026] Preferably, the backward monotonic trend includes:

[0027] Calculate the difference between each average voltage of the backward peak voltage at each detection point and the previous average voltage, and record it as a second difference;

[0028] The ratio of the number of the second differences in the backward peak voltages that are negative numbers to the number of all average voltages in the backward peak voltages is used as the backward monotonic trend of each detection point in each phase circuit.

[0029] Preferably, the front-to-rear voltage difference of each detection point of each phase circuit is determined as the ratio between the mean of all average voltages in the forward peak voltage and the mean of all average voltages in the backward peak voltage of each detection point of each phase circuit.

[0030] Preferably, the determining of the leakage index of each detection point of each phase circuit includes:

[0031] The difference between the forward monotonic trend and the backward monotonic trend is used as the forward and backward trend difference of each detection point of each phase circuit;

[0032] The product of the suspected leakage coefficient and the before-after trend difference is calculated, and the ratio of the product to the before-after voltage difference is used as the leakage index of each detection point of each phase circuit.

[0033] Preferably, the step of determining whether there is a leakage fault in the distribution box includes:

[0034] The segmentation threshold of the leakage index of all the detection points of each phase circuit is obtained; if there is a detection point whose leakage index is greater than the segmentation threshold, there is a leakage fault in the distribution box; otherwise, there is no leakage fault in the distribution box.

[0035] In a second aspect, an embodiment of the present application further provides a distribution box with a self-checking function, wherein the self-checking of the distribution box adopts any of the steps of a self-checking method for a distribution box with a self-checking function described above.

[0036] This application has at least the following beneficial effects:

[0037] The present application determines the current abnormality of each phase circuit according to the difference in the deviation of the current waveform in different time periods of each phase circuit, and its beneficial effect is that the degree of deviation of the current waveform from the sine wave is analyzed to reflect the distortion of the current waveform caused by the leakage fault; the relative difference of the current of each phase circuit is determined according to the difference in the current of different phase circuits at the same time, and its beneficial effect is that the difference in the current of different phase circuits at the same time is analyzed to reflect the imbalance between the three-phase currents; the correlation between the current of each phase circuit and the current change on the neutral circuit is analyzed, and the suspected leakage coefficient of each phase circuit is determined in combination with the current abnormality and the relative difference of the current, and its beneficial effect is that the correlation between the current of each phase circuit and the current change on the neutral circuit is analyzed to reflect the possibility of leakage fault in the corresponding phase circuit, and the phase circuit that meets the characteristics of leakage fault is preliminarily judged to improve the accuracy of subsequent leakage position judgment; the forward monotonic trend and the backward monotonic trend of each detection point of each phase circuit are determined according to the monotonic change trend of the average voltage of the front and rear detection points of each detection point of each phase circuit; According to the difference in average voltages between the front and rear detection points of each detection point in each phase circuit, the front and rear voltage differences of each detection point in each phase circuit are determined. The beneficial effect is that the voltage change trend of the front and rear circuits at the detection point and the voltage difference of the front and rear circuits are considered to reflect the possibility that the detection point is a leakage location; the difference between the forward monotonic trend and the backward monotonic trend is analyzed, and the leakage index of each detection point in each phase circuit is determined in combination with the suspected leakage coefficient and the front and rear voltage difference. The beneficial effect is that the possible degree of leakage at each detection point is analyzed, and whether the detection point is a leakage location or the detection point is affected by the leakage location can be determined relatively accurately. Based on the leakage index, it is judged whether there is a leakage fault in the distribution box, and the leakage fault of the circuit in the distribution box is checked. The beneficial effect is that the distribution box judges whether there is a leakage fault based on the leakage index, and performs circuit breaker protection on the distribution box, thereby improving the accuracy of leakage fault judgment, reducing misjudgment, thereby reducing the risk of false operation of triggering the overcurrent protection of the distribution box, and improving the power supply quality and safety while ensuring the safety of the distribution box. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The following is a further detailed description of a self-checking method for a distribution box with a self-checking function of the present application in conjunction with the accompanying drawings.

[0039] Figure 1A flow chart of the steps of a self-checking method for a distribution box with a self-checking function provided in an embodiment of the present application;

[0040] Figure 2 A schematic diagram of the waveform change of the leakage current of the circuit provided in the embodiment of the present application;

[0041] Figure 3 A flowchart of the steps of a method for obtaining a suspected leakage coefficient of each phase circuit provided in an embodiment of the present application;

[0042] Figure 4 A schematic diagram of average voltage changes at all detection points in a circuit provided in an embodiment of the present application;

[0043] Figure 5 A flowchart of the steps of a method for obtaining the leakage index of each detection point of each phase circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the following is a further detailed description of a distribution box with a self-checking function and a self-checking method proposed in the present application in combination with the accompanying drawings and implementation examples. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0045] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0046] See also Figure 1 , which shows a flow chart of a self-checking method for a distribution box with a self-checking function provided by an embodiment of the present application, the method comprising the following steps:

[0047] Step 1, obtaining the current of each phase circuit at each moment, the current of the neutral line circuit at each moment, and the average voltage of each detection point of each phase circuit.

[0048] The three-phase circuit in the three-phase distribution box is a common way of distributing electricity. In the low-voltage distribution network, the transmission circuit generally adopts a three-phase four-wire system, in which the three corresponding circuits are all live wires, and the other circuit is the neutral wire. In the three-phase circuit, the three phases form a loop, and under normal circumstances, the neutral wire has no current.

[0049] Therefore, current transformers are installed at the incoming lines of the three-phase circuits to measure the current of each phase circuit, and zero-sequence current transformers are installed at the incoming line of the neutral line to measure the current of the neutral line. Secondly, multiple detection points are set on each phase circuit, and voltage transformers are installed at the detection points to collect the voltage of each detection point of each phase circuit. The collection frequency is set to f, and the collection time is set to T. The current of each phase circuit at each moment, the current on the neutral line at each moment, and the voltage at each detection point of each phase circuit at each moment are collected. According to the order in which the current passes through the detection points, the average value of the voltages at all moments at each detection point of each phase circuit is recorded as the average voltage of each detection point of each phase circuit. The collected data is normalized to obtain the current of each phase circuit at each moment, the current on the neutral line circuit at each moment, and the average voltage of each detection point of each phase circuit.

[0050] Preferably, in this embodiment, the acquisition frequency is set to 1KHz and the acquisition time is 10 minutes. As other implementation modes, the implementer can set them according to the actual situation. The maximum and minimum normalization method is used to normalize the data, wherein the maximum and minimum normalization method is a well-known technology and will not be described here. As other implementation modes, the implementer can adopt other methods of the prior art, such as Z-score normalization method, etc. This embodiment does not impose any special restrictions on this.

[0051] It should be noted that the detection points can be set as the incoming line of each phase circuit, the starting point of each branch loop on each phase circuit, and the input end of the load on each phase circuit, where the incoming line refers to the location where the power supply or external power grid is connected to the distribution box, and the input end of the load refers to the input end of the device that consumes electrical energy connected to the circuit.

[0052] At this point, the current of each phase circuit at each moment, the current of the neutral line circuit at each moment, and the average voltage of each detection point of each phase circuit are obtained.

[0053] Step 2, determine the current abnormality of each phase circuit according to the difference in current waveform deviation in different time periods of each phase circuit; determine the relative difference in current of each phase circuit according to the degree of difference in current of different phase circuits at the same time; analyze the correlation between the current of each phase circuit and the current change on the neutral circuit, and determine the suspected leakage coefficient of each phase circuit in combination with the current abnormality and the current relative difference.

[0054] Under normal circumstances, when there is no fault in the distribution box, the three-phase circuit should be balanced, that is, the three-phase currents are equal, and because the three-phase currents cancel each other out, the current of the neutral line circuit is theoretically 0. In practical applications, due to the differences in the equipment loaded on each phase circuit, there may be a certain imbalance in the three-phase current, and the difference between the three-phase circuits will also cause a small current to appear in the neutral line. When a leakage fault occurs in the distribution box, the current of the leakage phase circuit will increase, thereby destroying the three-phase balance of the entire circuit, and the leakage current of the leakage phase circuit will significantly increase the current in the neutral line, that is, the more serious the leakage, the more balanced the three-phase current, and the more significant the current in the neutral line; secondly, the voltage on both sides of the leakage position will also show obvious abnormal changes.

[0055] Since the three-phase electricity has the same frequency and similar amplitude, under normal circumstances, the current in each phase circuit is approximately a sine wave with periodic changes. The periodic changes make the phase of the current in each time period of each phase circuit relatively consistent, so that the sinusoidal functions corresponding to the current waveforms in different time periods should also be basically the same. When a leakage fault occurs, the leakage current will be superimposed on the normal current, causing an abnormal increase in current. This abnormal increase manifests itself as an increase in the current peak or distortion of the current waveform, and may introduce additional harmonic components, causing the waveform to deviate from the sine wave.

[0056] Furthermore, the waveform diagram of the leakage current of the circuit provided in the embodiment of the present application is as follows: Figure 2 As shown, the horizontal axis is time and the vertical axis is normalized current. Figure 2 The solid line in the middle represents the change of leakage current of a phase circuit, and the dotted line represents the change of the circuit current which is approximately a sine wave under normal circumstances. As can be seen from the figure, when there is a leakage fault, the waveform of the leakage current deviates from the sine wave to a certain extent.

[0057] Based on the above analysis, the current of each phase circuit at all times is divided into various time periods, and the current distribution of each time period is analyzed, specifically:

[0058] The current of each phase circuit at all times is divided into each time period; each time in each time period of each phase circuit and its corresponding current are formed into a two-dimensional array;

[0059] Preferably, in this embodiment, the current of each phase circuit at all times within each minute is taken as a time period. As other implementation methods, the implementer can set it according to the actual situation.

[0060] Perform curve fitting on all two-dimensional arrays of each phase circuit in each time period to obtain a sinusoidal curve of each phase circuit in each time period;

[0061] It should be noted that the least square method is used for curve fitting, wherein the least square method is a well-known technology and will not be described in detail here.

[0062] Furthermore, based on the differences in the sinusoidal curves at different time periods, the current abnormality of each phase circuit is analyzed to reflect the extent to which the waveform of the current of each phase circuit may deviate from the sine wave due to the leakage fault, specifically:

[0063] Calculate the integral area between the sinusoidal curve and the horizontal axis in each period of each phase circuit;

[0064] The average of the differences in the integrated areas of all two arbitrary time periods of each phase circuit is used as the current abnormality degree of each phase circuit;

[0065] Preferably, in this embodiment, the absolute value of the difference between the integrated areas in any two time periods of each phase circuit is calculated, and the average of all the absolute values ​​of each phase circuit is taken as the current abnormality degree of each phase circuit.

[0066] It should be noted that under normal circumstances, the current is approximately a sine wave, so the difference between the sine curves of each time period is small, but a leakage fault will cause the current waveform to deviate from the sine wave, so that the difference in the integral area between any two time periods is large, and the resulting current anomaly is large, indicating that the possibility of a leakage fault in the corresponding phase circuit is greater.

[0067] Furthermore, when a leakage fault occurs in the distribution box, the current of the leakage phase circuit will increase, and the leakage current of the leakage phase circuit will significantly increase the current in the neutral line. Therefore, the current of each phase circuit is correlated with the current change on the neutral line, specifically:

[0068] Calculate the correlation between the current of each phase circuit at all times and the current of the neutral circuit at all times;

[0069] Preferably, in this embodiment, the Pearson correlation coefficient between the current at all times of each phase circuit and the current at all times of the neutral circuit is calculated, wherein the calculation method of the Pearson correlation coefficient is a well-known technology and will not be repeated here; as other implementation methods, the implementer may adopt other methods of the prior art, such as cosine similarity, Spearman correlation coefficient, etc., and this embodiment does not impose any special restrictions on this.

[0070] It should be noted that after a leakage fault occurs, the current in the leakage phase circuit will increase, and will also cause the originally small neutral line current to increase significantly, that is, there is a positive correlation between the leakage current and the neutral line current. The greater the degree of correlation, the more likely it is that leakage will occur.

[0071] Furthermore, the differences in currents of different phase circuits at the same time are analyzed to reflect the imbalance of the three-phase currents, specifically:

[0072] Calculate the ratio between the current at each moment of any phase circuit other than each phase circuit and the current at the same moment of each phase circuit;

[0073] The average of the ratios of each phase circuit to all other phase circuits at all times is taken as the relative difference of the current of each phase circuit;

[0074] Preferably, in this embodiment, the calculation formula for the relative difference of the current of each phase circuit is: ,in, For the The relative difference in current between the phase circuits, For the Phase circuit The current at the moment, For the Phase circuit The current at the moment, is the number of all moments, For the The number of all phase circuits except the phase circuit.

[0075] It should be noted that when When a leakage fault occurs in the phase circuit, The increase of current in the phase circuit will break the balance of the three-phase current. The current of the phase circuit is greater than the current of the other two phase circuits, so that Less than 1, the relative difference in current Smaller.

[0076] Further, based on the current abnormality, the correlation degree and the current relative difference, a suspected leakage coefficient is determined to reflect the possibility of a leakage fault in the corresponding phase circuit, specifically:

[0077] Calculating the product of the current abnormality and the correlation degree, and taking the ratio of the product to the current relative difference as the suspected leakage coefficient of each phase circuit;

[0078] It should be noted that when a leakage fault occurs in each phase circuit, the suspected leakage coefficient is large, and the more serious the leakage fault is, the larger the suspected leakage coefficient is; conversely, when no leakage fault characteristics occur in each phase circuit, the suspected leakage coefficient is small.

[0079] Further, the step flow chart of the method for obtaining the suspected leakage coefficient of each phase circuit provided in the embodiment of the present application is as follows: Figure 3 shown.

[0080] At this point, the suspected leakage coefficient of each phase circuit is obtained.

[0081] Step 3, determine the forward monotonic trend and backward monotonic trend of each detection point in each phase circuit according to the monotonic change trend of the average voltage of the front and rear detection points of each detection point in each phase circuit; determine the front and rear voltage difference of each detection point in each phase circuit according to the difference of the average voltage of the front and rear detection points of each detection point in each phase circuit; analyze the difference between the forward monotonic trend and the backward monotonic trend, and determine the leakage index of each detection point in each phase circuit in combination with the suspected leakage coefficient and the front and rear voltage difference.

[0082] Based on the above analysis, the suspected leakage coefficient can only measure the situation of the three-phase current and the neutral line current. However, in addition to the leakage fault, the change of the three-phase current and the neutral line current may also be caused by the short circuit between the three-phase circuits or the drift fault of the neutral line grounding; therefore, when the leakage degree of the leakage phase is low, the accuracy of the leakage fault judgment based only on the current difference will be affected to a certain extent. Therefore, combined with the change characteristics of the voltage caused by the leakage fault, the leakage fault is further analyzed and judged, and the leakage position is located.

[0083] When there is no leakage fault, the voltage before and after each detection point is basically the same. When a leakage fault occurs in a phase circuit, before the leakage position, that is, from the circuit input end to the leakage position, part of the current flows out through the leakage path, and the current will produce a voltage drop when passing through the wire. In addition, the leakage fault causes the input of the current to increase, further increasing the voltage drop, making the actual voltage on the line from the circuit input end to the leakage position lower than the expected value; due to the current shunting at the leakage position, the current after the leakage position is greatly reduced, and the voltage of the circuit after the leakage position is also significantly reduced.

[0084] Secondly, the reason for the voltage reduction before the leakage position is the increase in current and voltage drop, and the closer to the leakage position, the greater the voltage drop, so that the voltage is lower closer to the leakage position, that is, the voltage shows a monotonic change trend; and the voltage reduction after the leakage position is due to the reduction in input current, so there is a significant decrease in voltage, but the voltage fluctuation after the leakage position is not monotonic.

[0085] Furthermore, the schematic diagram of the average voltage change of all detection points in the circuit provided in the embodiment of the present application is as follows: Figure 4 As shown, the detection points are numbered in the order in which the current passes through them, the horizontal axis is the serial number corresponding to each detection point, and the vertical axis is the average voltage of each detection point. Figure 4 At the detection point of the leakage position numbered 10, the voltage drops significantly, showing a monotonically decreasing trend.

[0086] Based on the above analysis, the changes in the average voltages of the forward and backward detection points corresponding to each detection point of each phase circuit are analyzed to determine the forward peak voltage and backward peak voltage of each detection point, specifically:

[0087] Obtain the peak value of the average voltage of all detection points of each phase circuit; record all peak values ​​of detection points before each detection point of each phase circuit as the forward peak voltage of each detection point of each phase circuit, and record all peak values ​​of detection points after each detection point of each phase circuit as the backward peak voltage of each detection point of each phase circuit;

[0088] It should be noted that, assuming that all detection points of each phase circuit are in the order in which the current passes through the detection points, the average voltages of all detection points of each phase circuit are: , , , , , , , , then assume , , , , is the peak value, then the detection point The forward peak voltage is , ; Detection point The backward peak voltage is , .

[0089] Further, based on the forward peak voltage and the backward peak voltage of each detection point, the change trend of the forward voltage and the change trend of the backward voltage of each detection point are analyzed, specifically:

[0090] Calculate the difference between each average voltage in the forward peak voltage of each detection point of each phase circuit and the previous average voltage, and record it as the first difference;

[0091] The ratio of the number of the first differences in the forward peak voltages of the detection points of each phase circuit that are negative to the number of all average voltages in the forward peak voltages is used as the forward monotonic trend of the detection points of each phase circuit;

[0092] Calculate the difference between each average voltage and the previous average voltage in the backward peak voltage of each detection point of each phase circuit, and record it as the second difference;

[0093] The ratio of the number of the second differences in the backward peak voltages of the detection points of each phase circuit that are negative to the number of all average voltages in the backward peak voltages is used as the backward monotonic trend of the detection points of each phase circuit;

[0094] The difference between the forward monotonic trend and the backward monotonic trend is used as the forward and backward trend difference of each detection point of each phase circuit;

[0095] It should be noted that if the number of all average voltages in the forward peak voltage or backward peak voltage of each detection point is less than 3, the forward monotonic trend of each detection point in each phase circuit is assigned a value of 1, and the backward monotonic trend is assigned a value of 0.

[0096] It should be noted that when the first When the first detection point is the leakage position, All the average voltages in the forward peak voltages of the detection points show a monotonic decreasing trend, so that the first difference is almost all negative, and the forward monotonic trend is large, close to 1; there is no monotonic decreasing trend in the backward peak voltage, that is, the backward monotonic trend is small, and the greater the difference between the forward and backward trends, the more likely it is the leakage location.

[0097] Furthermore, since the voltages of the detection points before and after the leakage position are inconsistent, and the voltage before the leakage position is much greater than the voltage after the leakage position, the voltage difference before and after the leakage position is analyzed, specifically:

[0098] The ratio between the average of all average voltages in the forward peak voltages and the average of all average voltages in the backward peak voltages at each detection point of each phase circuit is used as the front-to-back voltage difference of each detection point of each phase circuit;

[0099] It should be noted that when a leakage fault occurs in each phase circuit, the voltage before the leakage position is much greater than the voltage after the leakage position, so the smaller the ratio of the backward mean voltage to the forward mean voltage, the closer the corresponding detection point is to the leakage position.

[0100] Further, based on the trend difference before and after, the voltage difference before and after, and the suspected leakage coefficient, a leakage index is determined to reflect the possibility of leakage faults at each detection point on each phase circuit and to determine the leakage location, specifically:

[0101] Calculate the product of the suspected leakage coefficient and the trend difference before and after, and use the ratio of the product to the voltage difference before and after as the leakage index of each detection point of each phase circuit;

[0102] Preferably, in this embodiment, the calculation formula of the leakage index of each detection point of each phase circuit is: ,in, For the Phase circuit The leakage index of each test point is For the The suspected leakage coefficient of the phase circuit, For the Phase circuit The forward monotonic trend of the detection points, For the Phase circuit The backward monotonic trend of the detection points, For the Phase circuit The voltage difference before and after the detection point is: The difference between the before and after trends.

[0103] It should be noted that, since the backward mean voltage and the forward mean voltage cannot be compared at the first and last detection points of each phase circuit, the forward and backward voltage difference between the first and last detection points of each phase circuit is assigned a value of 1.

[0104] It should be noted that the greater the difference between the front and rear trends, the more inconsistent the front and rear voltage change trends of the corresponding detection point are, and the more likely it is a leakage location. Phase circuit If the first detection point is a leakage location, it means The phase circuit is a leakage phase circuit, the corresponding suspected leakage coefficient is large, and the The greater the difference between the before and after trends of the detection points, the smaller the difference between the before and after voltages, and the higher the leakage index. The larger the The detection point is not the leakage position, the leakage index Relatively small; secondly, the closer the detection point is to the leakage location, the greater the impact of the leakage, and the greater the leakage index of the detection point.

[0105] Further, the step flow chart of the method for obtaining the leakage index of each detection point of each phase circuit provided in the embodiment of the present application is as follows: Figure 5 shown.

[0106] At this point, the leakage index of each detection point in each phase circuit is obtained.

[0107] Step 4: Based on the leakage index, determine whether there is a leakage fault in the distribution box.

[0108] Further, based on the leakage index, it is determined whether there is a leakage fault in the distribution box, and the leakage of the circuit is checked to ensure the safety of the distribution box, specifically:

[0109] Obtaining the segmentation threshold of the leakage index of all detection points of each phase circuit;

[0110] If there is a detection point where the leakage index is greater than the segmentation threshold, the distribution box outputs a leakage fault code 1, and it is determined that there is a leakage fault in the distribution box, and the distribution box is disconnected to ensure the safety of the distribution box; if there is no detection point where the leakage index is greater than the segmentation threshold, the distribution box outputs a leakage fault code 0, and it is determined that there is no leakage fault in the distribution box;

[0111] The detection point whose leakage index is greater than the segmentation threshold is recorded as a leakage point; all leakage points of all phase circuits are arranged in descending order according to the leakage index, and the maintenance personnel check the leakage points in turn based on the arrangement results.

[0112] Preferably, in this embodiment, the 3σ criterion, namely the Laida criterion, is used to obtain the leakage index distribution in The detection point of the interval, the upper limit of the interval As the segmentation threshold, the 3σ criterion is a well-known technology and will not be described in detail here. As other implementation methods, the implementer may adopt other methods of the prior art, such as the maximum inter-class variance method to obtain the segmentation threshold, and this embodiment does not impose any special restrictions on this.

[0113] It should be noted that the leakage fault code 0 indicates that there is no leakage fault, and the leakage fault code 1 indicates that there is a leakage fault; secondly, since leakage faults may occur in multi-phase circuits at the same time, the leakage points may be distributed in different phase circuits. According to the results of arranging all leakage points in descending order of leakage index, the larger the leakage index, the more likely it is the leakage location. Start from the leakage point with the largest leakage index and check and handle them in turn, so as to ensure the safety of the distribution box.

[0114] Based on the same inventive concept as the above method, an embodiment of the present application also provides a distribution box with a self-inspection function, and the self-inspection of the distribution box adopts the steps of any one of the above-mentioned self-inspection methods for a distribution box with a self-inspection function.

[0115] It should be understood that although Figure 1 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 1 At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least part of the sub-steps or stages of other steps.

[0116] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0117] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the present application. It should be pointed out that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application without departing from the content of the technical solution of the present application, shall fall within the protection scope of the technical solution of the present application.

Claims

1. A self-checking method for a distribution box with a self-checking function, characterized in that: The method comprises the following steps: Obtain the current of each phase circuit at each moment, the current of the neutral line circuit at each moment, and the average voltage of each detection point of each phase circuit; Determine the current anomaly of each phase circuit according to the difference in the current waveform deviation in different time periods of each phase circuit; determine the relative difference in the current of each phase circuit according to the difference in the current of different phase circuits at the same time; analyze the correlation between the current of each phase circuit and the current change on the neutral line circuit, and determine the suspected leakage coefficient of each phase circuit in combination with the current anomaly and the current relative difference; Determine the forward monotonic trend and the backward monotonic trend of each detection point of each phase circuit according to the monotonic change trend of the average voltage of the front and rear detection points of each detection point of each phase circuit; determine the front and rear voltage difference of each detection point of each phase circuit according to the difference of the average voltage of the front and rear detection points of each detection point of each phase circuit; analyze the difference of the forward monotonic trend and the backward monotonic trend, and determine the leakage index of each detection point of each phase circuit in combination with the suspected leakage coefficient and the front and rear voltage difference; Based on the leakage index, determine whether there is a leakage fault in the distribution box; The step of determining the forward monotonic trend of each detection point of each phase circuit comprises: Obtain the peak value of the average voltage of all detection points of each phase circuit; in the order in which the current passes through the detection points, record all the peak values ​​of the detection points before each detection point of each phase circuit as the forward peak voltage of each detection point of each phase circuit; record all the peak values ​​of the detection points after each detection point of each phase circuit as the backward peak voltage of each detection point of each phase circuit; For each detection point, calculating the difference between each average voltage in the forward peak voltage and its previous average voltage, and recording it as a first difference; Taking the ratio of the number of the first difference in the forward peak voltages being negative numbers to the number of all average voltages in the forward peak voltages as the forward monotonic trend of each detection point in each phase circuit; The backward monotonic trend includes: Calculate the difference between each average voltage of the backward peak voltage at each detection point and the previous average voltage, and record it as a second difference; Taking the ratio of the number of the second difference in the backward peak voltage that is a negative number to the number of all average voltages in the backward peak voltage as the backward monotonic trend of each detection point in each phase circuit; The determining of the front-to-back voltage difference of each detection point of each phase circuit is the ratio between the mean of all average voltages in the forward peak voltage and the mean of all average voltages in the backward peak voltage of each detection point of each phase circuit; Determining the leakage index of each detection point of each phase circuit includes: The difference between the forward monotonic trend and the backward monotonic trend is used as the forward and backward trend difference of each detection point of each phase circuit; The product of the suspected leakage coefficient and the before-after trend difference is calculated, and the ratio of the product to the before-after voltage difference is used as the leakage index of each detection point of each phase circuit.

2. A self-checking method for a distribution box with a self-checking function as claimed in claim 1, characterized in that: The step of determining the current abnormality of each phase circuit comprises: The current of each phase circuit at all times is divided into each time period; each time in each time period of each phase circuit and its corresponding current are formed into a two-dimensional array; Perform curve fitting on all two-dimensional arrays of each phase circuit in each time period to obtain a sinusoidal curve of each phase circuit in each time period; Calculate the integral area between the sinusoidal curve and the horizontal axis in each period of each phase circuit; The average value of the difference between the integrated areas of all two arbitrary time periods of each phase circuit is taken as the current abnormality degree of each phase circuit.

3. A self-checking method for a distribution box with a self-checking function as claimed in claim 1, characterized in that: Determining the relative difference in current of each phase circuit includes: Calculate the ratio between the current at each moment of any phase circuit other than each phase circuit and the current at the same moment of each phase circuit; The average of the ratios of each phase circuit to all other phase circuits at all times is taken as the relative current difference of each phase circuit.

4. A self-checking method for a distribution box with a self-checking function as claimed in claim 1, characterized in that: The determining of the suspected leakage coefficient of each phase circuit comprises: Calculate the correlation between the current of each phase circuit at all times and the current of the neutral circuit at all times; The product of the current abnormality and the correlation degree is calculated, and the ratio of the product to the current relative difference is used as the suspected leakage coefficient of each phase circuit.

5. A self-checking method for a distribution box with a self-checking function as claimed in claim 1, characterized in that: The determining whether there is a leakage fault in the distribution box includes: The segmentation threshold of the leakage index of all the detection points of each phase circuit is obtained; if there is a detection point whose leakage index is greater than the segmentation threshold, there is a leakage fault in the distribution box; otherwise, there is no leakage fault in the distribution box.

6. A distribution box with self-checking function, characterized in that: The self-inspection of the distribution box is implemented by using a distribution box self-inspection method with a self-inspection function as described in any one of claims 1 to 5.

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