CN119125745B - A distribution box with self-checking function and self-checking method - Google Patents
A distribution box with self-checking function and self-checking method Download PDFInfo
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- G—PHYSICS
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
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Abstract
本申请涉及配电箱检测技术领域，具体涉及一种具有自检功能的配电箱及自检方法，该方法包括：获得每相电路的各时刻的电流、零线电路上各时刻的电流，以及每相电路的各检测点的平均电压；确定每相电路的电流异常度；确定每相电路的电流相对差异；确定每相电路的疑似漏电系数；确定每相电路的各检测点的前向单调趋势和后向单调趋势；确定每相电路的各检测点的前后电压差异；确定每相电路的各检测点的漏电指数；基于所述漏电指数，判断配电箱是否存在漏电故障，对配电箱中电路的漏电故障进行排查。本申请减少触发配电箱过流保护的误动作风险，提高对漏电故障判断的准确性。
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
The application relates to the technical field of distribution box detection, in particular to a distribution box with a self-checking function and a self-checking method.
Background
As one of the infrastructures for guaranteeing social development and science and technology, the stability and safety of the electric power system are important. The distribution box is used as a main electric device in a power supply and distribution line, and is important for guaranteeing the safety and stability of power supply, so that fault detection of the distribution box becomes an important ring for guaranteeing the normal work of the distribution box. In actual use, the leakage fault is caused by infirm wiring, ageing of insulating materials and the like, and becomes one of common faults and serious faults in the distribution box, which can possibly cause damage to equipment and even serious risks such as fire.
In the prior art, devices such as a leakage protector and a current clamp meter are used for detecting the leakage fault, and the devices judge the leakage fault according to a residual current overcurrent protection method, so that the method is more convenient, but the utilized data is relatively single, so that relatively larger misoperation risk exists, and the sensitivity to smaller leakage current is insufficient, thereby causing unnecessary power failure or neglecting tiny leakage current to cause potential safety hazard.
Disclosure of Invention
In order to solve the technical problems, a distribution box with a self-checking function and a self-checking method are provided to solve the existing problems.
The application provides a distribution box with a self-checking function and a self-checking method, which comprise the following steps:
In a first aspect, an embodiment of the present application provides a self-checking method for a power distribution box with a self-checking function, where the method includes the following steps:
Obtaining the current at each moment of each phase circuit, the current at each moment of each zero line circuit and the average voltage of each detection point of each phase circuit;
Determining the current relative difference of each phase circuit according to the difference degree of the currents of different phase circuits at the same time, analyzing the correlation condition of the current of each phase circuit and the current variation on a zero line circuit, and determining the suspected leakage coefficient of each phase circuit by combining the current anomaly degree and the current relative difference;
Determining the forward monotone trend and the backward monotone trend of each detection point of each phase circuit according to the monotone change trend of the average voltage of the forward and backward detection points of each phase circuit, determining the difference of the forward and backward voltage of each detection point of each phase circuit according to the difference of the average voltage of the forward and backward detection points of each phase circuit, analyzing the difference of the forward monotone trend and the backward monotone trend, and determining the leakage index of each detection point of each phase circuit by combining the suspected leakage coefficient and the forward and backward voltage difference;
And judging whether the distribution box has an electric leakage fault or not based on the electric leakage index.
Preferably, the determining the current anomaly of each phase circuit includes:
Dividing the current of each phase circuit at all times into time periods, and forming a two-dimensional array by the time periods and the corresponding currents of each phase circuit at all times;
Performing curve fitting on all two-dimensional arrays of each period of each phase of circuit to obtain a sinusoidal curve of each period of each phase of circuit;
calculating the integral area between the sine curve and the abscissa axis of each period of each phase of circuit;
The average value of the difference of the integration areas of all arbitrary two periods of each phase circuit is taken as the current anomaly of each phase circuit.
Preferably, the determining the relative difference of the currents of each phase circuit includes:
Calculating the ratio between the current at each moment of any phase circuit except each phase circuit and the current at the same moment of each phase circuit;
and taking the average value of the ratio of each phase circuit to all the other phase circuits at all moments as the relative difference of the currents of each phase circuit.
Preferably, the determining the suspected leakage coefficient of each phase circuit includes:
Calculating the degree of correlation between the currents at all times of each phase circuit and the currents at all times on the zero line circuit;
And calculating the product of the current anomaly degree and the correlation degree, and taking the ratio of the product to the current relative difference as the suspected leakage coefficient of each phase of circuit.
Preferably, the determining the forward monotonic trend of each detection point of each phase circuit includes:
The method comprises the steps of obtaining the peak value of the average voltage of all detection points of each phase circuit, marking all the 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 according to the sequence of passing current through the detection points;
For each detection point, calculating the difference value between each average voltage in the forward peak voltage and the previous average voltage, and recording the difference value as a first difference value;
and taking the ratio of the number of the first difference values in the forward peak voltage to the number of all average voltages in the forward peak voltage as the forward monotonic trend of each detection point of each phase of circuit.
Preferably, the backward monotonous trend includes:
calculating the difference value between each average voltage in the backward peak voltage of each detection point and the previous average voltage of each average voltage, and recording the difference value as a second difference value;
And taking the ratio of the number of the second difference values in the backward peak voltage to the number of all average voltages in the backward peak voltage as the backward monotone trend of each detection point of each phase of circuit.
Preferably, the determining the difference between the front and rear voltages at each detection point of each phase circuit is a ratio between the average value of all average voltages in the forward peak voltage and the average value of all average voltages in the backward peak voltage at each detection point of each phase circuit.
Preferably, the determining the leakage index of each detection point of each phase circuit includes:
Taking the difference value of the forward monotonic trend and the backward monotonic trend as the difference between the forward and backward trends of each detection point of each phase of circuit;
and calculating the product of the suspected leakage coefficient and the front-back trend difference, and taking the ratio of the product to the front-back voltage difference as the leakage index of each detection point of each phase of circuit.
Preferably, the judging whether the distribution box has the leakage fault or not includes:
The method comprises the steps of obtaining a division threshold value of the leakage index of all detection points of each phase of circuit, if detection points with the leakage index larger than the division threshold value exist, generating leakage faults on the distribution box, otherwise, generating no leakage faults on the distribution box.
In a second aspect, an embodiment of the present application further provides a self-checking block terminal, where the self-checking of the block terminal uses the steps of the self-checking block terminal self-checking method with a self-checking function described in any one of the above.
The application has at least the following beneficial effects:
The application determines the current anomaly degree of each phase circuit according to the deviation of current waveforms in different time periods of each phase circuit, has the advantages of analyzing the deviation degree of current waveforms from sine waves to reflect the distortion condition of current waveforms caused by leakage faults, determining the current relative difference of each phase circuit according to the deviation degree of currents of different phase circuits at the same time, determining the monotonic change trend of the average voltage of each detection point of each phase circuit according to the monotonic change trend of the average voltage of each detection point of each phase circuit, determining the correlation condition of the current of each phase circuit and the current change of a zero line circuit, determining the suspected leakage coefficient of each phase circuit according to the correlation between the current anomaly degree and the current relative difference of each phase circuit, determining the suspected leakage coefficient of each phase circuit according to the correlation between the current of each phase circuit and the current change of the zero line circuit, preliminarily judging the phase circuit which accords with the leakage fault condition of the corresponding phase circuit so as to improve the accuracy of the judgment of the subsequent leakage positions, determining the monotonic change trend of the average voltage of each detection point of each phase circuit according to the prior and subsequent detection point of each phase circuit, determining the monotonic change trend of each detection point of each phase circuit according to the average voltage of each monotonic change trend, and the prior and subsequent leakage trend of each monotonic change trend of each phase circuit according to the prior to the difference trend of each phase circuit, and prior leakage coefficient of each phase circuit is determined prior to the prior change trend, the method has the advantages that the possible degree of leakage of each detection point is analyzed, whether the detection point is a leakage position or the detection point is influenced by the leakage position is judged, the leakage position can be relatively accurately positioned, whether the distribution box has a leakage fault or not is judged based on the leakage index, the leakage fault of a circuit in the distribution box is checked, whether the distribution box has the leakage fault or not is judged based on the leakage index, the distribution box is subjected to circuit breaking protection, the accuracy of the judgment on the leakage fault is improved, the misjudgment is reduced, the malfunction risk for triggering the overcurrent protection of the distribution box is reduced, and the power supply quality and the safety are improved while the safety of the distribution box is ensured.
Drawings
The application further provides a self-checking method of the distribution box with the self-checking function by combining the drawings.
Fig. 1 is a step flowchart of a self-checking method of a distribution box with a self-checking function according to an embodiment of the present application;
Fig. 2 is a schematic diagram of waveform change of leakage current of a circuit according to an embodiment of the present application;
Fig. 3 is a flowchart of a method for obtaining a suspected leakage coefficient of each phase of circuit according to an embodiment of the present application;
FIG. 4 is a schematic diagram showing average voltage variation at all detection points in a circuit according to an embodiment of the present application;
fig. 5 is a flowchart of a method for obtaining leakage index at each detection point of each phase circuit according to an embodiment of the present application.
Detailed Description
In order to make the objects, technical schemes and advantages of the present application more clear, the present application provides a distribution box with self-checking function and a self-checking method thereof, which are described in further detail below with reference to the accompanying drawings and the examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.
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.
Referring to fig. 1, a flowchart of a self-checking method for a distribution box with a self-checking function according to an embodiment of the application is shown, and the method includes the following steps:
And step 1, obtaining the current at each moment of each phase circuit, the current at each moment of the zero line circuit and the average voltage of each detection point of each phase circuit.
The three-phase circuit in the three-phase distribution box is a common power distribution mode, in a low-voltage distribution network, a power transmission circuit is generally made of three-phase four-wire, wherein three corresponding circuits are live wires, the other circuit is a zero wire, in the three-phase circuit, three phases form a loop, and the zero wire is normally currentless.
Therefore, a current transformer is installed at the inlet of the three-phase circuit, the current of each phase circuit is measured, a zero-sequence current transformer is installed at the inlet of the zero line, the current of the zero line is measured, secondly, a plurality of detection points are arranged on each phase circuit, a voltage transformer is installed at the detection points, the voltage of each detection point of each phase circuit is collected, the collection frequency is set to be f, the collection duration is set to be T, the current of each moment of each phase circuit, the current of each moment of the zero line and the voltage of each moment of each detection point of each phase circuit are collected, the average value of the voltages of all the moments of each detection point of each phase circuit is recorded as the average voltage of each detection point of each phase circuit according to the sequence of the current passing through the detection points, and the collected data are normalized to obtain the current of each moment of each phase circuit, the current of each moment of each zero line circuit and the average voltage of each detection point of each phase circuit.
Preferably, in this embodiment, the acquisition frequency is set to be 1KHz, the acquisition duration is set to be 10min, and as other embodiments, an implementer can set the data according to the actual situation by himself, and perform normalization processing by using a maximum and minimum normalization method, where the maximum and minimum normalization method is a known technology and is not described in detail herein, and as other embodiments, the implementer can use other methods in the prior art, for example, a Z-score normalization method, etc., and this embodiment is not limited in particular.
It should be noted that the detection points may be set as an incoming line position of each phase circuit, a starting point of each branch circuit on each phase circuit, and an input end of a load on each phase circuit, where the incoming line position refers to a position where a power supply or an external power grid is connected to the distribution box, and the input end of the load refers to an input end of a device connected to the circuit for consuming electric energy.
Thus, the current at each time of each phase circuit, the current at each time of the zero line circuit, and the average voltage at each detection point of each phase circuit are obtained.
Determining the current anomaly degree of each phase circuit according to the deviation difference conditions of current waveforms in different time periods of each phase circuit, determining the current relative difference of each phase circuit according to the difference degrees of currents of different phase circuits at the same time, analyzing the correlation condition of the current of each phase circuit and the current change of a zero line circuit, and determining the suspected leakage coefficient of each phase circuit by combining the current anomaly degree and the current relative difference.
Normally, when the distribution box does not have a fault, the three-phase circuits should be balanced, that is, the three-phase currents are equal, and the three-phase currents cancel each other, so that the current of the zero line circuit is theoretically 0. When the distribution box has leakage faults, the current of the leakage phase circuit can be increased, so that the three-phase balance of the whole circuit is damaged, the leakage current of the leakage phase circuit can obviously increase the current in the zero line, namely, the more serious the leakage is, the more balanced the three-phase current is, the more obvious the current in the zero line is, and secondly, the voltage at two sides of the leakage position can also obviously change abnormally.
Since the frequencies and amplitudes of the three-phase power are the same, the current of each phase circuit is similar to a sine wave under normal conditions, the periodic variation is carried out, and the phases of the currents of each phase circuit in each period are relatively consistent due to the periodic variation, so that the sine functions corresponding to the current waveforms in different periods are basically the same, when leakage faults occur, leakage currents are superimposed on normal currents, abnormal increase of the currents is caused, the abnormal increase is represented by increase of current peaks or distortion of the current waveforms, and harmonic components are possibly additionally introduced, so that the waveforms deviate from the sine wave.
Further, a schematic diagram of waveform change of leakage current of a circuit provided by the embodiment of the application is shown in fig. 2, wherein an abscissa is time, an ordinate is normalized current, a solid line in fig. 2 shows a change condition of leakage current of a certain phase of circuit, and a dotted line is a change condition that current of the circuit is approximate to sine wave under a normal condition, as can be seen from the figure, when leakage fault exists, the waveform of leakage current deviates from sine wave to a certain extent.
Based on the analysis, dividing the current of all the moments of each phase circuit into each period, and analyzing the current distribution condition of each period, wherein the current distribution condition is specifically as follows:
Dividing the current of each phase circuit at all times into time periods, and forming a two-dimensional array by the time periods and the corresponding currents of each phase circuit at all times;
Preferably, in this embodiment, the current at all times of each phase circuit in each minute is taken as a period, and as other embodiments, the practitioner can set the current according to the actual situation.
Performing curve fitting on all two-dimensional arrays of each period of each phase of circuit to obtain a sinusoidal curve of each period of each phase of circuit;
It should be noted that, the curve fitting is performed by using a least square method, where the least square method is a known technique, and will not be described herein.
Further, based on the difference conditions of the sinusoids in different time periods, the current anomaly of each phase circuit is analyzed to reflect the degree to which the leakage fault may deviate the waveform of the current of each phase circuit from a sine wave, specifically:
calculating the integral area between the sine curve and the abscissa axis of each period of each phase of circuit;
taking the average value of the difference of the integration areas of all any two time periods of each phase circuit as the current anomaly of each phase circuit;
Preferably, in the present embodiment, the absolute value of the difference value of the integration areas of any two periods of each phase circuit is calculated, and the average value of all the absolute values of each phase circuit is taken as the current anomaly of each phase circuit.
It should be noted that, under normal conditions, the current is approximately a sine wave, so that the difference between the sine curves of each period is small, but the waveform of the current deviates from the sine wave due to the leakage fault, so that the difference of the integration areas of any two periods is large, the obtained current anomaly is large, and the greater the possibility of the leakage fault of the corresponding phase circuit is.
Further, when the distribution box has a leakage fault, the current of the leakage phase circuit increases, and the leakage current of the leakage phase circuit also increases the current in the zero line obviously, so that the analysis of the current of each phase circuit has correlation with the current change on the zero line, specifically:
Calculating the degree of correlation between the currents at all times of each phase circuit and the currents at all times on the zero line circuit;
Preferably, in this embodiment, the pearson correlation coefficients between the currents at all times of each phase circuit and the currents at all times of the zero line circuit are calculated, where the method for calculating the pearson correlation coefficients is a known technology and is not described herein in detail.
It should be noted that, after the leakage fault occurs, the current of the leakage phase circuit will increase, and meanwhile, the originally tiny zero line current will also increase significantly, that is, there is a positive correlation between the leakage current and the zero line current, the greater the correlation degree, the more likely the leakage phenomenon will occur.
Further, the difference condition of the currents of different phase circuits at the same time is analyzed to reflect the unbalanced condition of the three-phase currents, specifically:
Calculating the ratio between the current at each moment of any phase circuit except each phase circuit and the current at the same moment of each phase circuit;
taking the average value of the ratio of each phase circuit to all the other phase circuits at all moments as the relative difference of the currents of each phase circuit;
preferably, in the present embodiment, a calculation formula of the current relative difference of each phase circuit is: Wherein, the method comprises the steps of, wherein, Is the firstThe relative difference in the currents of the phase circuits,Is the firstPhase circuit ofThe current at the moment in time is,Is the firstPhase circuit ofThe current at the moment in time is,For the number of all the moments in time,To divide byThe number of all phase circuits except the phase circuit.
It should be noted that, whenWhen the phase circuit has leakage fault, the firstThe current of the phase circuit increases to break the balance of three-phase current, namelyThe current of the phase circuit is greater than that of the other two-phase circuit, so thatLess than 1, the obtained current is relatively differentSmaller.
Further, based on the current anomaly, the correlation degree and the current relative difference, a suspected leakage coefficient is determined to reflect the possibility of the leakage fault of the corresponding phase circuit, specifically:
calculating the product of the current anomaly degree and the correlation degree, and taking the ratio of the product to the current relative difference as the suspected leakage coefficient of each phase of circuit;
when the electric leakage fault occurs in each phase circuit, the suspected electric leakage coefficient is larger, and the more serious the electric leakage fault is, the larger the suspected electric leakage coefficient is, otherwise, when the electric leakage fault feature does not occur in each phase circuit, the suspected electric leakage coefficient is smaller.
Further, a step flowchart of the method for obtaining the suspected leakage coefficient of each phase of circuit provided in the embodiment of the present application is shown in fig. 3.
Thus, the suspected leakage coefficient of each phase circuit is obtained.
Step 3, determining the forward monotone trend and the backward monotone trend of each detection point of each phase circuit according to the monotone change trend of the average voltage of each detection point of each phase circuit, determining the difference of the forward voltage and the backward voltage of each detection point of each phase circuit according to the difference of the average voltage of each detection point of each phase circuit, analyzing the difference of the forward monotone trend and the backward monotone trend, and determining the leakage index of each detection point of each phase circuit by combining the suspected leakage coefficient and the difference of the forward voltage and the backward voltage.
Based on the analysis, the suspected leakage coefficient only can measure the conditions of the three-phase current and the zero line current, but the three-phase current and the zero line current can be changed and caused by short circuit between three-phase circuits or drift fault of zero line grounding, so that when the leakage degree of a leakage phase is low, the accuracy of leakage fault judgment is affected to a certain extent only according to the current difference. Therefore, the change characteristics of the voltage caused by the leakage faults are combined, the leakage faults are further analyzed and judged, and the leakage positions are positioned.
When no leakage fault exists, the voltages before and after each detection point are basically consistent. When a certain phase of circuit has leakage fault, before the leakage position, namely the circuit input end is connected to the leakage position, partial current flows out through a leakage path, the current can generate voltage drop when passing through a lead, the input of the current is increased due to the leakage fault, the voltage drop is further increased, the actual voltage on the section of the circuit from the circuit input end to the leakage position is lower than an expected value, and the current after the leakage position is greatly reduced due to current split at the leakage position, so that the voltage of the circuit after the leakage position is also obviously reduced.
Secondly, the reason for the voltage decrease before the leakage position is the increase of current and the increase of voltage drop, and the voltage drop is larger at the position closer to the leakage position, so that the voltage at the position closer to the leakage position is lower, namely the voltage shows the monotonicity change trend, and the voltage decrease after the leakage position is the decrease of input current, so that the voltage is obviously decreased, but the fluctuation of the voltage after the leakage position does not exist monotonicity.
Further, the average voltage change schematic diagram of all the detection points in the circuit provided by the embodiment of the application is shown in fig. 4, wherein the abscissa is the serial number corresponding to each detection point according to the serial number of the current passing detection point, the ordinate is the average voltage of each detection point, and in fig. 4, the voltage is greatly reduced at the detection point of the leakage position with the serial number of 10, and the monotonic reduction trend is shown.
Based on the analysis, the change condition of the average voltage of the front and rear detection points corresponding to each detection point of each phase of circuit is analyzed, and the front peak voltage and the rear peak voltage of each detection point are determined, specifically:
the peak value of the average voltage of all detection points of each phase circuit is obtained, all the peak values of the detection points before each detection point of each phase circuit are recorded as forward peak voltages of each detection point of each phase circuit, and all the peak values of the detection points after each detection point of each phase circuit are recorded as backward peak voltages of each detection point of each phase circuit;
it should be noted that, assuming that all the detection points of each phase circuit, in order of passing the current through the detection points, the average voltages of all the detection points of each phase circuit are respectively: 、、、、、、、 Then assume that 、、、、Peak value, then detect pointIs the forward peak voltage of、Detecting pointIs the backward peak voltage of、。
Further, based on the forward peak voltage and the backward peak voltage of each detection point, a change trend of the forward voltage and a change trend of the backward voltage of each detection point are analyzed, specifically:
calculating the difference value between each average voltage in the forward peak voltage of each detection point of each phase circuit and the previous average voltage, and recording the difference value as a first difference value;
taking the ratio of the number of the first difference values in the forward peak voltages of all detection points of each phase circuit as the negative number to the number of all average voltages in the forward peak voltages as the forward monotonic trend of all detection points of each phase circuit;
Calculating the difference value between each average voltage in the backward peak voltage of each detection point of each phase circuit and the previous average voltage, and recording the difference value as a second difference value;
taking the ratio of the number of the second difference values in the backward peak voltages of the detection points of each phase circuit to the number of all average voltages in the backward peak voltages as the backward monotone trend of the detection points of each phase circuit;
Taking the difference value of the forward monotonic trend and the backward monotonic trend as the difference between the forward and backward trends of each detection point of each phase of circuit;
If the number of all the average voltages in the forward peak voltage or the backward peak voltage of each detection point is smaller than 3, the forward monotonic trend of each detection point of each phase circuit is assigned to be 1, and the backward monotonic trend is assigned to be 0.
It should be noted that, when the first phase is in the circuitWhen the detection points are electric leakage positions, the firstAll average voltages in forward peak voltages of the detection points show monotonically decreasing trend, so that the first difference value is almost a negative value, the forward monotonic trend is larger and is close to 1, the backward peak voltage does not have monotonic decreasing trend, namely the backward monotonic trend is smaller, and the larger the obtained difference between the forward and backward trends is, the more likely the leakage position is.
Further, since the voltages at the front and rear detection points of the leakage position are not uniform, and the voltage before the leakage position is far greater than the voltage after the leakage position, the voltage difference before and after the leakage position is analyzed, specifically:
Taking the ratio of the average value of all average voltages in the forward peak voltage and the average value of all average voltages in the backward peak voltage of each detection point of each phase circuit as the front-back voltage difference of each detection point of each phase circuit;
It should be noted that, when the leakage fault occurs in each phase of circuit, the voltage before the leakage position is far greater than the voltage after the leakage position, so the smaller the ratio of the backward average voltage to the forward average voltage is, the closer the corresponding detection point is to the leakage position.
Further, based on the front-back trend difference and the front-back voltage difference, the suspected leakage coefficient is combined to determine a leakage index so as to reflect the possibility of leakage faults of each detection point on each phase of circuit, and the leakage position is judged specifically as follows:
Calculating the product of the suspected leakage coefficient and the front-back trend difference, and taking the ratio of the product to the front-back voltage difference as the leakage index of each detection point of each phase of circuit;
Preferably, in the present embodiment, a calculation formula of the leakage index of each detection point of each phase circuit is as follows: Wherein, the method comprises the steps of, wherein, Is the firstPhase circuit ofThe leakage index of each detection point,Is the firstThe suspected leakage coefficient of the phase circuit,Is the firstPhase circuit ofThe forward monotonic trend of the individual detection points,Is the firstPhase circuit ofThe said backward monotonous trend of the detection points,Is the firstPhase circuit ofThe difference in voltage between the front and back of the detection points, wherein,Is the difference between the front and back trends.
It should be noted that, since the first and last detection points of each phase circuit cannot compare the backward average voltage with the forward average voltage, the difference between the forward and backward voltages of the first and last detection points of each phase circuit is assigned to be 1.
The greater the difference between the front and rear directions, the more inconsistent the front and rear direction voltage change trend of the corresponding detection point, the more likely to be the leakage position, when the firstPhase circuit ofDescription of the first embodiment when the detected points are leakage pointsThe phase circuit is a leakage phase circuit, the corresponding suspected leakage coefficient is larger, and the firstThe larger the difference of the front and back trend of each detection point is, the smaller the difference of the front and back voltage is, and the leakage index is obtainedThe larger if the firstThe detection points are not leakage positions and leakage indexesAnd secondly, the closer the detection point is to the leakage position, the larger the leakage influence is, and the larger the leakage index of the detection point is.
Further, a step flowchart of the method for obtaining the leakage index at each detection point of each phase circuit provided in the embodiment of the present application is shown in fig. 5.
Thus, the leakage index of each detection point of each phase circuit is obtained.
And step 4, judging whether the distribution box has an electric leakage fault or not based on the electric leakage index.
Further, based on the leakage index, whether the distribution box has a leakage fault or not is judged, and the leakage condition of the circuit is checked, so that the safety of the distribution box is ensured, and the method specifically comprises the following steps:
obtaining a segmentation threshold value of the leakage index of all detection points of each phase of circuit;
If the detection point with the leakage index being greater than the segmentation threshold value exists, the distribution box outputs a leakage fault code 1, the distribution box is judged to have leakage faults, and the distribution box is subjected to circuit breaking treatment, so that the safety of the distribution box is ensured;
And arranging all the leakage points of all the phase circuits according to descending order of the leakage index, and checking the leakage points in sequence by an maintainer based on the arrangement result.
Preferably, in the present embodiment, the 3 sigma criterion, i.e. the Laida criterion, is adopted to obtain the leakage index distributionA detection point of the interval, which is the upper limit of the intervalAs the segmentation threshold, 3 σ criterion is a well-known technique, and is not described herein, as other embodiments, the practitioner may use other methods of the prior art, such as the maximum inter-class variance method to obtain the segmentation threshold, which is not limited in particular in this embodiment.
It should be noted that, the leakage fault code 0 indicates that there is no leakage fault, the leakage fault code 1 indicates that there is a leakage fault, and secondly, because the leakage fault may occur in the multiphase circuit at the same time, the leakage points may be distributed in different phase circuits, according to the descending order of the leakage indexes, the greater the leakage index is, the more likely the leakage position is, and the sequential checking process is started from the leakage point with the largest leakage index, so as to ensure the safety of the distribution box.
Based on the same inventive concept as the above method, the embodiment of the application also provides a distribution box with a self-checking function, and the self-checking of the distribution box adopts the steps of any one of the distribution box self-checking methods with the self-checking function.
It should be understood that, although the steps in the flowchart of fig. 1 are shown in sequence as indicated by the arrows, the steps are not necessarily performed in sequence as indicated by the arrows. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders. Moreover, at least some of the steps in fig. 1 may include multiple sub-steps or stages that are not necessarily performed at the same time, but may be performed at different times, nor do the order in which the sub-steps or stages are performed necessarily performed in sequence, but may be performed alternately or alternately with at least a portion of other steps or sub-steps of other steps.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples merely represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the application. It should be noted that, for those skilled in the art, several variations and modifications can be made without departing from the spirit of the present application, and therefore, any simple modification, equivalent variation and modification of the above embodiments according to the technical substance of the present application fall within the protection scope of the technical solution of the present application.
Claims (6)
1. The self-checking method of the distribution box with the self-checking function is characterized by comprising the following steps of:
Obtaining the current at each moment of each phase circuit, the current at each moment of each zero line circuit and the average voltage of each detection point of each phase circuit;
Determining the current relative difference of each phase circuit according to the difference degree of the currents of different phase circuits at the same time, analyzing the correlation condition of the current of each phase circuit and the current variation on a zero line circuit, and determining the suspected leakage coefficient of each phase circuit by combining the current anomaly degree and the current relative difference;
Determining the forward monotone trend and the backward monotone trend of each detection point of each phase circuit according to the monotone change trend of the average voltage of the forward and backward detection points of each phase circuit, determining the difference of the forward and backward voltage of each detection point of each phase circuit according to the difference of the average voltage of the forward and backward detection points of each phase circuit, analyzing the difference of the forward monotone trend and the backward monotone trend, and determining the leakage index of each detection point of each phase circuit by combining the suspected leakage coefficient and the forward and backward voltage difference;
Judging whether the distribution box has an electric leakage fault or not based on the electric leakage index;
the determining the forward monotonic trend of each detection point of each phase circuit comprises the following steps:
The method comprises the steps of obtaining the peak value of the average voltage of all detection points of each phase circuit, marking all the 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 according to the sequence of passing current through the detection points;
For each detection point, calculating the difference value between each average voltage in the forward peak voltage and the previous average voltage, and recording the difference value as a first difference value;
taking the ratio of the number of the first difference values in the forward peak voltage to the number of all average voltages in the forward peak voltage as the forward monotonic trend of each detection point of each phase of circuit;
the backward monotonous trend includes:
calculating the difference value between each average voltage in the backward peak voltage of each detection point and the previous average voltage of each average voltage, and recording the difference value as a second difference value;
Taking the ratio of the number of the second difference values in the backward peak voltage to the number of all average voltages in the backward peak voltage as the backward monotone trend of each detection point of each phase of circuit;
the front-back voltage difference of each detection point of each phase circuit is determined as the ratio between the average value of all average voltages in the forward peak voltage and the average value of all average voltages in the backward peak voltage of each detection point of each phase circuit;
the determining the leakage index of each detection point of each phase circuit comprises the following steps:
Taking the difference value of the forward monotonic trend and the backward monotonic trend as the difference between the forward and backward trends of each detection point of each phase of circuit;
and calculating the product of the suspected leakage coefficient and the front-back trend difference, and taking the ratio of the product to the front-back voltage difference as the leakage index of each detection point of each phase of circuit.
2. A self-test method for a power distribution box having a self-test function as claimed in claim 1, wherein said determining the degree of current abnormality of each phase circuit comprises:
Dividing the current of each phase circuit at all times into time periods, and forming a two-dimensional array by the time periods and the corresponding currents of each phase circuit at all times;
Performing curve fitting on all two-dimensional arrays of each period of each phase of circuit to obtain a sinusoidal curve of each period of each phase of circuit;
calculating the integral area between the sine curve and the abscissa axis of each period of each phase of circuit;
The average value of the difference of the integration areas of all arbitrary two periods of each phase circuit is taken as the current anomaly of each phase circuit.
3. A self-test method for a self-test function of a power distribution box according to claim 1, wherein said determining the relative difference of the currents of each phase circuit comprises:
Calculating the ratio between the current at each moment of any phase circuit except each phase circuit and the current at the same moment of each phase circuit;
and taking the average value of the ratio of each phase circuit to all the other phase circuits at all moments as the relative difference of the currents of each phase circuit.
4. The self-checking method of a power distribution box with self-checking function according to claim 1, wherein said determining the suspected leakage coefficient of each phase circuit comprises:
Calculating the degree of correlation between the currents at all times of each phase circuit and the currents at all times on the zero line circuit;
And calculating the product of the current anomaly degree and the correlation degree, and taking the ratio of the product to the current relative difference as the suspected leakage coefficient of each phase of circuit.
5. The self-checking method for a distribution box with self-checking function according to claim 1, wherein said determining whether the distribution box has an electric leakage fault comprises:
The method comprises the steps of obtaining a division threshold value of the leakage index of all detection points of each phase of circuit, if detection points with the leakage index larger than the division threshold value exist, generating leakage faults on the distribution box, otherwise, generating no leakage faults on the distribution box.
6. A self-checking block terminal with self-checking function, characterized in that the self-checking of the block terminal is realized by adopting a block terminal self-checking method with self-checking function as set forth in any one of claims 1-5.
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| CN215498243U (en) * | 2021-08-11 | 2022-01-11 | 武汉通欣电气有限公司 | Leakage protection system of block terminal |
| CN115032498A (en) * | 2022-06-06 | 2022-09-09 | 北京四方继保工程技术有限公司 | Method and system for line protection PT disconnection identification based on voltage change trend and continuous current change characteristics |
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| JP2020094922A (en) * | 2018-12-13 | 2020-06-18 | 株式会社豊田自動織機 | Electric leakage detection circuit and method for detecting leakage |
| CN111308272B (en) * | 2020-03-09 | 2021-03-16 | 西南交通大学 | A method for locating small current ground fault sections |
| CN111398739A (en) * | 2020-04-20 | 2020-07-10 | 广东电网有限责任公司梅州供电局 | Device and method for detecting abnormal parallel of direct current system for station |
| JP2022112783A (en) * | 2021-01-22 | 2022-08-03 | 株式会社日立産機システム | Power conversion device and ground fault detection method |
| CN115236457A (en) * | 2022-08-11 | 2022-10-25 | 中国石油大学(华东) | Method, system, equipment and storage medium for positioning short-circuit fault section of oil field distribution network |
| EP4397985B1 (en) * | 2023-01-06 | 2025-04-16 | Schleich GmbH | Method for detecting voltage dependent faults in an electrical winding system |
| CN118091490B (en) * | 2024-04-28 | 2024-07-30 | 国网辽宁省电力有限公司辽阳供电公司 | A method for detecting current in overhead high voltage cable lines |
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| CN215498243U (en) * | 2021-08-11 | 2022-01-11 | 武汉通欣电气有限公司 | Leakage protection system of block terminal |
| CN115032498A (en) * | 2022-06-06 | 2022-09-09 | 北京四方继保工程技术有限公司 | Method and system for line protection PT disconnection identification based on voltage change trend and continuous current change characteristics |
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