CN-120802119-B - Leakage detection method for explosion-proof distribution box

CN120802119BCN 120802119 BCN120802119 BCN 120802119BCN-120802119-B

Abstract

The invention discloses an electric leakage detection method of an explosion-proof distribution box, which particularly relates to the technical field of electric safety of inflammable and explosive environments, and is used for solving the problems of electric leakage signal attenuation and insufficient detection sensitivity caused by the eddy current effect of a metal explosion-proof shell, constructing an eddy current compensation factor based on shell materials and thickness to perform gain compensation by acquiring an original electric leakage signal of a lead in the box, synchronously acquiring shell surface temperature distribution and three-dimensional magnetic field components, judging a compensation failure state through cooperative analysis of high-temperature area migration acceleration and magnetic field polarization angle offset, calculating the area integral value of spatial magnetic field rotation on the shell surface when compensation is effective, triggering tripping action when the time change gradient exceeds a preset threshold value, breaking through the shielding effect of shell eddy current on weak electric leakage signals, and realizing high-sensitivity electric leakage protection while maintaining explosion-proof integrity.

Inventors

HU HAIJUN
HU YUANJIE
YANG ZHOU
ZHAO JING

Assignees

浙江贵威照明科技有限公司

Dates

Publication Date: 20260505
Application Date: 20250901

Claims (7)

1. The electric leakage detection method of the explosion-proof distribution box is characterized by comprising the following steps of: s1, acquiring an original leakage signal of a wire in an explosion-proof distribution box; S2, constructing an eddy current compensation factor according to the material and the thickness of the explosion-proof distribution box metal shell, performing gain compensation on an original leakage signal, and generating a compensation leakage signal, wherein the method comprises the following steps: inquiring a pre-stored material parameter mapping table to obtain the resistivity and the magnetic permeability of the material of the metal shell of the explosion-proof distribution box; Calculating a reference eddy current attenuation coefficient according to the resistivity and the magnetic permeability; Determining a compensation weight coefficient based on the thickness of the explosion-proof distribution box metal shell, wherein the compensation weight coefficient is in a nonlinear incremental relation with the increase of the thickness; Multiplying the reference eddy current attenuation coefficient by the compensation weight coefficient to generate an eddy current compensation factor; applying gain multiple amplification processing corresponding to the eddy current compensation factor to the original leakage signal to generate a compensation leakage signal; s3, acquiring temperature distribution of the surface of the metal shell of the explosion-proof distribution box, and acquiring a three-dimensional magnetic field component corresponding to the compensation leakage signal; S4, extracting migration acceleration of a high-temperature area according to temperature distribution, and calculating magnetic field polarization angle offset according to three-dimensional magnetic field components; S5, when the compensation failure mark is not triggered, acquiring the spatial magnetic field distribution of the compensation leakage signal, and calculating the area integral value of the rotation of the spatial magnetic field distribution on the surface of the shell, wherein the method comprises the following steps: acquiring spatial magnetic field vector distribution corresponding to the compensation leakage signal through a plurality of triaxial magnetic field sensors distributed on the surface of the explosion-proof distribution box metal shell; calculating a magnetic field rotation vector of each spatial position point based on the spatial magnetic field vector distribution; Discretizing the surface of a metal shell of the explosion-proof distribution box into a plurality of surface units; Calculating the product of the normal component of the magnetic field spin vector in each surface unit and the surface unit area; Summing the product results of all the surface units to obtain a plane integral value of the rotation of the spatial magnetic field distribution on the surface of the shell; and S6, outputting an electric leakage fault instruction to the tripping actuating mechanism when the gradient of the surface integral value changing along with time exceeds a preset vorticity mutation threshold value.
2. The electrical leakage detection method of an explosion-proof electrical box according to claim 1, wherein obtaining an original electrical leakage signal of a wire in the explosion-proof electrical box comprises: the zero sequence current transformer is arranged around a grounded neutral line of a three-phase wire in the explosion-proof distribution box; The method comprises the steps that a signal conditioning circuit is used for carrying out band-pass filtering treatment on an induction signal output by a zero-sequence current transformer, a high-frequency electromagnetic interference component and a low-frequency drift component are filtered, and a passband range of the band-pass filtering treatment covers a power frequency fundamental wave and an integer harmonic frequency; And performing analog-to-digital conversion on the filtered signal to generate a digitized original leakage signal.
3. The electrical leakage detection method of an explosion-proof electrical distribution box according to claim 1, wherein the material parameter mapping table comprises resistivity and permeability data of carbon steel, stainless steel, aluminum alloy.
4. The leakage detection method of an explosion-proof power distribution box according to claim 1, wherein the steps of collecting a temperature distribution of a surface of a metal housing of the explosion-proof power distribution box, and obtaining a three-dimensional magnetic field component corresponding to a compensation leakage signal, comprise: acquiring infrared thermal radiation images of the surface of the metal shell of the explosion-proof distribution box at fixed time intervals by using an infrared thermal imager to generate temperature distribution data; synchronously acquiring an X-axis magnetic field component, a Y-axis magnetic field component and a Z-axis magnetic field component corresponding to the compensation leakage signal through a plurality of triaxial magnetic field sensors which are distributed on the surface of the metal shell of the explosion-proof distribution box at equal intervals; And performing time stamp alignment storage on the temperature distribution data acquired at the same time and the three-dimensional magnetic field component.
5. The electrical leakage detection method of an explosion-proof electrical box according to claim 4, wherein the field angle of the thermal infrared imager covers the entire explosion-proof electrical box metal housing surface.
6. The method for detecting leakage of an explosion-proof power distribution box according to claim 1, wherein extracting migration acceleration of a high temperature area according to temperature distribution, calculating a polarization angle offset of a magnetic field according to three-dimensional magnetic field components, generating a compensation failure flag and starting a calibration mode when a product of the migration acceleration and the polarization angle offset exceeds a preset cooperative failure threshold, and comprises: identifying a continuous high temperature region with a temperature exceeding a preset temperature threshold in the temperature distribution of the continuous time sequence; Calculating displacement variation of mass centers of the high-temperature areas at adjacent time points; calculating the migration acceleration of the high-temperature area according to the displacement variation and the time interval; extracting an X-axis magnetic field component and a Y-axis magnetic field component from the three-dimensional magnetic field component; calculating an instantaneous magnetic field polarization angle according to the ratio of the X-axis magnetic field component to the Y-axis magnetic field component; Counting standard deviation of instantaneous magnetic field polarization angles in a preset time window as magnetic field polarization angle offset; and when the product of the migration acceleration and the magnetic field polarization angle offset exceeds a preset cooperative failure threshold value, generating a compensation failure mark and starting a calibration mode.
7. The leakage detection method of an explosion-proof power distribution box according to claim 1, wherein when a gradient of a time-varying area integrated value exceeds a preset vorticity mutation threshold, outputting a leakage fault instruction to a trip execution mechanism, comprising: acquiring a surface integral value of the rotation of the spatial magnetic field distribution of the continuous time sequence on the surface of the shell; calculating the difference value of the integration values of the adjacent time points; dividing the difference by the corresponding time interval to obtain the unit time change rate of the area value along with the time change; When the unit time change rate exceeds a preset vorticity mutation threshold, generating an electric leakage fault instruction; And transmitting an electric leakage fault instruction to the tripping actuating mechanism to trigger the breaking action of the breaker.

Description

Leakage detection method for explosion-proof distribution box Technical Field The invention relates to the technical field of electric power safety in flammable and explosive environments, in particular to a leakage detection method of an explosion-proof distribution box. Background In the electric power system in inflammable and explosive environments, an explosion-proof distribution box provides safe distribution guarantee for downstream equipment (such as illumination and motors), the explosion-proof distribution box is used as key equipment for electric power distribution, the electric leakage detection reliability of the explosion-proof distribution box is directly related to production safety, a metal shell structure is required to be adopted for the explosion-proof distribution box according to requirements so as to realize an explosion-proof function, the current industry generally detects leakage current through a zero sequence current transformer, and the principle of the current transformer is based on induction output of change of a lead magnetic field on the secondary side of the transformer. However, the metal explosion-proof shell generates eddy current under the alternating magnetic field, so that the distortion attenuation of the leakage detection signal is caused, the alternating leakage magnetic field can excite eddy current in the shell due to the inherent metal material and structural thickness of the explosion-proof shell, and the reverse magnetic field generated by the eddy current obviously weakens the original magnetic field strength, so that the signal amplitude output by the zero-sequence current transformer is reduced. The physical effect causes the detection sensitivity to small current leakage (especially below 30 mA) to be reduced, and the safety protection requirement of explosive environment is difficult to meet. Disclosure of Invention In order to overcome the above-mentioned drawbacks of the prior art, the present invention provides a leakage detection method for an explosion-proof distribution box to solve the above-mentioned problems set forth in the background art. In order to achieve the above purpose, the present invention provides the following technical solutions: the electric leakage detection method of the explosion-proof distribution box comprises the following steps: s1, acquiring an original leakage signal of a wire in an explosion-proof distribution box; s2, constructing an eddy current compensation factor according to the material and thickness of the metal shell of the explosion-proof distribution box, performing gain compensation on an original leakage signal, and generating a compensation leakage signal; s3, acquiring temperature distribution of the surface of the metal shell of the explosion-proof distribution box, and acquiring a three-dimensional magnetic field component corresponding to the compensation leakage signal; S4, extracting migration acceleration of a high-temperature area according to temperature distribution, and calculating magnetic field polarization angle offset according to three-dimensional magnetic field components; s5, when the compensation failure mark is not triggered, acquiring the spatial magnetic field distribution of the compensation leakage signal, and calculating the plane integral value of the rotation of the spatial magnetic field distribution on the surface of the shell; and S6, outputting an electric leakage fault instruction to the tripping actuating mechanism when the gradient of the surface integral value changing along with time exceeds a preset vorticity mutation threshold value. Further, obtain the original leakage signal of the wire in the explosion-proof block terminal, include: the zero sequence current transformer is arranged around a grounded neutral line of a three-phase wire in the explosion-proof distribution box; The method comprises the steps that a signal conditioning circuit is used for carrying out band-pass filtering treatment on an induction signal output by a zero-sequence current transformer, a high-frequency electromagnetic interference component and a low-frequency drift component are filtered, and a passband range of the band-pass filtering treatment covers a power frequency fundamental wave and an integer harmonic frequency; And performing analog-to-digital conversion on the filtered signal to generate a digitized original leakage signal. Further, construct the vortex compensation factor according to explosion-proof block terminal metal casing's material and thickness, carry out gain compensation to original electric leakage signal, generate compensation electric leakage signal, include: inquiring a pre-stored material parameter mapping table to obtain the resistivity and the magnetic permeability of the material of the metal shell of the explosion-proof distribution box; Calculating a reference eddy current attenuation coefficient according to the resistivity and the magnetic permeability; Dete