A multi-layer grounding grid detection device and method based on a magnetic sensor array

Abstract

The application discloses a kind of multilayer ground grid detection device and method based on magnetic sensor array, multilayer magnetic sensor array is by multilayer same structure cross-shaped magnetic sensor array module along vertical arrangement composition, transmitter respectively to the each layer ground grid of multilayer ground grid injects fixed frequency AC excitation current, multilayer magnetic sensor array carries out ground scanning, to collect the magnetic field intensity analog signal of measured ground grid at different scanning points on ground, signal acquisition module will magnetic field intensity analog signal be converted into magnetic field intensity digital signal, GPS system is used to record the position information of the multilayer magnetic sensor array at different scanning points and transmit to microcontroller;Microcontroller calculates the distance of each scanning point position from the two ends of ground grid conductor and the distance of the bottom sensor array module of the multilayer magnetic sensor array from ground grid conductor, and obtains the horizontal topology structure diagram of each layer ground grid and corresponding buried depth;The application can realize the detection of multilayer ground grid.

Description

Technical Field

[0001] This invention relates to the field of grounding grid fault diagnosis technology, and in particular to a multi-layer grounding grid detection device and method based on a magnetic sensor array. Background Technology

[0002] Grounding grids are essential for the safe operation of substations and a crucial measure to ensure the safety of operating personnel. Buried underground, the grounding grid conductors are susceptible to corrosion due to factors such as poor welding during construction or chemical reactions caused by soil composition, thus reducing the original design performance of the grounding grid. Assessing the corrosion status of the grounding grid is a vital task for operation and maintenance departments. Furthermore, in practice, situations frequently arise where construction drawings are not updated with grounding grid renovations or expansions, actual installations deviate significantly from the drawings, or even drawings are unavailable. Moreover, grounding grids are not limited to single-layer designs but also include multi-layer structures. Therefore, non-destructive testing of multi-layer grounding grids has practical value. However, existing methods for testing single-layer grounding grids, including transient electromagnetic methods, surface potential detection methods, and electrochemical methods, cannot accurately measure the specific burial depth of the grounding grid conductors, thus failing to obtain information on the underground distribution structure of multi-layer grounding grids. Summary of the Invention

[0003] To address the above problems, this invention provides a multi-layer grounding grid detection device based on a magnetic sensor array, comprising a transmitter and a receiver. The receiver includes a multi-layer magnetic sensor array, a signal acquisition module, a microcontroller, and a GPS system. The multi-layer magnetic sensor array is composed of multiple cross-shaped magnetic sensor array modules with the same structure arranged vertically. The distance from the magnetic sensor in each layer to the center point of the cross is the same, and the height distance between adjacent layers is the same. The transmitter injects a fixed-frequency AC excitation current into each layer of the multi-layer grounding grid. The multi-layer magnetic sensor array performs ground scanning to collect analog magnetic field strength signals of the grounding grid at different scanning points. The signal acquisition module converts the analog magnetic field strength signals into digital magnetic field strength signals and transmits them to the microcontroller. The GPS system records the position information of the multi-layer magnetic sensor array at different scanning points and transmits it to the microcontroller. The microcontroller filters the digital magnetic field strength signals and calculates the distance from each scanning point to both ends of the grounding grid conductor, as well as the distance from the bottom layer sensor array module of the multi-layer magnetic sensor array to the grounding grid conductor, using an interval iteration method according to the following formula:

[0004]

[0005] Where i = 1, 2, ..., n, and n is the layer number where the top sensor array module of the multilayer magnetic sensor array is located. , , , These are the filtered digital signals of the magnetic field strength of the four sensors corresponding to the i-th layer sensor array module of the multilayer magnetic sensor array. μ 0 is the permeability of free space. The microcontroller is used to obtain the length and burial depth of the grounding grid conductor at each scanning point by performing an algorithm fitting based on the sum of the distances from each scanning point to the two ends of the grounding grid conductor and the distance from the bottom sensor array module of the multi-layer magnetic sensor array to the grounding grid conductor. It also maps the length and burial depth of the grounding grid conductor at all scanning points to the location information of each scanning point recorded by the GPS system, thereby obtaining the horizontal topology diagram and corresponding burial depth of each layer of the grounding grid. The microcontroller is further configured to use the distances from each scanning point to the two ends of the grounding grid conductor and the distance from the bottom sensor array module of the multi-layer magnetic sensor array to the grounding grid conductor.

[0006] Furthermore, the receiver is mounted on a trolley for scanning.

[0007] Furthermore, the microcontroller is also used to calculate the magnetic field change rate based on the filtered magnetic field strength digital signal, determine whether the grounding grid conductor is corroded based on whether the magnetic field change rate is abnormal, and determine the location of the abnormal magnetic field change rate by combining the location information of each inspection point recorded by the GPS system, thereby determining the location of the corrosion defect in the grounding grid. The size of the corrosion area of ​​the grounding grid conductor can be determined by combining the length of the horizontal and vertical coordinates of the abnormal magnetic field change rate signal.

[0008] Furthermore, the multilayer magnetic sensor array is composed of two layers of identical cross-shaped magnetic sensor array modules arranged vertically.

[0009] Furthermore, the rate of change of the magnetic field is obtained based on the approximate equivalent calculation of differential and difference methods, and the calculation formula is as follows:

[0010]

[0011] in, Let B be the rate of change of the magnetic field, B be the magnetic field strength signal, and x, y, and z be the coordinates in the three-dimensional coordinate system. , , B1, B2, B3, and B4 are the basis vectors in the x, y, and z directions, respectively. B1, B2, B3, and B4 are the filtered digital signals of the magnetic field strength of the four sensors in the first layer sensor array module of the corresponding two-layer magnetic sensor array from bottom to top. B5, B6, B7, and B8 are the filtered digital signals of the magnetic field strength of the four sensors in the second layer sensor array module of the corresponding two-layer magnetic sensor array from bottom to top.

[0012] This invention also provides a method for detecting multi-layer grounding grids based on a magnetic sensor array, implemented using the aforementioned multi-layer grounding grid detection device, comprising the following steps:

[0013] S1. Using the transmitter, inject a fixed frequency AC excitation current into one layer of the multi-layer grounding grid;

[0014] S2. The multi-layer magnetic sensor array is used to perform ground scanning to collect analog signals of magnetic field strength at different scanning points of the grounding grid under test and transmit them to the signal acquisition module. The signal acquisition module converts the analog magnetic field strength signals into digital magnetic field strength signals and transmits them to the microcontroller. At the same time, the GPS system records the position information of the multi-layer magnetic sensor array at different scanning points and transmits it to the microcontroller.

[0015] S3. The microcontroller filters the digital signal of magnetic field strength and calculates the distance from each scanning point to both ends of the grounding grid conductor and the distance from the bottom sensor array module of the multilayer magnetic sensor array to the grounding grid conductor using the interval iteration method according to the formula. Then, based on the sum of the distances from each scanning point to both ends of the grounding grid conductor and the distance from the bottom sensor array module of the multilayer magnetic sensor array to the grounding grid conductor, the length and burial depth of the grounding grid conductor at each scanning point are obtained by algorithm fitting. The length and burial depth of the grounding grid conductor at all scanning points are then mapped to the location information of each scanning point recorded by the GPS system to obtain the horizontal topology diagram and corresponding burial depth of the grounding grid.

[0016] S4. Repeat steps S1-S3 until the detection of all grounding grids of the multi-layer grounding grid is completed.

[0017] Furthermore, the receiver is mounted on a trolley for scanning.

[0018] Furthermore, step S3 also includes: the microcontroller calculates the magnetic field change rate based on the filtered magnetic field strength digital signal, determines whether the grounding grid conductor is corroded based on whether the magnetic field change rate is abnormal, and determines the location of the abnormal magnetic field change rate by combining the location information of each inspection point recorded by the GPS system, thereby determining the location of the corrosion defect in the grounding grid, and the size of the corrosion area of ​​the grounding grid conductor can be determined by combining the length of the horizontal and vertical coordinates of the abnormal magnetic field change rate signal.

[0019] Furthermore, the multilayer magnetic sensor array is composed of two layers of identical cross-shaped magnetic sensor array modules arranged vertically.

[0020] Furthermore, the rate of change of the magnetic field is obtained based on the approximate equivalent calculation of differential and difference methods, and the calculation formula is as follows:

[0021]

[0022] in, Let B be the rate of change of the magnetic field, B be the magnetic field strength signal, and x, y, and z be the coordinates in the three-dimensional coordinate system. , , B1, B2, B3, and B4 are the basis vectors in the x, y, and z directions, respectively. B1, B2, B3, and B4 are the filtered digital signals of the magnetic field strength of the four sensors in the first layer sensor array module of the corresponding two-layer magnetic sensor array from bottom to top. B5, B6, B7, and B8 are the filtered digital signals of the magnetic field strength of the four sensors in the second layer sensor array module of the corresponding two-layer magnetic sensor array from bottom to top.

[0023] Compared with the prior art, the beneficial effects of the present invention include:

[0024] (1) The multi-layer grounding grid detection device and method based on magnetic sensor array of the present invention includes a transmitter and a receiver. The receiver includes a multi-layer magnetic sensor array, a signal acquisition module, a microcontroller, and a GPS system. The multi-layer magnetic sensor array is composed of multiple cross-shaped magnetic sensor array modules with the same structure arranged vertically. The distance from the magnetic sensor to the center point of the cross is the same in each layer of the magnetic sensor array module, and the height distance between adjacent layers of the sensor array modules is the same. The transmitter is used to inject AC excitation current of a fixed frequency into each layer of the multi-layer grounding grid. The multi-layer magnetic sensor array is used to perform ground scanning to collect the magnetic field strength analog signal of the grounding grid under test at different scanning points on the ground. The signal acquisition module is used to convert the magnetic field strength analog signal into a magnetic field strength digital signal and transmit it to the microcontroller. The GPS system is used to record the position information of the multi-layer magnetic sensor array at different scanning points and transmit it to the microcontroller. The microcontroller is used to filter the magnetic field strength digital signal and pass it according to the following formula. The distances from each scanning point to both ends of the grounding grid conductor and the distance from the bottom sensor array module of the multi-layer magnetic sensor array to the grounding grid conductor are calculated using an interval iterative method. The microcontroller is also used to perform algorithm fitting based on the sum of the distances from each scanning point to both ends of the grounding grid conductor and the distance from the bottom sensor array module of the multi-layer magnetic sensor array to the grounding grid conductor to obtain the length and burial depth of the grounding grid conductor at each scanning point. The length and burial depth of the grounding grid conductor at all scanning points are then mapped to the location information of each scanning point recorded by the GPS system to obtain the horizontal topology diagram and corresponding burial depth of each layer of the grounding grid. This device and method can realize the detection of multi-layer grounding grids. By mapping the signals collected by the magnetic sensors to GPS, the topology of the multi-layer grounding grid, including the burial depth and horizontal topology of each layer, can be detected simultaneously, filling the current technical gap in the detection of multi-layer grounding grids. At the same time, the use of a multi-layer sensor array can effectively improve the technical problems of low accuracy and poor anti-interference ability.

[0025] (2) The magnetic field change rate is calculated by the microcontroller based on the filtered magnetic field strength digital signal. The grounding grid conductor is judged to be corroded based on whether the magnetic field change rate is abnormal. The location of the abnormal magnetic field change rate is determined by combining the location information of each inspection point recorded by the GPS system. Thus, the location of the corrosion defect in the grounding grid is determined. The size of the corrosion area of ​​the grounding grid conductor can be judged by combining the length of the horizontal and vertical coordinates of the abnormal magnetic field change rate signal. Thus, the detection of corrosion of multi-layer grounding grid is realized. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of a multi-layer grounding grid detection device based on a magnetic sensor array according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the structure of a multilayer magnetic sensor array according to an embodiment of the present invention.

[0028] Figure 3 This is a schematic flowchart of a multi-layer grounding grid detection method based on a magnetic sensor array according to an embodiment of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0030] The main problem this invention addresses is that existing grounding grid testing instruments on the market can only test single-layer grounding grids, and research on multi-layer grounding grid testing is still lacking. Furthermore, existing grounding grid testing methods suffer from low accuracy, poor anti-interference capabilities, large size, and high power consumption.

[0031] Example 1

[0032] This invention provides a multi-layer grounding grid detection device based on a magnetic sensor array. Please refer to [link / reference]. Figure 1 , 2 The system includes a transmitter and a receiver. The receiver comprises a multi-layer magnetic sensor array, a signal acquisition module, a microcontroller, and a GPS system. The multi-layer magnetic sensor array consists of multiple layers of identical cross-shaped magnetic sensor array modules arranged vertically. The distance from the magnetic sensor in each layer to the center point of the cross is the same, and the height distance between adjacent layers is the same. The transmitter injects a fixed-frequency AC excitation current into each layer of the multi-layer grounding grid. The multi-layer magnetic sensor array performs ground scanning to collect analog magnetic field strength signals from different scanning points on the ground. The signal acquisition module converts the analog magnetic field strength signals into digital magnetic field strength signals and transmits them to the microcontroller. The GPS system records the position information of the multi-layer magnetic sensor array at different scanning points and transmits it to the microcontroller. The microcontroller filters the digital magnetic field strength signals and calculates the distance from each scanning point to both ends of the grounding grid conductor, as well as the distance from the bottom layer of the multi-layer magnetic sensor array to the grounding grid conductor, using an interval iteration method according to the following formula:

[0033]

[0034] Where i = 1, 2, ..., n, and n is the layer number where the top sensor array module of the multilayer magnetic sensor array is located. , , , These are the filtered digital signals of the magnetic field strength of the four sensors corresponding to the i-th layer sensor array module of the multilayer magnetic sensor array. μ 0 is the permeability of free space. The microcontroller is used to obtain the length and burial depth of the grounding grid conductor at each scanning point by performing an algorithm fitting based on the sum of the distances from each scanning point to the two ends of the grounding grid conductor and the distance from the bottom sensor array module of the multi-layer magnetic sensor array to the grounding grid conductor. It also maps the length and burial depth of the grounding grid conductor at all scanning points to the location information of each scanning point recorded by the GPS system, thereby obtaining the horizontal topology diagram and corresponding burial depth of each layer of the grounding grid. The microcontroller is further configured to use the distances from each scanning point to the two ends of the grounding grid conductor and the distance from the bottom sensor array module of the multi-layer magnetic sensor array to the grounding grid conductor.

[0035] Specifically, the microcontroller uses a Kalman filter algorithm to filter the digital signal of magnetic field strength.

[0036] In a preferred embodiment, the receiver is mounted on a trolley for scanning, making it convenient to move the receiver around the ground for scanning.

[0037] In a preferred embodiment, the microcontroller is further configured to calculate the magnetic field change rate based on the filtered magnetic field strength digital signal, determine whether the grounding grid conductor is corroded based on whether the magnetic field change rate is abnormal, and then determine the location of the abnormal magnetic field change rate by combining the location information of each inspection point recorded by the GPS system, thereby determining the location of the corrosion defect in the grounding grid, and the size of the corrosion area of ​​the grounding grid conductor can be determined by combining the length of the horizontal and vertical coordinates of the abnormal magnetic field change rate signal.

[0038] Because the resistivity of the corroded and uncorroded parts of the grounding grid conductor is different, the current passing through the corroded and uncorroded parts of the grounding grid conductor is different, and thus the magnetic fields generated by the two are different. A magnetic sensor array is used to detect the magnetic field and obtain the rate of change of the magnetic field. By checking whether the rate of change of the magnetic field is abnormal, it can be determined whether the grounding grid is corroded.

[0039] When grounding grids corrode, the outer periphery of the conductor is replaced by corrosion products, and the effective metal portion becomes thinner or even breaks. This can be equivalent to the conductor's effective cross-sectional area decreasing due to corrosion, thus increasing the resistance R of that portion of the conductor.

[0040]

[0041] In the formula, For conductor resistivity, For the conductor length, This is the effective cross-sectional area of ​​the conductor;

[0042] At the same time, the greater the degree of corrosion, the smaller the conductor radius. When the conductor radius becomes smaller, the current flowing through it... It will also decrease:

[0043]

[0044] In the formula, The voltage injected into the transmitter.

[0045] According to the Biot-Savart law The magnetic flux density of the conductor can be determined as follows:

[0046]

[0047] In the formula, The permeability of free space, It is the unit vector of the position vector of the current element on the grounding grid conductor from the magnetic sensor. and Let be the angle between the current element at both ends of the grounding grid conductor and the position vector between it and the magnetic sensor. From the above formula, the magnetic flux density can be determined. and resistivity If the magnetic field strength is inversely proportional, then the magnetic induction intensity of the magnetic sensor in the corroded part of the grounding grid will be smaller than that in the uncorroded part.

[0048] In a preferred embodiment, the multilayer magnetic sensor array is composed of two layers of identical cross-shaped magnetic sensor array modules arranged vertically. The magnetic sensor array has a simple structure and low cost.

[0049] In a preferred embodiment, the rate of change of the magnetic field is obtained based on the approximate equivalent calculation of differential and difference methods, and the calculation formula is as follows:

[0050]

[0051] in, Let B be the rate of change of the magnetic field, B be the magnetic field strength signal, and x, y, and z be the coordinates in the three-dimensional coordinate system. , , B1, B2, B3, and B4 are the basis vectors in the x, y, and z directions, respectively. B1, B2, B3, and B4 are the filtered digital signals of the magnetic field strength of the four sensors in the first layer sensor array module of the corresponding two-layer magnetic sensor array from bottom to top. B5, B6, B7, and B8 are the filtered digital signals of the magnetic field strength of the four sensors in the second layer sensor array module of the corresponding two-layer magnetic sensor array from bottom to top.

[0052] Example 2

[0053] This invention also provides a method for detecting multi-layer grounding grids based on a magnetic sensor array, implemented using the aforementioned multi-layer grounding grid detection device, as described above. Figure 3 This includes the following steps:

[0054] S1. Using the transmitter, inject a fixed frequency AC excitation current into one layer of the multi-layer grounding grid;

[0055] S2. The multi-layer magnetic sensor array is used to perform ground scanning to collect analog signals of magnetic field strength at different scanning points of the grounding grid under test and transmit them to the signal acquisition module. The signal acquisition module converts the analog magnetic field strength signals into digital magnetic field strength signals and transmits them to the microcontroller. At the same time, the GPS system records the position information of the multi-layer magnetic sensor array at different scanning points and transmits it to the microcontroller.

[0056] S3. The microcontroller filters the digital signal of magnetic field strength and calculates the distance from each scanning point to both ends of the grounding grid conductor and the distance from the bottom sensor array module of the multilayer magnetic sensor array to the grounding grid conductor using the interval iteration method according to the formula. Then, based on the sum of the distances from each scanning point to both ends of the grounding grid conductor and the distance from the bottom sensor array module of the multilayer magnetic sensor array to the grounding grid conductor, the length and burial depth of the grounding grid conductor at each scanning point are obtained by algorithm fitting. The length and burial depth of the grounding grid conductor at all scanning points are then mapped to the location information of each scanning point recorded by the GPS system to obtain the horizontal topology diagram and corresponding burial depth of the grounding grid.

[0057] S4. Repeat steps S1-S3 until the detection of all grounding grids of the multi-layer grounding grid is completed.

[0058] In a preferred embodiment, the receiver is mounted on a trolley for scanning, making it convenient to move the receiver around the ground for scanning.

[0059] In a preferred embodiment, step S3 further includes: the microcontroller calculates the magnetic field change rate based on the filtered magnetic field strength digital signal, determines whether the grounding grid conductor is corroded based on whether the magnetic field change rate is abnormal, and determines the location of the abnormal magnetic field change rate by combining the location information of each scanning point recorded by the GPS system, thereby determining the location of the corrosion defect in the grounding grid, and the size of the corrosion area of ​​the grounding grid conductor can be determined by combining the length of the horizontal and vertical coordinates of the abnormal magnetic field change rate signal.

[0060] In a preferred embodiment, the multilayer magnetic sensor array is composed of two layers of identical cross-shaped magnetic sensor array modules arranged vertically. The magnetic sensor array has a simple structure and low cost.

[0061] In a preferred embodiment, the rate of change of the magnetic field is obtained based on the approximate equivalent calculation of differential and difference methods, and the calculation formula is as follows:

[0062]

[0063] in, Let B be the rate of change of the magnetic field, B be the magnetic field strength signal, and x, y, and z be the coordinates in the three-dimensional coordinate system. , , B1, B2, B3, and B4 are the basis vectors in the x, y, and z directions, respectively. B1, B2, B3, and B4 are the filtered digital signals of the magnetic field strength of the four sensors in the first layer sensor array module of the corresponding two-layer magnetic sensor array from bottom to top. B5, B6, B7, and B8 are the filtered digital signals of the magnetic field strength of the four sensors in the second layer sensor array module of the corresponding two-layer magnetic sensor array from bottom to top.

[0064] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A multi-layer grounding grid detection device based on a magnetic sensor array, characterized in that, The system includes a transmitter and a receiver. The receiver comprises a multi-layer magnetic sensor array, a signal acquisition module, a microcontroller, and a GPS system. The multi-layer magnetic sensor array consists of multiple layers of identical cross-shaped magnetic sensor array modules arranged vertically. The distance from the magnetic sensor in each layer to the center point of the cross is the same, and the height distance between adjacent layers is the same. The transmitter injects a fixed-frequency AC excitation current into each layer of the multi-layer grounding grid. The multi-layer magnetic sensor array performs ground scanning to collect analog magnetic field strength signals from different scanning points on the ground. The signal acquisition module converts the analog magnetic field strength signals into digital magnetic field strength signals and transmits them to the microcontroller. The GPS system records the position information of the multi-layer magnetic sensor array at different scanning points and transmits it to the microcontroller. The microcontroller filters the digital magnetic field strength signals and calculates the distance from each scanning point to both ends of the grounding grid conductor, as well as the distance from the bottom layer of the multi-layer magnetic sensor array to the grounding grid conductor, using an interval iteration method according to the following formula: Where i = 1, 2, ..., n, and n is the layer number where the top sensor array module of the multilayer magnetic sensor array is located. , , , These are the filtered digital signals of the magnetic field strength of the four sensors corresponding to the i-th layer sensor array module of the multilayer magnetic sensor array. μ 0 is the permeability of free space. The microcontroller is used to obtain the length and burial depth of the grounding grid conductor at each scanning point by performing an algorithm fitting based on the sum of the distances from each scanning point to the two ends of the grounding grid conductor and the distance from the bottom sensor array module of the multi-layer magnetic sensor array to the grounding grid conductor. It also maps the length and burial depth of the grounding grid conductor at all scanning points to the location information of each scanning point recorded by the GPS system, thereby obtaining the horizontal topology diagram and corresponding burial depth of each layer of the grounding grid. The microcontroller is further configured to use the distances from each scanning point to the two ends of the grounding grid conductor and the distance from the bottom sensor array module of the multi-layer magnetic sensor array to the grounding grid conductor.

2. The multi-layer grounding grid detection device as described in claim 1, characterized in that: The receiver is mounted on a trolley for scanning.

3. The multi-layer grounding grid detection device as described in claim 1, characterized in that: The microcontroller is also used to calculate the magnetic field change rate based on the filtered magnetic field strength digital signal, determine whether the grounding grid conductor is corroded based on whether the magnetic field change rate is abnormal, and then determine the location of the abnormal magnetic field change rate by combining the location information of each inspection point recorded by the GPS system, thereby determining the location of the corrosion defect in the grounding grid. The size of the corrosion area of ​​the grounding grid conductor can be determined by combining the length of the horizontal and vertical coordinates of the abnormal magnetic field change rate signal.

4. The multi-layer grounding grid detection device as described in claim 3, characterized in that: The multilayer magnetic sensor array consists of two layers of identical cross-shaped magnetic sensor array modules arranged vertically.

5. A method for detecting a multi-layer grounding grid based on a magnetic sensor array, implemented using the multi-layer grounding grid detection device of claim 1, comprising the following steps: S1. Using the transmitter, inject a fixed frequency AC excitation current into one layer of the multi-layer grounding grid; S2. The multi-layer magnetic sensor array is used to perform ground scanning to collect analog signals of magnetic field strength at different scanning points of the grounding grid under test and transmit them to the signal acquisition module. The signal acquisition module converts the analog magnetic field strength signals into digital magnetic field strength signals and transmits them to the microcontroller. At the same time, the GPS system records the position information of the multi-layer magnetic sensor array at different scanning points and transmits it to the microcontroller. S3. The microcontroller filters the digital signal of magnetic field strength and calculates the distance from each scanning point to both ends of the grounding grid conductor and the distance from the bottom sensor array module of the multilayer magnetic sensor array to the grounding grid conductor using the interval iteration method according to the formula. Then, based on the sum of the distances from each scanning point to both ends of the grounding grid conductor and the distance from the bottom sensor array module of the multilayer magnetic sensor array to the grounding grid conductor, the length and burial depth of the grounding grid conductor at each scanning point are obtained by algorithm fitting. The length and burial depth of the grounding grid conductor at all scanning points are then mapped to the location information of each scanning point recorded by the GPS system to obtain the horizontal topology diagram and corresponding burial depth of the grounding grid. S4. Repeat steps S1-S3 until the detection of all grounding grids of the multi-layer grounding grid is completed.

6. The multi-layer grounding grid detection method as described in claim 5, characterized in that: The receiver is mounted on a trolley for scanning.

7. The multi-layer grounding grid detection method as described in claim 5, characterized in that: Step S3 further includes: the microcontroller calculates the magnetic field change rate based on the filtered magnetic field strength digital signal, determines whether the grounding grid conductor is corroded based on whether the magnetic field change rate is abnormal, and determines the location of the abnormal magnetic field change rate by combining the location information of each inspection point recorded by the GPS system, thereby determining the location of the corrosion defect in the grounding grid, and the size of the corrosion area of ​​the grounding grid conductor can be determined by combining the length of the horizontal and vertical coordinates of the abnormal magnetic field change rate signal.

8. The multi-layer grounding grid detection method as described in claim 7, characterized in that: The multilayer magnetic sensor array consists of two layers of identical cross-shaped magnetic sensor array modules arranged vertically.

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