Ground surface magnetic field vector imaging method and system for grounding system conduction test

Abstract

The invention relates to the technical field of grounding systems, in particular to an earth surface magnetic field vector imaging method and system for a grounding system conduction test, and the system comprises a measurement area building unit which is used for building an earth surface magnetic field measurement system for the conduction test, completing earth surface magnetic field measurement wiring for the conduction test, and forming an earth surface magnetic field measurement area; the resultant magnetic field imaging unit is used for measuring earth surface vector magnetic field data based on the earth surface magnetic field measurement area and completing three-dimensional resultant magnetic field imaging; and the additional synthetic magnetic field unit is used for taking out a characteristic measuring line according to the three-dimensional synthetic magnetic field imaging result of the earth surface synthetic magnetic field and completing data sampling of additional synthetic magnetic fields at different heights according to local peak value positions of the characteristic measuring line. By judging the specific burial depth of the grounding grid and the through-flow current on each branch conductor, the frame position and the specific burial depth of the grounding grid can be clearly determined, the excavation detection of the grounding grid can be better assisted, and the detection and excavation efficiency of the grounding grid is improved.

Description

Technical Field

[0001] This invention relates to the field of grounding system technology, and in particular to a method and system for grounding system continuity testing using surface magnetic field vector imaging. Background Technology

[0002] The grounding grid is a concealed underground engineering structure that plays a vital protective role in the power system. During normal operation, the grounding grid clamps overvoltages on the metal casings of equipment and conducts fault currents to the earth, ensuring the safety of personnel and equipment. However, the bare metal conductors of the grounding grid are subject to long-term soil corrosion, posing a risk of failure. Therefore, a continuity test is conducted annually within the power system to analyze the continuity resistance between the downleads and assess the operating status of the grounding grid. However, the continuity resistance measurement method only obtains the resistance value between the downleads and cannot reflect the specific condition of the underground conductors.

[0003] Existing continuity resistance tests cannot determine the specific burial depth of the grounding grid or the test current passing through each branch conductor. In addition, once a problem is found in the continuity test, the grounding grid needs to be excavated for inspection. However, the current excavation is done blindly, and the specific location of the grounding grid is not clear on site. Therefore, there are problems of blindness and excessive workload. Summary of the Invention

[0004] This invention provides a method and system for surface magnetic field vector imaging in grounding system continuity testing, which overcomes the shortcomings of the prior art. It can effectively solve the problem of large workload caused by blindly excavating when the specific location of the grounding grid is not known in existing grounding grid continuity tests.

[0005] To solve the above problems, one of the technical solutions of this invention is achieved through the following method: a ground magnetic field vector imaging method for grounding system continuity testing, comprising the following steps: Construct a surface magnetic field measurement system for the continuity test, complete the surface magnetic field measurement wiring for the continuity test, and form a surface magnetic field measurement area; Based on the surface magnetic field measurement area, measure the surface vector magnetic field data and complete the three-dimensional synthetic magnetic field imaging; Based on the three-dimensional synthetic magnetic field imaging results of the surface synthetic magnetic field, characteristic survey lines are extracted, and data sampling of additional synthetic magnetic fields at different heights is completed according to the local peak positions of the characteristic survey lines. Based on the data sampling results of the additional composite magnetic field at different heights, the burial depth of the conductor and the current flowing through it are calculated.

[0006] The aforementioned surface magnetic field measurement system for conducting the continuity test includes: A dedicated square wave power supply for conduction testing is constructed; the square wave power supply includes a rectifier module and a square wave control module connected in sequence, and the rectifier module is connected to the three-phase power supply.

[0007] The aforementioned surface magnetic field measurement system for conducting the continuity test also includes: A three-dimensional magnetic field measurement array was constructed: five three-dimensional magnetic field sensors, C1 to C5, were selected as surface measuring points, arranged at intervals on a fixed pole, and 15 measurement channels were formed. The 15-channel data acquisition unit collects real-time surface vector magnetic field data from 15 measurement channels, and the wireless signal transmission unit receives the real-time data and sends it to the host computer.

[0008] The above-mentioned measurement of surface vector magnetic field data, based on the surface magnetic field measurement area, and completion of three-dimensional synthetic magnetic field imaging, includes: The surface vector magnetic field data of 15 measurement channels in the surface magnetic field measurement area were measured for 2 seconds. Based on 2-second surface vector magnetic field data from 15 measurement channels, the effective magnetic field response data for each surface vector magnetic field component is obtained by subtracting the mean valley magnetic field value from the mean peak magnetic field value. The calculation method is as follows: , In the formula, k For measuring channel numbering, C k for k Effective magnetic field response data of the measurement channel, unit: T. C kp for k Mean peak magnetic field of the measurement channel, unit: T. C kv for k Mean magnetic field at the bottom of the valley in the measurement channel, unit: T; Based on the locations of five surface measuring points, and according to the effective magnetic field response data of each surface vector magnetic field component, the composite magnetic field of the five surface measuring points is calculated as follows: , In the formula, c 1~ c 5 represents the composite magnetic field from 5 surface measuring points, in tons (T). C 1~ C 15 The effective magnetic field response data for measurement channels 1 through 15 are shown in T. Based on the composite magnetic field data from five surface measuring points, a three-dimensional composite magnetic field image was created.

[0009] The aforementioned characteristic survey lines were extracted based on the three-dimensional synthetic magnetic field imaging results of the surface synthetic magnetic field. Data sampling of the vector magnetic field at different heights was completed based on the local peak positions of these characteristic survey lines, including: Based on the three-dimensional synthetic magnetic field imaging results of the surface synthetic magnetic field, characteristic survey lines are extracted in two perpendicular directions. The characteristic survey lines cross the middle section of the peak skeleton of the synthetic magnetic field from the two perpendicular directions. Plot the composite magnetic field curves of each characteristic survey line; Five three-dimensional magnetic field sensors, D1 to D5, were selected as additional measuring points on the ground surface and arranged at 0.1-meter intervals on a fixed rod made of non-magnetic material. The fixed rod was placed vertically at the ground surface where the local peak of the composite magnetic field curve was located; D1 was located at the ground surface and D5 was located at the top. The 15-channel data acquisition unit performs real-time measurement of additional surface vector magnetic field data for 2 seconds on 15 measurement channels, and the wireless signal transmission unit receives the additional surface vector magnetic field data and sends it to the host computer. For the 2-second additional surface vector magnetic field data from 15 measurement channels, the average value of the valley magnetic field is subtracted from the peak magnetic field value of each surface vector magnetic field component to obtain the additional effective magnetic field response data of each surface vector magnetic field component. The calculation method is as follows: , In the formula, k Channel number, D k for k Additional effective magnetic field response data for the channel, in tons (T). D kp for k The mean peak magnetic field of the channel, in tons (T). D kv for k Mean magnetic field at the bottom of the channel, unit: T; Record the locations of 5 additional surface measuring points, and calculate the additional composite magnetic field at the 5 additional surface measuring points at different heights. The calculation method is as follows: , In the formula, d 1~ d 5 represents the additional composite magnetic field at five additional surface measuring points at five different elevations, in tons (T). D 1~ D 15 The data represent the additional effective magnetic field response data for measurement channels 1 through 15, in tons (T).

[0010] Based on the data sampling results of the additional composite magnetic field at different heights, the burial depth and current carrying capacity of the conductor are calculated, including: conductor burial depth Sand current The calculation method is as follows: , The current flowing through the cylinder is calculated using the above formula. and burial depth S They are respectively: , , In the formula, d 1~ d 5 represents the additional composite magnetic field at five additional surface measuring points at five different elevations, in tons. The current is expressed in amperes (A). S The burial depth of the conductor, in meters (m). The permeability of free space, ; Based on the above formula, complete the additional measurements at the local peak of the synthetic magnetic field curve of all characteristic measurement lines, as well as the calculation of the conductor's burial depth and current flow. Determine if the conductor's burial depth is less than 0.6. If the determination result is yes, issue a warning that the burial depth is too shallow.

[0011] The second technical solution of this invention is achieved through the following means: a surface magnetic field vector imaging system for grounding system continuity testing, using a surface magnetic field vector imaging method for grounding system continuity testing, comprising: The measurement area construction unit is used to build the surface magnetic field measurement system for the continuity test, complete the surface magnetic field measurement wiring for the continuity test, and form the surface magnetic field measurement area. The synthetic magnetic field imaging unit measures surface vector magnetic field data based on the surface magnetic field measurement area and completes three-dimensional synthetic magnetic field imaging. Additional synthetic magnetic field units are used to extract feature survey lines based on the three-dimensional synthetic magnetic field imaging results of the surface synthetic magnetic field, and data sampling of additional synthetic magnetic fields at different heights is completed based on the local peak positions of the feature survey lines. The result calculation unit calculates the burial depth and current carrying capacity of the conductor based on the data sampling results of the additional synthetic magnetic field at different heights.

[0012] The aforementioned synthetic magnetic field imaging unit includes: The data measurement module measures the surface vector magnetic field data for 2 seconds continuously across 15 measurement channels in the surface magnetic field measurement area. The response calculation module, based on 2-second surface vector magnetic field data from 15 measurement channels, calculates the effective magnetic field response data for each surface vector magnetic field component by subtracting the mean value of the valley magnetic field from the mean value of the peak magnetic field. The calculation method is as follows: , In the formula, k For measuring channel numbering, C k for k Effective magnetic field response data of the measurement channel, unit: T. C kp for k Mean peak magnetic field of the measurement channel, unit: T. C kv for k Mean magnetic field at the bottom of the valley in the measurement channel, unit: T; The composite magnetic field module calculates the composite magnetic field of the five surface measuring points based on their locations and the effective magnetic field response data of each magnetic field component. The calculation method is as follows: , In the formula, c 1~ c 5 represents the composite magnetic field from 5 surface measuring points, in tons (T). C 1~ C 15 The effective magnetic field response data for measurement channels 1 through 15 are shown in T. The three-dimensional imaging module synthesizes a three-dimensional synthetic magnetic field image based on the synthetic magnetic field data from five surface measuring points.

[0013] The aforementioned additional synthetic magnetic field units include: The feature survey line module extracts feature survey lines in two perpendicular directions based on the three-dimensional synthetic magnetic field imaging results of the surface synthetic magnetic field. The feature survey lines cross the middle section of the peak skeleton of the synthetic magnetic field from the two perpendicular directions. The curve plotting module plots the composite magnetic field curve of each characteristic survey line. The additional measuring point module uses five three-dimensional magnetic field sensors, D1 to D5, as additional measuring points on the ground surface. These sensors are arranged at 0.1-meter intervals on a fixed rod made of non-magnetic material. The fixed rod is placed vertically at the ground surface where the local peak of the synthetic magnetic field curve is located. D1 is located at the ground surface, and D5 is located at the top. The acquisition and transmission module consists of a 15-channel data acquisition unit that performs real-time measurements of additional surface vector magnetic field data for 2 seconds on 15 measurement channels, and a wireless signal transmission unit that receives the additional surface vector magnetic field data and transmits it to the host computer. The magnetic field response module calculates the additional effective magnetic field response data for each surface vector magnetic field component by subtracting the average valley magnetic field value from the peak magnetic field value of each surface vector magnetic field component from the 2-second additional surface vector magnetic field data of 15 measurement channels. The calculation method is as follows: , In the formula,k Channel number, D k for k Additional effective magnetic field response data for the channel, in tons (T). D kp for k The mean peak magnetic field of the channel, in tons (T). D kv for k Mean magnetic field at the bottom of the channel, unit: T; The additional composite magnetic field module records the locations of five additional surface measuring points and calculates the additional composite magnetic field at these five points at different elevations. The calculation method is as follows: , In the formula, d 1~ d 5 represents the additional composite magnetic field at five additional surface measuring points at five different elevations, in tons. D 1~ D 15 The data represent the additional effective magnetic field response data for measurement channels 1 through 15, in tons (T).

[0014] This invention establishes a surface magnetic field measurement system for continuity testing. It uses a dedicated square-wave test power supply to correct for the influence of the background magnetic field and employs a surface magnetic field measurement array to rapidly acquire synthetic magnetic field data of the vector magnetic field. By measuring the surface vector magnetic field data and completing three-dimensional synthetic magnetic field imaging, the general framework of the underground grounding grid is obtained. Furthermore, feature survey lines are extracted from the imaging results, and based on the local peak positions of these feature survey lines, vector magnetic fields at different heights are measured. This allows for the inversion and solution of the burial depth and current carrying capacity of local conductors. Thus, by determining the specific burial depth of the grounding grid and the current carrying capacity of each branch conductor, this invention can clearly determine the framework location and specific burial depth of the grounding grid. This facilitates better assistance in grounding grid excavation and inspection, avoiding the blind excavation and excessive workload associated with not knowing the specific location of the grounding grid, thereby improving the efficiency of grounding grid inspection and excavation. Attached Figure Description

[0015] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0016] Figure 1 This is a flowchart of the method in Embodiment 1 of the present invention.

[0017] Figure 2 This is a schematic diagram of the dedicated square wave power supply in Embodiment 1 of the present invention.

[0018] Figure 3 This is a schematic diagram of the configuration of the multi-magnetic field sensor array in Embodiment 1 of the present invention.

[0019] Figure 4 This is the wiring diagram for measuring the surface magnetic field in the continuity test of Embodiment 1 of the present invention.

[0020] Figure 5 This is a three-dimensional synthetic magnetic field imaging effect diagram in Embodiment 1 of the present invention.

[0021] Figure 6 This is a schematic diagram of the feature survey line in Embodiment 1 of the present invention.

[0022] Figure 7 This is a schematic diagram of the synthesized magnetic field curve in Embodiment 1 of the present invention, wherein (a) is a schematic diagram of the synthesized magnetic field curve of the characteristic measurement lines Line1 and Line2, and (b) is a schematic diagram of the synthesized magnetic field curve of the characteristic measurement lines Line3 to Line5.

[0023] Figure 8 This is a system block diagram of Embodiment 2 of the present invention. Detailed Implementation

[0024] The present invention is not limited to the following embodiments, and the specific implementation can be determined according to the technical solution of the present invention and the actual situation.

[0025] Example 1: As Figure 1 As shown in the figure, this invention discloses a method for surface magnetic field vector imaging in grounding system continuity testing, comprising the following steps: Step S101: Build the surface magnetic field measurement system for the continuity test, complete the surface magnetic field measurement wiring for the continuity test, and form the surface magnetic field measurement area; Step S102: Based on the surface magnetic field measurement area, measure the surface vector magnetic field data and complete the three-dimensional synthetic magnetic field imaging; obtain the general framework of the underground grounding grid; Step S103: Based on the three-dimensional synthetic magnetic field imaging results of the surface synthetic magnetic field, feature survey lines are extracted, and data sampling of additional synthetic magnetic fields at different heights is completed according to the local peak positions of the feature survey lines. Step S104: Calculate the burial depth and current carrying capacity of the conductor based on the data sampling results of the additional synthetic magnetic field at different heights.

[0026] In step S101 above, the surface magnetic field measurement system for the continuity test is constructed, including: like Figure 2 As shown, a dedicated square wave power supply for conduction testing is constructed; the square wave power supply includes a rectifier module and a square wave control module connected in sequence, and the rectifier module is connected to the three-phase power supply.

[0027] Among them, there is a background DC vector magnetic field at the scene, and the magnetic field is xyzThe magnitude of the component is generally several to tens of microteslas. However, in order to more effectively measure the vector magnetic field of the Earth's surface, the present invention uses a dedicated square wave power supply for the test power supply. The dedicated square wave power supply has an output voltage of 0~400V (adjustable), an output measurement current of 0~130A (adjustable), an output square wave current period of 2 seconds, and a duty cycle of 50%. In step S101 above, such as Figure 3 As shown, the surface magnetic field measurement system for the continuity test also includes: A three-dimensional magnetic field measurement array was constructed: Five three-dimensional magnetic field sensors, C1 to C5, were selected as measurement points on the ground and arranged at 0.1-meter intervals on a fixed rod made of non-magnetic material, forming 15 measurement channels. The 15-channel data acquisition unit collects surface vector magnetic field data (C) from 15 measurement channels. 1x C 1y C 1z C 2x C 2y C 2z C 3x C 3y C 3z C 4x C 4y C 4z C 5x C 5y C 5z Real-time data acquisition is achieved by receiving real-time data from the wireless signal transmission unit and sending it to the host computer.

[0028] The 15-channel data acquisition unit samples real-time data at 1kHz and transmits the data to the host computer via wireless communication through the wireless signal transmission unit. The host computer can be a laptop, tablet, etc. The host computer receives and stores the data.

[0029] In step S101 above, the ground magnetic field measurement wiring for the continuity test is completed, forming the ground magnetic field measurement area; this includes: selecting an open surface between the two down conductors of the continuity test as the ground magnetic field measurement area (see schematic diagram). Figure 4 , region length L Width W A dedicated square wave power supply was inserted between the two leads of the continuity test, and a 15-channel data acquisition unit for receiving data was set up near the surface magnetic field measurement area.

[0030] In step S102 above, based on the surface magnetic field measurement area, surface vector magnetic field data is measured, and three-dimensional synthetic magnetic field imaging is completed; including: The surface vector magnetic field data of 15 measurement channels in the surface magnetic field measurement area were measured for 2 seconds. Based on 2-second surface vector magnetic field data from 15 measurement channels, the effective magnetic field response data for each surface vector magnetic field component is obtained by subtracting the mean valley magnetic field value from the mean peak magnetic field value. The calculation method is as follows: , In the formula, k For measuring channel numbering, C k for k Effective magnetic field response data of the measurement channel, unit: T. C kp for k Mean peak magnetic field of the measurement channel, unit: T. C kv for k The mean magnetic field at the bottom of the valley in the measurement channel, in tons (T); where, C k With (C) 1x C 1y C 1z C 2x C 2y C 2z C 3x C 3y C 3z C 4x C 4y C 4z C 5x C 5y C 5z The correspondence between ) is shown in Figure 2 The red square wave current output from the circuit represents the peak magnetic field, while the red bottom portion of the current corresponds to the valley magnetic field. C kp for k The peak value (maximum value of square wave current) and average magnetic field value of the measurement channel are measured. C kv for k The mean magnetic field at the valley bottom (minimum value of square wave current) of the measurement channel; Based on the locations of five surface measuring points, and according to the effective magnetic field response data of each surface vector magnetic field component, the composite magnetic field of the five surface measuring points is calculated as follows: , In the formula, c 1~ c 5 represents the composite magnetic field from 5 surface measuring points, in tons (T). C 1~ C 15The effective magnetic field response data for measurement channels 1 through 15 are shown in T. Based on the composite magnetic field data from five surface measuring points, a three-dimensional composite magnetic field image was created, such as... Figure 5 As shown, the unit of magnetic field is T.

[0031] In step S103 above, characteristic survey lines are extracted based on the three-dimensional synthetic magnetic field imaging results of the surface synthetic magnetic field, and data sampling of vector magnetic fields at different heights is completed based on the local peak positions of the characteristic survey lines, including: Based on the three-dimensional synthetic magnetic field imaging results of the surface synthetic magnetic field, characteristic survey lines are extracted along two perpendicular directions. These characteristic survey lines cross the middle section of the peak skeleton of the synthetic magnetic field from these two perpendicular directions, such as... Figure 6 As shown; Plot the composite magnetic field curves of each characteristic survey line, such as Figure 7 As shown, Figure 7 (a) is Figure 6 The composite magnetic field curve of characteristic curves Line1 and Line2. Figure 7 (b) is Figure 6 The composite magnetic field curve of the characteristic curves Line 3 to Line 5; Five three-dimensional magnetic field sensors, D1~D5, were selected as additional measuring points on the ground surface and arranged at 0.1-meter intervals on a fixed rod made of non-magnetic material. The fixed rod was placed vertically at the local peak of the synthetic magnetic field curve (e.g., Figure 7 In (a), x = 58、 x =66、 x =74、 x =82) at the surface; where D1 is located at the surface and D5 is located at the top. Additional surface vector magnetic field data were collected for 2 seconds from 15 measurement channels by a 15-channel data acquisition unit. D 1x , D 1y , D 1z , D 2x , D 2y , D 2z , D 3x , D 3y , D 3z , D 4x , D 4y , D 4z ,D 5x , D 5y , D 5z The real-time measurement of the Earth's surface vector magnetic field is received by the wireless signal transmitting unit and then sent to the host computer. For the 2-second additional surface vector magnetic field data from 15 measurement channels, the average value of the valley magnetic field is subtracted from the peak magnetic field value of each surface vector magnetic field component to obtain the additional effective magnetic field response data of each surface vector magnetic field component. The calculation method is as follows: , In the formula, k Channel number, D k for k Additional effective magnetic field response data for the channel, in tons (T). D kp for k The mean peak magnetic field of the channel, in tons (T). D kv for k Mean magnetic field at the bottom of the channel, unit: T; D k and( D 1x , D 1y , D 1z , D 2x , D 2y , D 2z , D 3x , D 3y , D 3z , D 4x , D 4y , D 4z , D 5x , D 5y , D 5z The correspondence between ) is shown in Figure 2 The red square wave current output from the circuit represents the peak magnetic field, while the red bottom portion of the current corresponds to the valley magnetic field. D kp for kThe peak value (maximum value of square wave current) and average magnetic field value of the measurement channel are measured. D kv for k The mean magnetic field at the valley bottom (minimum value of square wave current) of the measurement channel; Record the locations of 5 additional surface measuring points, and calculate the additional composite magnetic field at 5 different heights (0m, 0.1m, 0.2m, 0.3m, 0.4m). The calculation method is as follows: , In the formula, d 1~ d 5 represents the additional composite magnetic field at five additional measuring points on the ground at five different heights (0m, 0.1m, 0.2m, 0.3m, and 0.4m), in tons (T). D 1~ D 15 The data represent the additional effective magnetic field response data for measurement channels 1 through 15, in tons (T).

[0032] In step S104 above, based on the data sampling results of the additional synthetic magnetic field at different heights, the burial depth and current carrying capacity of the conductor are calculated, including: According to Ampere's law, neglecting the influence of the magnetic fields of other conductors, the magnitude of the magnetic field near a conductor is related to its burial depth. S Inversely proportional to the current flowing through it. I Proportional to: the burial depth of the conductor S and current I The calculation method is as follows: , The current flowing through the cylinder is calculated using the above formula. and burial depth S They are respectively: , , In the formula, d 1~ d 5 represents the additional composite magnetic field at five additional surface measuring points at five different elevations, in tons. The current is expressed in amperes (A). S The burial depth of the conductor, in meters (m). The permeability of free space, ; Based on the above formula, complete the additional measurements at the local peak of the synthetic magnetic field curve of all characteristic measurement lines, as well as the calculation of the conductor's burial depth and current flow. The system determines whether the conductor's burial depth is less than 0.6. If the result is yes, a warning of insufficient burial depth is issued, requiring grounding modifications. This could involve increasing the burial depth of the grounding conductor after excavation, or thickening the surface soil if local backfilling is feasible. If the result is no, the system is saved. Figure 6 The data includes the conductor burial depth, current carrying capacity, and test output current ratio at the local peaks of all characteristic test lines.

[0033] Among them, the current flowing through is and burial depth S The formula is derived as follows: Based on the well-known relationship between Ampere's circuital law and magnetic fields, it can be known that the composite magnetic field on the Earth's surface... d equal (Unit: T), where Current (unit: A) S The burial depth of the conductor (unit: m). The permeability of free space, ; Based on the above, combined d 1~ d The formula for the additional combined magnetic field at 5 different surface measurement points at different elevations is obtained as follows: , Further results were obtained: , Also:

[0034] Taking the geometric mean of the above formula, we get: .

[0035] Example 2: Figure 8 As shown, this invention discloses a surface magnetic field vector imaging system for grounding system continuity testing, and a method for surface magnetic field vector imaging for grounding system continuity testing, comprising: The measurement area construction unit is used to build the surface magnetic field measurement system for the continuity test, complete the surface magnetic field measurement wiring for the continuity test, and form the surface magnetic field measurement area. The synthetic magnetic field imaging unit measures surface vector magnetic field data based on the surface magnetic field measurement area and completes three-dimensional synthetic magnetic field imaging. Additional synthetic magnetic field units are used to extract feature survey lines based on the three-dimensional synthetic magnetic field imaging results of the surface synthetic magnetic field, and data sampling of additional synthetic magnetic fields at different heights is completed based on the local peak positions of the feature survey lines. The result calculation unit calculates the burial depth and current carrying capacity of the conductor based on the data sampling results of the additional synthetic magnetic field at different heights.

[0036] The synthetic magnetic field imaging unit includes: The data measurement module measures the surface vector magnetic field data for 2 seconds continuously across 15 measurement channels in the surface magnetic field measurement area. The response calculation module, based on 2-second surface vector magnetic field data from 15 measurement channels, calculates the effective magnetic field response data for each surface vector magnetic field component by subtracting the mean value of the valley magnetic field from the mean value of the peak magnetic field. The calculation method is as follows: , In the formula, k For measuring channel numbering, C k for k Effective magnetic field response data of the measurement channel, unit: T. C kp for k Mean peak magnetic field of the measurement channel, unit: T. C kv for k Mean magnetic field at the bottom of the valley in the measurement channel, unit: T; The composite magnetic field module calculates the composite magnetic field of the five surface measuring points based on their locations and the effective magnetic field response data of each magnetic field component. The calculation method is as follows: , In the formula, c 1~ c 5 represents the composite magnetic field from 5 surface measuring points, in tons (T). C 1~ C 15 The effective magnetic field response data for measurement channels 1 through 15 are shown in T. The three-dimensional imaging module synthesizes a three-dimensional synthetic magnetic field image based on the synthetic magnetic field data from five surface measuring points.

[0037] The additional synthetic magnetic field unit includes: The feature survey line module extracts feature survey lines in two perpendicular directions based on the three-dimensional synthetic magnetic field imaging results of the surface synthetic magnetic field. The feature survey lines cross the middle section of the peak skeleton of the synthetic magnetic field from the two perpendicular directions. The curve plotting module plots the composite magnetic field curve of each characteristic survey line. The additional measuring point module uses five three-dimensional magnetic field sensors, D1 to D5, as additional measuring points on the ground surface. These sensors are arranged at 0.1-meter intervals on a fixed rod made of non-magnetic material. The fixed rod is placed vertically at the ground surface where the local peak of the synthetic magnetic field curve is located. D1 is located at the ground surface, and D5 is located at the top. The acquisition and transmission module consists of a 15-channel data acquisition unit that performs real-time measurements of additional surface vector magnetic field data for 2 seconds on 15 measurement channels, and a wireless signal transmission unit that receives the additional surface vector magnetic field data and transmits it to the host computer. The magnetic field response module calculates the additional effective magnetic field response data for each surface vector magnetic field component by subtracting the average valley magnetic field value from the peak magnetic field value of each surface vector magnetic field component from the 2-second additional surface vector magnetic field data of 15 measurement channels. The calculation method is as follows: , In the formula, k Channel number, D k for k Additional effective magnetic field response data for the channel, in tons (T). D kp for k The mean peak magnetic field of the channel, in tons (T). D kv for k Mean magnetic field at the bottom of the channel, unit: T; The additional composite magnetic field module records the locations of five additional surface measuring points and calculates the additional composite magnetic field at these five points at different elevations. The calculation method is as follows: , In the formula, d 1~ d 5 represents the additional composite magnetic field at five additional measuring points on the ground at five different heights (0m, 0.1m, 0.2m, 0.3m, and 0.4m), in tons (T). D 1~ D 15 The data represent the additional effective magnetic field response data for measurement channels 1 through 15, in tons (T).

[0038] In summary, this invention establishes a surface magnetic field measurement system for continuity testing, uses a dedicated square wave test power supply to correct for the influence of the background magnetic field, and employs a surface magnetic field measurement array to quickly obtain synthetic magnetic field data of the vector magnetic field. By measuring the surface vector magnetic field data and completing three-dimensional synthetic magnetic field imaging, the general framework of the underground grounding grid is obtained. Furthermore, feature survey lines are extracted from the imaging results, and based on the local peak positions of the feature survey lines, vector magnetic fields at different heights are measured. This allows for the inversion calculation of the burial depth and current flow of local conductors. Thus, by determining the specific burial depth of the grounding grid and the current flow on each branch conductor, this invention can clearly determine the framework location and specific burial depth of the grounding grid. This facilitates better assistance in the excavation and inspection of the grounding grid, avoiding the blind excavation and excessive workload caused by not knowing the specific location of the grounding grid, and improving the efficiency of grounding grid inspection and excavation.

Claims

1. A method for surface magnetic field vector imaging in grounding system continuity testing, characterized in that, Includes the following steps: Construct a surface magnetic field measurement system for the continuity test, complete the surface magnetic field measurement wiring for the continuity test, and form a surface magnetic field measurement area; Based on the surface magnetic field measurement area, measure the surface vector magnetic field data and complete the three-dimensional synthetic magnetic field imaging; Based on the three-dimensional synthetic magnetic field imaging results of the surface synthetic magnetic field, characteristic survey lines are extracted, and data sampling of additional synthetic magnetic fields at different heights is completed according to the local peak positions of the characteristic survey lines. Based on the data sampling results of the additional composite magnetic field at different heights, the burial depth of the conductor and the current flowing through it are calculated.

2. The ground magnetic field vector imaging method for grounding system continuity testing according to claim 1, characterized in that, The surface magnetic field measurement system for constructing the conduction test includes: A dedicated square wave power supply for conduction testing is constructed; the square wave power supply includes a rectifier module and a square wave control module connected in sequence, and the rectifier module is connected to the three-phase power supply.

3. The ground magnetic field vector imaging method for grounding system continuity testing according to claim 1, characterized in that, The surface magnetic field measurement system for constructing the conduction test also includes: A three-dimensional magnetic field measurement array was constructed: five three-dimensional magnetic field sensors, C1 to C5, were selected as surface measuring points, arranged at intervals on a fixed pole, and 15 measurement channels were formed. The 15-channel data acquisition unit collects real-time surface vector magnetic field data from 15 measurement channels, and the wireless signal transmission unit receives the real-time data and sends it to the host computer.

4. The surface magnetic field vector imaging method for grounding system continuity testing according to claim 3, characterized in that, The method involves measuring surface vector magnetic field data within the measured area and completing a three-dimensional synthetic magnetic field image; this includes: The surface vector magnetic field data of 15 measurement channels in the surface magnetic field measurement area were measured for 2 seconds. Based on 2-second surface vector magnetic field data from 15 measurement channels, the effective magnetic field response data for each surface vector magnetic field component is obtained by subtracting the mean valley magnetic field value from the mean peak magnetic field value. The calculation method is as follows: ， In the formula, k For measuring channel numbering, C k for k Effective magnetic field response data of the measurement channel, in tons (T); C kp for k Mean peak magnetic field of the measurement channel, unit: T; C kv for k Mean magnetic field at the bottom of the valley in the measurement channel, unit: T; Based on the locations of five surface measuring points, and according to the effective magnetic field response data of each surface vector magnetic field component, the composite magnetic field of the five surface measuring points is calculated as follows: ， In the formula, c 1~ c 5 represents the composite magnetic field from 5 surface measuring points, in tons (T). C 1~ C 15 The effective magnetic field response data for measurement channels 1 through 15 are shown in T. Based on the composite magnetic field data from five surface measuring points, a three-dimensional composite magnetic field image was created.

5. The surface magnetic field vector imaging method for grounding system continuity testing according to claim 4, characterized in that, The characteristic survey lines are extracted based on the three-dimensional synthetic magnetic field imaging results of the surface synthetic magnetic field, and data sampling of vector magnetic fields at different heights is completed based on the local peak positions of the characteristic survey lines, including: Based on the three-dimensional synthetic magnetic field imaging results of the surface synthetic magnetic field, characteristic survey lines are extracted in two perpendicular directions. The characteristic survey lines cross the middle section of the peak skeleton of the synthetic magnetic field from the two perpendicular directions. Plot the composite magnetic field curves of each characteristic survey line; Five three-dimensional magnetic field sensors, D1 to D5, were selected as additional measuring points on the ground surface and arranged at 0.1-meter intervals on a fixed rod made of non-magnetic material. The fixed rod was placed vertically at the ground surface where the local peak of the composite magnetic field curve was located; D1 was located at the ground surface and D5 was located at the top. The 15-channel data acquisition unit performs real-time measurement of additional surface vector magnetic field data for 2 seconds on 15 measurement channels, and the wireless signal transmission unit receives the additional surface vector magnetic field data and sends it to the host computer. For the 2-second additional surface vector magnetic field data from 15 measurement channels, the average value of the valley magnetic field is subtracted from the peak magnetic field value of each surface vector magnetic field component to obtain the additional effective magnetic field response data of each surface vector magnetic field component. The calculation method is as follows: ， In the formula, k Channel number, D k for k Additional effective magnetic field response data for the channel, in tons (T). D kp for k The mean peak magnetic field of the channel, in tons (T). D kv for k Mean magnetic field at the bottom of the channel, unit: T; Record the locations of 5 additional surface measuring points, and calculate the additional composite magnetic field at the 5 additional surface measuring points at different heights. The calculation method is as follows: ， In the formula, d 1~ d 5 represents the additional composite magnetic field at five additional surface measuring points at five different elevations, in tons (T). D 1~ D 15 The data represent the additional effective magnetic field response data for measurement channels 1 through 15, in tons (T).

6. The ground magnetic field vector imaging method for grounding system continuity testing according to claim 4, characterized in that, The calculation of the conductor's burial depth and current flow based on data sampling results of the additional composite magnetic field at different heights includes: conductor burial depth S and current The calculation method is as follows: ， The current flowing through the cylinder is calculated using the above formula. and burial depth S They are respectively: ， ， In the formula, d 1~ d 5 represents the additional composite magnetic field at five additional surface measuring points at five different elevations, in tons. The current is expressed in amperes (A). S The burial depth of the conductor, in meters (m). The permeability of free space, ; Based on the above formula, complete the additional measurements at the local peak of the synthetic magnetic field curve of all characteristic measurement lines, as well as the calculation of the conductor's burial depth and current flow. Determine if the conductor's burial depth is less than 0.

6. If the determination result is yes, issue a warning that the burial depth is too shallow.

7. A surface magnetic field vector imaging system for grounding system continuity testing, using the surface magnetic field vector imaging method for grounding system continuity testing as described in any one of claims 1 to 6, characterized in that, include: The measurement area construction unit is used to build the surface magnetic field measurement system for the continuity test, complete the surface magnetic field measurement wiring for the continuity test, and form the surface magnetic field measurement area. The synthetic magnetic field imaging unit measures surface vector magnetic field data based on the surface magnetic field measurement area and completes three-dimensional synthetic magnetic field imaging. Additional synthetic magnetic field units are used to extract feature survey lines based on the three-dimensional synthetic magnetic field imaging results of the surface synthetic magnetic field, and data sampling of additional synthetic magnetic fields at different heights is completed based on the local peak positions of the feature survey lines. The result calculation unit calculates the burial depth and current carrying capacity of the conductor based on the data sampling results of the additional synthetic magnetic field at different heights.

8. The surface magnetic field vector imaging system for grounding system continuity testing according to claim 7, characterized in that, The synthetic magnetic field imaging unit includes: The data measurement module measures the surface vector magnetic field data for 2 seconds continuously across 15 measurement channels in the surface magnetic field measurement area. The response calculation module, based on 2-second surface vector magnetic field data from 15 measurement channels, calculates the effective magnetic field response data for each surface vector magnetic field component by subtracting the mean value of the valley magnetic field from the mean value of the peak magnetic field. The calculation method is as follows: ， In the formula, k For measuring channel numbering, C k for k Effective magnetic field response data of the measurement channel, unit: T. C kp for k Mean peak magnetic field of the measurement channel, unit: T. C kv for k Mean magnetic field at the bottom of the valley in the measurement channel, unit: T; The composite magnetic field module calculates the composite magnetic field of the five surface measuring points based on their locations and the effective magnetic field response data of each magnetic field component. The calculation method is as follows: ， In the formula, c 1~ c 5 represents the composite magnetic field from 5 surface measuring points, in tons (T). C 1~ C 15 The effective magnetic field response data for measurement channels 1 through 15 are shown in T. The three-dimensional imaging module synthesizes a three-dimensional synthetic magnetic field image based on the synthetic magnetic field data from five surface measuring points.

9. The surface magnetic field vector imaging system for grounding system continuity testing according to claim 7, characterized in that, The additional synthetic magnetic field unit includes: The feature survey line module extracts feature survey lines in two perpendicular directions based on the three-dimensional synthetic magnetic field imaging results of the surface synthetic magnetic field. The feature survey lines cross the middle section of the peak skeleton of the synthetic magnetic field from the two perpendicular directions. The curve plotting module plots the composite magnetic field curve of each characteristic survey line. The additional measuring point module uses five three-dimensional magnetic field sensors, D1 to D5, as additional measuring points on the ground surface. These sensors are arranged at 0.1-meter intervals on a fixed rod made of non-magnetic material. The fixed rod is placed vertically at the ground surface where the local peak of the synthetic magnetic field curve is located. D1 is located at the ground surface, and D5 is located at the top. The acquisition and transmission module consists of a 15-channel data acquisition unit that performs real-time measurements of additional surface vector magnetic field data for 2 seconds on 15 measurement channels, and a wireless signal transmission unit that receives the additional surface vector magnetic field data and transmits it to the host computer. The magnetic field response module calculates the additional effective magnetic field response data for each surface vector magnetic field component by subtracting the average valley magnetic field value from the peak magnetic field value of each surface vector magnetic field component from the 2-second additional surface vector magnetic field data of 15 measurement channels. The calculation method is as follows: ， In the formula, k Channel number, D k for k Additional effective magnetic field response data for the channel, in tons (T). D kp for k The mean peak magnetic field of the channel, in tons (T). D kv for k Mean magnetic field at the bottom of the channel, unit: T; The additional composite magnetic field module records the locations of five additional surface measuring points and calculates the additional composite magnetic field at these five points at different elevations. The calculation method is as follows: ， In the formula, d 1~ d 5 represents the additional composite magnetic field at five additional surface measuring points at five different elevations, in tons. D 1~ D 15 The data represent the additional effective magnetic field response data for measurement channels 1 through 15, in tons (T).

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