A method and system for fast reconfiguration of grounding grid topology based on TMR tunnel magnetoresistance sensor

Abstract

The application discloses a grounding net topology structure quick reconstruction method and system based on a TMR tunnel magnetoresistance sensor, and the method is a quick reconstruction method based on the TMR tunnel magnetoresistance sensor and a "circumferential paving method" topology structure; wherein the method can greatly reduce the volume of a power system current sensor, and is helpful to realize convenient live installation; the "circumferential method" is used for detecting the overall trend of the grounding net branch near a grounding down conductor, so that the grounding net main net conductor positioning can be realized by only obtaining the test point branch condition, and the grounding net positioning process and flow are greatly reduced; the "paving method" uses a "node searching" method to efficiently replace a "branch searching" method in related research, and uses a pair of nodes to determine the existing grounding net branch. The whole measurement process of the application is simple to operate, the effective data amount is reduced, the detection process is greatly reduced, and the strong anti-interference property in an extreme test environment is obtained.

Description

Technical Field

[0001] This invention belongs to the field of substation grounding grid technology, and relates to a method for rapid reconstruction of grounding grid topology, particularly a method and system for rapid reconstruction of grounding grid topology based on TMR tunnel magnetoresistive sensors combined with the "circumferential method + paving method". Background Technology

[0002] As a crucial guarantee for the safe, reliable, and stable operation of a power system, the grounding grid is essential. When its performance deteriorates and it fails to quickly conduct lightning strikes or large short-circuit currents to the ground, voltage backflash can occur, severely endangering the electrical equipment and personnel safety of the substation. Therefore, regularly monitoring the grounding performance of the substation's grounding grid is a vital task in substation safety inspections.

[0003] In my country, galvanized flat steel with specifications of 5mm×50mm and 6mm×60mm is the primary choice for conductor materials in large grounding grids of substations; for transmission lines, round steel with a diameter of 10-20mm is commonly used. Grounding grids laid using flat or round steel are generally rectangular meshes, laid at a depth of 0.6m-2m underground, and the area of ​​the grounding grid is generally the same as the construction area of ​​the substation or power plant. Due to the complex soil environment, after the grounding grid conductors have been buried underground for a long time, the metal will corrode in the soil, generally through electrochemical corrosion.

[0004] When the conductors of a grounding grid corrode, their cross-sectional area decreases, leading to increased grounding resistance and reduced grounding performance. In extreme cases, this can cause conductor breakage, rendering the grounding grid ineffective in protecting electrical equipment and personnel, posing a serious accident threat. Furthermore, since the grounding grid is laid underground using welded galvanized flat steel, negligence during construction can result in incomplete or missed welds, causing corrosion and failure at the weld points, leading to poor electrical connections and affecting the grounding grid's performance. Substation power outages due to substandard grounding grid performance are also frequent occurrences.

[0005] In order to more clearly understand the performance status of the grounding grid, a hidden project, relevant regulations have relatively detailed provisions on the inspection of the grounding grid status of the power system. According to the requirements of DL / T 596-2005 "Regulations for Preventive Tests of Electric Equipment" for grounding equipment of various types of substations: 1) The detection interval of the grounding resistance of various electric equipment shall not exceed 6 years. Considering that seasonal changes will affect the soil resistivity, the grounding resistance below 0.5 Ω is qualified; 2) The test period of the conduction resistance between the down-lead of the electric equipment and the grounding grid shall not exceed 3 years; 3) When the substation has been in operation for more than 10 years, it is necessary to conduct sampling excavation of the grounding grid. According to the on-site situation, randomly select 5-8 points of the grounding grid for excavation inspection, and observe the corrosion condition of the conductor to judge whether it is necessary to increase the number of excavation points or expand the excavation area. However, according to the current maintenance methods, there are the following problems in actual projects: 1) According to relevant statistical data, there are approximately 10,000 substations in the country that have been in operation for more than ten years and need to conduct excavation detection of the grounding grid, which will bring heavy work pressure to the power maintenance department and the economic cost is high. 2) The typical sampling excavation process needs to select excavation points according to the design drawings of the grounding grid. However, for some substations, especially the old substations built more than 15 years ago, there are problems with the loss of grounding grid drawings. In addition, for the modified grounding grid, there is a common phenomenon that the drawings are not updated or the modification plan is not recorded. There are also situations where the actual buried positions of some main grounding grid conductors are inconsistent with the design plan or have large errors. The problem of unknown conductor positions and burial depths caused by the above situations brings the problem of "not being able to dig" to the sampling excavation project. 3) Relevant scientific research institutions have carried out a lot of research on the corrosion diagnosis of the grounding grid and achieved some results. Among them, new technologies related to accurate corrosion diagnosis, especially the local corrosion point positioning technology that the operation and maintenance department pays more attention to, generally need to be carried out under the condition of known accurate buried positions or topological structures of the grounding grid conductors. Therefore, problems such as the long-term loss of drawings or the inconsistency between the drawings and the actual situation also hinder the application and promotion of the non-excavation diagnosis technology of the grounding grid; 4) For the grounding grid with serious corrosion, it is necessary to carry out the grounding grid transformation work. According to relevant research, the formulation of the transformation plan needs to be calculated and verified to achieve optimal design, and this process also depends on the topological structure and attribute parameters of the existing grounding grid.

[0006] Therefore, researching the conductor positioning and topological structure reconstruction technology of the grounding grid is a necessary means to achieve the lean management of the grounding grid. This technology can provide point selection guidance for traditional excavation-type detection methods and also provide strong support for non-excavation local corrosion positioning technology. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the defects of the prior art and to provide a method and system for rapid reconstruction of the grounding grid topology for testing in actual engineering, so as to quickly and efficiently determine the topology of the grounding grid.

[0008] To achieve the above objectives, the present invention provides a technical solution as follows: a method for rapid reconstruction of grounding grid topology based on a TMR tunnel magnetoresistive sensor, comprising:

[0009] Step 1: Detect the initial conductor using the circular method, the differential method, and a device based on a TMR tunnel magnetoresistive sensor: In the absence of any known grounding conductor location, first determine the measurement starting point, select a grounding down conductor near a corner or edge of the substation, and use this grounding down conductor as the center to measure the circumferential magnetic field distribution with radii of 1 meter and 2 meters respectively. Detect the conductor location using the differential method and the conductor direction using the circular method.

[0010] Step 2: Measure the magnetic field distribution using a sensor based on TMR tunneling magnetoresistive (TMR).

[0011] Based on the output characteristics of the TMR chip, the relationship between the TMR chip output voltage, the TMR chip supply voltage, and the magnitude of the magnetic field in the sensitive direction of the TMR chip is derived. The chip supply voltage is determined through the aforementioned calculations and analysis, and the relationship between the chip output voltage and the magnitude of the current in the measured conductor is derived, as expressed in the following expression:

[0012] ① Establish the relationship between magnetic field and current. According to Biot-Saffar's law, the magnetic field generated in space by a current-carrying conductor can be expressed as:

[0013]

[0014] ② Assuming a current flows inside a long straight conductor, and the distance between a point P in space and the conductor CD is r0, and the angles between the line connecting point P to the two ends of the long straight conductor and the conductor are θ1 and θ2 respectively, the magnetic field at point P can be expressed as:

[0015]

[0016] As can be seen from the characteristics of the TMR sensor, within a certain range of magnetic field strength, the output voltage of the TMR sensor is linearly related to the magnitude of the surrounding magnetic field. When a current I flows through the conductor, according to the right-hand screw rule, a helical magnetic field will be generated around the conductor, and the magnitude of the magnetic field is proportional to the magnitude of the current inside the conductor.

[0017] The output voltage of the bridge structure inside the TMR sensor is linearly related to the resistance of the tunneling magnetoresistive element. Therefore, the change in the external magnetic field caused by the change in conductor current, and the resulting change in the resistance of the tunneling magnetoresistive element, will linearly affect the output voltage of the TMR bridge structure. Thus, the TMR tunneling magnetoresistive sensor can measure the current of the corresponding conductor.

[0018] Step 3: Perform a higher-order differential on the magnetic field distribution curve measured by a device based on a TMR tunnel magnetoresistive sensor. The peak point corresponding to the differential curve is the conductor position. At the same time, use the side peak characteristics of the higher-order differential function to determine the conductor burial depth.

[0019] Step 4: When using the circular method to detect the conductor's direction, select the two peak points that are closest to each other measured by the double circles and connect them into a line. Select a straight line with an angle of approximately 90° between the two lines as the two initial conductors. These two straight lines are the x-axis and y-axis, respectively. Establish a rectangular coordinate system with the intersection of the two lines as the origin.

[0020] Step 5: Establish an observation line along the x-axis in the established rectangular coordinate system. Use a device based on a TMR tunnel magnetoresistive sensor to measure the magnetic field components along the line. Based on the magnetic field differential method position detection principle described in Step 3, determine the longitudinal conductor distribution according to the peak position after differentiation of the x-axis observation line, and select 1-3 sets of straight lines that are far from the x-axis and parallel to the x-axis for verification measurement.

[0021] Step 6: After determining the part of the grounding grid topology parallel to the y-axis of the rectangular coordinate system established in Step 4, repeat Step 5 in the y-axis direction of the rectangular coordinate system to obtain the part of the grounding grid topology parallel to the x-axis, determine the distribution of the transverse conductors, and thus obtain the rough topology of the entire grounding grid.

[0022] Step 7: Further refine the rough topology of the grounding grid;

[0023] Step 8: Determine the grounding grid topology diagram based on the locations of paired nodes.

[0024] Furthermore, in step 3, the higher-order differential step is as follows: According to Ampere's circuital law, the magnetic induction intensity B generated by the current-carrying conductor at point P, parallel to the ground, is... y (y) is:

[0025]

[0026] in, h represents the burial depth of the grounding grid branch, y represents the horizontal distance from point p to the grounding conductor, L1 represents the length of one conductor, L2 represents the length of another conductor, μ represents the permeability, and I represents the current injected into the conductor.

[0027] Find B yThe second and fourth derivatives of (y) are ignored.

[0028]

[0029]

[0030] Higher-order differential function |B y (y)|、 and The conductor exhibits a main peak characteristic, and its coordinates are used to determine the conductor's location.

[0031] Furthermore, in step 3, the burial depth of the conductor is determined using the side-peak characteristics of the higher-order differential function:

[0032] Let the shape function The peak distance between the main peak and the side peak is L y2 L y4 Find B y The third and fifth derivatives of (y), while neglecting the third and fifth derivatives of (y), get:

[0033]

[0034]

[0035] make and We can obtain: L y2 ≈h,

[0036] The above formula represents the shape function The peak distance between the main peak and the side peak is L y2 L y4 The relationship between the grounding grid branch burial depth h and the grounding grid branch burial depth is determined by solving the shape function. or The peak distance L between the main peak and the side peaks y2 or L y4 The burial depth h of the grounding grid branch is obtained directly.

[0037] Furthermore, the specific details of the rough topology of the grounding grid are as follows:

[0038] For the conductors inside the coarse topology of the grounding grid obtained in step 6, a device based on a TMR tunnel magnetoresistive sensor is used for refined measurement. The standard order is to measure the conductors parallel to the y-axis first, and then the conductors parallel to the x-axis. The coarse topology of the grounding grid determined in step 6 is refined according to the position of the peak of the magnetic field differential image obtained in each measurement, resulting in a refined schematic diagram of the grounding grid topology.

[0039] Furthermore, the specific details of determining the topology based on the positions of paired nodes are as follows:

[0040] For any grounding electrode branch, its nodes must appear in pairs on the adjacent vertical branches. After the node location is completed based on the initial judgment branch, it is necessary to determine whether each branch exists according to the principle of paired nodes to avoid misjudging the "T" structure caused by the initial judgment branch. At the same time, the conductor position is corrected by using the average value of the node position, and finally an accurate schematic diagram of the grounding grid topology is obtained.

[0041] Another technical solution adopted in this invention is: a method for rapid reconstruction of grounding grid topology based on a TMR tunnel magnetoresistive sensor, which includes:

[0042] The initial conductor detection unit uses the circumferential method, the differential method, and a device based on a TMR tunnel magnetoresistive sensor to detect the initial conductor: In the absence of any unknown grounding conductor location, the starting point of the measurement is first determined, and a grounding down conductor near the corner or edge of the substation is selected. With the grounding down conductor as the center, the circumferential magnetic field distribution with radii of 1 meter and 2 meters is measured respectively. The conductor location is detected by a device based on a TMR tunnel magnetoresistive sensor and the differential method, and the conductor direction is detected by the circumferential method.

[0043] The magnetic field distribution measurement unit employs a device based on a TMR tunneling magnetoresistive (TMR) sensor to measure the magnetic field distribution. The TMR-based current sensor includes a TMR chip measurement module, a data processing module, a display module, a temperature detection module, a control module, a heating module, and a housing. The TMR chip measurement module generates a voltage output signal under the influence of the conductor current's magnetic field and transmits the signal to the internal data processing module via a signal transmission line. The data processing module processes the data according to the TMR-based current measurement method, and, combined with the voltage signal gain of the signal amplification module within the data processing module, writes a corresponding microcontroller program algorithm. The algorithm uses an FFT algorithm for noise reduction to obtain an accurate current value of the measured conductor, which is then displayed on the display module. The control module consists of an integrated microcontroller. By selecting a military-grade main control chip with strong low-temperature resistance, it can operate normally in extremely cold temperature ranges and can be directly cold-started, allowing the core program of the TMR-based current sensor to start normally under extreme temperature conditions. During the measurement process, the temperature detection module monitors the internal temperature of the device and transmits the result to the control module. When the acquired temperature value is lower than a preset temperature threshold, the control module activates the heating module. Subsequently, when the temperature value acquired by the temperature detection module exceeds the preset upper temperature threshold, the control module deactivates the heating module. This cycle repeats to ensure that the internal temperature of the device remains within a suitable range. The FFT algorithm denoising process specifically includes:

[0044] ① Use an ADC to read the voltage output from the TMR sensor. ② Perform an FFT transform on the acquired discrete-time signal sequence. ③

[0045] The transformed spectrum is processed, and unwanted signals are set to zero to eliminate noise at specific frequency components.

[0046] The processed spectral signal is then subjected to an IFFT transform to obtain the filtered signal.

[0047] The higher-order differential unit performs higher-order differentiation on the magnetic field distribution curve measured by a device based on a TMR tunnel magnetoresistive sensor. The peak point corresponding to the differential curve is the conductor position. At the same time, the burial depth of the conductor is determined by using the side peak characteristics of the higher-order differential function.

[0048] In the unit for establishing a rectangular coordinate system, when using the circular method to detect the direction of a conductor, the two peak points that are closest to each other measured by the double circles are selected and connected to form a line. The two lines with an angle of approximately 90° are selected as the two initial conductors. These two lines are the x-axis and y-axis, respectively, and the intersection of the two lines is taken as the origin to establish a rectangular coordinate system.

[0049] The conductor distribution determination unit establishes an observation line along the x-axis in the established rectangular coordinate system. A device based on a TMR tunneling magnetoresistive sensor is used to measure the magnetic field components along the line. The device based on a TMR tunneling magnetoresistive sensor, described by a higher-order differential unit, and the magnetic field differential method position detection principle are used to determine the longitudinal conductor distribution based on the peak position after differentiation of the x-axis observation line. 1-3 sets of straight lines far from the x-axis and parallel to the x-axis are selected for verification measurement.

[0050] The grounding grid coarse topology acquisition unit, after determining the part of the grounding grid topology parallel to the y-axis of the rectangular coordinate system established by the rectangular coordinate system establishment unit, repeats the method used by the conductor distribution determination unit in the y-axis direction of the rectangular coordinate system to obtain the part of the grounding grid topology parallel to the x-axis, determines the transverse conductor distribution, and thus obtains the entire grounding grid coarse topology.

[0051] Grounding grid topology refinement unit, refines the coarse topology of the grounding grid;

[0052] The grounding grid topology diagram determination unit determines the grounding grid topology diagram based on the positions of paired nodes.

[0053] The beneficial technical effects of this invention are as follows:

[0054] This invention combines a TMR tunnel magnetoresistive sensor with the "circumferential method" and the "paving method". Based on electromagnetic field theory, it adopts the magnetic field differential method detection principle, which is simple to operate and can directly draw the topology diagram of the grounding grid. Furthermore, it can be applied to the diagnosis of problems such as corrosion and fracture of the grounding grid. The results show that the missed detection rate of this invention is low and the measurement efficiency is nearly twice that of ordinary methods. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of the grounding grid model in a specific embodiment of the present invention;

[0056] Figure 2 This is a schematic diagram illustrating how a circle is approximated as a regular octagon in a specific embodiment of the present invention;

[0057] Figure 3 This is a schematic diagram illustrating the principle of the circumferential detection method in a specific embodiment of the present invention;

[0058] Figure 4 This is a schematic diagram showing the results of calculating the initial coordinate system using the circumferential method in a specific embodiment of the present invention;

[0059] Figure 5 This is a graph showing the magnetic field differential curves along the x-axis at the locations of some conductor nodes in a specific embodiment of the present invention;

[0060] Figure 6 This is a graph showing the magnetic field differential curves along the y-axis at the locations of some conductor nodes in a specific embodiment of the present invention;

[0061] Figure 7 This is a rough topology diagram of the grounding grid as initially determined in a specific embodiment of the present invention;

[0062] Figure 8 This is a schematic diagram of a detailed measurement position in a specific embodiment of the present invention;

[0063] Figure 9 This is a diagram showing the differential calculation results along line L3 in a specific embodiment of the present invention;

[0064] Figure 10 This is a diagram of the grounding grid topology obtained after refining the topology along line L4 in a specific embodiment of the present invention.

[0065] Figure 11 This is a diagram showing the differential calculation results along line L4 in a specific embodiment of the present invention;

[0066] Figure 12 This is a diagram showing the differential calculation results along line L5 in a specific embodiment of the present invention;

[0067] Figure 13This is a grounding grid topology diagram obtained by refining the paving method along L4 and L5 in a specific embodiment of the present invention;

[0068] Figure 14 This is a diagram showing the results of the differential calculation along the longitudinal direction at 0m in a specific embodiment of the present invention;

[0069] Figure 15 This is a diagram showing the differential calculation results along the longitudinal direction at 5m in a specific embodiment of the present invention;

[0070] Figure 16 This is a diagram showing the results of the differential calculation along the longitudinal direction at 10m in a specific embodiment of the present invention;

[0071] Figure 17 This is a diagram showing the results of the differential calculation along the longitudinal direction at 15m in a specific embodiment of the present invention.

[0072] Figure 18 The final grounding grid topology diagram is drawn for a specific embodiment of the present invention. Detailed Implementation

[0073] The technical solution of the present invention will now be clearly and thoroughly described in conjunction with the accompanying drawings.

[0074] Example

[0075] This embodiment provides a method for rapid reconstructing of grounding grid topology, including the following steps:

[0076] See Figure 1 The circular differential method and a device based on a TMR tunnel magnetoresistive sensor are used to detect the initial conductor: When the location of any grounding electrode is unknown, the starting point of the measurement must first be determined. To do this, a grounding down conductor located near a corner or edge of the substation is selected. Using this down conductor as the center, the magnetic field distribution along circles with radii of 1 meter and 2 meters is measured respectively. The conductor's position is detected using a device based on a TMR tunnel magnetoresistive sensor and the differential method, while the conductor's trajectory is detected using the circular method.

[0077] The measurement of a circular magnetic field employs a 0.8m long device based on a TMR tunneling magnetoresistive sensor. This device consists of a measurement array of eight adjacent magnetic field coils spaced 0.1m apart. The circle is approximated as a regular octagon, and the measurement is performed by moving the device counterclockwise. (See [link to documentation]). Figure 2 .

[0078] See Figure 3The conductor orientation is detected using the circular method. The two peak points that are closest to each other measured by the double circle are selected and connected to form a line. The two lines with an angle of approximately 90° are selected as the two initial conductors. These two lines are the x-axis and y-axis, respectively. A rectangular coordinate system is established with the intersection of the two lines as the origin.

[0079] See Figure 4 Differential position detection uses differential formulas

[0080]

[0081] The peak point corresponding to the differential curve is the conductor's position. The specific steps are as follows: Perform a higher-order differential on the magnetic field distribution curve measured by the differential position detection device. The peak point corresponding to the differential curve is the conductor's position. According to Ampere's circuital law, the magnetic induction intensity B generated by the current-carrying conductor at point P, parallel to the ground, is... y (y) is:

[0082]

[0083] in

[0084] Find the second and fourth derivatives of formula (2), while neglecting the second and fourth derivatives.

[0085]

[0086]

[0087] Higher-order differential function B y (y) and It exhibits both primary peak and secondary peak characteristics. Let the shape function... The peak distance between the main peak and the side peak is L y2 L y4 .

[0088] Find the third and fifth derivatives of formula (2), while neglecting the third and fifth derivatives.

[0089]

[0090]

[0091] make and We can obtain:

[0092] L y2 ≈h (7)

[0093]

[0094] The above formula concisely describes the shape function. The peak distance between the main peak and the side peak is L y2 L y4 The relationship between the grounding grid branch burial depth h and the grounding grid branch burial depth is determined by solving the shape function. or The peak distance L between the main peak and the side peaks y2 or L y4 The burial depth h of the grounding grid branch can be obtained directly.

[0095] In the established rectangular coordinate system, a device based on a TMR tunnel magnetoresistive sensor is used to measure the magnetic field components along the x-axis. The measurement results are obtained using the position detection principle of the TMR tunnel magnetoresistive sensor. Figure 5 The y-axis conductor distribution of the grounding grid topology is determined by the peak position of the differential magnetic field image measured along the x-axis and marked with a straight line perpendicular to the x-axis.

[0096] After determining the portion of the grounding grid topology parallel to the y-axis of the established rectangular coordinate system, the magnetic field differential method for position detection is repeatedly applied along the y-axis direction of the rectangular coordinate system. The measurement results are shown in [reference needed]. Figure 6 This yields the portion of the grounding grid topology parallel to the x-axis, allowing for a preliminary rough estimate of the entire grounding grid's topology. (See [link to relevant documentation]). Figure 7 .

[0097] The coarse grounding grid topology was further refined. A device based on a TMR tunnel magnetoresistive sensor was used to refine the conductors within the initially drawn coarse grounding grid structure. The standard sequence was to measure conductors parallel to the y-axis first, followed by conductors parallel to the x-axis. The coarse network topology was refined based on the peak positions of the differential magnetic field images obtained from each measurement, resulting in a more accurate schematic diagram of the grounding grid topology. (See attached diagram). Figure 8 .

[0098] The methods for further refining the grounding grid topology are described in detail below:

[0099] See Figure 8 along Figure 7 Magnetic field measurements can be continued on other branches of the grounding grid to further refine and verify the distribution of each branch. For example, first determine the other nodes on the branch parallel to the x-axis at node (0, 5), i.e., measure... Figure 7 The magnetic field distribution along the straight line L3 is shown in the figure. The black line in the figure represents the current grounding grid conductor structure. L3 is on the ground surface and directly opposite the conductor below.

[0100] Differentiate the measured magnetic field and see the results. Figure 9Therefore, it can be determined that there are five nodes on this branch, four of which are connected to... Figure 7 The initial model was consistent with the previous one, but a new branch was found at x = 5m. Therefore, in Figure 7 Add a path to the existing grounding grid topology model. See the modified model below. Figure 10 .

[0101] Similarly, measurement Figure 10 The magnetic field distributions on L4 and L5 are shown in the figure below. The differential results are as follows: Figure 11 and Figure 12 .

[0102] See Figure 11 It can be seen that there are five peaks, i.e., five branch nodes, along L4, and they correspond one-to-one with the nodes of L3. See [link / reference]. Figure 12 It can be seen that there are only three nodes along L5, so there is no conductor for the missing peak between L4 and L5, meaning there is no grounding conductor at 5m and 15m. Based on these two sets of data, the grounding network topology should be modified (see [reference needed]). Figure 13 .

[0103] contrast Figure 1 Building model structure and Figure 13 The model structure is currently available, and it can be seen that only one branch remains undetected. This is achieved through transverse magnetic field measurements. Figure 13 The topological structure model is given, but the remaining topological structure still needs to be drawn by measuring the longitudinal magnetic field distribution. Longitudinal magnetic field measurements and differential analysis are performed at 0m, 5m, 10m, 15m, and 20m.

[0104] The differential calculation results after measuring the magnetic field distribution at 0m are shown below. Figure 14 There are four peaks, i.e. four branch nodes, along the longitudinal direction. Only the peak point at 10m is missing. Therefore, there are four conductors at 0m, 5m, 15m, and 20m, but no conductor at 10m.

[0105] The differential calculation results after measuring the magnetic field distribution at 5m are shown below. Figure 15 There are three peaks, i.e. three branch nodes, along the longitudinal direction. The peaks at 0m and 20m are missing. Therefore, there are three conductors at 5m, 10m and 15m, but no conductors at 0m and 20m.

[0106] The differential calculation results after measuring the magnetic field distribution at 10m are shown below. Figure 16 There are five peaks, i.e. five branch nodes, along the longitudinal direction. There are no missing peaks, so there are conductors at 0m, 5m, 10m, 15m, and 20m.

[0107] The differential calculation results after measuring the magnetic field distribution at 15m are shown below. Figure 17There are four peaks, i.e. four branch nodes, along the longitudinal direction. The peak point at 0m is missing. Therefore, there are four conductors at 5m, 10m, 15m, and 20m, but no conductor at 0m.

[0108] The differential calculation results after measuring the magnetic field distribution at 20m are shown below. Figure 18 There are five peaks, i.e. five branch nodes, along the longitudinal direction. There are no missing peaks, so there are conductors at 0m, 5m, 10m, 15m, and 20m.

[0109] Example 2

[0110] This embodiment provides a method for rapid reconstruction of grounding grid topology based on a TMR tunnel magnetoresistive sensor, which includes:

[0111] The initial conductor detection unit uses the circular method, the differential method, and a device based on a TMR tunnel magnetoresistive sensor to detect the initial conductor: when the location of any grounding conductor is unknown, the starting point of the measurement is first determined, and a grounding down conductor near the corner or edge of the substation is selected. With the grounding down conductor as the center, the circumferential magnetic field distribution with radii of 1 meter and 2 meters is measured respectively. The conductor position is detected by a device based on a TMR tunnel magnetoresistive sensor, and the conductor direction is detected by the circular method.

[0112] The magnetic field distribution measurement unit uses a device based on a TMR tunnel magnetoresistive sensor to measure the magnetic field distribution;

[0113] The higher-order differential unit performs higher-order differentiation on the magnetic field distribution curve measured by a device based on a TMR tunnel magnetoresistive sensor. The peak point corresponding to the differential curve is the conductor position. At the same time, the burial depth of the conductor is obtained by using the side peak characteristics of the higher-order differential function.

[0114] In the unit for establishing a rectangular coordinate system, when using the circular method to detect the direction of a conductor, the two peak points that are closest to each other measured by the double circles are selected and connected to form a line. The two lines with an angle of approximately 90° are selected as the two initial conductors. These two lines are the x-axis and y-axis, respectively, and the intersection of the two lines is taken as the origin to establish a rectangular coordinate system.

[0115] The conductor distribution determination unit establishes an observation line along the x-axis in the established rectangular coordinate system. A device based on a TMR tunnel magnetoresistive sensor is used to measure the magnetic field components along the line. The longitudinal conductor distribution is determined based on the peak position after differentiation of the x-axis observation line according to the magnetic field differentiation method position detection principle described by the higher-order differential unit. 1-3 sets of straight lines far from the x-axis and parallel to the x-axis are selected for verification measurement.

[0116] The grounding grid coarse topology acquisition unit, after determining the part of the grounding grid topology parallel to the y-axis of the rectangular coordinate system established by the rectangular coordinate system establishment unit, repeats the method used by the conductor distribution determination unit in the y-axis direction of the rectangular coordinate system to obtain the part of the grounding grid topology parallel to the x-axis, determines the transverse conductor distribution, and thus obtains the entire grounding grid coarse topology.

[0117] Grounding grid topology refinement unit, refines the coarse topology of the grounding grid;

[0118] The grounding grid topology diagram determination unit determines the grounding grid topology diagram based on the positions of paired nodes.

[0119] In the aforementioned higher-order differential unit, the steps of higher-order differentiation are as follows: According to Ampere's circuital law, the magnetic induction intensity B generated by the current-carrying conductor at point P, parallel to the ground, is... y (y) is:

[0120]

[0121] in, h represents the burial depth of the grounding grid branch, y represents the horizontal distance from point p to the grounding conductor, L1 represents the length of one conductor, L2 represents the length of another conductor, μ represents the permeability, and I represents the current injected into the conductor.

[0122] Find B y The second and fourth derivatives of (y) are ignored.

[0123]

[0124]

[0125] Higher-order differential function |B y (y)|、 and The conductor exhibits a main peak characteristic; its coordinates are used to determine the conductor's location. The burial depth is determined using the side peak characteristics of higher-order differential functions.

[0126] Let the shape function The peak distance between the main peak and the side peak is L y2 L y4 Find B y The third and fifth derivatives of (y), while neglecting the third and fifth derivatives of (y), get:

[0127]

[0128]

[0129] make and We can obtain: L y2 ≈h,

[0130] The above formula represents the shape function The peak distance between the main peak and the side peak is L y2 L y4 The relationship between the grounding grid branch burial depth h and the grounding grid branch burial depth is determined by solving the shape function. or The peak distance L between the main peak and the side peaks y2 or L y4 The burial depth h of the grounding grid branch is obtained directly.

[0131] The specific details of the grounding grid topology refinement unit are as follows:

[0132] For the conductors inside the coarse topology of the grounding grid obtained by the grounding grid coarse topology acquisition unit, a device based on a TMR tunnel magnetoresistive sensor is used for refined measurement. The standard order is to first measure the conductors parallel to the y-axis and then measure the conductors parallel to the x-axis. Based on the position of the peak value of the magnetic field differential image obtained from each measurement, the coarse topology of the grounding grid determined by the grounding grid coarse topology acquisition unit is refined to obtain a refined grounding grid topology schematic diagram.

[0133] The specific content of the unit for determining the grounding grid topology diagram is as follows:

[0134] For any grounding electrode branch, its nodes must appear in pairs on the adjacent vertical branches. After the node location is completed based on the initial judgment branch, it is necessary to determine whether each branch exists according to the principle of paired nodes to avoid misjudging the "T" structure caused by the initial judgment branch. At the same time, the conductor position is corrected by using the average value of the node position, and finally an accurate schematic diagram of the grounding grid topology is obtained.

[0135] The above embodiments should be understood as illustrative only and not as limiting the scope of protection of the present invention. After reading the description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent changes and modifications also fall within the scope defined by the claims of the present invention, "A Method and System for Rapid Reconstruction of Grounding Grid Topology Based on TMR Tunnel Magnetoresistive Sensor".

Claims

1. A method for rapid reconstructing of grounding grid topology based on TMR tunnel magnetoresistive sensors. Its features include the following steps: Step 1: A device based on a TMR tunnel magnetoresistive sensor is used to measure the magnetic field distribution and obtain the dynamic current values ​​of its branch nodes. Then, the magnetic induction intensity of the measurement area S is indirectly obtained through conversion, including the magnetic induction intensity perpendicular to the ground surface. and magnetic induction intensity parallel to the Earth's surface The specific measurement conversion formula is as follows: ① Establish the relationship between magnetic field and current. According to Biot-Saffar's law, the magnetic field generated in space by a current-carrying conductor can be represented as: ； ②Assume that a current flows inside a long straight conductor, and the distance between a point P in space and the conductor CD is... The angles between the line connecting point P to the two ends of the long straight conductor and the conductor are respectively... and The magnetic field at point P is represented as: ； As can be seen from the characteristics of the TMR sensor, within a certain range of magnetic field strength, the output voltage of the TMR sensor is linearly related to the magnitude of the surrounding magnetic field; when current flows through the conductor... When the current is applied, according to the right-hand screw rule, a spiral magnetic field will be generated around the conductor, and the magnitude of the magnetic field is proportional to the magnitude of the current inside the conductor. ③ The output voltage of the bridge structure inside the TMR sensor is linearly related to the resistance of the tunneling magnetoresistive element. Therefore, the change in the external magnetic field caused by the change in conductor current, and the resulting change in the resistance of the tunneling magnetoresistive element, will linearly affect the output voltage of the TMR bridge structure. Thus, the TMR tunneling magnetoresistive sensor measures the current of the corresponding conductor. Step 2: Detect the initial conductor using the circumferential method, the differential method, and a device based on a TMR tunnel magnetoresistive sensor: In the absence of any known grounding conductor location, first determine the measurement starting point, select a grounding down conductor near a corner or edge of the substation, and use this grounding down conductor as the center to measure the magnetic field distribution around the circumference with radii of 1 meter and 2 meters respectively. The conductor location is detected using the differential method, and the conductor direction is detected using the circumferential method. Step 3: Perform a higher-order differential on the magnetic field distribution curve measured by a device based on a TMR tunnel magnetoresistive sensor. The peak point corresponding to the differential curve is the conductor position. At the same time, use the side peak characteristics of the higher-order differential function to determine the conductor burial depth. Step 4: When using the circular method to detect the conductor's direction, select the two peak points that are closest to each other measured by the double circles and connect them into a line. Select a straight line with an angle of approximately 90° between the two lines as the two initial conductors. These two straight lines are the x-axis and y-axis, respectively, and establish a rectangular coordinate system with the intersection of the two lines as the origin. Step 5: Establish an observation line along the x-axis in the established rectangular coordinate system. Use a device based on a TMR tunnel magnetoresistive sensor to measure the magnetic field components along the line. Based on the detection principle of the device based on a TMR tunnel magnetoresistive sensor described in Step 3, determine the longitudinal conductor distribution according to the peak position after differentiation of the x-axis observation line, and select 1-3 sets of straight lines that are far from the x-axis and parallel to the x-axis for verification measurement. Step 6: After determining the part of the grounding grid topology parallel to the y-axis of the rectangular coordinate system established in Step 4, repeat Step 5 in the y-axis direction of the rectangular coordinate system to obtain the part of the grounding grid topology parallel to the x-axis, determine the distribution of the transverse conductors, and thus obtain the rough topology of the entire grounding grid. Step 7: Refine the rough topology of the grounding grid; Step 8: Determine the grounding grid topology diagram based on the paired node positions; The specific details of determining the topology based on the positions of paired nodes are as follows: For any grounding electrode branch, its nodes must appear in pairs on the adjacent vertical branches. After the node location is completed based on the initial judgment branch, it is necessary to determine whether each branch exists according to the principle of paired nodes to avoid misjudging the "T" structure caused by the initial judgment branch. At the same time, the conductor position is corrected by using the average value of the node position, and finally an accurate schematic diagram of the grounding grid topology is obtained. In step 3, the burial depth of the conductor is determined using the side-peak characteristics of the higher-order differential function: Let the shape function , The peak distance between the main peak and the side peaks is , Seeking The third and fifth derivatives, while neglecting ,get: ； ； make and ,get: , ; The above formula represents the shape function , The peak distance between the main peak and the side peaks is , Burial depth of grounding grid branch The relationship between them is solved by solving the shape functions. or Peak distance between the main peak and the side peaks or The burial depth of the grounding grid branch can be obtained directly. .

2. The method for rapid reconstruction of grounding grid topology based on a TMR tunnel magnetoresistive sensor according to claim 1, characterized in that, In step 3, the higher-order differential step is as follows: According to Ampere's circuital law, the magnetic induction intensity parallel to the ground generated by the current-carrying conductor at point P is... for: ； in, , , Indicates the burial depth of the grounding grid branch. L1 represents the horizontal distance from point p to the grounding conductor, L2 represents the length of one conductor, and L3 represents the length of the other conductor. Indicates magnetic permeability, Indicates the injected current into the conductor; Seeking The second and fourth derivatives, while neglecting : ， ； Higher-order differential functions , and The conductor exhibits a main peak characteristic, and its coordinates are used to determine the conductor's location.

3. The method for rapid reconstruction of grounding grid topology based on a TMR tunnel magnetoresistive sensor according to claim 1, characterized in that, The detailed content of the rough topology of the grounding grid is as follows: For the conductors inside the coarse topology of the grounding grid obtained in step 6, a device based on a TMR tunnel magnetoresistive sensor is used for refined measurement. The standard order is to measure the conductors parallel to the y-axis first, and then the conductors parallel to the x-axis. The coarse topology of the grounding grid determined in step 6 is refined according to the position of the peak of the magnetic field differential image obtained in each measurement, resulting in a refined schematic diagram of the grounding grid topology.

4. A rapid reconfiguration system for grounding grid topology based on a TMR tunnel magnetoresistive sensor, characterized in that, include: The initial conductor detection unit uses the circumferential method, the differential method, and a device based on a TMR tunnel magnetoresistive sensor to detect the initial conductor: In the absence of any unknown grounding conductor location, the starting point of the measurement is first determined, and a grounding down conductor near the corner or edge of the substation is selected. With the grounding down conductor as the center, the magnetic field distribution of the circumference with radii of 1 meter and 2 meters is measured respectively. The conductor location is detected by the differential method, and the conductor direction is detected by the circumferential method. The magnetic field distribution measurement unit uses a device based on a TMR tunnel magnetoresistive sensor to measure the magnetic field distribution. The current sensor based on TMR tunnel magnetoresistive sensor includes a TMR chip measurement module, a data processing module, a display module, a temperature detection module, a control module, a heating module, and a device housing. The TMR chip measurement module generates a voltage output signal under the action of the conductor current magnetic field and transmits the signal to the data processing module inside the device through a signal transmission line. The data processing module processes data according to the current measurement method based on TMR tunnel magnetoresistive (TMR). Combined with the voltage signal gain of the signal amplification module in the data processing module, a corresponding microcontroller program algorithm is written. The FFT algorithm is used in the program algorithm for noise reduction to obtain the accurate current value of the measured conductor. The current value of the conductor is then displayed on the display module. The control module consists of an integrated microcontroller. By selecting a military-grade main control chip with strong low-temperature resistance, it can operate normally in extremely cold temperature ranges and perform direct cold start, enabling the main program of the TMR tunnel magnetoresistive current sensor core module to start normally under extreme temperature conditions. During the measurement process, the temperature detection module detects the internal temperature of the device and transmits the detection result to the control module. When the acquired temperature value is lower than the preset temperature threshold, the control module starts the heating module. Subsequently, when the temperature value acquired by the temperature detection module exceeds the preset upper temperature threshold, the control module shuts off the heating module. This heating cycle is repeated to ensure that the internal temperature of the device remains within a suitable range. The FFT algorithm denoising process specifically includes: ① Use an ADC to read the voltage output from the TMR sensor; ② Perform FFT transformation on the acquired discrete-time signal sequence; ③ Process the transformed spectrum and set unwanted signals to zero to eliminate noise at specific frequencies; ④ Perform IFFT transformation on the processed spectrum signal to obtain the filtered signal; The higher-order differential unit performs higher-order differentiation on the magnetic field distribution curve measured by a device based on a TMR tunnel magnetoresistive sensor. The peak point corresponding to the differential curve is the conductor position. At the same time, the burial depth of the conductor is obtained by using the side peak characteristics of the higher-order differential function. In the unit for establishing a rectangular coordinate system, when using the circular method to detect the direction of a conductor, the two peak points that are closest to each other measured by the double circles are selected and connected to form a line. The two lines with an angle of approximately 90° are selected as the two initial conductors. These two lines are the x-axis and y-axis, respectively, and the intersection of the two lines is taken as the origin to establish a rectangular coordinate system. The conductor distribution determination unit establishes an observation line along the x-axis in the established rectangular coordinate system. A device based on a TMR tunnel magnetoresistive sensor is used to measure the magnetic field components along the line. The longitudinal conductor distribution is determined based on the peak position after differentiation of the x-axis observation line according to the magnetic field differentiation method position detection principle described by the higher-order differential unit. 1-3 sets of straight lines far from the x-axis and parallel to the x-axis are selected for verification measurement. The grounding grid coarse topology acquisition unit, after determining the part of the grounding grid topology parallel to the y-axis of the rectangular coordinate system established by the rectangular coordinate system establishment unit, repeats the method used by the conductor distribution determination unit in the y-axis direction of the rectangular coordinate system to obtain the part of the grounding grid topology parallel to the x-axis, determines the transverse conductor distribution, and thus obtains the entire grounding grid coarse topology. Grounding grid topology refinement unit, refines the coarse topology of the grounding grid; The grounding grid topology diagram determination unit determines the grounding grid topology diagram based on the positions of paired nodes. In the aforementioned higher-order differential unit, the conductor burial depth is determined using the side-peak characteristics of the higher-order differential function: Let the shape function , The peak distance between the main peak and the side peaks is , Seeking The third and fifth derivatives, while neglecting ,get: ； ； make and ,get: , ; The above formula represents the shape function , The peak distance between the main peak and the side peaks is , Burial depth of grounding grid branch The relationship between them is solved by solving the shape functions. or Peak distance between the main peak and the side peaks or The burial depth of the grounding grid branch can be obtained directly. .

5. The reconfiguration system according to claim 4, characterized in that, In the aforementioned higher-order differential unit, the steps of higher-order differentiation are as follows: According to Ampere's circuital law, the magnetic induction intensity parallel to the ground generated by the current-carrying conductor at point P is... for: ； in, , , Indicates the burial depth of the grounding grid branch. L1 represents the horizontal distance from point p to the grounding conductor, L2 represents the length of one conductor, and L1 represents the length of the other conductor. Indicates magnetic permeability, Indicates the injected current into the conductor; Seeking The second and fourth derivatives, while neglecting : ， ； Higher-order differential functions , and The conductor exhibits a main peak characteristic, and its coordinates are used to determine the conductor's location.

6. The reconfiguration system according to claim 4, characterized in that, The specific details of the grounding grid topology refinement unit are as follows: For the conductors inside the coarse topology of the grounding grid obtained by the grounding grid coarse topology acquisition unit, a device based on a TMR tunnel magnetoresistive sensor is used for refined measurement. The standard order is to first measure the conductors parallel to the y-axis and then measure the conductors parallel to the x-axis. The coarse topology of the grounding grid determined by the grounding grid coarse topology acquisition unit is refined according to the position of the peak of the magnetic field differential image obtained by each measurement, and a refined grounding grid topology schematic diagram is obtained. The specific content of the unit for determining the grounding grid topology diagram is as follows: For any grounding electrode branch, its nodes must appear in pairs on the adjacent vertical branches. After the node location is completed based on the initial judgment branch, it is necessary to determine whether each branch exists according to the principle of paired nodes to avoid misjudging the "T" structure caused by the initial judgment branch. At the same time, the conductor position is corrected by using the average value of the node position, and finally an accurate schematic diagram of the grounding grid topology is obtained.

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