Substation grounding system design method, device, equipment, storage medium and computer program product

Abstract

The application discloses a substation grounding system design method, device, equipment, storage medium and computer program product, relates to the grounding technology field of the power system, and the method comprises the steps of: soil resistivity testing of a substation in a target test range, constructing a horizontal layered soil model according to test data; determining the initial resistance reduction measures corresponding to the grounding grid of the substation according to the layered type of the horizontal layered soil model, and determining the initial voltage distribution measures on the basis of the initial resistance reduction measures; outputting the initial grounding system of the substation based on the initial resistance reduction measures and the initial voltage distribution measures; dynamically checking the safety of the initial grounding system, and iteratively correcting the initial grounding system according to the checking result to determine the optimal grounding system of the substation. The above method of the application can make the finally determined optimal grounding system effectively adapt to the complex dynamic environment in actual operation, thereby guaranteeing the normal operation of equipment and the safety of operation and maintenance personnel.

Description

Technical Field

[0001] This application relates to the field of power system grounding technology, and in particular to a design method, device, equipment, storage medium and computer program product for a substation grounding system. Background Technology

[0002] Substation grounding systems are a critical component in ensuring equipment and personnel safety. In related technologies, the design of substation grounding systems is typically based on given soil parameters and short-circuit current levels, using empirical formulas or simulation software to determine the grounding grid's resistance reduction measures and voltage equalization layout in one go. However, the actual operating environment presents complex dynamic factors such as seasonal variations in soil resistivity, permafrost thawing, and potential transfer from underground metal pipelines. This often leads to problems after grounding systems designed based on static parameters are put into operation, including excessive grounding resistance, uneven surface potential distribution, and contact or step voltage exceeding safety limits, seriously threatening the normal operation of equipment and the lives of maintenance personnel.

[0003] Therefore, how to make the designed grounding system effectively adapt to the complex dynamic environment in actual operation, so as to ensure the normal operation of equipment and the safety of maintenance personnel, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0004] The main purpose of this application is to provide a design method, device, equipment, storage medium and computer program product for a substation grounding system, which aims to solve the technical problem that existing substation grounding system design methods cannot guarantee the normal operation of equipment and the safety of maintenance personnel.

[0005] To achieve the above objectives, this application provides a substation grounding system design method, the method comprising the following steps: Soil resistivity tests were conducted on the substation within the target test area, and a horizontally layered soil model was constructed based on the test data. Based on the stratification type of the horizontal stratified soil model, the initial resistance reduction measures corresponding to the grounding grid of the substation are determined, and the initial equipotential bonding measures are determined based on the initial resistance reduction measures. Based on the initial resistance reduction measures and the initial voltage equalization measures, the initial grounding system of the substation is output; The initial grounding system is dynamically safety-checked, and the initial grounding system is iteratively corrected based on the check results to determine the optimal grounding system for the substation.

[0006] In one embodiment, the step of conducting soil resistivity tests on the substation within the target test range and constructing a horizontally layered soil model based on the test data includes: Soil resistivity tests were conducted on substations under different seasons within the target test range to obtain shallow soil resistivity and deep soil resistivity. The resistivity data of the shallow soil resistivity and the deep soil resistivity that belong to the preset terrain are corrected, and the corrected resistivity data and the uncorrected resistivity data are used as the test data of the substation. Based on the test data, the soil resistivity and thickness of each layer of the substation are inverted, and a horizontal stratified soil model of the substation is constructed based on the soil resistivity and thickness of each layer.

[0007] In one embodiment, before the step of conducting soil resistivity tests on the substation within the target test range and constructing a horizontally layered soil model based on the test data, the method further includes: Based on the equivalent side length of the substation's grounding grid, the vertical survey depth and horizontal survey range for soil resistivity testing are determined, and the maximum measurement electrode spacing is determined based on the vertical survey depth. Based on the vertical survey depth, the horizontal survey range, and the maximum measurement pole distance, the target test range for the substation when conducting soil resistivity testing is determined.

[0008] In one embodiment, the step of determining the initial resistance reduction measures corresponding to the substation's grounding grid based on the stratification type of the horizontally stratified soil model, and determining the initial equipotential bonding measures based on the initial resistance reduction measures, includes: Based on the stratification type of the horizontal stratified soil model, the corresponding initial drag reduction measures are selected from a preset mapping table, which contains a mapping relationship between several stratification types and several drag reduction measures. The initial voltage equalization measures are determined based on the initial resistance reduction measures. The initial voltage equalization measures include at least arranging the substation's grounding grid with unequal spacing grids and adding grounding electrodes as described in the initial resistance reduction measures at the edge of the grounding grid, in equipment concentration areas, or in areas where the potential gradient exceeds a preset threshold.

[0009] In one embodiment, the step of performing dynamic safety verification on the initial grounding system and iteratively correcting the initial grounding system based on the verification results includes: Based on the test data, construct the target soil model of the substation under different seasons; Based on the target soil model, the initial grounding system is checked for the effects of frozen soil to obtain a first check result, and the ground potential rise of the initial grounding system is determined based on the first check result. Based on the ground potential rise, determine whether to perform a risk check on the initial grounding system and obtain a second check result; The initial grounding system is iteratively corrected based on the first verification result, or the initial grounding system is iteratively corrected based on the first verification result and the second verification result.

[0010] In one embodiment, the step of determining whether to perform a risk check on the initial grounding system based on the ground potential rise and obtaining a second check result includes: If the ground potential rise is less than or equal to the first threshold, then no risk check is performed on the initial grounding system; If the ground potential rise is greater than the first threshold and less than or equal to the second threshold, then the risk check of the external metal pipe transfer potential of the initial grounding system is performed to obtain the second check result; If the ground potential rise is greater than the second threshold, the initial grounding system is subjected to external metal pipe transfer potential risk verification and surge arrester backflash risk verification to obtain the second verification result.

[0011] Furthermore, to achieve the above objectives, this application also proposes a substation grounding system design device, which includes: The soil model building module is used to conduct soil resistivity tests on substations within the target test range and build a horizontally layered soil model based on the test data. The initial measures determination module is used to determine the initial resistance reduction measures corresponding to the grounding grid of the substation based on the layering type of the horizontal layered soil model, and to determine the initial equipotential bonding measures based on the initial resistance reduction measures. The first output module is used to output the initial grounding system of the substation based on the initial resistance reduction measures and the initial voltage equalization measures; The second output module is used to perform dynamic safety verification on the initial grounding system and iteratively correct the initial grounding system based on the verification results to determine the optimal grounding system of the substation.

[0012] In addition, to achieve the above objectives, this application also proposes a substation grounding system design device, the device comprising: a memory, a processor, and a substation grounding system design program stored in the memory and executable on the processor, the substation grounding system design program being configured to implement the steps of the substation grounding system design method as described above.

[0013] In addition, to achieve the above objectives, this application also proposes a storage medium, which is a computer-readable storage medium, storing a substation grounding system design program thereon. When the substation grounding system design program is executed by a processor, it implements the steps of the substation grounding system design method as described above.

[0014] In addition, to achieve the above objectives, the present invention also provides a computer program product, which includes a substation grounding system design program. When the substation grounding system design program is executed by a processor, it implements the steps of the substation grounding system design method as described above.

[0015] This application conducts soil resistivity tests on substations within the target testing range, constructs a horizontally layered soil model based on the test data, determines the initial resistivity reduction measures corresponding to the substation's grounding grid based on the layering type of the horizontally layered soil model, and determines initial voltage equalization measures based on the initial resistivity reduction measures, outputs the initial grounding system of the substation based on the initial resistivity reduction measures and the initial voltage equalization measures, performs dynamic safety verification on the initial grounding system, and iteratively corrects the initial grounding system based on the verification results to determine the optimal grounding system of the substation. The method described in this application constructs a horizontally layered soil model based on soil resistivity test data, and determines initial resistance reduction and initial voltage equalization measures according to the layering type of the model. This avoids the problem of poor results caused by blindly applying resistance reduction methods, and enables the initial grounding system to initially match the actual soil structure. On this basis, by performing dynamic safety verification on the initial grounding system and iteratively correcting it based on the verification results, the safety hazards caused by neglecting dynamic factors such as seasonal changes, permafrost thawing, and transfer potential in static design are avoided. This enables the finally determined optimal grounding system to effectively adapt to the complex dynamic environment in actual operation, ensuring that the grounding resistance, surface potential distribution, contact voltage, and step voltage meet safety requirements under all operating conditions, and protecting the normal operation of equipment and the life safety of maintenance personnel. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart illustrating the first embodiment of the substation grounding system design method of this application; Figure 2 This is a flowchart illustrating the second embodiment of the substation grounding system design method of this application; Figure 3 This is a schematic diagram of soil resistivity testing for the substation grounding system design method of this application. Figure 4 A schematic diagram of a soil model for the substation grounding system design method of this application; Figure 5 This is a flowchart illustrating the third embodiment of the substation grounding system design method of this application; Figure 6 This is a schematic diagram showing the grounding resistance values ​​of the substation grounding system design method of this application under different frost layer thicknesses. Figure 7 This is a schematic diagram of the equivalent circuit for the backflashover of the surge arrester on the external line in the substation grounding system design method of this application. Figure 8 This is a structural block diagram of the first embodiment of the substation grounding system design device of this application; Figure 9 This is a structural schematic diagram of the substation grounding system design equipment of this application.

[0019] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] It should be understood that the specific embodiments described herein are only used to explain the technical solutions of this application and are not intended to limit this application.

[0021] It should be noted that the executing entity of the embodiments of this application can be a computing service device with data processing, network communication, and program execution functions, such as a smart wearable device, a personal computer, or a mobile phone, or an electronic device capable of realizing the above functions, such as the substation grounding system design device mentioned above. The following embodiments will be described using the substation grounding system design device as an example.

[0022] This application provides a substation grounding system design method, referring to... Figure 1 , Figure 1 This is a flowchart illustrating the first embodiment of the substation grounding system design method of this application. The technical solutions corresponding to the following steps in this embodiment constitute the first embodiment of the substation grounding system design method of this application.

[0023] In this embodiment, the substation grounding system design method includes the following steps: Step S10: Conduct soil resistivity tests on the substation within the target test range, and construct a horizontally layered soil model based on the test data.

[0024] It should be noted that the above target test range represents the overall range when conducting soil resistivity tests on substations, and the above horizontal stratified soil model represents a simplified approximate model of actual complex soil structures.

[0025] In practical implementation, a target test range that can cover the ground fault current dissipation area can be determined through simulation evaluation based on the voltage level of the proposed substation and the preliminary planned grounding grid size. Then, multiple test points are planned within this range to conduct soil resistivity tests on the substation, thereby obtaining relevant test data. Finally, all test data are input into a forward and inverse calculation program, which can construct the aforementioned horizontally layered soil model through numerical iteration.

[0026] Step S20: Determine the initial resistance reduction measures corresponding to the grounding grid of the substation based on the stratification type of the horizontal stratified soil model, and determine the initial equipotential bonding measures based on the initial resistance reduction measures.

[0027] It should be noted that the above-mentioned stratification type represents the category identifier obtained after summarizing and classifying the relative high and low resistivity of each soil layer in the vertical direction in the horizontal stratified soil model. The above-mentioned grounding grid represents the overall conductive network formed by horizontal grounding bodies, vertical grounding electrodes, and other conductive materials buried underground in a certain grid shape and interconnected to meet the needs of substation working grounding, safety grounding, and lightning protection grounding.

[0028] It should be understood that the aforementioned initial resistance reduction measures refer to a combination of one or more technical means initially selected from a variety of alternative technologies, based on the layering type, before detailed voltage equalization optimization and dynamic verification are carried out, aiming to reduce the overall grounding resistance of the grounding grid to below the design target value. For example, the initial resistance reduction measures may deploy a composite resistance reduction structure consisting of inclined grounding electrodes, ion grounding electrodes, and a local soil amendment layer; the inclined grounding electrodes are arranged at an angle of 30° to 45° with the horizontal plane, uniformly distributed along the edge of the substation's horizontal grounding grid, with the spacing between adjacent inclined grounding electrodes being 2-3 times their length; the ion grounding electrodes are vertically embedded in the soil, with an embedding depth not less than 1.2 times the thickness of the upper soil layer, and the penetration radius of their resistance reduction material is controlled to be 0.5m-1m; the local soil amendment layer is laid below the horizontal grounding grid, with a thickness of 0.5m-2m, and is made by mixing the resistance reduction agent with the local soil at a mass ratio of 1:3-1:5.

[0029] The aforementioned initial equipotential bonding measures represent a preliminary grounding grid structure layout scheme determined based on the selected initial resistance reduction measures, in order to improve the surface potential distribution of the grounding grid and reduce contact potential difference and step potential difference. This scheme works in conjunction with the resistance reduction measures. For example, the initial equipotential bonding measures can set the horizontal grounding grid as an unequal-spacing structure, with the edge grid spacing being 1.5-2 times that of the middle area grid spacing; the resistance reduction structure parameters can be adjusted according to the soil stratification model type, in soils with a high upper layer and a low lower layer, the ion grounding electrode can penetrate the upper soil layer and enter the lower low-resistivity soil layer, with a penetration depth of not less than 5m; in soils with a low upper layer and a high lower layer, the proportion of horizontal extension of the inclined grounding electrode can be increased.

[0030] Step S30: Based on the initial resistance reduction measures and the initial voltage equalization measures, output the initial grounding system of the substation.

[0031] It should be noted that the aforementioned initial grounding system refers to the complete technical solution formed by integrating initial resistance reduction measures and initial voltage equalization measures, which describes all the constituent elements and their spatial arrangement relationships of the substation grounding network. For example, for a 220kV substation, its "initial grounding system" can be specifically described as follows: a 210m × 210m rectangular horizontal grounding network, buried at a depth of 0.8m, using an unequal-spacing grid arrangement (15m grid spacing in the central area, gradually decreasing to 8m at the edges); at the perimeter of the grounding network, eight 30m long copper-clad steel inclined grounding electrodes are evenly installed at a 30° angle to the horizontal plane; at the four corners of the grounding network, four additional 20m long ion grounding electrodes are installed, penetrating the upper soil layer to reach the lower low-resistivity layer. All the above conductors are reliably connected into an electrical whole by welding or crimping.

[0032] In practical implementation, the initial resistance reduction measures and initial voltage equalization measures can be integrated to construct the initial grounding system of the substation. That is, the abstract "resistance reduction measures" and "voltage equalization measures" are concretized into a quantifiable "initial grounding system" that includes all geometric, material, and connection parameters.

[0033] Step S40: Perform dynamic safety verification on the initial grounding system, and iteratively correct the initial grounding system based on the verification results to determine the optimal grounding system for the substation.

[0034] It should be noted that dynamic safety verification refers to the process of systematically simulating and evaluating the safety of the initial grounding system under various time-varying conditions, taking into account the dynamic changes in soil electrical parameters due to seasonal variations (such as permafrost thawing and alternating wet and dry periods). This process not only evaluates conventional indicators such as grounding resistance, contact potential difference, and step potential difference, but also specifically assesses secondary risks caused by ground potential rise (GPR), including the risk of surge arrester backflashover within the substation and the risk of potential transfer in metal pipelines leading out of the substation. The aforementioned optimal grounding system represents the final grounding system design scheme that, after one or more rounds of iterative corrections, meets the qualification requirements of all dynamic safety verification items (including the effects of permafrost, surge arrester backflashover, and potential transfer in external pipelines), and achieves an acceptable balance in terms of economy and construction feasibility.

[0035] In practical implementation, soil resistivity varies significantly with seasonal changes (freeze-thaw cycles, wet and dry conditions), causing fluctuations in the actual performance of the grounding system (grounding resistance, surface potential distribution). Simultaneously, the ground potential rise generated during a fault may be conducted through electrical or metallic pathways to surge arresters within the substation or metal pipelines outside, triggering secondary disasters. Therefore, these dynamic changes and hidden risks must be considered during the design phase, i.e., dynamic safety verification of the initial grounding system. Specifically, different verification items have different physical mechanisms for non-compliance, thus requiring targeted correction strategies. For example, non-compliance of contact voltage is mainly related to the surface potential gradient distribution, requiring adjustments to equalization measures (such as denser grids, adding auxiliary electrodes); non-compliance of grounding resistance or excessively high GPR requires strengthening resistance reduction measures (such as increasing the number or length of vertical grounding electrodes, replacing resistance reduction technologies); surge arresters exceeding energy limits should be replaced with high-energy surge arresters; and pipeline transfer potential risks require increasing the insulation section length or optimizing the insulation joint layout. Employing a "feedback iteration" mechanism, rather than blindly modifying the system all at once, can efficiently converge to a feasible solution. After several rounds of iteration, when all dynamic safety verification items (permafrost, surge arresters, pipelines) meet the safety limits, it indicates that the current design scheme can withstand the most severe seasonal environmental changes and secondary risks in the region, and possesses safety and reliability throughout its entire life cycle. At this point, the iteration is terminated, and the scheme is determined as the final design.

[0036] This embodiment conducts soil resistivity tests on a substation within the target test range and constructs a horizontally layered soil model based on the test data. Initial resistivity reduction measures are determined for the substation's grounding grid based on the layering type of the horizontally layered soil model, and initial voltage equalization measures are determined based on these initial resistivity reduction measures. Based on the initial resistivity reduction measures and the initial voltage equalization measures, the initial grounding system of the substation is output. The initial grounding system undergoes dynamic safety verification, and the initial grounding system is iteratively corrected based on the verification results to determine the optimal grounding system for the substation. In this embodiment, the method described above constructs a horizontally layered soil model based on soil resistivity test data, and determines initial resistance reduction measures and initial voltage equalization measures according to the layering type of the model. This avoids the problem of poor results caused by blindly applying resistance reduction methods, and enables the initial grounding system to initially match the actual soil structure. On this basis, by performing dynamic safety verification on the initial grounding system and iteratively correcting it based on the verification results, the safety hazards caused by neglecting dynamic factors such as seasonal changes, permafrost thawing, and transfer potential in static design are avoided. This enables the finally determined optimal grounding system to effectively adapt to the complex dynamic environment in actual operation, ensuring that the grounding resistance, surface potential distribution, contact voltage, and step voltage meet safety requirements under all operating conditions, and protecting the normal operation of equipment and the life safety of maintenance personnel.

[0037] Reference Figure 2 , Figure 2This is a flowchart illustrating the second embodiment of the substation grounding system design method of this application. The technical solutions corresponding to the following steps in this embodiment constitute the second embodiment of the substation grounding system design method of this application.

[0038] In one feasible implementation, step S10 may include: Step S101: Conduct soil resistivity tests on substations under different seasons within the target test range to obtain shallow soil resistivity and deep soil resistivity.

[0039] It should be noted that different seasons refer to different periods of the year when soil physical properties such as moisture content and temperature vary significantly due to climate change. The purpose of testing in different seasons is to capture the dynamic changes in soil resistivity with environmental factors (such as alternating wet and dry seasons and freeze-thaw cycles). For example, considering the characteristics of a province with distinct wet and dry seasons and high-altitude permafrost, measurements are taken once at the end of the wet season and once in the middle of the dry season. In high-altitude permafrost areas, an additional measurement is taken in winter to comprehensively capture the seasonal changes in resistivity.

[0040] It should be understood that the Wenner four-electrode method can be used to measure the resistivity of shallow soil (0 to 500m) in the substation site area. The electrodes are arranged equidistantly along a straight line, with the maximum electrode spacing... Based on target detection depth Confirmed, satisfied The distance should be no less than 2 / 3 of the maximum diagonal of the proposed grounding grid. Measurements should be taken away from underground metal pipes and areas with strong electromagnetic interference, and should be conducted after three consecutive days of clear weather. The coordinates of the measurement points, topography, and soil type should be recorded. The electrode spacing adjustment logic for the four-electrode method is as follows: when the surface soil resistivity is ≤1000Ω... When the surface soil resistivity is >1000Ω, the maximum electrode spacing is set to 50m; When the maximum polar distance is 100m, the maximum polar distance is extended to 100m.

[0041] Please refer to Figure 3 , Figure 3 This is a schematic diagram of soil resistivity testing for the substation grounding system design method described in this application. Figure 3 As shown, four points were selected for soil resistivity testing. Due to on-site construction, the wiring direction was along the side length of the substation, and the wiring range was concentrated on the west side of the substation. Different electrode spacings of 1m, 3m, 5m, 7m, 10m, 30m, 50m, 70m, and 100m were used. Figure 3 In the table, C1 and C2 are current electrodes, and P1 and P2 are voltage electrodes. Point O is defined as the center point, i.e., the placement position of the megger (electrical testing and measuring instrument) equipment. Table 1 shows the position of each grounding electrode from the center point for different electrode spacings.

[0042] Table 1. Location of the center point of each grounding electrode at different electrode spacings.

[0043] Meanwhile, in and around the substation area, magnetotelluric methods can be used to measure the resistivity of deep soil layers (500m to tens of kilometers, such as 500m to 50km), with multiple measuring points deployed to obtain broadband apparent resistivity curves. Furthermore, methods such as electromagnetic array profiling (EMAP) or wavelet analysis can be used to correct for static effects and improve data reliability.

[0044] Step S102: Correct the resistivity data of the shallow soil resistivity and the deep soil resistivity that belong to the preset terrain, and use the corrected resistivity data and the uncorrected resistivity data as the test data of the substation.

[0045] It should be noted that the aforementioned preset terrain may include caves, tunnels, steep terrain, or other terrains that require correction of resistivity data. The specific settings can be flexibly configured by the testers according to the test requirements, and this embodiment does not impose any restrictions on them.

[0046] It should be understood that for areas with known caves, tunnels, or steep terrain, the cave exploration four-electrode method can be used to lay electrodes inside the cave, measure the resistivity of the rock and soil near the cave walls, and incorporate the cave geometry into the forward model to correct the measurement results.

[0047] Step S103: Based on the test data, the soil resistivity and soil thickness of each layer of the substation are inverted, and a horizontal layered soil model of the substation is constructed based on the soil resistivity and soil thickness of each layer.

[0048] In practical implementation, all test data can be input into a computer, and a high-precision calculation method for layered geodetic functions based on transmission line theory and linear filtering (using Guptasarma-Singh's 61-point filtering coefficients) can be used. Combined with partial derivative solving theory, parameter inversion is performed to obtain a horizontally layered soil model, which includes the resistivity and thickness of each soil layer. For example, the apparent resistivity sequence measured at different electrode spacings (e.g., 300 Ω·m at 10m, 250 Ω·m at 30m, and 200 Ω·m at 100m) can be input into the inversion program. Based on transmission line theory and linear filtering, the program iteratively adjusts the layer parameters of the hypothetical model to minimize the error between the theoretical apparent resistivity calculated in the forward model and the measured value. The final output is something like "First layer thickness 5m, resistivity 500 Ω·m; Second layer thickness 15m, resistivity 150 Ω·m; Third layer infinitely thick, resistivity 300 Ω·m". The inversion process of the horizontally layered soil model includes: based on the apparent resistivity data measured by the four-pole method, using the partial derivative solution theory of parameter inversion, and combining the conjugate gradient method to minimize the difference between the measured and theoretical values ​​of apparent resistivity, thereby obtaining the resistivity and thickness parameters of each soil layer.

[0049] In one feasible implementation, prior to step S10, the following may also be included: Step S1: Determine the vertical survey depth and horizontal survey range for soil resistivity testing based on the equivalent side length of the substation's ground grid, and determine the maximum measurement electrode distance based on the vertical survey depth.

[0050] It should be noted that the equivalent side length of the grounding grid mentioned above refers to the side length of the square when the proposed horizontal grounding grid of the substation is approximated as a square. The vertical survey depth mentioned above represents the minimum vertical distance from the ground surface downwards, determined to ensure that soil resistivity test data can cover the deep soil layers that significantly affect grounding resistance. The horizontal survey range mentioned above represents the minimum radial horizontal distance from the center of the grounding grid outwards, determined to ensure that soil resistivity test data can cover the horizontal area around the grounding grid that significantly affects the surface potential distribution. The maximum measurement electrode spacing mentioned above represents the distance between the two outermost current electrodes (C1 and C2) when using the Wenner four-electrode method for shallow soil resistivity testing, denoted by the symbol... This indicates that the polar distance determines the maximum detection depth of the four-pole method, and must be based on the determined vertical survey depth. To set it so that the current line can penetrate to a certain depth .

[0051] It should be understood that the grounding grid area can be initially determined based on the substation voltage level, and then the square root of the grounding grid area can be taken to calculate the equivalent side length of the grounding grid. .

[0052] Step S2: Based on the vertical survey depth, the horizontal survey range, and the maximum measurement pole distance, determine the target test range for the substation when conducting soil resistivity testing.

[0053] In practical implementation, the forward and inverse modeling methods can be used to represent the actual soil environment as a two-layer soil model, with the upper layer being the surveyed area (thickness...). resistivity The lower layer is an unknown region (resistivity). In ρ to ρ The variation between them, take ρ ρ Calculate the grounding resistance of the grounding grid under the equivalent model. Grounding resistance when the unknown area is considered the same as the upper layer relative error between Gradually increase until At this time This is the required vertical survey depth. Simulation results show that under normal working conditions... In complex working conditions (such as mountains and permafrost) The potential decay method can be used, requiring a radius of [missing information - likely related to grounding grid]. The surface potential within the area drops to below 10% of the potential at the center of the ground grid. Simulations show that under normal operating conditions... Under complex working conditions Based on the determined vertical survey depth Calculate the maximum current-electrode spacing required for the four-electrode method measurement. : Normal operating conditions Complex working conditions (such as mountainous areas and permafrost areas) .

[0054] In one feasible implementation, step S20 may include: Step S201: Based on the stratification type of the horizontal stratified soil model, select the corresponding initial drag reduction measures from the preset mapping table, which contains the mapping relationship between several stratification types and several drag reduction measures.

[0055] It should be noted that the above-mentioned stratification types can include typical structures such as homogeneous soil, two-layer soil (high on top, low on bottom; low on top, high on bottom), and three-layer soil (high-low-high; low-high-low). Please refer to [the relevant documentation / reference]. Figure 4 , Figure 4 This is a schematic diagram of the soil model for the substation grounding system design method of this application.

[0056] Two-layer soil model as Figure 4As shown in (a), where h1 = 10m and h2 = ∞. High-low type: Upper layer resistivity... Take 100Ω respectively m, 500Ω m, 1000Ω m, 2000Ω m, 4000Ω m, resistivity of the lower layer Take 100Ω respectively m, 500Ω m, 1000Ω m, 2000Ω m, 4000Ω m. Low at the top, high at the bottom: lower layer resistivity Take 100Ω respectively m, 500Ω m, 1000Ω m, 2000Ω m, 4000Ω m, upper resistivity Take 100Ω respectively m, 500Ω m, 1000Ω m, 2000Ω m, 4000Ω m.

[0057] Three-layer soil model as follows Figure 4 As shown in (b), where h1=10m, h3=∞. For a three-layer soil structure with high-low-high topsoil, the length of the inclined grounding electrode is set to cover the middle layer of low-resistivity soil without penetrating to the lower layer of high-resistivity soil, and the coverage depth is 1-1.2 times the thickness of the middle layer of soil. For a three-layer soil structure with low-high-low bottomsoil, the length of the ion grounding electrode needs to penetrate the upper and middle layers of soil, and the depth into the lower layer of low-resistivity soil should not be less than 3m. In particular, the inclined grounding electrode and the ion grounding electrode are made of copper-clad steel with an anti-corrosion coating on the surface, and the diameter is 16mm-20mm.

[0058] Furthermore, the grounding grid size can be determined based on the substation voltage level (e.g., 35kV: 56m×56m; 110kV: 100m×100m; 220kV: 210m×210m), with a burial depth of 0.8m and a horizontal grounding electrode spacing of 10m. Grounding grid simulation models under different soil models are established in CDEGS software. Then, through simulation analysis of the resistance reduction effects of different resistance reduction measures (vertical grounding electrode, inclined grounding electrode, ion grounding electrode, explosive grounding, grounding resistance reducing agent, etc.) under different soil models, a preset mapping table is established. This table contains the mapping relationship between several layer types and several resistance reduction measures. The preset mapping table represents a data structure formed in advance through extensive simulation calculations (e.g., using CDEGS software to simulate different soil models and different resistance reduction measures) and engineering experience summaries, used to establish the correspondence between "soil layer types" and "preferred resistance reduction measures." This mapping table clarifies which resistance reduction measure has the optimal comprehensive effect in terms of resistance reduction efficiency, economy, and construction feasibility for each specific layer type.

[0059] For example, for soils with a high upper layer and a low lower layer (high resistance in the upper layer and low resistance in the lower layer), deep vertical grounding electrodes or ion grounding electrodes are preferred. The length of the grounding electrode should penetrate from the upper layer to the lower layer, and the number should be 4 to 8 electrodes, arranged at the edge of the grounding grid. Ion grounding electrodes have a better resistance reduction effect than ordinary vertical grounding electrodes, with a resistance reduction rate of 60% to 70%. For uniform soils, explosive grounding technology is preferred. By drilling and blasting, a low-resistance channel is formed with an equivalent radius of 2 to 5 meters, which can significantly expand the current dissipation area and achieve a resistance reduction rate of over 30%. For soils with a low upper layer and a high lower layer (low resistance in the upper layer and high resistance in the lower layer), inclined grounding electrodes are recommended. For soils with a high-low-high three-layer structure (high resistance in the upper layer, low resistance in the middle layer, and high resistance in the lower layer), a tilted grounding electrode with an inclination angle of about 30° is preferred, so that the grounding electrode has the longest path in the middle low-resistivity layer. Increasing the number of electrodes (e.g., 8 electrodes) can effectively reduce the grounding resistance. For soils with a low-high-low three-layer structure (low resistance in the upper layer, high resistance in the middle layer, and low resistance in the lower layer), a deep vertical grounding electrode or explosive grounding is preferred, which penetrates the middle high-resistivity layer and enters the lower low-resistivity layer. The length should be greater than the sum of the thicknesses of the upper and middle layers.

[0060] Step S202: Determine the initial voltage equalization measures based on the initial resistance reduction measures. The initial voltage equalization measures include at least arranging the substation's grounding grid using unequal spacing grids and adding grounding electrodes from the initial resistance reduction measures at the edge of the grounding grid, in equipment concentration areas, or in areas where the potential gradient exceeds a preset threshold.

[0061] It should be noted that the aforementioned unequal-spacing grid represents a method of arranging horizontal conductors in a grounding grid. The spacing between adjacent parallel conductors is not fixed but gradually decreases from the geometric center of the grid towards the edges. This non-uniform arrangement aims to make the conductors denser in the edge areas of the grounding grid, thereby effectively reducing the rapidly increasing potential gradient at the edges and improving the uniformity of the surface potential distribution throughout the entire grid. For example, for a 210m × 210m grounding grid, the grid spacing in the central area is 15m, the second ring is 12m, the third ring is 10m, and the outermost ring shrinks to 8m. The conductor spacing of the entire grid shows a decreasing trend from the center to the edges.

[0062] The aforementioned equipment concentration area refers to the area within a substation site that houses electrical equipment (such as transformers, circuit breakers, disconnectors, surge arresters, voltage transformers, current transformers, control cabinets, protection panels, etc.) and where these electrical devices are geographically clustered. Specifically, the criterion for determining clustering is: if a predetermined number of electrical devices are housed within a predetermined range of the substation site, then that predetermined range is considered an equipment concentration area. Both the predetermined range and the predetermined number can be set by the testing personnel according to actual testing needs. For example, the predetermined range can be set as a circular area with a radius of 10 meters centered on any one device, and the predetermined number can be set to 5 devices. This embodiment does not restrict the values ​​of the predetermined range and the predetermined number. The aforementioned potential gradient refers to the change in potential per unit distance on the ground surface. When a ground fault occurs, the fault current is dissipated through the grounding grid, forming a potential distribution on the ground surface around the grounding grid. The equipotential lines are most densely packed at the edges and corners of the grounding grid, i.e., the potential gradient is greatest. An excessively large potential gradient is the direct cause of dangerous contact potential differences and step potential differences experienced by the human body. The aforementioned preset threshold refers to a pre-defined critical value used to determine whether the potential gradient is too large to warrant additional voltage equalization measures. This threshold can be an absolute value (e.g., 30V / m) or a relative ratio (e.g., the ratio of the maximum potential gradient at the edge to the average potential gradient at the center exceeds 3 times). Its specific value can be determined through simulation sensitivity analysis or engineering experience, so that areas exceeding this threshold become key locations for adding auxiliary grounding electrodes.

[0063] In practical implementation, based on the above mapping relationship, one or more resistance reduction measures can be selected and combined with the actual project conditions (land acquisition boundary, construction conditions, economic efficiency) to form a preliminary resistance reduction measure. Based on the preliminary resistance reduction measure, an unequal-spacing grid layout is used to optimize the grounding grid's voltage equalization performance. The grid spacing gradually decreases from the center to the edge of the grounding grid to reduce the potential gradient. The unequal-spacing layout rule is determined through simulation based on soil stratification characteristics and grounding grid dimensions. Specifically, the initial voltage equalization measures include adding vertical grounding electrodes, inclined grounding electrodes, or deep-well grounding electrodes already selected in the initial resistance reduction measures as auxiliary voltage equalization measures at the edge of the grounding grid, in areas with concentrated equipment, or in areas with large potential gradients. These grounding electrodes not only reduce resistance but also improve local potential distribution and reduce contact voltage and step voltage.

[0064] This embodiment uses soil resistivity testing at substations in different seasons to obtain shallow and deep resistivity data. It then specifically corrects resistivity data for pre-defined terrain, avoiding the problems of single-season testing failing to reflect seasonal changes in soil resistivity and data distortion caused by special terrain features. This allows for the construction of a horizontally layered soil model based on the obtained resistivity and thickness of each layer, better reflecting the actual dynamic environment and terrain characteristics, providing accurate input for subsequent resistivity reduction and voltage equalization design. Furthermore, this embodiment determines the vertical survey depth and horizontal survey range based on the equivalent side length of the substation's grounding grid, and accordingly determines the maximum measurement electrode spacing. This avoids the problems of insufficient testing range leading to missing data in key soil areas or excessive testing range causing resource waste. In addition, this embodiment matches corresponding initial resistivity reduction measures from a pre-defined mapping table based on the layer type of the horizontally layered soil model, and determines initial voltage equalization measures based on these measures, including unequal-spacing grid arrangements and the addition of grounding electrodes at edges or in high-potential gradient areas. This avoids the problems of blindly applying resistivity reduction methods resulting in poor effects and uneven surface potential distribution caused by unequal-spacing grids.

[0065] Reference Figure 5 , Figure 5 This is a flowchart illustrating the third embodiment of the substation grounding system design method of this application. The technical solutions corresponding to the following steps in this embodiment constitute the third embodiment of the substation grounding system design method of this application.

[0066] In one feasible implementation, step S40 may include: Step S401: Construct the target soil model of the substation under different seasons based on the test data.

[0067] It should be noted that the aforementioned target soil model refers to a dedicated horizontal stratified soil model constructed based on measured seasonal soil resistivity data for dynamic safety verification under specific verification conditions (such as the spring thaw period). The different seasons mentioned above represent different periods within a year when the physicochemical properties of the soil at the substation, such as moisture content, temperature, and pore water salinity, change due to periodic variations in climatic factors such as precipitation and temperature, thereby causing changes in soil resistivity. Examples include the dry season, rainy season, winter freezing period, and spring thaw period.

[0068] In practical implementation, a simulation model of the impact of frozen soil thickness can be established as the target soil model. The frozen soil layer is considered as the upper high-resistivity layer (resistivity of 4000 Ω·m), and the lower layer is the non-frozen soil layer (resistivity of 300 Ω·m). The grounding resistance under different frozen soil thicknesses (0~10m) can be calculated. In a feasible implementation, the spring thawing period (when the frozen soil begins to thaw but has not completely disappeared, the grounding resistance is still relatively high, while the surface soil resistivity has decreased) can be used as the most dangerous working condition for verification.

[0069] Step S402: Based on the target soil model, the initial grounding system is checked for the effects of frozen soil to obtain a first check result, and the ground potential rise of the initial grounding system is determined according to the first check result.

[0070] It should be understood that the permafrost impact verification refers to the evaluation process for substations in permafrost areas, where performance parameters such as grounding resistance, maximum contact potential difference, and maximum step potential difference of the initial grounding system are simulated and calculated under different permafrost thicknesses (typically 0-10m), and compared with safety limits. This verification aims to quantify the degree of degradation of grounding performance by the permafrost layer and identify the most dangerous operating conditions (usually during the spring thaw). The aforementioned ground potential rise... This indicates the rise in the potential of the grounding grid relative to the reference ground potential at infinity when a ground fault occurs, as the fault current flows into the earth through the grounding grid. Its value is equal to the product of the grounding resistance and the fault current flowing into the earth. ).

[0071] Specifically, if the grounding resistance of the initial grounding system satisfies ( If the grounding resistance is less than the grounding short-circuit current, then the grounding resistance is deemed to meet the verification requirements for the impact of frozen soil. Furthermore, the maximum contact potential difference and maximum step potential difference of the initial grounding system can be calculated through simulation and compared with safety limits. If both the maximum contact potential difference and the maximum step potential difference are less than the safety limits, then the maximum contact potential difference and the maximum step potential difference are deemed to meet the verification requirements for the impact of frozen soil. The safety limits can be calculated based on the following formula: ; ; in, The maximum safe limit for contact potential difference. The maximum step potential difference is the safety limit. The soil resistivity at the point where a person stands. The surface attenuation coefficient is... This represents the duration of the ground short-circuit fault.

[0072] The initial grounding system can only be deemed to have passed the permafrost influence verification if its grounding resistance, maximum contact potential difference, and maximum step potential difference all meet the requirements for permafrost influence verification. If any requirement is not met, the grid layout should be adjusted or additional grounding electrodes should be added until the permafrost influence verification requirements are met.

[0073] Because the thickness of the frozen soil layer varies in winter depending on the latitude of different regions, to investigate the impact of frozen soil layer thickness on the grounding resistance of a typical grounding grid, the model and parameters remain unchanged, and the frozen soil layer thickness is set to 0~10m, with the frozen soil resistivity taken as 4000Ω·m and the non-frozen soil resistivity taken as 300Ω·m. Please refer to... Figure 6 , Figure 6 This is a schematic diagram illustrating the grounding resistance values ​​of the substation grounding system design method under different frost layer thicknesses. (See Table 2 below.) Figure 6 It can be seen that the grounding resistance value increases linearly with the increase of the resistivity of the underlying soil. When the thickness of the frozen soil layer is small, the increase in grounding resistance value is more significant with the increase of the frozen soil layer thickness.

[0074] Table 2. Influence of different thicknesses of frozen soil layer on the grounding resistance of the grounding grid.

[0075] When the upper soil layer is thick, the current-dissipating resistance of the horizontal grounding electrode is mainly determined by the resistivity of the upper soil layer. When the upper soil layer is thin, the resistivity of the lower soil layer will have some influence, but the resistivity of the upper soil layer still plays a role. In permafrost regions, as the temperature gradually warms until summer, a certain thickness of thawed soil layer will form on the earth's surface as the seasonally frozen and thawed layers gradually melt. These thawed soil layers have low resistivity, and the resistance of the horizontal grounding electrode buried in them will decrease, which is very beneficial for the lightning protection grounding of transmission lines. For vertical grounding electrodes located in double soil layers, except at the electrode tip, the current-dissipating current density of all parts of the electrode is inversely proportional to the resistivity of the surrounding soil. When the resistivity of the lower soil layer is low, as long as the thickness of the upper soil layer is slightly greater than the electrode length, the influence of soil stratification on the current-dissipating resistance can be ignored; once the electrode extends into the lower soil layer, the resistance will change abruptly, and the current-dissipating resistance of the entire electrode will mainly depend on the lower soil layer. Therefore, for permafrost regions with seasonally frozen layers, using vertical electrodes that penetrate the frozen layer has significant advantages.

[0076] In permafrost regions, the grounding resistance of grounding devices is relatively high during winter freezing, resulting in higher contact potential and step potential differences. However, due to the high resistivity of the frozen soil surface, the permissible contact and step potential differences for the human body also increase, making winter relatively safe. In summer, as the seasonally frozen and thawed layers melt, the soil resistivity decreases, and the permissible contact and step potential differences for the human body also decrease. However, the grounding resistance, contact and step potential differences of the grounding device also decrease, making it relatively safe as well. Spring is the most dangerous time in permafrost regions because the surface soil begins to thaw, and only a thin layer with low resistivity lowers the permissible contact and step potential differences. Meanwhile, the seasonally frozen and thawed layers below the surface have not yet thawed, causing the grounding resistance, contact and step potential differences of the grounding device to remain at the higher values ​​seen in winter. Therefore, spring conditions should be used as the basis for calculating the grounding safety of power plants, substations and power equipment when designing grounding systems, so as to ensure the safety of operating personnel at all times.

[0077] Please refer to Figure 7 , Figure 7 This is a schematic diagram of the equivalent circuit for the backflashover of the surge arrester on the external line, based on the substation grounding system design method of this application. In engineering practice, the surge arrester's volt-ampere characteristic curve can be fitted to... Figure 7 The equivalent circuit model is calculated to be relatively accurate.

[0078] Step S403: Determine whether to perform a risk check on the initial grounding system based on the ground potential rise and obtain a second check result.

[0079] It should be understood that risk verification refers to a special assessment conducted when the local potential rise exceeds a certain threshold to address potential secondary risks.

[0080] Step S404: Iteratively correct the initial grounding system based on the first verification result, or iteratively correct the initial grounding system based on the first verification result and the second verification result.

[0081] In practical implementation, the design parameters of the initial grounding system can be adjusted specifically based on the non-compliant items in the first and / or second verification results, and a dynamic safety verification cyclic optimization process can be repeated. This process continues until all verification items are qualified. For example, for the "contact potential difference is unqualified" in the first verification result, the equalization measures are revised, such as densifying the grid spacing at the edge of the grounding grid and adding auxiliary equalization electrodes; for the "surge arrester backflash risk is unqualified" in the second verification result, the resistance reduction measures are revised, such as replacing the surge arrester with one with a larger current capacity. After modification, all verifications under the target soil model during the spring thaw period are re-executed until all indicators are qualified.

[0082] In one feasible implementation, step S403 may include: Step S4031: If the ground potential rise is less than or equal to the first threshold, then the initial grounding system is not subject to risk verification.

[0083] It should be understood that if the ground potential rise is less than or equal to the first threshold, then... The value is within the safe low range. The transfer potential on the external metal conduit is determined to be within the safe range, and the risk of surge arrester backflashover is negligible. Therefore, no risk check is performed on the initial grounding system. The second check result can be recorded as no risk or left blank.

[0084] Step S4032: If the ground potential rise is greater than the first threshold and less than or equal to the second threshold, then the initial grounding system is subjected to a risk check of the transfer potential of the external metal pipe to obtain a second check result.

[0085] It should be noted that the aforementioned first threshold is used to determine whether the ground potential rise threshold for the risk verification of the external metal pipeline transfer potential needs to be initiated. When the threshold is exceeded, a transfer potential that may pose a danger to human health is considered to be generated on the metal pipeline outside the station. The first threshold can be set to 2kV; the aforementioned second threshold is used to determine whether additional surge arresters are needed for backflashover risk verification of the ground potential rise threshold. If the threshold is exceeded, it is considered that the surge arrester in the station may be damaged by backflash due to excessively high ground potential rise. The second threshold can be set to 8kV.

[0086] In practical implementation, when a ground fault occurs in a substation causing the ground potential to rise above the first threshold, a special safety check is performed on the metal pipelines (such as water pipelines, gas pipelines, and cable metal sheaths) connected to the substation's grounding grid and leading outside the station. The check includes: calculating the magnitude of potential transfer on the pipeline and determining the minimum length of the insulation section required to prevent dangerous potential transfer. Alternatively, design a segmented insulation scheme (insulated joints + inner insulation coating) and verify that the maximum contact current is less than the safe value (e.g., 183.4mA). If 2kV < GPR ≤ 8kV, a potential transfer risk assessment of the external metal conduit is required, and the length of the insulation section should be determined. The following formula can be used for calculation: ; in, for , The inner diameter of the pipe. The resistivity of water. The duration of the fault. Alternatively, a segmented insulation scheme with insulated joints and an inner insulating coating can be adopted. The number and location of insulated joints can be determined through an optimization algorithm to ensure that the maximum contact current is less than a safe value (e.g., 183.4mA).

[0087] Step S4033: If the ground potential rise is greater than the second threshold, the initial grounding system is subjected to external metal pipe transfer potential risk verification and surge arrester backflash risk verification to obtain the second verification result.

[0088] In practical implementation, when a ground fault occurs in a substation causing the ground potential to rise above the second threshold, a special safety check is performed on the surge arresters connected to the grounding grid within the substation. The check includes: establishing an equivalent circuit (e.g., surge arrester volt-ampere characteristics, system neutral grounding method, line-to-ground capacitance, etc.) that incorporates parameters such as surge arrester volt-ampere characteristics, system neutral grounding method, and line-to-ground capacitance. Figure 7 As shown in the figure, calculate the energy absorbed by the surge arrester during a fault and compare it with the surge arrester's current carrying capacity (e.g., 9000J for a 10kV surge arrester, 6150J for a 6kV surge arrester) to determine whether there is a risk of thermal collapse or damage. If A backflash risk assessment is required for station surge arresters. A simulation circuit can be built using EMTP-ATP (a simulation software for electromagnetic transient analysis of power systems), considering factors such as the system neutral grounding method and line-to-ground capacitance, to calculate the energy absorbed by the surge arrester and compare it with its current carrying capacity (e.g., 9000J for a 10kV surge arrester and 6150J for a 6kV surge arrester). If the energy exceeds the limit, a surge arrester with a larger current carrying capacity (e.g., a 400A square wave current carrying capacity) should be selected.

[0089] This embodiment verifies the impact of frozen soil on the initial grounding system by constructing a target soil model during the spring thawing period. Based on the ground potential rise obtained during the verification, it determines whether further risk verification is needed, and then iteratively corrects the system based on the verification results. This avoids the problem of static design neglecting the most dangerous dynamic condition of frozen soil thawing, thus ensuring that the final grounding system still meets safety requirements during the period when the frozen soil layer begins to thaw but has not completely disappeared. This effectively adapts to seasonal changes in actual operation, ensuring normal equipment operation and the safety of maintenance personnel. Furthermore, this embodiment determines whether to conduct risk verification for the transfer potential of external metal pipelines and surge arrester backflash risk based on the comparison results of the ground potential rise with the first and second thresholds. This avoids unnecessary risk verification at low ground potential rises, which would waste resources, and also avoids safety hazards caused by neglecting necessary risk verification at high ground potential rises. Therefore, the final grounding system can take corresponding verification measures for different risk levels, effectively adapting to dynamic risks such as the transfer potential of external pipelines and surge arrester backflash in actual operation, ensuring equipment safety and personnel safety.

[0090] In addition, this application also provides a resistance-reducing and voltage-equalizing device suitable for mountain substations with high soil resistivity, including a horizontal grounding grid, grounding electrode components and a soil resistivity testing module.

[0091] The soil resistivity testing module employs an optimized four-electrode testing structure. The testing electrodes are arranged along the contour lines of the substation site, with an electrode spacing of 5m-100m. Testing is conducted three times: during the middle of the dry season, the end of the wet season, and in winter. The grounding electrode assembly includes inclined grounding electrodes and ion grounding electrodes. The inclined grounding electrodes have an angle of 30°-45° with the horizontal plane and are evenly distributed along the edge of the horizontal grounding grid. The ion grounding electrodes are vertically embedded in the soil, with a resistivity-reducing material penetration radius of 0.5m-1m. The lengths of the inclined and ion grounding electrodes are determined based on the thickness of the upper soil layer in the soil stratification model. A local soil amendment layer is provided below the horizontal grounding grid, with a thickness of 0.5m-2m and a resistivity lower than 50% of the original upper soil resistivity. The test data from the soil resistivity testing module is used to construct a two- or three-layer soil stratification model. The inclined grounding electrodes, ion grounding electrodes, and local soil amendment layer are parameter-matched according to the resistivity distribution of the soil stratification model.

[0092] The number of inclined grounding electrodes is 4-8, each with a length of 20m-40m, and the spacing between adjacent inclined grounding electrodes is 2-3 times their length. The length of the ion grounding electrodes is 30m-50m, and their embedding depth in the soil is not less than 1.2 times the thickness of the upper soil layer. The ion grounding electrodes and inclined grounding electrodes are arranged alternately. The local soil amendment layer is made by mixing a resistance-reducing agent with local soil at a mass ratio of 1:3-1:5, and the resistivity of the resistance-reducing agent is ≤5Ω. m. When the soil stratification model is high at the top and low at the bottom, the length of the ion grounding electrode penetrates the upper soil layer and enters the lower low-resistivity soil layer, with a penetration depth of not less than 5m. The horizontal grounding grid adopts an unequal spacing arrangement, with the grid spacing at the edge of the grounding grid being 1.5-2 times that of the grid spacing in the middle area. The electrode spacing adjustment logic of the four-electrode method test module is as follows: surface soil resistivity ≤1000Ω At m, the maximum electrode distance is 50m; the surface soil resistivity is >1000Ω. At m, the maximum electrode spacing is 100m. The burial depth of the horizontal grounding grid is 0.8m-1.2m, and in high-altitude permafrost areas, the burial depth of the horizontal grounding grid is not less than 1.5 times the thickness of the permafrost layer. The soil resistivity testing module also includes a data inversion unit, which uses a high-precision calculation method of layered geodetic functions to invert the soil layer thickness and resistivity parameters. The inclined grounding electrode and the ion grounding electrode are made of copper-clad steel, with a diameter of 16mm-20mm and an anti-corrosion coating on the surface.

[0093] Furthermore, this application illustrates the relevant beneficial effects in conjunction with two embodiments.

[0094] Example 1: Substation A is located in an area with an altitude of 2280~2340m, in a hilly region where soil moisture content fluctuates significantly seasonally. The method described in this application is used to design the substation grounding system. The specific steps are as follows: Step 1: Four-electrode tests were conducted in both the dry and wet seasons, with a maximum electrode spacing of 100m. After obtaining the apparent resistivity data, a three-layer soil model was obtained through inversion: upper layer (0~5m) resistivity 800Ω·m, middle layer (5~20m) resistivity 200Ω·m, and lower layer (>20m) resistivity 600Ω·m, which is a high-low-high type.

[0095] Step 2: The geological grid size is 260m × 260m, with an equivalent side length aeq = 260. The vertical survey depth is determined based on complex working conditions. Horizontal breadth Maximum measuring polar distance The current testing depth is basically sufficient.

[0096] Step 3: Based on the soil type (high-low-high type), select the optimal inclined grounding electrode. Design eight inclined grounding electrodes, each 30m long and tilted at a 30° angle, and arrange them at the edge of the grounding grid. Simulation shows that the grounding resistance drops from 0.45Ω without inclined electrodes to 0.27Ω, a resistance reduction rate of 40%.

[0097] Step 4: An unequal-spacing grid was used, with a grid spacing of 15m in the central area and gradually decreasing to 8m at the edges. The maximum contact potential difference was calculated to be 320V and the maximum step potential difference to be 180V, both of which are less than the safety limits (t=0.5s, surface soil resistivity 200Ω·m, allowable contact potential difference of approximately 450V, and step potential difference of approximately 550V).

[0098] Step 5: During the winter frozen soil period (frozen soil layer thickness 1m), the simulated grounding resistance increased to 0.35Ω. Spring thawing period (frozen soil layer thickness 0.5m) Surge arrester backflashover check: The 10kV system adopts a neutral point ungrounded configuration, with a line-to-ground capacitance of 5μF. The surge arrester absorbs less than 9000J of energy, which meets the requirements. The calculated insulation section length of the external metal water pipe (inner diameter 200mm, water resistivity 20Ω·m) is approximately 50m. An insulation joint + internal insulation coating scheme is adopted, with 6 insulation joints installed. The maximum contact current is 120mA, which meets the safety requirements.

[0099] Example 2: Substation B is located in an area where soil moisture content varies greatly seasonally and the soil is dry during the dry season. The substation grounding system is designed using the method described in this application. The specific steps are as follows: Step 1: The soil resistivity was high during the dry season and decreased with increasing depth, which was inverted to a two-layer soil with a high upper layer and a low lower layer: the upper layer (0~8m) had a resistivity of 800Ω·m and the lower layer (>8m) had a resistivity of 120Ω·m.

[0100] Step 2: The ground grid size is 150m × 150m, the equivalent side length aeq = 150, and the vertical depth is taken. Horizontal breadth Maximum measuring polar distance .

[0101] Step 3: Top-high-bottom-low type, deep vertical grounding electrode preferred. Eight 20m long vertical grounding electrodes were designed, penetrating the upper layer and entering the lower layer. Simulation results showed that the grounding resistance decreased from 0.65Ω to 0.32Ω, a resistance reduction rate of 50.8%.

[0102] Step 4: After the unequal spacing grid is arranged, the contact potential difference and step potential difference meet the requirements.

[0103] Step 5: Dry Season During the wet season, the soil is moist. The voltage was reduced to 2.8kV, which is safe. There are no external pipelines, therefore no evaluation is required.

[0104] The above embodiments demonstrate that the method of this application can effectively guide the design of substation grounding systems in areas with high soil resistivity, ensuring safety and reliability, and has the following beneficial effects: High testing accuracy: By integrating multiple methods such as the ground quadrupole method, magnetotelluric method, and cave quadrupole method, and taking into account seasonal changes, a more accurate and realistic soil stratification model was constructed.

[0105] Highly targeted resistance reduction: A mapping relationship between resistance reduction measures and soil stratification types was established, avoiding indiscriminate application. Simulation results show that for soils with a high top and low bottom, the resistance reduction rate using ion grounding electrodes can reach 69.5%, for uniform soils, the resistance reduction rate using explosive grounding electrodes is 32.3%, and for soils with a low top and high bottom, the resistance reduction rate using inclined grounding electrodes is 5.6%.

[0106] Excellent voltage equalization effect: Through the optimization of unequal spacing grid and auxiliary grounding electrode, the contact voltage and step voltage are effectively reduced, ensuring personal safety.

[0107] Safer Design: The design takes into account the impact of seasonal changes such as frozen soil and alternating wet and dry conditions on grounding performance, and systematically assesses hidden risks such as surge arrester backflash and potential transfer from external pipelines, ensuring the safety of the grounding system throughout its entire life cycle.

[0108] Highly scalable: It has formed a standardized design process that is applicable to regions with similar geological conditions, such as plateaus.

[0109] Reference Figure 8 , Figure 8 This is a structural block diagram of the first embodiment of the substation grounding system design device of this application.

[0110] like Figure 8 As shown, the substation grounding system design device proposed in this application includes: Soil model building module 801 is used to conduct soil resistivity tests on substations within the target test range and to build a horizontally layered soil model based on the test data. The initial measures determination module 802 is used to determine the initial resistance reduction measures corresponding to the grounding grid of the substation based on the layering type of the horizontal layered soil model, and to determine the initial equipotential bonding measures based on the initial resistance reduction measures. The first output module 803 is used to output the initial grounding system of the substation based on the initial resistance reduction measures and the initial voltage equalization measures; The second output module 804 is used to perform dynamic safety verification on the initial grounding system and iteratively correct the initial grounding system based on the verification results to determine the optimal grounding system of the substation.

[0111] This embodiment conducts soil resistivity tests on a substation within the target test range and constructs a horizontally layered soil model based on the test data. Initial resistivity reduction measures are determined for the substation's grounding grid based on the layering type of the horizontally layered soil model, and initial voltage equalization measures are determined based on these initial resistivity reduction measures. Based on the initial resistivity reduction measures and the initial voltage equalization measures, the initial grounding system of the substation is output. The initial grounding system undergoes dynamic safety verification, and the initial grounding system is iteratively corrected based on the verification results to determine the optimal grounding system for the substation. In this embodiment, the method described above constructs a horizontally layered soil model based on soil resistivity test data, and determines initial resistance reduction measures and initial voltage equalization measures according to the layering type of the model. This avoids the problem of poor results caused by blindly applying resistance reduction methods, and enables the initial grounding system to initially match the actual soil structure. On this basis, by performing dynamic safety verification on the initial grounding system and iteratively correcting it based on the verification results, the safety hazards caused by neglecting dynamic factors such as seasonal changes, permafrost thawing, and transfer potential in static design are avoided. This enables the finally determined optimal grounding system to effectively adapt to the complex dynamic environment in actual operation, ensuring that the grounding resistance, surface potential distribution, contact voltage, and step voltage meet safety requirements under all operating conditions, and protecting the normal operation of equipment and the life safety of maintenance personnel.

[0112] Based on the first embodiment of the substation grounding system design device described in this application, a second embodiment of the substation grounding system design device of this application is proposed.

[0113] In this embodiment, the soil model construction module 801 is further used to conduct soil resistivity tests on the substation under different seasons within the target test range to obtain shallow soil resistivity and deep soil resistivity; correct the resistivity data belonging to the preset terrain in the shallow soil resistivity and deep soil resistivity, and use the corrected resistivity data and the uncorrected resistivity data as the test data of the substation; invert the soil resistivity and soil thickness of each layer of the substation based on the test data, and construct a horizontal stratified soil model of the substation based on the soil resistivity and soil thickness of each layer.

[0114] Furthermore, the soil model construction module 801 is also used to determine the vertical survey depth and horizontal survey range of the soil resistivity test based on the equivalent side length of the substation's grounding grid, and to determine the maximum measurement electrode distance based on the vertical survey depth; and to determine the target test range of the substation when conducting soil resistivity tests based on the vertical survey depth, the horizontal survey range, and the maximum measurement electrode distance.

[0115] Furthermore, the initial measure determination module 802 is also used to select the corresponding initial resistance reduction measure from a preset mapping table according to the layering type of the horizontal layered soil model. The preset mapping table contains a mapping relationship between several layering types and several resistance reduction measures. The initial resistance reduction measure is used to determine the initial equalization measure. The initial equalization measure includes at least arranging the grounding grid of the substation with unequal spacing grids and adding grounding electrodes in the initial resistance reduction measure at the edge of the grounding grid, in the equipment concentration area, or in the area where the potential gradient exceeds a preset threshold.

[0116] Furthermore, the second output module 804 is also used to construct a target soil model of the substation under different seasons based on the test data; to perform a permafrost impact check on the initial grounding system based on the target soil model to obtain a first check result, and to determine the ground potential rise of the initial grounding system based on the first check result; to determine whether to perform a risk check on the initial grounding system based on the ground potential rise and to obtain a second check result; to perform iterative correction on the initial grounding system based on the first check result, or to perform iterative correction on the initial grounding system based on the first check result and the second check result.

[0117] Furthermore, the second output module 804 is also configured to: if the ground potential rise is less than or equal to the first threshold, then not perform risk verification on the initial grounding system; if the ground potential rise is greater than the first threshold and less than or equal to the second threshold, then perform risk verification on the external metal pipe transfer potential of the initial grounding system to obtain a second verification result; if the ground potential rise is greater than the second threshold, then perform risk verification on the external metal pipe transfer potential and surge arrester backflash risk of the initial grounding system to obtain a second verification result.

[0118] Other embodiments or specific implementations of the substation grounding system design device of this application can be referred to the above-described method embodiments, and will not be repeated here.

[0119] This application provides a substation grounding system design device, which includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, which are executed by the at least one processor to enable the at least one processor to perform the substation grounding system design method in the above embodiment 1.

[0120] The following reference Figure 9The diagram illustrates a structural schematic of a substation grounding system design device suitable for implementing embodiments of this application. The substation grounding system design device in this application may include, but is not limited to, mobile terminals such as mobile phones, laptops, digital radio receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Description), PMPs (Portable Media Players), vehicle terminals (e.g., vehicle navigation terminals), and fixed terminals such as digital TVs and desktop computers. Figure 9 The substation grounding system design equipment shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of this application.

[0121] like Figure 9 As shown, the substation grounding system design equipment may include a processing unit 1001 (e.g., a central processing unit, a graphics processing unit, etc.), which can perform various appropriate actions and processes according to a program stored in a read-only memory 1002 or a program loaded from a storage device 1003 into a random access memory 1004. The random access memory 1004 also stores various programs and data required for the operation of the substation grounding system design equipment. The processing unit 1001, the read-only memory 1002, and the random access memory 1004 are interconnected via a bus 1005. An input / output interface 1006 is also connected to the bus. Typically, the following systems can be connected to the input / output interface 1006: input devices 1007 including, for example, touchscreens, touchpads, keyboards, mice, image sensors, microphones, accelerometers, gyroscopes, etc.; output devices 1008 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; storage devices 1003 including, for example, magnetic tapes, hard disks, etc.; and communication devices 1009. Communication device 1009 allows the substation grounding system design equipment to communicate wirelessly or wiredly with other equipment to exchange data. Although the figure shows substation grounding system design equipment with various systems, it should be understood that implementation or possession of all the systems shown is not required. More or fewer systems may be implemented alternatively.

[0122] Specifically, according to the embodiments disclosed in this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments disclosed in this application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device, or installed from storage device 1003, or installed from read-only memory 1002. When the computer program is executed by processing device 1001, it performs the functions defined in the methods of the embodiments disclosed in this application.

[0123] The substation grounding system design equipment provided in this application, employing the substation grounding system design method described in the above embodiments, can solve the technical problem that existing substation grounding system design methods cannot guarantee the normal operation of equipment and the safety of maintenance personnel. Compared with the prior art, the beneficial effects of the substation grounding system design equipment provided in this application are the same as those of the substation grounding system design method provided in the above embodiments, and other technical features of this substation grounding system design equipment are the same as those disclosed in the previous embodiment method, and will not be repeated here.

[0124] It should be understood that the various parts disclosed in this application can be implemented using hardware, software, firmware, or a combination thereof. In the description of the above embodiments, specific features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0125] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0126] This application provides a computer-readable storage medium having computer-readable program instructions (i.e., a computer program) stored thereon, which are used to execute the substation grounding system design method in the above embodiments.

[0127] The computer-readable storage medium provided in this application may be, for example, a USB flash drive, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems or devices, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system or device. The program code contained on the computer-readable storage medium may be transmitted using any suitable medium, including but not limited to: wires, optical cables, RF (Radio Frequency), etc., or any suitable combination thereof.

[0128] The aforementioned computer-readable storage medium may be included in the substation grounding system design equipment; or it may exist independently and not be assembled into the substation grounding system design equipment.

[0129] The aforementioned computer-readable storage medium carries one or more programs that, when executed by the substation grounding system design equipment, enable the substation grounding system design equipment to write computer program code for performing the operations of this application in one or more programming languages ​​or a combination thereof. These programming languages ​​include object-oriented programming languages ​​such as Java, Smalltalk, and C++; and also conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network, such as a local area network (LAN) or a wide area network (WAN), or connected to an external computer (e.g., via the Internet using an Internet service provider).

[0130] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0131] The modules described in the embodiments of this application can be implemented in software or hardware. The names of the modules do not necessarily limit the functionality of the unit itself.

[0132] The readable storage medium provided in this application is a computer-readable storage medium that stores computer-readable program instructions (i.e., a computer program) for executing the above-described substation grounding system design method. This solves the technical problem that existing substation grounding system design methods cannot guarantee the normal operation of equipment and the safety of maintenance personnel. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided in this application are the same as those of the substation grounding system design method provided in the above embodiments, and will not be elaborated upon here.

[0133] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the substation grounding system design method described above.

[0134] The computer program product provided in this application can solve the technical problems in the design of substation grounding systems. Compared with the prior art, the beneficial effects of the computer program product provided in this application are the same as those of the substation grounding system design method provided in the above embodiments, and will not be repeated here.

[0135] The above description is only a part of the embodiments of this application and does not limit the scope of protection of this application. All equivalent structural transformations made under the technical concept of this application and using the content of this application specification and drawings, or direct / indirect applications in other related technical fields, are included in the scope of protection of this application.

Claims

1. A design method for a substation grounding system, characterized in that, The method includes the following steps: Soil resistivity tests were conducted on the substation within the target test area, and a horizontally layered soil model was constructed based on the test data. Based on the stratification type of the horizontal stratified soil model, the initial resistance reduction measures corresponding to the grounding grid of the substation are determined, and the initial equipotential bonding measures are determined based on the initial resistance reduction measures. Based on the initial resistance reduction measures and the initial voltage equalization measures, the initial grounding system of the substation is output; The initial grounding system is dynamically safety-checked, and the initial grounding system is iteratively corrected based on the check results to determine the optimal grounding system for the substation.

2. The substation grounding system design method as described in claim 1, characterized in that, The steps of conducting soil resistivity tests on the substation within the target test range and constructing a horizontally layered soil model based on the test data include: Soil resistivity tests were conducted on substations under different seasons within the target test range to obtain shallow soil resistivity and deep soil resistivity. The resistivity data of the shallow soil resistivity and the deep soil resistivity that belong to the preset terrain are corrected, and the corrected resistivity data and the uncorrected resistivity data are used as the test data of the substation. Based on the test data, the soil resistivity and thickness of each layer of the substation are inverted, and a horizontal stratified soil model of the substation is constructed based on the soil resistivity and thickness of each layer.

3. The substation grounding system design method as described in claim 1, characterized in that, Before the step of conducting soil resistivity tests on the substation within the target test range and constructing a horizontally layered soil model based on the test data, the method further includes: Based on the equivalent side length of the substation's grounding grid, the vertical survey depth and horizontal survey range for soil resistivity testing are determined, and the maximum measurement electrode spacing is determined based on the vertical survey depth. Based on the vertical survey depth, the horizontal survey range, and the maximum measurement pole distance, the target test range for the substation when conducting soil resistivity testing is determined.

4. The substation grounding system design method as described in claim 1, characterized in that, The steps of determining the initial resistance reduction measures corresponding to the substation's grounding grid based on the stratification type of the horizontally stratified soil model, and determining the initial equipotential bonding measures based on the initial resistance reduction measures, include: Based on the stratification type of the horizontal stratified soil model, the corresponding initial drag reduction measures are selected from a preset mapping table, which contains a mapping relationship between several stratification types and several drag reduction measures. The initial voltage equalization measures are determined based on the initial resistance reduction measures. The initial voltage equalization measures include at least arranging the substation's grounding grid using unequal spacing grids and adding grounding electrodes as described in the initial resistance reduction measures at the edge of the grounding grid, in equipment concentration areas, or in areas where the potential gradient exceeds a preset threshold.

5. The substation grounding system design method as described in claim 1, characterized in that, The step of performing dynamic safety verification on the initial grounding system and iteratively correcting the initial grounding system based on the verification results includes: Based on the test data, construct the target soil model of the substation under different seasons; Based on the target soil model, the initial grounding system is checked for the effects of frozen soil to obtain a first check result, and the ground potential rise of the initial grounding system is determined based on the first check result. Based on the ground potential rise, determine whether to perform a risk check on the initial grounding system and obtain a second check result; The initial grounding system is iteratively corrected based on the first verification result, or the initial grounding system is iteratively corrected based on the first verification result and the second verification result.

6. The substation grounding system design method as described in claim 5, characterized in that, The step of determining whether to perform a risk check on the initial grounding system based on the ground potential rise and obtaining a second check result includes: If the ground potential rise is less than or equal to the first threshold, then no risk check is performed on the initial grounding system; If the ground potential rise is greater than the first threshold and less than or equal to the second threshold, then the risk check of the external metal pipe transfer potential of the initial grounding system is performed to obtain the second check result; If the ground potential rise is greater than the second threshold, the initial grounding system is subjected to external metal pipe transfer potential risk verification and surge arrester backflash risk verification to obtain the second verification result.

7. A design device for a substation grounding system, characterized in that, The substation grounding system design device includes: The soil model building module is used to conduct soil resistivity tests on substations within the target test range and build a horizontally layered soil model based on the test data. The initial measures determination module is used to determine the initial resistance reduction measures corresponding to the grounding grid of the substation based on the layering type of the horizontal layered soil model, and to determine the initial equipotential bonding measures based on the initial resistance reduction measures. The first output module is used to output the initial grounding system of the substation based on the initial resistance reduction measures and the initial voltage equalization measures; The second output module is used to perform dynamic safety verification on the initial grounding system and iteratively correct the initial grounding system based on the verification results to determine the optimal grounding system of the substation.

8. A design device for a substation grounding system, characterized in that, The device includes: a memory, a processor, and a substation grounding system design program stored in the memory and executable on the processor, the substation grounding system design program being configured to implement the steps of the substation grounding system design method as described in any one of claims 1 to 6.

9. A storage medium, characterized in that, The storage medium is a computer-readable storage medium, and the storage medium stores a substation grounding system design program. When the substation grounding system design program is executed by a processor, it implements the steps of the substation grounding system design method as described in any one of claims 1 to 6.

10. A computer program product, characterized in that, The computer program product includes a substation grounding system design program, which, when executed by a processor, implements the steps of the substation grounding system design method as described in any one of claims 1 to 6.

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