A grounding device and arrangement method for reducing step voltage on transmission line towers

Abstract

This invention discloses a grounding device and arrangement method for transmission line towers to reduce step voltage, aiming to solve the technical problems of excessive step voltage, cumbersome construction, and inability to adapt to the safety requirements of different personnel activity areas in existing tower grounding devices. The device includes a horizontal grounding grid, grounding electrodes, grounding down conductors, and prefabricated mechanical connection components. The horizontal grounding grid consists of concentric square closed loops centered on the tower center and radial rays. Vertical grounding wires are welded to the apexes of the square closed loops. The tower feet are connected to the grounding electrodes via grounding down conductors and are connected to the horizontal grounding grid through prefabricated mechanical connection components. This invention, by adjusting the number and spacing of the square closed loops, can limit the step voltage to a safe threshold without laying a high-resistivity ground layer. Using prefabricated connectors instead of welding facilitates construction, adapts to different soil resistivities and personnel activity areas, provides reliable grounding, and is suitable for high-voltage transmission line towers, ensuring personal and equipment safety.

Description

Technical Field

[0001] This invention relates to the field of power transmission line safety protection technology, specifically to a power transmission line tower grounding device and its arrangement method for reducing step voltage. Background Technology

[0002] Grounding devices are crucial for the safe operation of power transmission lines. Under abnormal conditions such as lightning strikes and short circuits, they can conduct fault currents to the ground, protecting power equipment and the safety of people in the surrounding area.

[0003] As power grids expand, transmission lines extend into densely populated areas, generating dangerous step voltages near towers during single-phase grounding faults. However, existing grounding systems prioritize lightning protection, often neglecting step voltage protection, and compatible devices are scarce. The few devices that do consider step voltage rely on welded connections, which are cumbersome to install; moreover, they often employ single-frame grounding grid structures, resulting in step voltages far exceeding safety limits during leakage, failing to meet the needs of areas with high population density. Simply increasing the length of the grounding electrode has limited resistance reduction and wastes materials, while increasing the spacing between grounding electrodes cannot meet the diverse safety requirements of areas with varying population densities. Summary of the Invention

[0004] In view of the shortcomings of the existing technology and in accordance with relevant specifications, there are clear step voltage limits for personnel activity areas. Existing devices cannot meet this requirement. Therefore, there is an urgent need for a grounding device that can be quickly assembled, adapt to regional differences, and effectively reduce step voltage.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this invention is as follows: A grounding device for transmission line towers to reduce step voltage includes a horizontal grounding grid, grounding electrodes, and grounding down conductors buried in the soil. The horizontal grounding grid, grounding electrodes, and grounding down conductors are all connected to the tower feet of the transmission line tower. The horizontal grounding grid consists of several concentric square closed loops centered on the tower center and radial rays extending outward from the four corners of the innermost square closed loop. Vertical grounding wires are welded vertically downward at the four vertices of each square closed loop. The grounding electrodes are separately installed and vertically embedded in the soil. The tower feet of the transmission line tower are connected to the grounding electrodes through the grounding down conductors and form an electrically connected whole with the horizontal grounding grid through prefabricated mechanical connection components. The square closed loops, radial rays, grounding down conductors, and grounding electrodes are all reliably connected through prefabricated mechanical connection components; the number of square closed loops N≥, and the layer spacing between adjacent square closed loops is D.

[0006] In a preferred embodiment, the prefabricated mechanical connection components include C-type connectors, M-type connectors, and E-type connectors; The C-type connector is used for cross-connection, T-type connection or parallel connection between square closed loop and radial line, square closed loop and grounding down conductor; The M-type connector is used for the fixed crimping of one end of the grounding lead to the tower foot of the transmission line; The E-type connector is used to connect the other end of the grounding down conductor to the grounding electrode, and at the same time realizes the transition connection between the horizontal grounding grid and the grounding down conductor.

[0007] In the preferred embodiment, the vertical grounding wire is a short conductor of the same material as the square closed loop, with a length of 0.3 to 0.5 meters, and is welded to the corner of the square closed loop to equalize the potential; The grounding electrode is made of copper-clad steel and is 0.8 to 1.2 meters long, which is longer than the length of the vertical grounding wire. It is installed on the vertical extension line after the grounding down conductor enters the ground. The burial depth h of the horizontal grounding grid is controlled within the range of meters to meters.

[0008] In the preferred embodiment, there are a total of 4 radial rays, which extend outward along the diagonal of the concentric square closed loop and form a 45° angle with the edge of the square closed loop. The grounding down conductor extending from the base of the transmission line tower is fitted with an insulating PVC conduit that penetrates the concrete protective layer of the tower foundation.

[0009] A method for arranging grounding devices on transmission line towers to reduce step voltage includes the following steps: S1. On-site measurement of soil resistivity in the area where the transmission line towers are located. Record measurement data and organize and archive it; S2. Assess the frequency of personnel activity in the tower area, classify safety zone levels, and determine the permissible limit for step voltage. ; S3, based on and The number N of square closed loops to be arranged and the total length L of the horizontal grounding grid are calculated using a preset calculation model. S4. Excavate a grounding trench with a preset depth h, arrange a square closed loop and radial rays according to the calculated parameters, and weld a vertical grounding wire at each vertex of the square closed loop. S5. Use C-type connectors to assemble and fix the horizontal grounding body composed of a square closed loop and radial rays, and use M-type connectors to connect the tower feet of the transmission line to the grounding down conductor; S6. Drive the grounding electrode vertically into the preset position, ensuring that the grounding electrode is driven to the required depth. Use the E-type connector to connect the grounding lead to the grounding electrode and connect it to the horizontal grounding grid. S7. Backfill the excavated grounding trench, compact the soil in layers, and ensure that the grounding electrode is in close contact with the soil.

[0010] In the preferred embodiment, in step S2, the safety zone level is divided into the following two categories based on the frequency of personnel activity: 6.1 Frequently Passed Areas: Defined as areas where people frequently walk and move around, with permissible step voltage limits set. ; 6.2 Public Dense Areas: Defined as areas where people are likely to gather and where barefoot walking may occur, a step voltage allowable limit is set. .

[0011] In the preferred embodiment, in step S3: For frequently traversed areas, the number of square closed loops is set to N=4 and the layer spacing is D=2 meters to ensure that the total length of the horizontal grounding grid is L≥338 meters; For densely populated public areas, the number of square closed loops is set to N=5 and the layer spacing is D=2 meters to ensure that the total length of the horizontal grounding grid is L≥420 meters; If the calculation results show that the preset number of square closed loop layers N cannot be satisfied... If required, the outward extension length of the radial rays is increased, and the calculation is recalculated until the requirements are met.

[0012] In the preferred embodiment, the calculation and verification of the step voltage in step S3 follows the model below: ; in: To predict step voltage; This refers to the fault current that flows to ground. It is a function of the effective length of the grounding system, including the sum of the effective lengths of all square closed loops, radial rays, vertical grounding wires and grounding electrodes, and monotonically increases with the number of layers N; For square grid geometric coefficients, which are related to the interlayer spacing D and the burial depth h; is the coefficient for non-uniform current distribution; the value of N is adjusted iteratively until the inequality condition is met.

[0013] In the preferred embodiment, in step S3, the first... i Side length of the closed loop of the square Determined by the following formula:

[0014] Where: i is the level index ( ), The innermost square's side length is determined by the root opening size of the transmission line tower's base, and D is the layer spacing. Vertical grounding wires are welded to each layer's side length The positions of the four corner points.

[0015] In the preferred embodiment, if the soil resistivity of the construction area is higher than the preset threshold of 500Ω... If m, then add a physical drag-reducing agent to the backfill soil; The aforementioned resistance-reducing agent is mainly wrapped around the grounding electrode and at the apex of the square closed loop where the vertical grounding wire is welded, with a wrapping radius of not less than 0.1 meters.

[0016] A grounding device and arrangement method for reducing step voltage on transmission line towers, the device having the following beneficial effects during use: 1. This invention uses a horizontal grounding grid composed of concentric square closed loops and radial rays, combined with a vertical grounding wire at the vertices of the squares, to balance the potential distribution around the tower. Combined with the auxiliary grounding effect of the grounding electrode, there is no need to lay a high-resistance ground layer. By simply adjusting the number N of the square closed loops and the layer spacing D, the step voltage can be precisely limited to within the safe threshold, meeting the differentiated safety requirements of areas with frequent personnel passage and densely populated public areas. This effectively solves the technical problem of excessive step voltage in existing grounding devices that endanger personal safety. 2. This invention uses prefabricated mechanical connection components (C-type, M-type, and E-type connectors) to replace the traditional welding process, enabling rapid connection of various components of the horizontal grounding grid, grounding down conductors, grounding electrodes, and tower feet, eliminating the need for on-site welding operations, simplifying the construction process, and shortening the construction cycle; at the same time, the modular design facilitates component transportation and on-site assembly, significantly reducing the labor intensity of construction personnel and construction costs; 3. This invention can flexibly adjust the number of square closed loops, the interlayer spacing, and the extension length of radial rays according to the soil resistivity and the frequency of personnel activities in the area where the tower is located, to adapt to the usage requirements of different scenarios; and the size design of the grounding electrode and vertical grounding wire can be flexibly adjusted to adapt to various high-voltage transmission line towers, with strong versatility, eliminating the need to design grounding devices separately for different scenarios, thus reducing design and manufacturing costs. 4. The vertical grounding wire is made of the same material as the square closed loop, and the grounding electrode is made of copper-clad steel, which is corrosion-resistant and has excellent conductivity. The grounding electrode is set on the vertical extension line of the grounding down conductor, which can enhance the grounding effect and improve the stability of the grounding system. At the same time, the grounding down conductor is wrapped with an insulating PVC pipe to avoid friction damage with the concrete of the tower foundation, extend the overall service life of the device, and ensure the long-term safe and stable operation of the transmission line. 5. This invention does not require the additional laying of a high-resistivity ground layer, nor does it require excessively increasing the length of the grounding electrode. By optimizing the grounding structure design, the step voltage can be met, reducing material waste. For areas with high soil resistivity, the resistance-reducing agent can be wrapped only in key parts to achieve the resistance reduction effect, avoiding the resource waste and environmental impact caused by the large-scale use of resistance-reducing agents, thus balancing economy and environmental protection. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a top view of the square closed loop and radial ray arrangement structure of the present invention; Figure 2 This is a structural diagram of the vertical grounding wire arrangement of the present invention; Figure 3 A sectional view of the connection structure of the prefabricated mechanical connection assembly; Figure 4 This is a diagram showing the structure and connection arrangement of the C-type connector; Figure 5 This is a diagram showing the structure and connection layout of the M-type connector; Figure 6 This is a diagram showing the structure and connection layout of the E-type connector.

[0018] In the diagram: 1. Square closed loop; 2. Vertical grounding wire; 3. Grounding down conductor; 4. Radial rays; 5. Prefabricated mechanical connection assembly; 5. C-type connector; 501. M-type connector; 502. E-type connector; 503. Grounding electrode; 6. Tower foot of transmission line tower; 7. Detailed Implementation

[0019] like Figure 1 and Figure 2As shown, a grounding device for transmission line towers to reduce step voltage includes a horizontal grounding grid buried in the soil, grounding electrodes 6, and grounding down conductors 3. The horizontal grounding grid, grounding electrodes 6, and grounding down conductors 3 are all connected to the tower feet 7 of the transmission line tower. The horizontal grounding grid consists of several concentric square closed loops 1 centered on the tower center, and radial rays 4 extending outward from the four corners of the innermost square closed loop. The square closed loops 1 are made of hot-dip galvanized flat steel with a cross-sectional size of 40mm × 4mm. The interlayer spacing D can be adjusted to 1.5-2.5 mm according to the actual scenario. The innermost square closed loop's side length Wbase is determined by the root opening size of the tower foot 7, typically 2-3 meters. Vertical grounding wires 2 are welded vertically downwards at each of the four vertices of the square closed loop 1. The welding is double-sided full welding, with a weld height of not less than 4mm, and anti-corrosion treatment is applied after welding. Grounding electrodes 6 are separately installed and vertically embedded in the soil at a depth of not less than 2.5 meters. The tower foot 7 of the transmission line is connected to the grounding electrode 6 via grounding down conductors 3, and forms an electrically connected whole with the horizontal grounding grid through prefabricated mechanical connection components 5, ensuring smooth conduction of fault current. The square closed loop 1, radial rays 4, grounding down conductor 3 and grounding electrode 6 are all reliably connected by prefabricated mechanical connection components 5. After connection, a continuity test is required to ensure that the contact resistance is not greater than 0.01Ω and to ensure electrical continuity performance. This device limits the step voltage around the tower to a safe threshold without laying a high-resistivity ground layer by adjusting the number N (N≥1) of square closed loops 1 and the interlayer spacing D. The value of N can be flexibly adjusted according to the soil resistivity ρ. The higher the ρ, the larger the value of N, ensuring that the step voltage meets the safety limit requirements of the corresponding area.

[0020] Preferred solutions include Figures 3 to 6 As shown, the prefabricated mechanical connection assembly 5 includes a C-type connector 501, an M-type connector 502, and an E-type connector 503. All three are made of high-strength cast steel and have a hot-dip galvanized anti-corrosion treatment on the surface. They are compatible with grounding components with a specification of 40mm×4mm. Among them, the C-type connector 501 is used for cross connection, T-type connection or parallel connection between the square closed loop 1 and the radial rays 4 and the grounding down conductor 3. The connector is provided with anti-slip teeth and is fastened by two M12 galvanized bolts. The fastening torque is controlled at 45-50 N·m to ensure a firm connection and good contact. Among them, the M-type connector 502 is used to fix and crimp one end of the grounding down conductor 3 to the tower foot 7 of the transmission line. The crimping process is hydraulic and the number of crimping times is not less than 2. After crimping, the connector fits tightly with the grounding down conductor 3 and the tower foot 7 without looseness or gaps. The E-type connector 503 is used to connect the other end of the grounding down conductor 3 to the grounding electrode 6, and to realize the transition connection between the horizontal grounding grid and the grounding down conductor 3. Positioning slots are provided at both ends of the connector to ensure that the grounding electrode 6 and the grounding down conductor 3 are installed in place. After connection, anti-corrosion sealant is applied to prevent soil corrosion.

[0021] Preferred solutions include Figure 1 and Figure 2 As shown, the vertical grounding wire 2 uses a short conductor of the same material as the square closed loop 1, namely hot-dip galvanized flat steel, with a length of 0.3 meters to 0.5 meters. The specific length can be adjusted according to the soil texture. When the soil has good permeability, take 0.3 meters, and when the soil is heavy clay, take 0.5 meters. It is welded to the corner of the square closed loop 1 to equalize the potential. The weld slag must be removed and anti-corrosion paint must be applied to the weld to prevent rust. The grounding electrode 6 is made of copper-clad steel with a copper layer thickness of not less than 0.2 mm. Its length is greater than that of the vertical grounding wire 2, specifically 0.8 meters to 1.2 meters. It is set on the vertical extension line after the grounding down conductor 3 enters the ground. When implanting, ensure that the top of the grounding electrode 6 is not less than 0.6 meters below the ground. The burial depth h of the horizontal grounding grid is controlled within the range of 0.6 meters to 0.8 meters. When burying, the grounding grid is in close contact with the soil to avoid being suspended or loose. The trench excavation width is 0.4-0.5 meters to facilitate the laying and backfilling of the grounding body.

[0022] Preferred solutions include Figure 1 and Figure 2 As shown, there are a total of 4 radial rays 4, which are made of hot-dip galvanized flat steel with the same specifications as the square closed ring 1. They extend outward along the diagonal of the concentric square closed ring 1 and form a 45° angle with the edge of the square closed ring 1. The extension length can be adjusted according to the soil resistivity and the safety zone level, usually 5-10 meters. The grounding down conductor 3, which is led out from the tower foot 7 of the transmission line tower, is made of copper-clad steel stranded wire with a cross-sectional area of ​​50 mm². It is covered with an insulating PVC conduit with a diameter of 25 mm and a wall thickness of not less than 2 mm. The PVC conduit passes through the concrete protective layer of the tower foundation. The contact point between the conduit and the concrete is sealed with sealant to prevent rainwater from seeping in and corroding the grounding down conductor 3.

[0023] Example: This example discloses a method for arranging grounding devices on transmission line towers to reduce step voltage. The method specifically includes the following steps: S1. First, engineers arrived at the transmission line tower site with a soil resistivity tester and used the Wenner four-electrode method to measure the soil resistivity of the area where the tower was located. ; The measurement should select multiple sets of data from different directions and take the average value. The recorded measurement data should be organized and archived as the basic parameters for subsequent calculation and design. S2. Assess the environment and personnel activity around the tower, classify the area into "frequently passed areas" or "densely populated public areas," and determine the permissible limit for step voltage accordingly. : S2.1, Scenario 1 (Frequently Passed Areas): If the tower is located in farmland, roadsides, or other areas where people frequently walk or move around, set an allowable limit for step voltage. ; S2.2, Scenario Two (Densely Populated Public Areas): If the tower is located near parks, villages, or other areas where people easily gather and barefoot walking is possible, a step voltage allowable limit is set to provide higher safety redundancy. ; S3, based on the measurements obtained in step S1 And determined in step S2 The number N of square closed loops and the total length L of the horizontal grounding grid are determined using a preset calculation model; S3.1 Initial Scheme Setting: For frequently traversed areas, the initial number of square closed loops is set. Interlayer spacing meters, at this time it is necessary to ensure the total length of the horizontal grounding grid. rice; For densely populated public areas, the initial number of square closed loops is set. Interlayer spacing meters, at this time it is necessary to ensure the total length of the horizontal grounding grid. rice; S3.2, Geometric Dimension Calculation: No. Side length of the closed loop of the square Determined according to the following formula: ; Where i is the layer index ( ), D is the side length of the innermost square (determined by the opening size at the base of the tower), and D is the layer spacing (2 meters). S3.3 Model Validation: The following step voltage calculation model was used for verification: ; in: To predict step voltage; This refers to the fault current that flows to ground. This is a function of the effective length of the grounding system, encompassing the sum of the effective lengths of all square closed loops, radial lines, vertical grounding wires, and grounding electrodes. For geometric coefficients of a square grid; The coefficient for non-uniform current distribution; If the calculation results show that the initially set N-layer structure is calculated... Then, the outward extension length of the radial rays is increased in the model, and the calculation is iterated again until the condition is met. ; S4. Based on the calculated geometric parameters, the excavation depth... Square and radial grounding trenches (typically 0.6m-0.8m in diameter): S4.1 Arrange a square closed loop (1) and radial rays (4) in the trench. S4.2 At the four vertices of each square closed loop, short copper stranded wire or round steel is welded vertically downward as a vertical grounding wire (2) to balance the corner potential; S5. Prefabricated mechanical connection components (5) are used to replace the traditional full welding process to achieve rapid assembly: S5.1. Use C-type connector (501) to press and fix the square closed loop (1) and the radial rays (4) at the intersection, and realize the electrical connection between the layers of the square closed loop through the C-type connector; S5.2. Use M-type connector (502) to fix and press the hardware of the tower foot (7) of the transmission line tower to one end of the grounding lead (3) with a large contact surface. S6. Vertically drive in a copper-clad steel grounding electrode (6) at the preset location (usually where the grounding lead enters the ground), ensuring that the implantation depth meets the requirements: Use type E connector (503) to vertically connect the other end of the grounding lead (3) to the grounding electrode (6); ensure that the grounding lead (3) is also electrically connected to the horizontal grounding grid (square closed loop); S7. After completing all connections, check the tightness of each connection point: If the soil resistivity measured in step S1 Higher than a preset threshold (e.g.) Before backfilling, apply a physical resistance-reducing agent, focusing on wrapping the grounding (6) area and... At the apex of the square closed loop, weld the vertical grounding wire, with the radius of the wrapping layer not less than 0.1 meters; finally, backfill the excavated grounding trench and compact the soil in layers to ensure close contact between the grounding electrode and the soil, thus completing the construction.

Claims

1. A grounding device for transmission line towers to reduce step voltage, comprising a horizontal grounding grid, a grounding electrode (6), and a grounding down conductor (3) buried in the soil, wherein the horizontal grounding grid, the grounding electrode (6), and the grounding down conductor (3) are all connected to the tower feet (7) of the transmission line tower; characterized in that: The horizontal grounding grid consists of several concentric square closed loops (1) centered on the tower center and radial rays (4) extending outward from the four corners of the innermost square closed loop; vertical grounding wires (2) are welded vertically downward at the four vertices of the square closed loops (1); the grounding electrode (6) is set separately and vertically embedded in the soil, and the tower feet (7) of the transmission line tower are connected to the grounding electrode (6) through the grounding down conductor (3), and form an electrically connected whole with the horizontal grounding grid through the prefabricated mechanical connection assembly (5); The square closed loop (1), radial rays (4), grounding down conductor (3) and grounding electrode (6) are all reliably connected by prefabricated mechanical connection components (5); The number of square closed loops (1) is N≥1, and the layer spacing between adjacent square closed loops is D.

2. The transmission line tower grounding device for reducing step voltage according to claim 1, characterized in that: The prefabricated mechanical connection assembly (5) includes a C-type connector (501), an M-type connector (502), and an E-type connector (503); The C-type connector (501) is used for cross-connection, T-connection or parallel connection between the square closed loop (1) and the radial rays (4), and between the square closed loop (1) and the grounding lead (3); M-type connector (502) is used for the fixed crimping of one end of the grounding lead (3) to the tower foot (7) of the transmission line tower; The E-type connector (503) is used to connect the other end of the grounding down conductor (3) to the grounding electrode (6), and at the same time realizes the transition connection between the horizontal grounding grid and the grounding down conductor (3).

3. The transmission line tower grounding device for reducing step voltage according to claim 1, characterized in that: The vertical grounding wire (2) is a short conductor of the same material as the square closed loop (1), with a length of 0.3 to 0.5 meters, and is welded to the corner of the square closed loop (1) to equalize the potential; The grounding electrode (6) is made of copper-clad steel and is 0.8 to 1.2 meters long, which is longer than the vertical grounding wire (2). It is set on the vertical extension line after the grounding down conductor (3) enters the ground. The burial depth h of the horizontal grounding grid is controlled within the range of 0.6 to 0.8 meters.

4. The transmission line tower grounding device for reducing step voltage according to claim 1, characterized in that: There are a total of 4 radial rays (4), which extend outward along the diagonal of the concentric square closed loop (1) and form a 45° angle with the edge of the square closed loop (1); The grounding down conductor (3) led out from the tower foot (7) of the transmission line is covered with an insulating PVC conduit, which passes through the concrete protection of the tower foundation.

5. A method for arranging grounding devices on transmission line towers to reduce step voltage, characterized in that, Includes the following steps: S1. On-site measurement of soil resistivity in the area where the transmission line towers are located. Record measurement data and organize and archive it; S2. Assess the frequency of personnel activity in the tower area, classify safety zone levels, and determine the permissible limit for step voltage. ; S3, based on and The number N of square closed loops to be arranged and the total length L of the horizontal grounding grid are calculated using a preset calculation model. S4. Excavate a grounding trench with a preset depth h, arrange a square closed loop (1) and radial rays (4) according to the calculated parameters, and weld a vertical grounding wire (2) at each vertex of the square closed loop. S5. Use C-type connector (501) to assemble and fix the horizontal grounding body composed of square closed loop (1) and radial rays (4), and use M-type connector (502) to connect the tower foot (7) of the transmission line pole to the grounding down conductor (3). S6. Drive the grounding electrode (6) vertically into the preset position to ensure that the implantation depth of the grounding electrode (6) meets the requirements. Use the E-type connector (503) to connect the grounding lead (3) to the grounding electrode (6) and connect it to the horizontal grounding grid. S7. Backfill the excavated grounding trench, compact the soil in layers, and ensure that the grounding electrode is in close contact with the soil.

6. The method for arranging grounding devices for transmission line towers to reduce step voltage according to claim 5, characterized in that, In step S2, the safety zone level is divided into the following two categories based on the frequency of personnel activity: 6.1 Frequently Passed Areas: Defined as areas where people frequently walk and move around, with permissible step voltage limits set. ; 6.2 Public Dense Areas: Defined as areas where people are likely to gather and where barefoot walking may occur, a step voltage allowable limit is set. .

7. The method for arranging grounding devices for transmission line towers to reduce step voltage according to claim 6, characterized in that, In step S3: For frequently traversed areas, the number of square closed loops is set to N=4, the layer spacing is D=2 meters, and the total length of the horizontal grounding grid is L≥338 meters; For densely populated public areas, the number of square closed loops is set to N=5, the layer spacing is D=2 meters, and the total length of the horizontal grounding grid is L≥420 meters; If the calculation results show that the preset number of square closed loop layers N cannot be satisfied... If required, the outward extension length of the radial rays (4) is increased, and the calculation is repeated until the requirements are met.

8. The method for arranging grounding devices for transmission line towers to reduce step voltage according to claim 5, characterized in that, The calculation and verification of the step voltage in step S3 follows the model below: in: To predict step voltage; This refers to the fault current that flows to ground. The effective length of the grounding system is a function of the effective length of the grounding system, which includes the sum of the effective lengths of all square closed loops (1), radial rays (4), vertical grounding wires (2) and grounding electrodes (6), and increases monotonically with the number of layers $N$. For square grid geometric coefficients, which are related to the interlayer spacing D and the burial depth h; is the coefficient for non-uniform current distribution; the value of N is adjusted iteratively until the inequality condition is met.

9. The method for arranging grounding devices for transmission line towers to reduce step voltage according to claim 5, characterized in that, In step S3, the first i Side length of the closed loop of the square layer (1) Determined by the following formula: Where: i is the level index ( ), The innermost square's side length is determined by the root opening size of the tower foot (7) of the transmission line tower, and D is the layer spacing; Vertical grounding wire (2) is welded to each layer side length The positions of the four corner points.

10. The method for arranging grounding devices for transmission line towers to reduce step voltage according to claim 5, characterized in that, If the soil resistivity in the construction area is higher than the preset threshold of 500Ω If m, then add a physical drag-reducing agent to the backfill soil; The aforementioned resistance-reducing agent is mainly wrapped around the grounding electrode (6) and at the apex of the square closed loop (1) where the vertical grounding wire (2) is welded. The radius of the wrapping layer is not less than 0.1 meters.

Images