Construction method of grounding device

Abstract

The invention belongs to the technical field of power system grounding engineering, and relates to a grounding device construction method, which specifically comprises the following steps of: vertically layering a plurality of copper bars and electrically connecting the copper bars through a mortise and tenon joint structure, embedding grounding electrodes below the copper bars according to a spiral array, coating nano graphite powder / epoxy resin / curing agent mixed gel at joints and performing pressurization treatment; finally, pulse current is applied to measure grounding resistance, and the grounding resistance is qualified when the error is + / -5%. According to the method, a current diffusion path is optimized through a three-dimensional network, conductivity and corrosion resistance are enhanced by utilizing composite gel, construction precision is improved by combining a dynamic measurement technology, the method is mainly applied to engineering scenes such as electric power systems and high-rise buildings with high requirements on grounding reliability, grounding resistance can be remarkably reduced, and the service life of the device can be prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of grounding engineering in power systems and relates to a construction method for grounding devices. Background Art

[0002] As an important infrastructure for ensuring the safe operation of power systems, the construction quality of grounding devices directly affects the reliability and service life of the system. Traditional construction methods for grounding devices have exposed several technical problems that need to be solved urgently in long-term practice. First, there are limitations in controlling the grounding resistance. Existing technologies mostly adopt a single-directional arrangement of grounding electrodes horizontally or vertically, resulting in a single current dissipation path and difficulty in adapting to complex soil resistivity distributions. When the soil has a layered structure, the conventional grounding electrode arrangement is prone to form local resistance concentration areas. Especially in high-resistivity geological conditions, it is difficult to stably meet the grounding resistance standard. In addition, traditional construction methods rely on empirical formulas to calculate grounding parameters, without fully considering the non-linear characteristics and dynamic changes of the soil, resulting in a large deviation between the design value and the actual measured value. Second, there is a contradiction between construction efficiency and detection accuracy. The traditional construction process requires multiple excavations, measurements, and adjustments, with a long cycle. Conventional grounding resistance measurement methods are significantly affected by power frequency interference, and multi-point synchronous measurement technology has not been popularized, making it difficult to accurately reflect the true performance of the grounding system. It is urgent to break through the above technical limitations through innovative construction methods. Summary of the Invention

[0003] An object of an embodiment of the present invention is to solve at least the above problems and / or defects and provide at least the advantages described hereinafter.

[0004] Solve the problem of the single current dissipation path and unstable grounding resistance caused by the planar arrangement of traditional grounding devices, especially difficult to meet the design requirements in complex soil environments.

[0005] Solve the problems of oxide layer formation, increased contact resistance, and insufficient mechanical strength in the copper bar connection process, and improve the conductivity and reliability of the connection part.

[0006] Solve the problem of low current dissipation efficiency caused by the lack of a scientific basis for the arrangement of grounding electrodes, and adapt to soil resistivity changes by optimizing the spiral array parameters.

[0007] Solve the problems of power frequency interference in grounding resistance measurement and the lack of multi-point synchronous measurement technology, and improve the detection accuracy and fault location efficiency.

[0008] Solve the problem of electrochemical corrosion caused by the simple anti-corrosion treatment process on the surface of copper bars, and extend the service life of the grounding device.

[0009] Solve the problems of insufficient conductivity and poor interface contact of the mortise and tenon connection structure, and enhance the conductivity and corrosion resistance of the connection part.

[0010] Solve the problem of increased contact resistance caused by oxidation or mechanical stress at the copper busbar contact surface, and optimize the contact area through a serrated structure.

[0011] Solve the problems of high resistance at the contact interface between the grounding electrode and the soil and poor penetration effect of the resistance reduction material, and construct a three-dimensional conductive network.

[0012] Solve the problems of fixed pulse current detection frequency and weak fault location ability, and achieve dynamic frequency adjustment and accurate positioning of the defective area.

[0013] Solve the problems of insufficient wear resistance and conductivity caused by the single material of the serrated contact surface, and improve the comprehensive performance through a gradient structure.

[0014] For this reason, the technical solution provided by the present invention is as follows: A construction method of a grounding device includes the following steps: 1) Arrange multiple copper busbars in layers vertically to form a three-dimensional grounding network, and make electrical connections between adjacent copper busbars; 2) Vertically bury the grounding electrodes in the soil below the copper busbars in a spiral array manner, and fixedly connect the top ends of the grounding electrodes to the bottommost copper busbar; 3) Coat a conductive and anticorrosive gel at the connection between the copper busbar and the grounding electrode, and keep it for 5 to 10 minutes under a pressure of 0.5 MPa to 1 MPa to make the gel fill the contact gap. The gel is made by mixing nano-graphite powder, epoxy resin and curing agent in a weight ratio of 3:4~6:2; 4) Apply a pulse current between the copper busbar and the grounding body, verify the grounding resistance value through multi-point synchronous measurement, compare the calculated grounding resistance value with a preset standard value. If the error is within ±5%, it is considered that the grounding resistance value meets the requirements, and the copper busbar construction is completed. If the error exceeds ±5%, further analyze the measurement data, check whether there is a fault in the measurement system or a defect in the grounding system, and take corresponding measures for adjustment and repair.

[0015] Preferably, in the construction method of the grounding device, in step 1), the step of arranging multiple copper busbars in layers vertically to form a three-dimensional grounding network and making electrical connections between adjacent copper busbars is specifically as follows: First, perform deoxidation treatment on the surface of the copper busbar to be installed, then divide the copper busbar into at least three layers, the vertical distance between each layer of copper busbar is 0.5 - 1.5 meters, and adjacent layers of copper busbars are parallel to each other. The depth of the top layer of copper busbar from the ground is 0.3 - 0.5 meters; Finally, make electrical connections between adjacent copper busbars using a mortise and tenon structure.

[0016] Preferably, in the construction method of the grounding device, in step 2), the spiral array is composed of multiple grounding electrodes. The grounding electrodes of the spiral array include at least three layers of concentric spiral structures. The outermost spiral radius is 5 to 8 times the length of the grounding electrode. The calculation formula for the pitch p of adjacent spiral layers is: where ρ i is the soil resistivity of the current layer, ρ 0 is the resistivity of the reference layer, D is the diameter of the grounding electrode, k takes a value of 1.2 to 1.5; the outermost spiral radius is extended to times the length of the grounding electrode, and the current dissipation path is optimized through numerical simulation.

[0017] Preferably, in the construction method of the grounding device, in step 4), the steps of applying a pulsed current between the copper busbar and the grounding body and verifying the grounding resistance value through multi-point synchronous measurement include: Arrange at least 5 measurement points around the grounding body, and each measurement point is equipped with a voltage sensor and a current sensor Use a pulsed current generator to synchronously collect voltage and current data for at least 5 of the measurement points, and calculate the grounding resistance value using a curve fitting algorithm based on the least squares method; Compare the calculated grounding resistance value with a preset standard value. If the error is within ±5%, it is considered that the grounding resistance value meets the requirements. If the error exceeds ±5%, first further analyze the measurement data to check whether there is a fault in the measurement system or a defect in the grounding system, and take corresponding measures for adjustment and repair. Then, detect the electrical connection between the copper busbars and the connection between the copper plate and the grounding electrode until the error is detected within ±5% again.

[0018] Preferably, in the construction method of the grounding device, after completing the electrical connection, anti-corrosion treatment is carried out on the copper busbar and the connection parts: First, pickle and passivate the surface of the copper busbar to remove the oxide layer and impurities on the surface. Then, spray a layer of anti-corrosion coating with a thickness of 0.1 - 0.3 mm on the surface of the copper busbar. This anti-corrosion coating has good water resistance, corrosion resistance, and weather resistance, and can effectively prevent the copper busbar from being corroded in the soil.

[0019] Preferably, in the construction method of the grounding device, the tenon-mortise structure includes a tenon provided at one end of the copper bar and a mortise provided at the other end of the adjacent copper bar. The cross-sectional shape of the tenon is adapted to the cross-sectional shape of the mortise, and the cross-sectional area of the tenon is larger than the cross-sectional area of the mortise. The tenon of one copper bar is inserted into the mortise of another adjacent copper bar, and spring pieces are provided on both sides of the tenon-mortise structure. Conductive enhancement layers are provided on the contact surfaces of the tenon and the mortise. The conductive enhancement layer includes a bottom layer made of copper material, a surface layer made of silver or gold material, and a graphene composite coating coated on the surface layer. The bottom layer covers the contact surfaces of the tenon and the mortise through electroplating or electroless plating process. The surface layer covers the copper layer through vacuum sputtering or electroplating process. The thickness of the graphene composite coating is 0.05 - 0.1 mm, and the graphene content is 5 - 10 wt%.

[0020] Preferably, in the construction method of the grounding device, in step 1), serrated conductive contact surfaces are provided on the surface of each layer of copper bar. The serrated conductive contact surfaces are composed of a plurality of uniformly distributed serration units. The serration unit is a triangular or trapezoidal structure, and its height is 1 / 3 to 1 / 2 of the thickness of the copper bar, and the bottom width is 1 / 5 to 1 / 4 of the width of the copper bar. The serrated conductive contact surfaces of adjacent copper bars are engaged with each other, and the engagement surface is the inclined surface of the serration unit. A conductive enhancement layer is provided on the surface of the serration unit, and the thickness of the conductive enhancement layer is 0.1 mm to 0.5 mm.

[0021] Preferably, in the construction method of the grounding device, the spiral array of grounding electrodes adopts a hollow structure, and the inside is filled with a composite resistance reducing material. The composite resistance reducing material is composed of nanoscale activated carbon particles, bentonite and graphene mixed in a mass ratio of 5:3:2. When burying the grounding electrode, the composite resistance reducing material is injected into the hollow cavity of the grounding electrode through a pressure grouting device, and a resistance reducing electrolyte containing 0.1 - 0.3 wt% silver nitrate is simultaneously injected into the soil to form a three-dimensional conductive network, reducing the contact resistance between the grounding electrode and the soil by more than 30%.

[0022] Preferably, in the construction method of the grounding device, the pulse current generator adopts an adaptive frequency control technology, analyzes the spectral characteristics of the soil impedance in real time through Fourier transform, dynamically adjusts the pulse frequency from 10 kHz to 1 MHz, and optimizes the multi-point synchronous measurement path in combination with the genetic algorithm. When detecting abnormal grounding resistance, a three-dimensional resistance cloud map is automatically generated to locate the defective area of the system.

[0023] Preferably, in the construction method of the grounding device, the serrated conductive contact surface adopts a gradient structure design. The serration units are arranged in sequence from the edge of the copper bar to the center as follows: Outer layer: a diamond nanowire-reinforced silver-based alloy layer with a thickness of 0.05 - 0.1 mm; Middle layer: The carbon nanotube / epoxy resin composite transition layer with a thickness of 0.2 - 0.3 mm; Inner layer: Pure copper substrate.

[0024] The embodiments of the present invention at least include the following beneficial effects: The present invention adopts a three-dimensional hierarchical copper bus network and a spiral array grounding electrode, significantly expanding the current dissipation area, reducing the grounding resistance by more than 40%, and adapting to the dynamic changes of complex soil environments.

[0025] The hierarchical arrangement of the present invention combined with the mortise and tenon connection process avoids the problem of welding oxidation, reduces the contact resistance to 1 / 3 of the traditional process, and improves the mechanical strength of the connection part by 50%.

[0026] The spiral array parameter calculation model based on soil resistivity in the present invention improves the matching degree between the grounding electrode arrangement and soil characteristics by 60% and enhances the current dissipation efficiency by 35%.

[0027] The multi-point synchronous measurement technology of the present invention combined with the least squares fitting method controls the measurement error within ±3%, and improves the fault location efficiency by 70%.

[0028] The pickling, passivation and anti-corrosion coating process of the present invention reduces the corrosion rate of the copper bus by 80% and extends the service life to more than 20 years.

[0029] The design of the spring piece with a mortise and tenon structure and the gradient conductive enhancement layer in the present invention reduces the fluctuation range of the contact resistance to ±5% and enhances the anti-electrochemical corrosion ability by 90%.

[0030] The serrated contact surface of the present invention increases the effective contact area by 2.5 times, reduces the contact resistance by 65%, and significantly enhances the anti-mechanical stress performance.

[0031] The synergistic effect of the hollow structure and the composite resistance reduction material in the present invention reduces the contact resistance between the grounding electrode and the soil by more than 30%, and the resistance reduction effect is stable in the long term.

[0032] The adaptive frequency control technology of the present invention improves the validity of the measurement data by 85%, the positioning accuracy of the three-dimensional resistance cloud map reaches ±0.2 m, and the defect repair efficiency is increased by 2 times.

[0033] The gradient material structure of the present invention increases the hardness of the contact surface by 40%, extends the wear-resistant life by 3 times, and maintains stable conductivity for more than 15 years.

[0034] Other advantages, objectives and features of the embodiments of the present invention will be partially reflected by the following description, and partially will also be understood by those skilled in the art through the research and practice of the embodiments of the present invention. Detailed implementation manners

[0035] The following further describes the embodiments of the present invention in detail in conjunction with the accompanying drawings, so that those skilled in the art can implement it according to the text of the specification.

[0036] The present invention provides a construction method for a grounding device, including the following steps: 1) Arrange multiple copper bars in layers in the vertical direction to form a three-dimensional grounding network, and make electrical connections between adjacent copper bars; optionally, arrange multiple copper bars in layers in the vertical direction, and the vertical distance between layers can be selected as 0.8 meters or 1.2 meters, and adjacent layers are kept parallel. The deoxidation treatment of the copper bar surface can adopt mechanical grinding or chemical pickling methods, for example, soak in a sulfuric acid solution with a concentration of 5% for 3 minutes.

[0037] 2) Vertically bury the grounding electrodes in the soil below the copper bars in a spiral array manner, and fixedly connect the top ends of the grounding electrodes to the bottommost layer of copper bars; optionally, the grounding electrodes are vertically buried in a spiral array manner, and the number of spiral layers can be selected as 3 layers or 4 layers, and the outermost spiral radius is calculated according to the length of the grounding electrode. When burying, a spiral drill (such as XY-100 type) can be used for drilling, and the hole depth matches the length of the grounding electrode.

[0038] 3) Coat a conductive anti-corrosion gel at the connection between the copper bar and the grounding electrode, and keep it under a pressure of 0.5 MPa to 1 MPa for a time of 5 minutes to 10 minutes to make the gel fill the contact gap. The gel is made by mixing nano-graphite powder, epoxy resin and curing agent in a weight ratio of 3:4~6:2; for the conductive anti-corrosion gel coated at the connection between the copper bar and the grounding electrode, commercially available nano-graphite powder (particle size 50 nm), E51 epoxy resin and T31 curing agent can be selected as raw materials. The mixing ratio can be selected as 3:5:2, and the stirring time is controlled within 5 minutes. When performing the pressure treatment, the pressure value can be set as 0.7 MPa or 0.9 MPa, and the pressure holding time is 8 minutes.

[0039] 4) Apply a pulsed current between the copper bar and the grounding body, verify the grounding resistance value through multi-point synchronous measurement, compare the calculated grounding resistance value with a preset standard value. If the error is within ±5%, it is considered that the grounding resistance value meets the requirements, and the copper bar construction is completed. If the error exceeds ±5%, further analyze the measurement data, check whether there are faults in the measurement system or defects in the grounding system, and take corresponding measures for adjustment and repair. The pulsed current detection adopts multi-point synchronous measurement, and the number of measurement points can be selected as 5 or 7 The working process of the grounding device construction method of the present invention is as follows: first, multiple copper bars are arranged vertically in layers, the interlayer spacing is controlled within the range of 0.5-1.5 meters, the adjacent copper bars are kept in a parallel state, the top layer is buried at a depth of 0.3-0.5 meters, and the layers are electrically connected through a mortise and tenon structure. Then, the grounding electrode is vertically buried in the soil under the copper bar in a spiral array. The spiral structure includes at least 3 concentric layers, the outermost radius is 5-8 times the length of the grounding electrode, and the pitch of the adjacent layers is calculated and determined according to the soil resistivity. Subsequently, a conductive anti-corrosion gel mixed with nanographite powder, epoxy resin, and curing agent in a ratio of 3:4~6:2 is coated at the connection between the copper bar and the grounding electrode, and a pressure of 0.5-1MPa is applied and maintained for 5-10 minutes. Finally, a pulse current generator is used to apply current between the copper bar and the grounding body, and the voltage and current data of at least 5 measuring points are collected synchronously. The grounding resistance value is calculated by the least squares method. The construction is completed within an error of ±5% compared with the standard value. If the error is exceeded, a system investigation and repair is required.

[0040] In one of the schemes of the present invention, preferably, in step 1), a plurality of copper bars are arranged in layers along a vertical direction to form a three-dimensional grounding network, and the steps of electrically connecting adjacent copper bars are specifically as follows: First, the surface of the copper busbar to be installed is deoxidized. The deoxidation treatment of the copper busbar surface can be mechanically polished or chemically pickled, for example, soaking in a 5% sulfuric acid solution for 3 minutes. Then the copper busbar is divided into at least three layers, the vertical spacing between each layer of copper busbars is 0.5-1.5 meters and the adjacent layers of copper busbars are parallel to each other. The depth of the top layer of copper busbar from the ground is 0.3-0.5 meters to ensure that it is in a relatively stable soil environment and reduce the interference of external factors. Each layer of copper busbar uses a T2 copper busbar with a thickness of 3-8 mm and a width of 30-100 mm, and its purity is not less than 99.9% to ensure good conductivity. When arranged in layers, the number of layers can be selected as 3 or 4 layers, the vertical spacing between layers can be set to 0.8 meters or 1.2 meters, and the parallelism error of adjacent layers is controlled within ±2°. The buried depth of the top copper busbar can be selected to be 0.4m or 0.5m, and the depth can be calibrated by a laser rangefinder (such as Leica DISTO D2). The copper busbar can be made of T2 copper with a thickness of 6mm and a width of 50mm. In one of the schemes of the present invention, each copper busbar can be fixed by a high-strength insulating bracket pre-buried in the soil. The insulating bracket is made of high-strength engineering plastic with a withstand voltage of not less than 10kV to prevent the copper busbar from directly contacting the conductive material in the soil and causing leakage. The spacing of the insulating brackets is 1-2 meters to ensure that the copper busbar is firmly fixed and will not be displaced due to factors such as soil settlement.

[0041] Finally, the adjacent copper bars are electrically connected by a mortise and tenon structure.

[0042] In one of the embodiments of the present invention, preferably, in step 2), the spiral array is composed of multiple grounding electrodes, and the grounding electrodes of the spiral array include at least three layers of concentric spiral structures. The outermost spiral radius is 5 to 8 times the length of the grounding electrode. The calculation formula for the pitch p of adjacent spiral layers is: Wherein, ρ i is the soil resistivity of the current layer, ρ 0 is the resistivity of the reference layer, D is the diameter of the grounding electrode, k takes a value of 1.2 to 1.5; the outermost spiral radius is extended to times the length of the grounding electrode, and the current dissipation path is optimized through numerical simulation. The pitch of the spiral array is dynamically adjusted according to the soil resistivity gradient. The number of spiral layers of the grounding electrode can be selected as 3 or 4 layers, and the outermost spiral radius is 6 times the length of the grounding electrode (for example, a length of 2 meters corresponds to a radius of 12 meters). The k value in the calculation formula for the spiral layer spacing is selected as 1.3 or 1.4 according to the soil type. The reference layer resistivity ρ0 is determined by soil sampling tests (such as using a four-electrode method tester). The grounding electrode is made of a hollow steel pipe (such as Q235 material, with a diameter of 50 mm) and a wall thickness of 3 mm. When burying, a spiral drill (such as XY-150 type) can be used, and the drilling diameter is 20 mm larger than the outer diameter of the grounding electrode to ensure the grouting space. The composite resistance reduction material is composed of nano-activated carbon particles (particle size 20 nm), bentonite (montmorillonite content ≥ 90%), and graphene (flake diameter 5 - 10 μm) mixed in a ratio of 5:3:2. When injecting, a piston grouting pump (such as BW250 type) is used, and the grouting pressure is controlled at 0.8 - 1.0 MPa and the flow rate is 50 L / min. The resistance reduction electrolyte injected synchronously contains 0.2 wt% silver nitrate (analytical pure reagent), and the injection volume is calculated according to 5% of the soil volume. During the grouting process, a pressure sensor (such as Honeywell 16PC series) is used for real-time monitoring to ensure uniform penetration of the material. The COMSOL Multiphysics software can be used to establish a three-dimensional soil-grounding electrode model, and the measured resistivity data is input for simulation. When optimizing the parameters of the spiral array, the pitch p is adjusted so that the deviation of the current density of each layer of grounding electrode is less than 15%, and the optimal spiral trajectory is determined through iterative calculation. Before construction, a 1:10 scale model is made (such as a grounding electrode length of 0.5 meters and a spiral radius of 3 meters), and the current dissipation effect under different soil conditions is simulated in the laboratory. The error between the simulation and the measured data is controlled within ±8%.

[0043] In one of the embodiments of the present invention, preferably, in step 4), the steps of applying a pulsed current between the copper bar and the grounding body and verifying the grounding resistance value through multi-point synchronous measurement include: Arrange at least 5 measurement points around the grounding electrode. Each measurement point is equipped with a voltage sensor and a current sensor. The number of measurement points can be selected as 5 or 7, and they are distributed in a circular pattern around the grounding electrode, 5 - 10 meters away from the grounding electrode. Install a voltage sensor (such as a PVM-500 voltage divider sensor) and a current sensor (such as an FWT-100 Rogowski coil sensor) at each measurement point, and connect them to a data acquisition instrument through a shielded cable (such as RVVP 4×1.5mm²). The installation position of the sensor should avoid metal structures, and the burial depth is 0.3 - 0.5 meters. Use an impact drill (such as Bosch GBH 2-26) to drill holes for fixation.

[0044] Use a pulse current generator to synchronously collect voltage and current data at at least 5 of the said measurement points, and calculate the grounding resistance value using a curve fitting algorithm based on the least squares method; the sensors can be selected as Rogowski coil current sensors (such as FWT-100 type) and voltage divider voltage sensors (such as PVM-500 type). The least squares method is used for measuring data fitting, and the correlation coefficient of the fitting curve should reach above 0.99.

[0045] Compare the calculated grounding resistance value with a pre-set standard value. If the error is within ±5%, it is considered that the grounding resistance value meets the requirements. If the error exceeds ±5%, first further analyze the measurement data, check whether there are faults in the measurement system or defects in the grounding system, and take corresponding measures for adjustment and repair. Then, detect the electrical connection between copper bars and the connection between the copper plate and the grounding electrode until the error is within ±5% again during the re-detection. The output frequency of the pulse current generator (such as HAIPEIHEP HPS-500 type) can be dynamically adjusted from 10kHz to 1MHz, and the amplitude is 5 - 10A. The data acquisition synchronization error is controlled within ±1μs, and an NI USB-6366 data acquisition card is used for analog-to-digital conversion. When calculating the resistance, the correlation coefficient of the least squares fitting curve should be ≥0.99, and the number of iterations is set to 50 times. When the detection error exceeds ±5%, start the automatic re-measurement program, and the re-measurement interval time is 10 minutes.

[0046] In one of the embodiments of the present invention, preferably, after the electrical connection is completed, anti-corrosion treatment is carried out on the copper busbar and the connection parts: First, the surface of the copper busbar is pickled and passivated to remove the oxide layer and impurities on the surface. Then, an anti-corrosion coating with a thickness of 0.1 - 0.3 mm is sprayed on the surface of the copper busbar. This anti-corrosion coating has good water resistance, corrosion resistance and weather resistance, and can effectively prevent the copper busbar from being corroded in the soil. The pickling treatment can use a sulfuric acid solution with a concentration of 5 - 8%, the temperature is controlled at 40 - 50 °C, the soaking time is 3 - 5 minutes, and an ultrasonic cleaner (such as KQ-500DE type) is used to assist in removing the oxide layer. The passivation treatment uses a chromate solution (such as potassium dichromate) with a concentration of 3 - 5%, the soaking time is 1 - 2 minutes, and the pH value is adjusted to 6 - 7. After treatment, the surface roughness Ra of the copper busbar should be ≤ 0.8 μm, and it is detected using a roughness meter (such as Mitutoyo SJ-210). The anti-corrosion coating can be selected from epoxy resin-based materials (such as Hempel Hempadur Mastic 353), and the thickness is controlled at 0.15 - 0.25 mm. The spraying equipment uses a high-pressure airless spraying machine (such as Graco X7), the pressure is set at 15 - 20 MPa, and the spraying distance is 20 - 30 cm. The coating curing conditions are drying at room temperature for 24 hours or baking at 60 °C for 2 hours, and the hardness should reach above 2H (pencil hardness test) In one embodiment of the present invention, preferably, the mortise and tenon structure includes a tenon provided at one end of the copper bar and a mortise provided at the other end of the adjacent copper bar. The cross-sectional shape of the tenon is adapted to the cross-sectional shape of the mortise, and the cross-sectional area of the tenon is larger than the cross-sectional area of the mortise. The tenon of one copper bar is inserted into the mortise of another adjacent copper bar, and spring pieces are provided on both sides of the mortise and tenon structure. Conductive enhancement layers are provided on the contact surfaces of the tenon and the mortise. The conductive enhancement layer includes a bottom layer made of copper material, a surface layer made of silver or gold material, and a graphene composite coating coated on the surface layer. The bottom layer covers the contact surfaces of the tenon and the mortise through electroplating or electroless plating processes. The surface layer covers the copper layer through vacuum sputtering or electroplating processes. The thickness of the graphene composite coating is 0.05 - 0.1 mm, and the graphene content is 5 - 10 wt%. The cross-sectional shapes of the tenon and the mortise of the mortise and tenon structure can be designed as trapezoids, and the area difference is controlled between 15% - 20%. The insertion depth of the tenon is 2 / 3 of the thickness of the copper bar, and spring pieces (such as 304 stainless steel with a thickness of 0.2 mm) are installed on both sides to maintain the contact pressure. The bottom layer of the conductive enhancement layer uses an electroless copper plating process (thickness 5 microns), the surface layer is plated with silver through vacuum sputtering (thickness 3 microns), and the graphene composite coating (thickness 0.08 mm, containing 8 wt% graphene) is covered by a spraying process. A CNC milling machine (such as DMG MORI CMX 1010) can be selected as the processing equipment for forming the mortise and tenon structure. The cross-sectional shapes of the tenon and the mortise can be designed as trapezoids or rectangles, and the area difference is controlled between 15% - 20%. The insertion depth of the tenon is 2 / 3 of the thickness of the copper bar, and spring pieces (such as 304 stainless steel with a thickness of 0.2 mm) are installed on both sides to maintain the contact pressure. For copper bar processing, a CNC milling machine (such as DMG MORI CMX 1010) can be selected, and the dimensional accuracy of the mortise and tenon is controlled within ±0.05 mm. A torque wrench (such as Norbar 200N・m) is used during connection to ensure uniform assembly pressure. The bottom layer of the conductive enhancement layer uses an electroless copper plating process (thickness 5 microns), and the solution formula is 25 g / L of copper sulfate, 10 ml / L of formaldehyde, and 30 g / L of EDTA sodium salt. The surface layer is plated with silver through vacuum sputtering (thickness 3 microns), the sputtering power is 150 W, and the vacuum degree is 5×10 -4 Pa. The graphene composite coating (thickness 0.08 mm, containing 8 wt% graphene) is applied by a spraying process using a pneumatic spray gun (such as SATAjet 4000 B), and the spraying pressure is 0.3 MPa.

[0047] In one of the embodiments of the present invention, preferably, in step 1), a serrated conductive contact surface is provided on the surface of each layer of copper busbar. The serrated conductive contact surface is composed of a plurality of evenly distributed serration units; the serration units are of triangular or trapezoidal structure, and their height is 1 / 3 to 1 / 2 of the thickness of the copper busbar, and the bottom width is 1 / 5 to 1 / 4 of the width of the copper busbar; the serrated conductive contact surfaces of adjacent copper busbars are engaged with each other, and the engagement surface is the inclined surface of the serration unit; a conductive enhancement layer is provided on the surface of the serration unit, and the thickness of the conductive enhancement layer is 0.1 mm to 0.5 mm. The serration units can be designed as isosceles triangles or right trapezoids, with the height being 1 / 3 (such as 2 mm) or 1 / 2 (such as 3 mm) of the thickness of the copper busbar, and the bottom width being 1 / 5 (such as 10 mm) or 1 / 4 (such as 12.5 mm) of the width of the copper busbar. Tooth profile machining can use a CNC milling machine (such as DMG MORI CMX 1010), the fillet radius of the tooth tip ≤ 0.2 mm, and the surface roughness Ra of the tooth surface ≤ 0.4 μm. When adjacent copper busbars are engaged, the contact pressure on the tooth surface is controlled at 15 - 20 MPa, and a pressure sensor (such as HBM PW27) is used for real-time monitoring. The conductive enhancement layer adopts a composite structure of electroless copper plating (thickness 10 μm) and vacuum sputtering silver plating (thickness 5 μm). The formula of the electroless copper plating solution is 25 g / L of copper sulfate, 10 ml / L of formaldehyde, 30 g / L of EDTA sodium salt, and the pH value is 12.5 ± 0.2. The vacuum sputtering process parameters are a power of 200 W, a vacuum degree of 6×10 -4 Pa, and the silver plating time is 15 minutes. The graphene composite coating (thickness 0.3 mm, containing 10 wt% graphene) adopts a thermal spraying process, using a plasma spraying device (such as Praxair TAFA 9000), and the spraying temperature is 1500℃.

[0048] In one embodiment of the present invention, preferably, the grounding electrode of the spiral array has a hollow structure, and the interior is filled with a composite resistance-reducing material. The composite resistance-reducing material is composed of nano-scale activated carbon particles, bentonite, and graphene mixed in a mass ratio of 5:3:2. When burying the grounding electrode, the composite resistance-reducing material is injected into the hollow cavity of the grounding electrode through a pressure grouting device, and a resistance-reducing electrolyte containing 0.1 - 0.3 wt% silver nitrate is simultaneously injected into the soil to form a three-dimensional conductive network, reducing the contact resistance between the grounding electrode and the soil by more than 30%. The grounding electrode is made of seamless steel pipe (such as Q235 material), the outer diameter can be selected as 50 mm or 70 mm, and the wall thickness is 3 mm, meeting the GB / T 8162 standard. The diameter of the hollow cavity is 1 / 3 of the outer diameter of the grounding electrode (such as 16.7 mm), and sealing plates (with a thickness of 5 mm) are welded at both ends. Before burial, a diameter gauge (such as Mitutoyo CD-15APX) is used to check the pipe diameter deviation to ensure uniform grouting space. The composite resistance-reducing material is composed of nano-activated carbon particles (particle size 20 nm), bentonite (montmorillonite content ≥ 90%), and graphene (flake diameter 5 - 10 μm) mixed in a ratio of 5:3:2. A plunger grouting pump (such as BW250 type) is used for injection, the grouting pressure is controlled at 0.8 - 1.0 MPa, and the flow rate is 50 L / min. The simultaneously injected resistance-reducing electrolyte contains 0.2 wt% silver nitrate (analytical pure reagent), and the injection volume is calculated based on 5% of the soil volume. During the grouting process, a pressure sensor (such as Honeywell 16PC series) is used for real-time monitoring to ensure uniform penetration of the material.

[0049] In one of the embodiments of the present invention, preferably, the pulsed current generator adopts an adaptive frequency control technology to analyze the spectral characteristics of soil impedance in real time through Fourier transform, dynamically adjust the pulse frequency from 10 kHz to 1 MHz, and optimize the multi-point synchronous measurement path in combination with the genetic algorithm; when an abnormal grounding resistance is detected, a three-dimensional resistance cloud map is automatically generated to locate the defective area of the system. The output frequency of the pulsed current generator (such as HAIPEIHEP HPS-500) can be dynamically adjusted from 10 kHz to 1 MHz with a step size of 1 kHz. The Fourier transform module (such as NI PXI-5663) analyzes the soil impedance spectrum in real time, with a sampling rate set to 200 kHz and a frequency resolution of 0.5 Hz. The dynamic adjustment algorithm selects 3 optimal frequency points (such as 10 kHz, 50 kHz, 100 kHz) for measurement according to the impedance peak frequency to reduce the influence of power frequency interference. The genetic algorithm parameters are set as follows: population size 20, number of iterations 50, crossover probability 0.8, and mutation probability 0.1. The optimization objective is to minimize the total length of the measurement path while satisfying the condition that the distance between measurement points is ≥5 meters. The path planning result is visually displayed through a GIS system (such as ArcGIS Desktop) to guide the arrangement of on-site sensors. The measurement point device uses a wireless synchronization module (such as Decawave DW1000) with a synchronization accuracy of ±1 μs. The three-dimensional modeling adopts an Octree data structure with a resolution of 0.5 meters. The resistance cloud map is generated by Kriging interpolation, and the Gaussian model is selected as the variogram function. The positioning algorithm sets the threshold to 1.5 times the average resistance value, and when an abnormal area is detected, a repair suggestion plan is automatically generated.

[0050] In one of the embodiments of the present invention, preferably, the serrated conductive contact surface adopts a gradient structure design, and the serrated units are arranged in sequence from the edge of the copper bar to the center as follows: The outer layer: a diamond nanowire-reinforced silver-based alloy layer with a thickness of 0.05 - 0.1 mm; The middle layer: a carbon nanotube / epoxy resin composite transition layer with a thickness of 0.2 - 0.3 mm; Inner layer: pure copper substrate. The serrated contact surface is divided into three layers from the edge to the center: the outer layer is a diamond nanowire-reinforced silver-based alloy (thickness 0.07 mm), the middle layer is a carbon nanotube / epoxy resin composite material (thickness 0.25 mm), and the inner layer is a pure copper substrate. The thickness error of each layer is controlled within ±5%, and an online monitor is carried out using a laser thickness gauge (such as Keyence LK-G80). The interlayer bonding adopts a hot pressing process, with a temperature of 180 °C, a pressure of 5 MPa, and a pressure holding time of 10 minutes. The outer layer material is selected as a commercially available diamond nanowire (diameter 5 - 10 nm, purity ≥99%) and a silver-based alloy (Ag-90Cu-10) composite, which is prepared by powder metallurgy. The middle layer material is a carbon nanotube (outer diameter 10 - 20 nm, length 1 - 2 μm) and E51 epoxy resin mixed in a ratio of 3:7, and an ultrasonic dispersion process (power 500 W, time 30 minutes) is adopted. The inner pure copper substrate is selected as T2 red copper, with a purity ≥99.95%.

[0051] To enable those skilled in the art to better understand the technical solution of the present invention, the following embodiments are provided for further illustration: A construction method for a grounding device includes the following steps: 1) Arranging multiple copper bars in layers vertically to form a three-dimensional grounding network, and making electrical connections between adjacent copper bars: The steps of arranging multiple copper bars in layers vertically to form a three-dimensional grounding network and making electrical connections between adjacent copper bars are specifically as follows: First, the surface of the copper bar to be installed is subjected to deoxidation treatment, and then the copper bar is divided into at least three layers. The vertical distance between each layer of copper bars is 0.5 - 1.5 meters, and adjacent layers of copper bars are parallel to each other. The depth of the top layer of copper bar from the ground is 0.3 - 0.5 meters; Finally, the adjacent copper bars are electrically connected by a mortise and tenon structure.

[0052] After the electrical connection is completed, the copper bars and the connection parts are subjected to anti-corrosion treatment: First, the surface of the copper bar is pickled and passivated to remove the surface oxide layer and impurities, and then a layer of anti-corrosion coating with a thickness of 0.1 - 0.3 mm is sprayed on the surface of the copper bar. This anti-corrosion coating has good water resistance, corrosion resistance, and weather resistance, and can effectively prevent the copper bar from being corroded in the soil.

[0053] The tenon-mortise structure includes a tenon provided at one end of the copper bar and a mortise provided at the other end of the adjacent copper bar. The cross-sectional shape of the tenon is adapted to the cross-sectional shape of the mortise, and the cross-sectional area of the tenon is larger than that of the mortise. The tenon of one copper bar is inserted into the mortise of another adjacent copper bar, and spring pieces are provided on both sides of the tenon-mortise structure. Conductive enhancement layers are provided on the contact surfaces of the tenon and the mortise. The conductive enhancement layer includes a bottom layer made of copper material, a surface layer made of silver or gold material, and a graphene composite coating coated on the surface layer. The bottom layer is covered on the contact surfaces of the tenon and the mortise by electroplating or electroless plating processes. The surface layer is covered on the copper layer by vacuum sputtering or electroplating processes. The thickness of the graphene composite coating is 0.05 - 0.1 mm, and the graphene content is 5 - 10 wt%.

[0054] 2) Vertically bury the grounding electrode in the soil under the copper bar in a spiral array manner, and fixedly connect the top end of the grounding electrode to the bottommost copper bar; the spiral array is composed of multiple grounding electrodes, and the grounding electrodes of the spiral array include at least three layers of concentric spiral structures. The outermost spiral radius is 5 - 8 times the length of the grounding electrode. The calculation formula for the pitch p of adjacent spiral layers is: where, ρ i is the soil resistivity of the current layer, ρ 0 is the resistivity of the reference layer, D is the diameter of the grounding electrode, k The value ranges from 1.2 to 1.5; the outermost spiral radius is extended to times the length of the grounding electrode, and the current dissipation path is optimized through numerical simulation.

[0055] 3) Coat a conductive and anti-corrosion gel at the connection between the copper bar and the grounding electrode, and keep it under a pressure of 0.5 MPa to 1 MPa for a time of 5 minutes to 10 minutes to make the gel fill the contact gap. The gel is made by mixing nano-graphite powder, epoxy resin, and curing agent in a weight ratio of 3:4 - 6:2; 4) Apply a pulsed current between the copper bar and the grounding body, verify the grounding resistance value through multi-point synchronous measurement, compare the calculated grounding resistance value with a preset standard value. If the error is within ±5%, it is considered that the grounding resistance value meets the requirements, and the copper bar construction is completed. If the error exceeds ±5%, further analyze the measurement data, check whether there are faults in the measurement system or defects in the grounding system, and take corresponding measures for adjustment and repair.

[0056] The steps of applying a pulsed current between the copper bar and the grounding body and verifying the grounding resistance value through multi-point synchronous measurement include: Arrange at least 5 measurement points around the grounding body, and each measurement point is equipped with a voltage sensor and a current sensor A pulse current generator is used to synchronously collect voltage and current data at at least 5 of the said measurement points, and a curve fitting algorithm based on the least squares method is used to calculate the value of the grounding resistance; The calculated grounding resistance value is compared with a preset standard value. If the error is within ±5%, the grounding resistance value is considered to meet the requirements. If the error exceeds ±5%, first, the measurement data is further analyzed to check whether there are faults in the measurement system or defects in the grounding system, and corresponding measures are taken for adjustment and repair. Then, the electrical connection between the copper bars and the connection between the copper plate and the grounding electrode are detected until the error is detected to be within ±5% again.

[0057] The grounding electrode of the spiral array adopts a hollow structure, and the inside is filled with a composite resistance reducing material, which is composed of nanoscale activated carbon particles, bentonite and graphene mixed in a mass ratio of 5:3:2; when burying the grounding electrode, the composite resistance reducing material is injected into the hollow cavity of the grounding electrode through a pressure grouting device, and a resistance reducing electrolyte containing 0.1-0.3wt% silver nitrate is synchronously injected into the soil to form a three-dimensional conductive network, reducing the contact resistance between the grounding electrode and the soil by more than 30%.

[0058] The pulse current generator adopts an adaptive frequency control technology, analyzes the spectral characteristics of the soil impedance in real time through Fourier transform, dynamically adjusts the pulse frequency from 10kHz to 1MHz, and optimizes the multi-point synchronous measurement path in combination with the genetic algorithm; when an abnormal grounding resistance is detected, a three-dimensional resistance cloud map is automatically generated to locate the defective area of the system.

[0059] The overall working process of the construction method of the grounding device of the present invention is as follows: The surface of the T2 copper bar is polished mechanically or pickled with 5% sulfuric acid solution to remove the oxide layer, and is arranged vertically in 3-4 layers with a layer spacing of 0.5-1.5 meters and a top layer burial depth of 0.3-0.5 meters. Adjacent copper bars are connected by a mortise and tenon structure, and the area difference between the tenon and the mortise is 15%-20%. The contact surfaces are successively plated with copper, silver and graphene composite coatings (thickness 0.05-0.1mm), and stainless steel spring sheets (thickness 0.2mm) are installed on both sides to maintain the contact pressure.

[0060] Use a spiral drill to drill holes in a three-layer concentric structure. The radius of the outermost layer is 5-8 times the length of the grounding electrode (for example, a 2-meter electrode length corresponds to a 10-16-meter radius). After the hollow steel pipe (diameter 50-70mm) is buried vertically, a mixed resistance reducing material of nano-activated carbon, bentonite and graphene (5:3:2) is injected, and a 0.1-0.3wt% silver nitrate electrolyte is synchronously injected to form a three-dimensional conductive network.

[0061] The connection between the copper busbar and the grounding electrode is coated with a mixed gel of nano-graphite powder, epoxy resin, and curing agent (3:4~6:2), and a pressure of 0.5-1 MPa is applied for 5-10 minutes for pressure holding. After pickling and passivation of the copper busbar surface, an epoxy resin anti-corrosion coating with a thickness of 0.1-0.3 mm is sprayed, and a serrated contact surface (tooth height is 1 / 3-1 / 2 of the busbar thickness) is used at the connection part to enhance the contact area.

[0062] Arrange 5-7 measurement points around the grounding body, use a pulse current generator (frequency 10 kHz - 1 MHz) to synchronously collect voltage and current data, and calculate the grounding resistance by least squares fitting. It is qualified within an error of ±5%. When the error exceeds the standard, start the three-dimensional resistance cloud map to locate the defect, adjust the connection structure or supplement the resistance-reducing material until it meets the standard.

[0063] This method expands the current dissipation area through a three-dimensional network, enhances the electrical conductivity and anti-corrosion performance with gradient materials, and improves the construction accuracy with intelligent detection, reducing the grounding resistance by more than 40%, stabilizing the contact resistance below 0.05 Ω, and extending the overall service life to more than 20 years.

[0064] Although the implementation schemes of the embodiments of the present invention have been disclosed as above, they are not limited to only the applications listed in the description and implementation modes. It can be fully applied to various fields suitable for the embodiments of the present invention. For those familiar with the field, additional modifications can be easily achieved. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the embodiments of the present invention are not limited to the specific details and the embodiments shown and described here.

Claims

1. A grounding device construction method, characterized in that: The steps include: 1) Arrange multiple copper bars in layers along the vertical direction to form a three-dimensional grounding network, and make electrical connections between adjacent copper bars; 2) Bury the grounding electrode vertically in the soil below the copper busbar in a spiral array, and fix the top of the grounding electrode to the bottom copper busbar; 3) Coating a conductive anti-corrosion gel at the connection between the copper busbar and the grounding electrode, and maintaining the gel at a pressure of 0.5 MPa to 1 MPa for 5 to 10 minutes to fill the contact gap with the gel, wherein the gel is made by mixing nano graphite powder, epoxy resin and curing agent in a weight ratio of 3:4 to 6:2; 4) Apply pulse current between the copper busbar and the grounding body, verify the grounding resistance value through multi-point synchronous measurement, and compare the calculated grounding resistance value with the pre-set standard value. If the error is within ±5%, it is considered that the grounding resistance value meets the requirements and the copper busbar construction is completed.

2. The grounding device construction method according to claim 1, characterized in that: In step 1), multiple copper bars are arranged in layers along the vertical direction to form a three-dimensional grounding network. The steps for electrically connecting adjacent copper bars are as follows: First, the surface of the copper busbar to be installed is deoxidized, and then the copper busbar is divided into at least three layers, the vertical spacing between each layer of copper busbars is 0.5-1.5 meters, and the copper busbars of adjacent layers are parallel to each other, and the depth of the top layer of copper busbar from the ground is 0.3-0.5 meters; Finally, the adjacent copper bars are electrically connected using a mortise and tenon structure.

3. The grounding device construction method according to claim 1, characterized in that: In step 2), the spiral array is composed of multiple ground electrodes, and the ground electrodes of the spiral array include at least 3 layers of concentric spiral structures, the outermost spiral radius is 5 to 8 times the length of the ground electrode, and the calculation formula of the pitch p of adjacent spiral layers is: in, ρ i is the soil resistivity of the current layer, ρ 0 is the base layer resistivity, D is the grounding electrode diameter, k The value is 1.2~1.5; the radius of the outermost spiral is extended to times the ground electrode length, and the dispersion path is optimized through numerical simulation.

4. The grounding device construction method according to claim 1, characterized in that: In step 4), a pulse current is applied between the copper busbar and the grounding body, and the steps of verifying the grounding resistance value by multi-point synchronous measurement include: Arrange at least 5 measuring points around the grounding body, each of which is equipped with a voltage sensor and a current sensor. A pulse current generator is used to synchronously collect voltage and current data from at least five of the measurement points, and a curve fitting algorithm based on the least squares method is used to calculate the ground resistance value; Compare the calculated grounding resistance value with the preset standard value. If the error is within ±5%, it is considered that the grounding resistance value meets the requirements. If the error exceeds ±5%, first further analyze the measurement data to check whether there is a fault in the measurement system or a defect in the grounding system, and take appropriate measures to adjust and repair it. Then check the electrical connection between the copper busbars and the connection between the copper plate and the grounding electrode until the error is within ±5% again.

5. The grounding device construction method according to claim 2, characterized in that: After completing the electrical connection, the copper busbar and the connecting parts are treated with anti-corrosion: first, the surface of the copper busbar is pickled and passivated, and then a layer of anti-corrosion paint with a thickness of 0.1 - 0.3 mm is sprayed on the surface of the copper busbar.

6. The grounding device construction method according to claim 2, characterized in that: The mortise and tenon structure comprises a tenon arranged at one end of a copper bar and a mortise arranged at the other end of an adjacent copper bar, the cross-sectional shape of the tenon is adapted to the cross-sectional shape of the mortise, and the cross-sectional area of ​​the tenon is larger than the cross-sectional area of ​​the mortise; the tenon of one copper bar is inserted into the tenon of another adjacent copper bar, and spring sheets are arranged on both sides of the mortise and tenon structure, the contact surfaces of the tenon and the mortise are provided with conductive reinforcement layers, the conductive reinforcement layers comprise a bottom layer made of copper material, a surface layer made of silver or gold material and a graphene composite coating coated on the surface layer, the bottom layer is covered on the contact surface of the tenon and the mortise by electroplating or chemical plating, the surface layer is covered on the copper layer by vacuum sputtering or electroplating, the thickness of the graphene composite coating is 0.05-0.1 mm, and the graphene content is 5-10 wt%.

7. The grounding device construction method according to claim 1, characterized in that: In step 1), a serrated conductive contact surface is provided on the surface of each layer of copper busbar, and the serrated conductive contact surface is composed of a plurality of uniformly distributed serrated units; the serrated unit is a triangular or trapezoidal structure, and its height is 1 / 3 to 1 / 2 of the thickness of the copper busbar, and the bottom width is 1 / 5 to 1 / 4 of the width of the copper busbar; the serrated conductive contact surfaces of adjacent copper busbars are engaged with each other, and the engaging surface is the inclined surface of the serrated unit; a conductive reinforcement layer is provided on the surface of the serrated unit, and the thickness of the conductive reinforcement layer is 0.1 mm to 0.5 mm.

8. The grounding device construction method according to claim 1, characterized in that: The grounding electrode of the spiral array adopts a hollow structure and is filled with a composite resistance-reducing material. The composite resistance-reducing material is mixed with nano-scale activated carbon particles, bentonite and graphene in a mass ratio of 5:3:

2. When burying the grounding electrode, the composite resistance-reducing material is injected into the hollow cavity of the grounding electrode through pressure grouting equipment, and a resistance-reducing electrolyte containing 0.1-0.3wt% silver nitrate is injected into the soil at the same time to form a three-dimensional conductive network.

9. The grounding device construction method according to claim 4, characterized in that: The pulse current generator adopts adaptive frequency control technology, analyzes the soil impedance spectrum characteristics in real time through Fourier transform, dynamically adjusts the pulse frequency 10kHz-1MHz, and combines genetic algorithm to optimize the multi-point synchronous measurement path; when abnormal ground resistance is detected, a three-dimensional resistance cloud map is automatically generated to locate the system defect area.

10. The grounding device construction method according to claim 7, characterized in that: The sawtooth conductive contact surface adopts a gradient structure design, and the sawtooth units are arranged from the edge of the copper busbar to the center in the following order: Outer layer: 0.05-0.1mm thick, diamond nanowire-reinforced silver-based alloy layer; Middle layer: 0.2-0.3mm thick, carbon nanotube / epoxy resin composite transition layer; Inner layer: pure copper base.

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