A construction method of a substation red copper grounding private network

Abstract

The application relates to a construction method of a substation red copper grounding special network, and the construction method comprises the following steps: adjusting a red copper rod to expose the metal luster of the red copper rod; preheating and setting a mold for a conductor to be welded, and placing the conductor to be welded in butt joint, and then clamping the conductor to be welded by a mold; placing a metal isolation iron sheet at the bottom of a mold reaction cavity, adding melting powder and gunpowder, igniting and welding, and releasing heat to melt and weld; opening the mold, cleaning the mold, and arranging the tool in a tool box after cleaning. The process is optimized as follows: firstly, a drill is used to drill a hole, then a gluey resistance reducing agent is poured into the drilled hole, and then a grounding electrode is manually and easily punched into the hole to form a pouring type grounding electrode construction technology. Through the use of the technology, the construction difficulty problem that the copper rod grounding electrode is not tightly contacted with soil and the grounding electrode is difficult to punch into the soil is successfully solved, the operation safety of the construction is reduced, the labor is saved, the construction quality of the grounding electrode is ensured, and the finished product is easy to protect.

Description

Technical Field

[0001] This invention relates to the field of building engineering technology, and more specifically, to a construction method for a dedicated copper grounding network in a substation. Background Technology

[0002] According to the "Geotechnical Engineering Investigation Report of Plots B23 and B24 in the Central Area of ​​Olympic Park, Chaoyang District, Beijing," the soil resistivity of the site where the new Guohui 110kV substation is located is 50Ωm, the calculated grounding resistance is 0.514Ω, the contact potential does not meet the allowable value (235V) required by the regulations, and the step voltage does not meet the allowable value (269V) required by the regulations. The copper grounding network of the new Guohui 110kV substation is an independent grounding system designed separately to meet the grounding and contact potential safety requirements of the 110kV substation equipment. The design requires that the copper grounding network of the 110kV substation be constructed using fire-mortar welding at all connection nodes. After forming a closed grounding network, the design requires that the resistance value measured on-site by a third-party testing unit of the power department not exceed 0.27Ω to meet the requirements of the regulations for contact potential and step potential.

[0003] Since the copper rod grounding electrode is 2.5 meters long, the conventional construction process involves directly striking it with a sledgehammer. This requires setting up an operating ladder for working at height and poses a risk of bending the copper rod, making the operation difficult. In addition, the copper rod grounding electrode is prone to swinging during the striking process, resulting in poor contact between the grounding electrode and the soil.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The technical problem this invention aims to solve is to overcome the shortcomings of existing technologies and provide a construction method for a dedicated copper grounding network in substations. This method addresses the problems of traditional processes by optimizing the process to first use a drilling machine to drill holes, then fill the drilled holes with an adhesive resistance-reducing agent, and finally manually drive in the grounding electrode, forming a filling-type grounding electrode construction technique. This technique successfully solves the construction problems of poor contact between the copper rod grounding electrode and the soil, and the difficulty in driving the grounding electrode in. It also reduces operational safety, saves labor, ensures the construction quality of the grounding electrode, and facilitates finished product protection.

[0006] To solve the above-mentioned technical problems, the basic concept of the technical solution adopted by the present invention is as follows:

[0007] A method for constructing a dedicated copper grounding grid for a substation, the method comprising the following steps:

[0008] Step 1: Adjust the copper rod to expose its metallic luster;

[0009] Step 2: Preheat and fix the conductors to be welded, and then clamp them with the mold after placing them stably together;

[0010] Step 3: Place the metal isolation iron sheet at the bottom of the mold reaction chamber, add molten powder and gunpowder, ignite and weld, and perform exothermic fusion welding;

[0011] Step 4: Open the mold, clean the mold, and then put the tools back into the toolbox.

[0012] In a preferred embodiment of any of the above solutions, adjusting the copper rod to expose a metallic luster includes:

[0013] Step 11: First, adjust the verticality of the copper rod, and use a steel brush to clean the outer surface of the copper rod 150mm from the top of the copper rod to expose the metallic luster of the copper rod.

[0014] Step 12: Adjust the level of the copper strip. At the welding point where the copper strip and the copper rod are joined, with the copper rod as the center, level the copper strip within a range of 100mm to the left and right. After leveling, use a spirit level to check. After passing the inspection, use a steel brush to clean the impurities on the surface. The copper strip will then have a metallic luster.

[0015] In a preferred embodiment of any of the above solutions, the conductors to be welded are preheated and molded, and after being stably placed and joined, they are clamped with a mold, including:

[0016] Step 21: Preheating before welding: Before butt welding and mold setting, use a spray gun to preheat the mold and the materials to be welded to remove condensation on the surface of the mold and the materials to be welded.

[0017] Step 22: Connecting and fixing the mold. The surface of the metal conductor to be welded must be kept smooth. Polish the area to be welded with 400# sandpaper. Connect the preheating and welding parts of the copper rod and copper strip. After the conductor to be welded is placed stably and connected, clamp it with the mold. Then use the mold clamp to tighten and fix the upper and lower openings of the mold. The joint of the conductor to be welded should be aligned with the center guide hole of the mold. No gap is needed between small cross-section conductors. There should be a 1-3 mm gap between large cross-section conductors. After fixing, observe whether the conductor is placed stably and whether there are obvious gaps in the mold to prevent slurry leakage during the reaction process.

[0018] In a preferred embodiment of any of the above solutions, when using a spray gun to preheat the mold and the material to be welded, the heating points include the entire mold, the copper rod, and the surface of the copper strip. The heating time is 10 to 15 minutes, and the heating time is adjusted according to the ambient temperature. After preheating, the material feels warm to the touch and is free of moisture.

[0019] In a preferred embodiment of any of the above schemes, a metal isolating iron sheet is placed at the bottom of the mold reaction chamber, molten powder and gunpowder are added, and welding is initiated through ignition and exothermic fusion welding, including:

[0020] Step 31: Place the isolation plate. Place the metal isolation plate at the bottom of the mold reaction chamber, with the concave side of the metal isolation plate facing upwards.

[0021] Step 32: Add molten powder and gunpowder, and pour in the welding powder corresponding to the grade of the mold top cover label. Pour the ignition powder onto the mold lip and a small amount onto the welding powder.

[0022] Step 33: Ignite the flame and perform exothermic welding. Cover the mold with the mold cover, and use a lighter to ignite the ignition powder on the mold lip for exothermic welding.

[0023] In a preferred embodiment of any of the above solutions, the mold is opened, the grinding wheel is cleaned, and after cleaning, the tools are organized and placed in the toolbox, including:

[0024] Step 41: Open the mold. After the reaction has completely ended (5 minutes), open the mold.

[0025] Step 42: Cleaning. Use a brush to clean the mold until the slag is completely removed. If a small amount of slag adheres to the reaction chamber, it can be cleaned with 600# sandpaper after the mold has cooled. The welded joint should be placed stably. After the welded joint has completely cooled, inspect the surface of the welded joint. A small amount of unevenness, pitting, or black spots on the surface is normal, but there should be no cracks or penetrating pores. Otherwise, cut it off and re-weld it.

[0026] Step 43: Organize. Put all the tools into the toolbox for later use.

[0027] In a preferred embodiment of any of the above solutions, after cleaning and organizing the tools into the toolbox, the method further includes:

[0028] After welding is completed, the joint surface is inspected. A small amount of unevenness, pitting, and black spots are normal, but there must be no cracks. Otherwise, it must be cut off and remade.

[0029] After passing the inspection, a complete fire-mortar fusion joint has been fabricated.

[0030] In a preferred embodiment of any of the above solutions, before adjusting the copper rod to expose a metallic luster, the method further includes:

[0031] According to the design drawings of the main grounding grid, the laying position and grid size of the grounding electrode or grid are laid out. After the site of the civil engineering subbase is leveled and filled, lime is used to measure and lay out the grounding grid for the trench excavation of the main grounding grid.

[0032] After the measurement and layout are completed, the grounding grid trench is excavated by a combination of a small excavator and manual digging. The grounding grid trench is 350mm wide and 450mm deep.

[0033] In a preferred embodiment of any of the above schemes, after laying out the location and mesh size of the grounding electrode or mesh, the method further includes:

[0034] Procurement of vertical grounding electrodes should be made according to the design or specification length.

[0035] The vertical grounding electrode is installed by manual hammering. The vertical grounding electrode is installed in the position according to the design drawings. After the grounding electrode is installed, the top hammering part is treated with anti-corrosion.

[0036] In the preferred embodiment of any of the above schemes, after the main grounding grid under the substation subbase has passed the test and the concealed works inspection and acceptance, the grounding trench and operating pit are promptly backfilled using the original soil. The specific backfilling steps include:

[0037] Backfill with original soil or plain soil to a depth of 350mm to the bottom elevation of the cushion layer;

[0038] First, backfill with 200mm of original soil or plain soil, then backfill with 300mm of C10 plain concrete to the bottom elevation of the cushion layer.

[0039] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art.

[0040] To address the problems of traditional processes, this technology has been optimized by first drilling holes using a drilling machine, then filling the drilled holes with an adhesive resistance-reducing agent, and finally manually driving in the grounding electrode. This creates a filling-type grounding electrode construction technique. By applying this technique, the construction problems of poor contact between the copper rod grounding electrode and the soil, and difficulty in driving in the grounding electrode have been successfully solved. At the same time, it reduces operational safety, saves labor, ensures the construction quality of the grounding electrode, and facilitates the protection of the finished product.

[0041] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0042] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. Some specific embodiments of this application will be described in detail below with reference to the accompanying drawings in an exemplary and non-limiting manner. The same reference numerals in the drawings designate the same or similar parts or components. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0043] Figure 1This is a schematic diagram of the construction method for the copper grounding network of a substation according to the present invention.

[0044] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. The elements in the drawings are schematic and not drawn to scale. Detailed Implementation

[0045] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative effort should fall within the scope of protection of the present application.

[0046] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0047] In the description of this application, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0048] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0049] The following embodiments of this application use the construction method of the copper grounding network of a substation as an example to illustrate the solution of this application in detail. However, this embodiment does not limit the scope of protection of this application.

[0050] Example

[0051] like Figure 1As shown, this invention provides a construction method for a dedicated copper grounding network in a substation, the construction method comprising the following steps:

[0052] Step 1: Adjust the copper rod to expose its metallic luster;

[0053] Step 2: Preheat and fix the conductors to be welded, and then clamp them with the mold after placing them stably together;

[0054] Step 3: Place the metal isolation iron sheet at the bottom of the mold reaction chamber, add molten powder and gunpowder, ignite and weld, and perform exothermic fusion welding;

[0055] Step 4: Open the mold, clean the mold, and then put the tools back into the toolbox.

[0056] In the substation copper grounding grid construction method described in this embodiment of the invention, the problems of traditional processes are overcome by optimizing the process by first drilling holes with a drilling machine, then filling the drilled holes with an adhesive resistance-reducing agent, and then manually driving in the grounding electrode. This forms the filling-type grounding electrode construction technology. By applying this technology, the construction problems of poor contact between the copper rod grounding electrode and the soil and difficulty in driving the grounding electrode are successfully solved. At the same time, it reduces the operational safety of construction, saves labor, ensures the construction quality of the grounding electrode, and facilitates the protection of finished products.

[0057] In the substation copper grounding grid construction method described in this embodiment of the invention, adjusting the copper rod to expose its metallic luster includes:

[0058] Step 11: First, adjust the verticality of the copper rod, and use a steel brush to clean the outer surface of the copper rod 150mm from the top of the copper rod to expose the metallic luster of the copper rod.

[0059] Step 12: Adjust the level of the copper strip. At the welding point where the copper strip and the copper rod are joined, with the copper rod as the center, level the copper strip within a range of 100mm to the left and right. After leveling, use a spirit level to check. After passing the inspection, use a steel brush to clean the impurities on the surface. The copper strip will then have a metallic luster.

[0060] In the substation copper grounding grid construction method described in this embodiment of the invention, the conductor to be welded is preheated and molded, and after the conductor to be welded is stably placed and joined, it is clamped with a mold, including:

[0061] Step 21: Preheating before welding: Before butt welding and mold setting, use a spray gun to preheat the mold and the materials to be welded to remove condensation on the surface of the mold and the materials to be welded.

[0062] Step 22: Connecting and fixing the mold. The surface of the metal conductor to be welded must be kept smooth. Polish the area to be welded with 400# sandpaper. Connect the preheating and welding parts of the copper rod and copper strip. After the conductor to be welded is placed stably and connected, clamp it with the mold. Then use the mold clamp to tighten and fix the upper and lower openings of the mold. The joint of the conductor to be welded should be aligned with the center guide hole of the mold. No gap is needed between small cross-section conductors. There should be a 1-3 mm gap between large cross-section conductors. After fixing, observe whether the conductor is placed stably and whether there are obvious gaps in the mold to prevent slurry leakage during the reaction process.

[0063] In the substation copper grounding grid construction method described in this embodiment of the invention, when using a spray gun to preheat the mold and the material to be welded, the heating points include the entire mold, the copper rod, and the surface of the copper strip. The heating time is 10 to 15 minutes, and the heating time is adjusted according to the ambient temperature. After preheating, the material feels warm to the touch and is free of moisture.

[0064] In the substation copper grounding grid construction method described in this embodiment of the invention, the metal isolation iron sheet is placed at the bottom of the mold reaction chamber, molten powder and gunpowder are added, and ignition welding and exothermic fusion welding are performed, including:

[0065] Step 31: Place the isolation plate. Place the metal isolation plate at the bottom of the mold reaction chamber, with the concave side of the metal isolation plate facing upwards.

[0066] Step 32: Add molten powder and gunpowder, and pour in the welding powder corresponding to the grade of the mold top cover label. Pour the ignition powder onto the mold lip and a small amount onto the welding powder.

[0067] Step 33: Ignite the flame and perform exothermic welding. Cover the mold with the mold cover, and use a lighter to ignite the ignition powder on the mold lip for exothermic welding.

[0068] In a preferred embodiment of any of the above solutions, the mold is opened, the grinding wheel is cleaned, and after cleaning, the tools are organized and placed in the toolbox, including:

[0069] Step 41: Open the mold. After the reaction has completely ended (5 minutes), open the mold.

[0070] Step 42: Cleaning. Use a brush to clean the mold until the slag is completely removed. If a small amount of slag adheres to the reaction chamber, it can be cleaned with 600# sandpaper after the mold has cooled. The welded joint should be placed stably. After the welded joint has completely cooled, inspect the surface of the welded joint. A small amount of unevenness, pitting, or black spots on the surface is normal, but there should be no cracks or penetrating pores. Otherwise, cut it off and re-weld it.

[0071] Step 43: Organize. Put all the tools into the toolbox for later use.

[0072] In the substation copper grounding network construction method described in this embodiment of the invention, after cleaning and organizing the tools into the toolbox, the method further includes:

[0073] After welding is completed, the joint surface is inspected. A small amount of unevenness, pitting, and black spots are normal, but there must be no cracks. Otherwise, it must be cut off and remade.

[0074] After passing the inspection, a complete fire-mortar fusion joint has been fabricated.

[0075] In the substation copper grounding grid construction method described in this embodiment of the invention, before adjusting the copper rod to expose its metallic luster, the method further includes:

[0076] According to the design drawings of the main grounding grid, the laying position and grid size of the grounding electrode or grid are laid out. After the site of the civil engineering subbase is leveled and filled, lime is used to measure and lay out the grounding grid for the trench excavation of the main grounding grid.

[0077] After the measurement and layout are completed, the grounding grid trench is excavated by a combination of a small excavator and manual digging. The grounding grid trench is 350mm wide and 450mm deep.

[0078] In the substation copper grounding network construction method described in this embodiment of the invention, after laying out the laying position and grid size of the grounding electrode or grid, the method further includes:

[0079] Procurement of vertical grounding electrodes should be made according to the design or specification length.

[0080] The vertical grounding electrode is installed by manual hammering. The vertical grounding electrode is installed in the position according to the design drawings. After the grounding electrode is installed, the top hammering part is treated with anti-corrosion.

[0081] In the preferred embodiment of any of the above schemes, after the main grounding grid under the substation subbase has passed the test and the concealed works inspection and acceptance, the grounding trench and operating pit are promptly backfilled using the original soil. The specific backfilling steps include:

[0082] Backfill with original soil or plain soil to a depth of 350mm to the bottom elevation of the cushion layer;

[0083] First, backfill with 200mm of original soil or plain soil, then backfill with 300mm of C10 plain concrete to the bottom elevation of the cushion layer.

[0084] In the substation copper grounding grid construction method described in the embodiments of the present invention, good fusion welding means that after fusion welding is completed, the joint surface is bright, without pores or inclusions, and after the fusion welded joint is cut open, the material is dense and there are no defects such as pores or inclusions inside.

[0085] There are two main factors affecting the fusion welding effect, the most significant of which is moisture, including water vapor adhering to the welding mold, welding powder, or the conductor being welded. Therefore, preventing and removing moisture is the most important measure to ensure the exothermic fusion welding effect. The other major factor is the cleanliness of the mold and the conductor being welded. Therefore, it is essential to clean the surface of the conductor to be welded, removing dust, grease, oxide film, burrs, etc. Any remaining weld slag inside the welding mold, especially in the reaction chamber, must be thoroughly cleaned; otherwise, the surface of the weld joint will be dull and rough, easily leading to surface inclusions.

[0086] In addition, special attention should be paid to:

[0087] The amount of flux used for a single welding operation should be appropriate for the specifications of the welding mold used. It is forbidden to use a large amount of flux to weld a smaller conductor, and it is even more forbidden to use a small amount of flux to weld a larger conductor. The welding powder has been protected against moisture at the factory, but users should still pay attention to avoiding moisture during storage and use. Before welding, check the tightness between the mold and the connecting conductor, and seal the joints of the mold with fireproof putty as appropriate to prevent copper from flowing out.

[0088] After the construction of each main grounding trench is completed, a grounding insulation test shall be conducted using a grounding resistance meter, and the test results shall be recorded to form a test record. After the construction of the main grounding grid under the entire subgrade is completed, before the grounding trench is backfilled, a power frequency grounding resistance test shall be conducted in accordance with relevant specifications. The test data shall be accurate and reliable, and records shall be kept. After the construction of the main grounding grid under the entire subgrade is completed and the grounding trench is backfilled, a 110KV power frequency grounding resistance test shall be conducted in accordance with relevant specifications. The test data shall be accurate and reliable, and records shall be kept.

[0089] After the completion of the entire 110kV substation grounding network construction, the 110kV power frequency grounding resistance test shall be conducted in accordance with relevant specifications. The test data shall be accurate and reliable, and records shall be kept. After the completion of the entire B23 plot building grounding system construction, the 110kV substation grounding system grounding resistance test shall be conducted in accordance with relevant specifications. The test data shall be accurate and reliable, and records shall be kept.

[0090] After the main grounding grid under the 110kV substation substation floor passed the test and the concealed works inspection and acceptance, the grounding trench and operating pit were promptly backfilled using the original soil (plain soil). The specific backfilling plan is as follows:

[0091] The backfilling scheme for the grounding trench of the copper strip connector is as follows: use the original soil (plain soil) to backfill 350mm to the bottom elevation of the cushion layer. The backfilling scheme for the operating pit of the copper rod grounding body is as follows: first use the original soil (plain soil) to backfill 200mm, and then use C10 plain concrete to backfill 300mm to the bottom elevation of the cushion layer.

[0092] This construction method offers safe, reliable, reasonable, and effective welding. By optimizing the construction process and overcoming construction challenges, it employs innovative technologies such as T-shaped fire-mortar welding of copper strips and anti-uplift pile reinforcement, immersion-type grounding electrode construction technology, and single-type assembly line fire-mortar welding construction technology. This ensures that the grounding resistance value meets the safety requirements of substations. It can be widely applied to grounding systems of 10KV, 35KV, 110KV, 220KV, and 500KV substations. This method can be used for welding connections between different materials (ordinary steel, stainless steel, copper-clad steel, cast iron, galvanized steel, bronze, brass, and copper, etc.) and between the same material, as well as for welding connections of different cross-section materials in the form of "one," "ten," and "T."

[0093] Through research on fire-mud fusion welding technology and combined with the actual characteristics of the project, this paper analyzes aspects such as customized molds, powder, operation procedures and key points. It addresses construction difficulties from the perspectives of integrating construction resources, optimizing construction flow, and efficient construction management, thus forming a construction method for the 110kV substation copper grounding network. This method, by adopting a combination of manual and mechanical methods and innovating in the specific construction process, achieves the goals of saving construction time and creating benefits.

[0094] This technology streamlines the welding process, including grinding, cleaning, mold preheating, material preheating, and welding, by utilizing the time differences between each step. It mimics factory assembly line production, creating a continuous welding workflow with fixed steps. This streamlined workflow ensures clear division of labor, standardized quality standards, rigorous training and implementation, and strict quality acceptance. By applying this technology, different welding node operations become streamlined, sequential, and mechanized, improving welding efficiency and quality while saving construction time.

[0095] The reinforcing bars in the anti-tension piles are threaded steel, and their surfaces have oxidized and rusted due to prolonged exposure to air. When T-welding the reinforcing bars with copper strips, it is necessary to treat the surface of the reinforcing bars to expose their metallic luster, while simultaneously addressing the issues of fit and sealing between the reinforcing bars and the mold. Therefore, this technique involves grinding the reinforcing bars to create a smooth, round surface, increasing the fit between the reinforcing bars and the welding mold. Simultaneously, fireproof putty is used to seal small gaps on the outside of the mold, successfully resolving the problem of weld melt leakage caused by poor contact during the welding of threaded reinforcing bars and copper strips, thus ensuring the quality of the weld.

[0096] Grounding trench excavation will be carried out using a combination of manual and mechanical methods. If the foundation is natural, the following methods can be used to address the disturbance to the natural foundation: a combination of grounding trenches and operating pits will be employed, and the trench excavation plan will be optimized accordingly. A construction plan of the grounding trench excavation for the dedicated grounding network will be drawn up. Through communication with the structural design team, it is determined that the ratio of the grounding trench excavation area to the substation foundation area should not exceed 10%, allowing for mechanical trench excavation. Increasing the thickness of the reserved soil layer and selecting appropriate equipment will reduce the disturbance impact of construction machinery on the natural foundation.

[0097] Vertical grounding electrode construction is carried out using the immersion grounding electrode construction technology, key welding nodes are constructed using the single-type assembly line fire mud welding construction technology, and the welding problem between the grounding grid and the anti-uplift pile reinforcement is solved by using the "T"-shaped fire mud welding technology of copper strip and anti-uplift pile reinforcement.

[0098] The grounding trench backfilling adopts a combination of plain soil and plain concrete. If the foundation is natural, the following methods can be used to address the backfill compaction coefficient issue: The copper grounding grid construction will proceed after the foundation probing and trench inspection process. Through prior communication with the geological survey unit, it is required that the backfill soil compaction coefficient reach 0.97 after the copper grounding trench backfilling, necessitating backfill soil sampling tests. Therefore, grounding trench backfilling takes a long time, and achieving a compaction coefficient of 0.97 is difficult. Given that the grounding trench excavation area accounts for 10%, the disturbance to the original natural foundation is minimal, and the backfill soil compaction coefficient is not required. Based on the results of the design communication and coordination meeting with the design institute on December 25, 2019, the final backfilling plan, jointly negotiated and determined with the design party, geological survey party, construction party, and supervision party, is as follows:

[0099] 1) Backfilling concealment time: After the main grounding grid under the 110KV substation cushion layer has passed the test and the concealed works inspection and acceptance has been completed;

[0100] 2) Grounding trench backfilling scheme: Use original soil (plain soil) to backfill 350mm to the bottom elevation of the cushion layer;

[0101] 3) Backfilling plan for the operation pit: First, backfill with 200mm of original soil (plain soil), then backfill with 300mm of C10 plain concrete to the bottom elevation of the cushion layer.

[0102] A probing machine was used to drill a grounding hole with a diameter of φ25mm and a depth of 1.5 meters, avoiding high-altitude operations and solving the problems of unsafe high-altitude operations and the difficulty of deep grounding electrode construction. The injection of resistance-reducing agent effectively solved the problem of loose gaps, and the resistance-reducing agent itself also enhanced the grounding effect of the system. A wooden block was placed on the top of the grounding electrode to prevent the top of the copper rod from being damaged by a heavy hammer, and solved the problems of finished product protection and reliable connection between the contact surfaces during the welding process.

[0103] The single-type assembly line fire-mud welding technology is suitable for welding critical nodes such as cross-shaped and straight-line connections between copper strips, and T-shaped connections between copper strips and copper rods. The specific operation points are as follows:

[0104] This invention adopts a single-discipline construction process flow construction method. In addition to the flow construction of different professional work surfaces and processes, it also realizes the flow construction of a single professional construction process flow construction method. By repeatedly studying the content and time arrangement of the entire fire mud welding process, the time difference between each process is utilized, each process is classified and grouped, and the preceding process is inserted into the construction in advance to realize the flow construction of a single professional construction process flow construction method.

[0105] By introducing factory-style assembly line production and forming a streamlined construction process, this invention introduces the concept of factory-style assembly line production management and imitates the assembly line production arrangement of factories to form a streamlined construction process. Through this method, the traditional step-by-step construction process time is shortened from 55 minutes to 33 minutes, saving 22 minutes of process time.

[0106] The "T"-shaped fire-mortar welding technology for copper strips and anti-tension pile reinforcement is applicable to the "T"-shaped welding of pile head reinforcement and copper strips. The key points of the construction process for this technology are as follows:

[0107] 1. Use an angle grinder to grind the reinforcing bars of the horizontal section of the pile head, grind the threads of the reinforcing bars flat, and grind the length of the grinding is 150mm. Use 400# sandpaper to polish the parts that need to be welded until the reinforcing bars show a metallic luster and the surface is smooth.

[0108] 2. Select two diagonally opposite reinforcing bars at the pile head of the tension pile and clean them with a steel brush to remove the dirt from the surface of the reinforcing bars. Heat the cleaned reinforcing bars with a spray gun, and then bend them at 90° with pipe pliers (absolute bending is not allowed). The height of the bend should be 400mm from the pile head surface, and the horizontal length should be 200mm.

[0109] 3. Butt-joint the preheated copper strip with the corresponding treated pull-out rebar. After the conductor to be welded is stably placed and joined with the mold, clamp the mold in place. Seal the gap between the mold and the conductor to be welded with fireproof putty to prevent the weld liquid from flowing out during the fusion reaction and affecting the welding quality.

[0110] 4. The 300 type of flux powder is used for the "T"-shaped fire mud welding of copper strip and anti-uplift pile reinforcement. Other key points of operation are the same as those for single-type assembly line fire mud welding construction.

[0111] The 110kV substation's copper grounding network is laid 300mm below the foundation slab of the four underground levels of the substation's main structure (B23). This is a preliminary step in the foundation slab construction. This method ensures the safe and rational construction of the grounding network, minimizing disturbance to the natural foundation, saving costs, facilitating worker operation, and shortening the construction period. It also creates favorable conditions for the early and effective insertion of subsequent procedures. Process control during construction validated the rationality and effectiveness of this method, which received unanimous recognition and praise from the construction and supervision units. The management approach of this method has effectively promoted the brand of a top-tier central enterprise and enhanced its management image, providing a valuable reference for similar future projects.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for constructing a dedicated copper grounding grid for a substation, characterized in that, The construction method includes the following steps: Step 1: According to the design drawings of the main grounding grid, lay out the laying position and grid size of the grounding electrode or grid. After the site of the civil engineering subbase is leveled and filled, lime is used to measure and lay out the grounding grid. After the measurement and laying out are completed, the grounding grid trench is excavated by a combination of small excavators and manual excavation. The grounding grid trench is 350mm wide and 450mm deep. Step 2: Procure vertical grounding electrodes according to the design or specification length; install vertical grounding electrodes using a pouring construction technique, specifically: use a drilling machine to drill holes, pour an adhesive resistance-reducing agent into the drilled holes, and then manually drive the grounding electrode in easily; install the vertical grounding electrodes according to the design drawings, and after the grounding electrodes are installed, treat the top impact area with anti-corrosion treatment. Step 3: Adjust the copper rod to expose its metallic luster; Step 4: Preheat and mold the conductors to be welded, and then clamp them with the mold after placing them stably together; Step 5: Place the metal isolation iron sheet at the bottom of the mold reaction chamber, add molten powder and gunpowder, ignite and weld, and perform exothermic fusion welding; Step 6: Open the mold, clean the mold, and then put the tools back into the toolbox. Step 7: After the main grounding grid under the substation subbase has passed the test and the concealed works inspection and acceptance, the grounding trench and operating pit shall be backfilled. The original soil or plain soil shall be used for backfilling 350mm to the bottom elevation of the subbase; first, the original soil or plain soil shall be used for backfilling 200mm, and then C10 plain concrete shall be used for backfilling 300mm to the bottom elevation of the subbase. The process of adjusting the copper rod to expose its metallic luster includes: First, adjust the verticality of the copper rod, and then use a steel brush to clean the outer surface of the copper rod 150mm from the top, revealing the metallic luster of the copper rod. After straightening the copper strip, at the welding point where the copper strip and the copper rod meet, with the copper rod as the center, the copper strip within a range of 100mm to the left and right is leveled. After leveling, a spirit level is used to check. After passing the inspection, the impurities on the surface are cleaned with a steel brush, and the copper strip shows a metallic luster. The process includes preheating and molding the conductors to be welded, and then clamping them with a mold after the conductors are stably placed and joined. Preheating before welding: Before butt welding and mold setting, use a spray gun to preheat the mold and the materials to be welded to remove condensation on the surface of the mold and the materials to be welded. For docking and mold setting, the surface of the metal conductors to be welded must be kept smooth. Use 400# sandpaper to polish the area to be welded. Connect the preheating and welding parts of the copper rod and copper strip. After the conductors to be welded are placed stably and docked, clamp them with the mold. Then use the mold clamp to tighten and fix the upper and lower openings of the mold. The joint of the conductor to be welded should be aligned with the center guide hole of the mold. No gap is needed between small cross-section conductors, while there is a 1-3 mm gap between large cross-section conductors. After fixing, observe whether the conductors are placed stably and whether there are obvious gaps in the mold to prevent slurry leakage during the reaction process.

2. The construction method for a dedicated copper grounding grid in a substation according to claim 1, characterized in that, When using a spray gun to preheat the mold and the material to be welded, the heating points include the entire mold, the copper rod, and the surface of the copper strip. The heating time is 10 to 15 minutes. Adjust the heating time according to the ambient temperature. After preheating, the material should feel warm to the touch and be free of moisture.

3. The construction method for a dedicated copper grounding grid in a substation according to claim 2, characterized in that, The metal isolation sheet is placed at the bottom of the mold reaction chamber, molten powder and gunpowder are added, and welding is initiated through ignition and exothermic fusion welding, including: Step 51: Place the isolation plate. Place the metal isolation plate at the bottom of the mold reaction chamber, with the concave side of the metal isolation plate facing upwards. Step 52: Add molten powder and gunpowder, and pour in the welding powder corresponding to the grade of the mold top cover label. Pour the ignition powder onto the mold lip and a small amount onto the welding powder. Step 53: Ignite the flame and perform exothermic welding. Cover the mold with the mold cover, and use a lighter to ignite the ignition powder on the mold lip for exothermic welding.

4. The construction method for a dedicated copper grounding grid in a substation according to claim 3, characterized in that, Open the mold, clean the grinding wheel, and then organize the tools in the toolbox, including: Step 61: Open the mold. After the reaction has completely ended (5 minutes), open the mold. Step 62: Cleaning. Use a brush to clean the mold until the slag is completely removed. If a small amount of slag adheres to the reaction chamber, it can be cleaned with 600# sandpaper after the mold has cooled. The welded joint should be placed stably. After the welded joint has completely cooled, inspect the surface of the welded joint. A small amount of unevenness and black spots on the surface is normal, but there should be no cracks or penetrating pores. Otherwise, cut it off and re-weld it. Step 63: Organize. Put all the tools into the toolbox for later use.

5. The construction method for a dedicated copper grounding grid in a substation according to claim 4, characterized in that, After cleaning and organizing the tools into the toolbox, the following is also included: After welding is completed, inspect the joint surface. A small amount of unevenness, pitting, and black spots on the surface are normal, but there must be no cracks. Otherwise, cut it off and remake it. After passing the inspection, a complete fire-mortar fusion joint has been fabricated.

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