Preparation and application of a pot-type insulator with modified coating

Abstract

The present invention relates to the design and manufacturing of high-voltage switchgear and discloses a method for preparing a pot-type insulator with a modified coating and its application. Specifically, the method comprises the following steps: first, a central insert and an epoxy casting are formed by a vacuum casting process and then assembled into one piece with a grounding shell on a GIS or GIL; then, the central insert is connected to a concave conductor and a convex conductor to form a high-voltage conductive path, and a modified coating is added to the creepage surface of the epoxy casting. The present invention applies a nano-modified coating to a high-voltage pot-type insulator, and adjusts the electric field distribution of the overall structure through the different dielectric constants of the nano-coating. By utilizing the relationship between the dielectric constant and the voltage distribution, the field strength in the flange air gap is reduced, eliminating partial discharge in the air gap. In addition, by adjusting the surface electric field distribution of the pot-type insulator, the problem of field strength concentration at the three intersections of high and low potentials is reduced, thereby improving the reliability of the product during use and facilitating overall miniaturization.

Description

Technical Field

[0001] The invention relates to the field of design and manufacture of high-voltage switchgear, in particular to the preparation and application of a pot-type insulator with a modified coating. Background Art

[0002] As a key component of GIS and GIL equipment, basin insulators play the role of isolating the gas chamber, supporting the conductor, and providing insulation. The current basin insulator structure mainly consists of an epoxy resin cast basin, a center conductor insert, and an outer flange (which can be epoxy resin or metal flange). As a key component of GIS and GIL, the reliability of basin insulators is crucial to the operation of the entire equipment and line. Therefore, the requirements for electrical and mechanical properties of basin insulators are becoming increasingly stringent during the design and production process. With the rapid development of high voltage and ultra-high voltage, the electrical performance requirements are particularly prominent.

[0003] A Chinese patent discloses a nano-silicon oxide insulator for suppressing VFTO (authorization publication number CN107359028B). Based on the application of the basin insulator and the overall electric field distribution, the patent shows that the field strength is primarily concentrated at three intersections in the high-voltage area (around the central insert) and at three intersections in the low-voltage area (fixed flange). However, in actual testing, discharge often begins in these areas and ultimately forms surface flashover. Therefore, the solution in the patent cannot effectively solve this problem.

[0004] A Chinese patent discloses a high creepage distance, charge-adaptive dissipation high-voltage DC basin insulator (authorization publication number CN 108511138B). This patent includes an insulating zone, an adaptive zone, and a creepage zone. The adaptive zone is located at the bottom of the insulating zone, and the creepage zone is located at the top of the insulating zone. A connecting flange is provided around the adaptive zone, and a central insert is provided in the middle of the insulating zone. A protrusion is added to the top to increase the creepage distance. In the structural design of the basin insulator, we emphasize shape uniformity to minimize the surface electric field to meet product requirements and comply with the requirements of the vacuum casting production process. Although this patent solution increases creepage distance, it can lead to excessively high field strength at the rounded corner transition location, causing charge accumulation.

[0005] A Chinese patent discloses a flexible gradient surface treatment method for pot-type insulators used in ultra-high voltage AC GILs (authorization publication number CN111599553A). This patent electrospins a PVA / BaTiO3 film with a dielectric constant gradient distribution onto the surface of an epoxy resin substrate. This deposit forms a two-dimensional dielectric constant gradient layer on the pot-type insulator surface. Due to the single substrate, only a distribution trend of decreasing dielectric gradient can be achieved, and flexible adjustment configuration based on specific electric field distribution is not possible. Furthermore, the coating quality of this treatment method is inferior to the strength and adhesion properties of nano-coatings, and it cannot effectively address the surface field strength issue at the product's three intersection points.

[0006] Combining the above patents and existing market analysis, the current problems are as follows:

[0007] 1. Due to the design and manufacturing process of the current basin insulator, there is a certain gas gap between the epoxy resin and the outer metal flange. This gas gap is an air gap. As the voltage level increases, this gap is prone to partial discharge problems.

[0008] 2. In addition, due to the development of high voltage and ultra-high voltage and the demand for product miniaturization, the surface field strength of the basin insulator is getting higher and higher when the overall structure and surface creepage distance remain unchanged. In particular, the three-point problem in the low potential and high voltage areas is very prominent. It is easy to cause gap discharge and surface flashover during the experiment, affecting the performance and life of the product. Therefore, those skilled in the art provide a preparation and application of a basin insulator with a modified coating to solve the problems raised in the above background technology. Summary of the Invention

[0009] The purpose of the present invention is to provide a method for preparing a pot-type insulator with a modified coating and its application, so as to solve the problems raised in the above background technology.

[0010] To achieve the above object, the present invention provides the following technical solution: a preparation method for a pot-type insulator with a modified coating, wherein the preparation steps are as follows:

[0011] S1. The insulator includes a central insert, an epoxy casting body, a grounding shell, a modified coating, a concave conductor, and a convex conductor;

[0012] S2. The center insert and epoxy casting body are formed by vacuum casting process and then assembled into one piece with the grounding shell on the GIS or GIL;

[0013] S3. The central insert is then connected to the concave conductor and the convex conductor to form a high-voltage conductive path, and an insulating gas with a certain pressure and high insulation strength is filled between the high-voltage conductive path and the grounding shell;

[0014] S4. A wedge-shaped air gap is formed at the end fillets of the concave and convex conductors, the epoxy casting, and the insulating gas, and as a triple intersection area, this location is prone to discharge.

[0015] S5. A wedge-shaped air gap is also formed at the rounded corner of the grounded housing flange, the epoxy casting body, and the insulating gas. As a triple intersection area, this location is prone to discharge.

[0016] S6. Divide the modified coating into three areas according to different dielectric constants used on the creepage surface of the epoxy cast body, and then sequentially add the modified coating to the creepage surface of the epoxy cast body to complete the preparation of the insulator.

[0017] As a further solution of the present invention: the insulating gas with a certain pressure and high insulation strength filled in S3 is sulfur hexafluoride gas.

[0018] As a further solution of the present invention: the modified coating is made into a conductor coating by adding conductive materials such as carbon black and graphene, and then a nanocoating made of materials with different dielectric constants is made through a sol-gel process, and finally attached to the outer ring of the epoxy casting body through spraying or brush plating.

[0019] As a further solution of the present invention: the modified coating is divided into three areas, namely the near-ground side modified coating, the middle modified coating of the insulating area, and the high-voltage side modified coating of the insulating area. Through the distribution conditions of the dielectric constant to the voltage, in the insulating area, the dielectric constant is adjusted from low potential to high potential and from low to high on the creepage surface of the epoxy cast body.

[0020] As a further solution of the present invention: the dielectric constant of the modified coating on the near-ground side is 4, the dielectric constant of the modified coating in the middle of the insulating area is 4.4, and the dielectric constant of the modified coating on the high-voltage side of the insulating area is 4.8.

[0021] As a further solution of the present invention: the pot-type insulator with modified coating prepared by the present invention is mainly used on the core insulation parts in GIS and GIL equipment, wherein GIS refers to gas-insulated metal switchgear and GIL refers to gas-insulated metal enclosed transmission line.

[0022] As a further solution of the present invention: the pot-type insulator with the modified coating is connected to the core insulation of the GIS and GIL equipment through a central insert and a conductive rod.

[0023] Compared with the prior art, the present invention has the following beneficial effects: the preparation and application of a pot-type insulator with a modified coating designed by the present invention. In actual operation, the present invention applies a nano-modified coating to a high-voltage pot-type insulator, adjusts the electric field distribution of the overall structure through the different dielectric constants of the nano-coating, and utilizes the relationship between the dielectric constant and the voltage distribution to reduce the field strength in the flange air gap and eliminate partial discharge in the air gap.

[0024] The present invention mainly uses a coating or gel process on the surface of the basin to allow nano-coatings with different dielectric constants to adhere to the surface of the basin, thereby adjusting the surface electric field distribution of the basin and improving the pressure resistance level of the product.

[0025] In addition, by adjusting the surface electric field distribution of the basin insulator, the field strength concentration problem at the three intersections of high and low potentials can be reduced, thereby improving the reliability of the product during use. It is also conducive to overall miniaturization. It is mainly used in core insulating parts in GIS and GIL equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of the insulator structure of Example 1 in the preparation and application of a pot-type insulator with a modified coating;

[0027] Figure 2 This is an enlarged schematic diagram of part B of Example 1 for the preparation and application of a pot-type insulator with a modified coating;

[0028] Figure 3 A schematic diagram of the insulator structure of Example 2 in the preparation and application of a pot-type insulator with a modified coating;

[0029] Figure 4 This is an enlarged schematic diagram of part A of Example 2 in the preparation and application of a basin-type insulator with a modified coating.

[0030] In the figure: 1. Center insert; 2. Epoxy casting; 3. Grounding shell; 4. Modified coating; 5. Air gap; 6. Concave conductor; 7. Convex conductor; 4.1. Modified coating on the near-ground side; 4.2. Modified coating in the middle of the insulation area; 4.3. Modified coating on the high-voltage side of the insulation area. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] Example 1

[0033] See also Figures 1-2 In an embodiment of the present invention, a pot-type insulator with a modified coating is prepared, and the preparation steps are as follows: the insulator includes a central insert 1, an epoxy casting body 2, a grounding shell 3, a modified coating 4, a concave conductor 6, and a convex conductor 7;

[0034] First, the center insert 1 and the epoxy casting body 2 are formed by vacuum casting and then assembled into one piece with the grounding shell 3 on the GIS or GIL. Then, the center insert 1 is connected to the concave conductor 6 and the convex conductor 7 to form a high-voltage conductive path. The space between the high-voltage conductive path and the grounding shell 3 is filled with an insulating gas with a certain pressure and high dielectric strength, which is sulfur hexafluoride gas.

[0035] Furthermore, a wedge-shaped air gap is formed at the rounded corners of the concave conductor 6 and the convex conductor 7, the epoxy casting body 2, and the insulating gas, and discharge is easily generated at this location as a triple intersection area.

[0036] Furthermore, a wedge-shaped air gap is formed at the rounded corner of the flange end of the grounded housing 3, the epoxy casting 2 and the insulating gas, and as a triple intersection area, this location is prone to discharge.

[0037] Finally, the modified coating 4 is divided into three regions according to different dielectric constants used on the creepage surface of the epoxy casting 2, and then the modified coating 4 is added to the creepage surface of the epoxy casting 2 in sequence, thereby completing the preparation of the insulator;

[0038] Among them, the modified coating 4 is made into a conductor coating by adding conductive materials such as carbon black and graphene, and then a nano-coating made of materials with different dielectric constants is made through the existing mature sol-gel process, and finally attached to the outer ring of the epoxy casting body 2 by spraying or brush plating;

[0039] Furthermore, the modified coating 4 is divided into three regions, namely, a modified coating 4.1 on the near-ground side, a modified coating 4.2 in the middle of the insulating region, and a modified coating 4.3 on the high-voltage side of the insulating region. Based on the distribution condition of the dielectric constant to the voltage, the dielectric constant is adjusted from low to high in the insulating region and distributed on the creepage surface of the epoxy casting 2 in sequence;

[0040] The near-ground side modified coating 4.1, the insulating region intermediate modified coating 4.2, and the insulating region high-voltage side modified coating 4.3 are all nano-modified coatings. The difference is that the near-ground side modified coating 4.1 has a dielectric constant of 4, the insulating region intermediate modified coating 4.2 has a dielectric constant of 4.4, and the insulating region high-voltage side modified coating 4.3 has a dielectric constant of 4.8.

[0041] Furthermore, the pot-type insulator with a modified coating prepared by the present invention is mainly used on the core insulating parts in GIS and GIL equipment, wherein GIS is a gas-insulated metal switch and GIL is a gas-insulated metal-enclosed transmission line; the pot-type insulator with the modified coating 4 is connected to the core insulating parts in the GIS and GIL equipment through the central insert 1 and the conductive rod.

[0042] It should be noted that due to the different overall structures of different basin-type insulators, the electric field distribution varies greatly. Through the mechanism of dielectric constant on voltage distribution conditions, the modified coating 4 can be arranged in the insulating area according to the distribution principle of high dielectric constant from low potential to high potential and low dielectric constant in the intermediate creepage area, thereby changing the entire internal electric field distribution, reducing the discharge of the above-mentioned three intersections, and improving the reliability of the product.

[0043] Example 2

[0044] The difference from Example 1 is that the modified coating 4 is applied to a different position on the epoxy casting body 2 in this embodiment. Figures 3-4 In this embodiment, a pot-type insulator with a modified coating is prepared, and the preparation steps are as follows: the insulator includes a central insert 1, an epoxy casting body 2, a grounding shell 3, a modified coating 4, an air gap 5, a concave conductor 6, and a convex conductor 7;

[0045] Furthermore, the central insert 1 and the epoxy casting body 2 can be formed by a vacuum casting process and then assembled with the grounding shell 3 on the GIS or GIL. The central insert 1 is then connected to the concave conductor 6 and the convex conductor 7 to form a high-voltage conductive path. A gas with a certain pressure and high insulation strength is filled between the high-voltage conductive path and the grounding shell 3. The insulating gas is sulfur hexafluoride.

[0046] Furthermore, due to design and assembly requirements, an air gap 5 exists between the outer ring of the epoxy casting body 2 and the flange of the grounded housing 3. Since the dielectric strength of air is lower than that of sulfur hexafluoride, and the air gap structure is also prone to causing partial discharge in the product, a modified coating 4 is added to the outer ring of the epoxy casting body 2 to eliminate partial discharge in the air gap 5.

[0047] The modified coating 4 can be made into a conductive coating by adding conductive materials such as carbon black and graphene, and then a material with a high dielectric constant is made into a nano-coating through a sol-gel process. The modified coating 4 is then attached to the outer ring of the epoxy casting body 2 by spraying or brush plating. The modified coating 4 forms an equipotential with the grounded shell 3 through its conductive properties, thereby covering the air gap 5, thereby playing a shielding role and eliminating discharge in the air gap 5.

[0048] Therefore, the voltage value of the air gap 5 is reduced through the mechanism of the dielectric constant on the voltage distribution condition, thereby reducing the field strength of the air gap 5 and reducing the discharge of the air gap 5;

[0049] Furthermore, the pot-type insulator with modified coating prepared by the present invention is mainly used on the core insulation parts in GIS and GIL equipment, wherein GIS is a gas-insulated metal switch and GIL is a gas-insulated metal-enclosed transmission line.

[0050] In summary, according to Example 2, the present invention adds a high-dielectric-constant nanocoating layer to the outer ring of the epoxy resin (i.e., the epoxy casting 2), thereby adjusting the voltage distribution within the pot insulator and the gas gap, reducing the field strength within the air gap 5, and thus solving the partial discharge problem at this location;

[0051] In addition, according to Example 1, uneven electric field distribution is also prone to occur at the triple intersections formed by the high-voltage conductor, the insulating material, and the insulating gas, and at the triple intersections formed by the low-potential flange, the insulating material, and the insulating gas. This can lead to problems such as excessive local field strength, resulting in partial discharge or flashover. Therefore, the present invention mainly uses a coating or gel process on the surface of the basin (i.e., the epoxy casting body 2) to allow nano-coatings with different dielectric constants to adhere to the surface of the basin, thereby adjusting the electric field distribution along the surface of the basin and improving the product's withstand voltage level.

[0052] From the above summary, it can be seen that the present invention mainly applies nano-modified coatings to high-voltage basin insulators. The different dielectric constants and characteristics of the nano-coatings are used to adjust the electric field distribution of the overall structure. The relationship between the dielectric constant and the voltage distribution is utilized to reduce the field strength in the flange air gap 5 and eliminate local discharge in the air gap 5. In addition, the problem of field strength concentration at the three intersections of high potential and low potential is reduced by adjusting the surface electric field distribution of the basin insulator.

[0053] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0054] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for preparing a pot-type insulator with a modified coating, characterized in that: The preparation steps are: S1. The insulator comprises a central insert (1), an epoxy casting body (2), a grounding shell (3), a modified coating (4), an air gap (5), a concave conductor (6), and a convex conductor (7); an air gap (5) exists between the outer ring of the epoxy casting body (2) and the flange position of the grounding shell (3); S2, forming the central insert (1) and the epoxy casting body (2) by a vacuum casting process and then assembling them together with the grounding shell (3) on the GIS or GIL; S3, the central insert (1) is then connected to the concave conductor (6) and the convex conductor (7) to form a high-voltage conductive channel, and an insulating gas with a certain pressure and high insulation strength is filled between the high-voltage conductive channel and the grounding shell (3); S4. A wedge-shaped air gap is formed at the rounded corners of the end portions of the concave conductor (6) and the convex conductor (7) with the epoxy casting (2) and the insulating gas, and discharge is easily generated at this location as a triple intersection area; S5. A wedge-shaped air gap is also formed at the rounded corner of the flange end of the grounding shell (3) and the epoxy casting body (2) and the insulating gas, and discharge is easily generated at this location as a triple intersection area; S6. Using different dielectric constants, the modified coating (4) is divided into three regions on the creepage surface of the epoxy casting (2), and then the modified coating (4) is added to the creepage surface of the epoxy casting (2) in sequence; a modified coating (4) with a high dielectric constant is added to the outer ring of the epoxy casting (2) to cover the air gap (5), thereby completing the preparation of the insulator; The modified coating (4) is a nano-coating made of materials with different dielectric constants by a sol-gel process, and is finally attached to the outer ring of the epoxy casting body (2) by a spraying or brush plating process; The modified coating (4) is distributed on the creepage surface of the epoxy casting body (2) in sequence according to the dielectric constant to voltage distribution condition in the insulation area in the manner of adjusting the dielectric constant from low to high from low potential to high potential.

2. The method for preparing a pot-type insulator with a modified coating according to claim 1, characterized in that: The insulating gas filled in S3 with a certain pressure and high insulation strength is sulfur hexafluoride gas.

3. The method for preparing a pot-type insulator with a modified coating according to claim 1, characterized in that: The modified coating (4) is a conductive coating made by adding carbon black and graphene conductive materials.

4. The method for preparing a pot-type insulator with a modified coating according to claim 1, characterized in that: The modified coating (4) is divided into three regions, namely, a modified coating on the near-ground side (4.1), an intermediate modified coating in the insulating region (4.2), and a modified coating on the high-voltage side of the insulating region (4.3).

5. The method for preparing a pot-type insulator with a modified coating according to claim 4, characterized in that: The dielectric constant of the modified coating (4.1) on the near-ground side is 4, the dielectric constant of the modified coating (4.2) in the insulating region is 4.4, and the dielectric constant of the modified coating (4.3) on the high-voltage side of the insulating region is 4.

8.

6. Application of a pot-type insulator with a modified coating prepared by the method according to any one of claims 1 to 5, characterized in that: The prepared pot-type insulator with the modified coating (4) is applied to the core insulation parts in GIS and GIL equipment, wherein GIS refers to gas-insulated metal switchgear and GIL refers to gas-insulated metal enclosed transmission line.

7. The use according to claim 6, characterized in that The prepared pot-type insulator with the modified coating (4) is connected to the core insulation of the GIS and GIL equipment through the central insert (1) and the conductive rod.

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