Polishing basin type insulator surface repairing method based on uniform charge treatment

Abstract

This invention discloses a method for repairing the surface of polished basin-type insulators based on uniform charge treatment. The method employs a stepped repair material based on uniform charge treatment, and repairs the polished insulator using a polishing insulator surface repair device while maintaining the surface hardness. Before polishing, a 3D scanner is used to determine the insulator morphology as a sample reference. The insulator is then polished, and a working voltage is applied to the central conductor. The difference in electric displacement between the inner and outer normals of the insulator surface after polishing is calculated, thereby determining the surface charge value Q2. The number of stepped layers in the polished area can be adjusted according to the process. The sprayed material is a mixture of epoxy resin, alumina, and a curing agent, with a dielectric constant between 3 and 10. After preliminary repair, the difference between the measured and calculated surface charge values ​​is compared. If the error is less than 10%, the repair is considered complete. This invention can be widely applied in the field of polished surface repair of insulating devices.

Description

Technical Field

[0001] This invention relates to a method for repairing the surface of a polished basin-type insulator based on uniform charge treatment, belonging to the technical field of polished surface repair of insulating devices. Background Technology

[0002] Pot-type insulators are key components in gas-insulated transmission pipelines and fully enclosed gas-insulated switchgear in power systems. They face increasingly demanding operating conditions and are prone to surface discharge or breakdown accidents. During the casting process, factors such as mold parting lines, mold wear, or embedded impurities can cause surface protrusions of varying sizes and orientations on the insulator surface, necessitating polishing. However, statistical data shows that surface discharge accidents often occur near the polished area. Therefore, finding a method to reduce surface charge accumulation after polishing to prevent discharge accidents is crucial.

[0003] Under the influence of a high-voltage electric field, the accumulation of surface charge on an insulator mainly originates from insulator body conduction, insulator surface conduction, and gas-side space charge accumulation. This charge accumulation is related to the insulator's conductivity, surface conductivity, and the gas conductivity. In highly electronegative gases, such as SF6, most free electrons attach to gas molecules, forming negative ions. The movement and diffusion of these charged particles in the electric field determine the dynamic changes in surface charge.

[0004] The dielectric constant of a dielectric material is a crucial factor influencing the electric field distribution and charge accumulation. A dielectric with a higher dielectric constant can store charge more effectively, thus affecting charge accumulation and distribution. Therefore, by altering the surface dielectric constant of the dielectric, the charge accumulation on the insulator surface can be adjusted, thereby affecting its electrical properties.

[0005] The commonly used methods to reduce surface charge accumulation in insulators mainly include the following: 1. Surface Treatment Technology: Modifying the surface roughness of insulators through methods such as sandblasting can alter the distribution of surface charge. However, microscopic examination using an atomic force microscope reveals that sandblasting causes the harder alumina to protrude, affecting the local electric field on the insulator surface. This results in the accumulation of oppositely polarized charges at polished areas, increasing the local potential difference and raising the risk of partial discharge. Even with epoxy resin repair, the low hardness of epoxy resin makes it prone to secondary scratches, thus failing to provide effective repair.

[0006] 2. Change the insulator structure: Improved insulator structures can reduce the accumulation of charge on the insulator surface, but this is ineffective for insulators that are already in operation.

[0007] 3. Regular cleaning and maintenance: Regular cleaning of the insulator surface can remove accumulated dirt and charge, maintaining its good insulation performance. However, since the insulators in GIL and GIS are in enclosed spaces, it is not convenient to perform regular cleaning for short periods of time.

[0008] Therefore, there is currently no more effective solution for suppressing the localized uneven accumulation of charge in polished insulators.

[0009] In AC power systems, the performance of insulators is crucial to the system's stability and safety. By subjecting polished insulators to uniform charge treatment, the local potential difference on the insulator surface can be further reduced while maintaining the surface hardness, thereby preventing partial discharge, improving insulator performance, and ensuring the reliable operation of the power system. Summary of the Invention

[0010] This invention overcomes the shortcomings of the existing technology and provides a method for repairing the surface of polished basin insulators based on uniform charge treatment. The method uses a stepped repair material based on uniform charge treatment, and repairs the polished insulators using a polished insulator surface repair device while maintaining the hardness of the insulator surface.

[0011] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for repairing the surface of polished basin-type insulators based on uniform charge treatment, which is implemented according to the following steps: The first step is to use a 3D scanner to determine the micron-level morphology of the insulator as a sample reference before polishing. The accuracy of the 3D scanner is 20μm to 100μm. The second step is to polish the protruding parts or impurities of the insulator and compare them with the morphology detected by the 3D scanner to form a 0-2mm depression in the polished area. The third step is to use a 3D scanner to re-determine the morphology of the insulator and compare it with the sample to determine the depth h of the polishing depression; The fourth step is to apply a working voltage to the center conductor of the insulator. After the power is turned off, the surface charge measurement device of the insulator is used to determine the surface charge distribution pattern M1 and the surface charge value Q1 of the insulator. The fifth step is to calculate the difference in electric displacement between the inner and outer normals of the insulator surface after polishing, based on the adsorption and accumulation effect of space charge after the dielectric polarization under AC conditions, and then obtain the surface charge value Q2 of the insulator. Step 6: Determine the number of repair steps and the dielectric constant of the sprayed material based on the surface charge value Q2 of the insulator. The number of repair steps in the polished area can be adjusted according to the process. During repair, a mixture of epoxy resin and alumina with a high proportion of alumina (not less than 80%) needs to be sprayed first. The thickness of the multiple sprays may be the same or different. In the final sprayed epoxy resin and alumina mixture layer, the proportion of alumina is the same as the proportion K of the original alumina in the repaired insulator. The sprayed material is a mixture of epoxy resin, alumina and curing agent, and the dielectric constant of the mixture is between 3 and 10. Step 7: Apply the working voltage to the center conductor of the insulator again. After power is cut off, use the insulator surface charge measuring device to determine the insulator surface charge distribution pattern M3 and the insulator surface charge value Q3. Then, based on the new insulator surface charge distribution pattern M3, repeat step 5 to calculate Q'2 under the new distribution pattern. Compare Q'2 and Q3. If the error between Q'2 and Q3 is less than 10%, the repair is complete. Otherwise, repeat steps 2 to 7.

[0012] Furthermore, in the fifth step, by comparing Q1 and Q2, if the error in the values ​​of Q1 and Q2 is less than 10%, the number of repaired stair layers and the dielectric constant of the corresponding sprayed material are determined; if the error is greater than 10%, the scanning angle of the 3D scanner needs to be readjusted, and steps two through five are repeated.

[0013] Furthermore, in the sixth step, the sprayed repair layer is multi-layered, wherein the proportion of alumina is K to 80%, and the sprayed repair material is not higher than the surface height of the original insulator.

[0014] Furthermore, in the fourth and seventh steps, the insulator surface charge measuring device uses an electrostatic potentiometer or a nanocoulometer. During measurement, a stepper motor or a lead screw device is used to control the probe of the above instrument to move on the insulator surface, directly or indirectly obtaining the insulator surface charge distribution patterns M1 and M3 and the insulator surface charge values ​​Q1 and Q3.

[0015] Furthermore, the calculation process for Q2 in the fifth step is as follows: In an electric field environment, the motion of gas-side charge carriers depends on the Coulomb force acting on the particles, while the diffusion of charge carriers is determined by the uniformity of their concentration. The dynamic change of positive charge carrier concentration can be expressed by the generation, recombination, and migration of positive and negative ions, as shown in formulas (1) to (2): (1) (2) In the formula, ∂ n IP / ∂t represents the ion pair formation rate; D+ , D − These are the diffusion coefficients of positive and negative ions, respectively; k r The recombination coefficient of positive and negative ions; n + , n − These represent the concentrations of positive and negative ions, respectively. b + , b − These represent the migration rates of positive and negative ions, respectively. E Electric field strength; According to Einstein's equations, we can obtain... D + / − = b + / − kT / e ,in e For electron charge, k Boltzmann's constant, T Ambient temperature; Since most free electrons in highly electronegative gases attach to gas molecules, forming negative ions, and neglecting the effects of temperature on gas pressure and field emission from electrodes, we can assume that the charge carriers in the gas are only positive and negative ions. The recombination coefficient of these positive and negative ions... k r From Langevin's principle, we can derive: (3) In the formula ： ε The dielectric constant of the insulating gas; Based on the charge accumulation process on the insulator surface, the current density on the insulator side and the gas side at the gas-solid interface can be used as an important boundary condition at the insulator-gas interface, as shown below: (4) (5) In the formula, J I , J G Current densities on the insulator side and the insulating gas side, respectively; γ 2 represents the solid-side bulk conductivity; E n2 , En1 These are the normal components of the electric field strength at the gas-solid interface on the insulator side and the insulating gas side, respectively. The charge accumulation at the gas-solid interface is as follows: (6) (7) In the formula, σ s Surface charge density; n The normal vector of the medium surface; D 1. D 2 represents the electric displacement vector on the solid and gas sides; The charge that causes the change in electric potential and electric field distribution can be obtained by the Poisson equation, as shown in formulas (8) and (9): (8) (9) In the formula, ρ It is the charge density of freely moving ions and electrons; By inputting equations (1) to (9) as constraint and control equations into the electric field analysis software, the normal component of the electric displacement on the interface between the gas side and the substrate side of the insulator surface can be calculated, and the difference between the normal components of the electric displacement, i.e., the surface charge density σ, can be obtained. s As shown in formula (7); Then the surface charge density σ s Substituting into formula (10), the surface charge value Q2 of the insulator is obtained: (10) In the formula, S is the tip area of ​​the instrument probe of an electrostatic potentiometer or nanocoulometer that can test the surface charge of an insulator.

[0016] Compared with the prior art, the beneficial effects of this invention are as follows: This invention addresses the problem of uneven charge accumulation on the surface of polished basin insulators, which leads to local high potential differences and high distorted electric fields causing partial discharge. It adopts a method based on uniform charge treatment to set up a stepped repair material and develops a polished insulator surface repair device to repair polished insulators while maintaining the hardness of the insulator surface. Attached Figure Description

[0017] The present invention will now be further described with reference to the accompanying drawings.

[0018] Figure 1 This is a schematic diagram of the local electric field distortion in the polishing depression of the insulator in this invention.

[0019] Figure 2 This is a schematic diagram illustrating the principle of the present invention.

[0020] Figure 3 This is a schematic diagram of the vertical electrical displacement change of the polished surface after repair according to the present invention. Detailed Implementation

[0021] The present invention will be further described below with reference to specific embodiments.

[0022] like Figures 1-3 As shown, the present invention provides a method for repairing the surface of a polished basin-type insulator based on uniform charge treatment, which is implemented according to the following steps: The first step is to use a 3D scanner to determine the micron-level morphology of the insulator as a sample reference before polishing. The accuracy of the 3D scanner is 20μm to 100μm. The second step is to polish the protruding parts or impurities of the insulator and compare them with the morphology detected by the 3D scanner to form a 0-2mm depression in the polished area. The third step is to use a 3D scanner to re-determine the morphology of the insulator and compare it with the sample to determine the depth h of the polishing depression; The fourth step is to apply a working voltage to the center conductor of the insulator. After the power is turned off, the surface charge measurement device of the insulator is used to determine the surface charge distribution pattern M1 and the surface charge value Q1 of the insulator. The fifth step is to calculate the difference in electric displacement between the inner and outer normals of the insulator surface after polishing, based on the adsorption and accumulation effect of space charge after the dielectric polarization under AC conditions, and then obtain the surface charge value Q2 of the insulator. Step 6: Determine the number of repair steps and the dielectric constant of the sprayed material based on the surface charge value Q2 of the insulator. The number of repair steps in the polished area can be adjusted according to the process. During repair, a mixture of epoxy resin and alumina with a high proportion of alumina (not less than 80%) needs to be sprayed first. The thickness of the multiple sprays may be the same or different. In the final sprayed epoxy resin and alumina mixture layer, the proportion of alumina is the same as the proportion K of the original alumina in the repaired insulator. The sprayed material is a mixture of epoxy resin, alumina and curing agent, and the dielectric constant of the mixture is between 3 and 10. Step 7: Apply the working voltage to the center conductor of the insulator again. After power is cut off, use the insulator surface charge measuring device to determine the insulator surface charge distribution pattern M3 and the insulator surface charge value Q3. Then, based on the new insulator surface charge distribution pattern M3, repeat step 5 to calculate Q'2 under the new distribution pattern. Compare Q'2 and Q3. If the error between Q'2 and Q3 is less than 10%, the repair is complete. Otherwise, repeat steps 2 to 7.

[0023] Furthermore, in the fifth step, by comparing Q1 and Q2, if the error in the values ​​of Q1 and Q2 is less than 10%, the number of repaired stair layers and the dielectric constant of the corresponding sprayed material are determined; if the error is greater than 10%, the scanning angle of the 3D scanner needs to be readjusted, and steps two through five are repeated.

[0024] Furthermore, in the sixth step, the sprayed repair layer is multi-layered, wherein the proportion of alumina is K to 80%, and the sprayed repair material is not higher than the surface height of the original insulator.

[0025] Furthermore, in the fourth and seventh steps, the insulator surface charge measuring device uses an electrostatic potentiometer or a nanocoulometer. During measurement, a stepper motor or a lead screw device is used to control the probe of the above instrument to move on the insulator surface, directly or indirectly obtaining the insulator surface charge distribution patterns M1 and M3 and the insulator surface charge values ​​Q1 and Q3.

[0026] Furthermore, the calculation process for Q2 in the fifth step is as follows: In an electric field environment, the motion of gas-side charge carriers depends on the Coulomb force acting on the particles, while the diffusion of charge carriers is determined by the uniformity of their concentration. The dynamic change of positive charge carrier concentration can be expressed by the generation, recombination, and migration of positive and negative ions, as shown in formulas (1) to (2): (1) (2) In the formula, ∂ n IP / ∂t represents the ion pair formation rate; D + , D − These are the diffusion coefficients of positive and negative ions, respectively; k r The recombination coefficient of positive and negative ions; n + , n − These represent the concentrations of positive and negative ions, respectively. b + , b − These represent the migration rates of positive and negative ions, respectively. E Electric field strength; According to Einstein's equations, we can obtain... D + / − = b + / − kT / e ,in e For electron charge, k Boltzmann's constant, T Ambient temperature; Since most free electrons in highly electronegative gases attach to gas molecules, forming negative ions, and neglecting the effects of temperature on gas pressure and field emission from electrodes, we can assume that the charge carriers in the gas are only positive and negative ions. The recombination coefficient of these positive and negative ions... k r From Langevin's principle, we can derive: (3) In the formula ： ε The dielectric constant of the insulating gas; Based on the charge accumulation process on the insulator surface, the current density on the insulator side and the gas side at the gas-solid interface can be used as an important boundary condition at the insulator-gas interface, as shown below: (4) (5) In the formula, J I , J G Current densities on the insulator side and the insulating gas side, respectively; γ 2 represents the solid-side bulk conductivity; E n2 , E n1 These are the normal components of the electric field strength at the gas-solid interface on the insulator side and the insulating gas side, respectively. The charge accumulation at the gas-solid interface is as follows: (6) (7) In the formula, σ s Surface charge density; n The normal vector of the medium surface; D 1. D 2 represents the electric displacement vector on the solid and gas sides; The charge that causes the change in electric potential and electric field distribution can be obtained by the Poisson equation, as shown in formulas (8) and (9): (8) (9) In the formula, ρ It is the charge density of freely moving ions and electrons; By inputting equations (1) to (9) as constraint and control equations into the electric field analysis software, the normal component of the electric displacement on the interface between the gas side and the substrate side of the insulator surface can be calculated, and the difference between the normal components of the electric displacement, i.e., the surface charge density σ, can be obtained. s As shown in formula (7); Then the surface charge density σ s Substituting into formula (10), the surface charge value Q2 of the insulator is obtained: (10) In the formula, S is the tip area of ​​the instrument probe of an electrostatic potentiometer or nanocoulometer that can test the surface charge of an insulator.

[0027] This invention combines the simplicity of the process and operation of magnetron sputtering and other spraying materials, in... Figure 2 First, a mixture of epoxy resin and alumina, with an alumina content of over 80% and a total height h / 3, is sprayed into the depression. Then, a mixture of the original epoxy resin and alumina, with an alumina ratio of h / 3 (where the alumina ratio is the same as the original alumina ratio K in the insulator being repaired), is sprayed last. This process can be divided into multiple layers, with the alumina ratio ranging from K to 80%. The total spraying height is less than or equal to the surface height of the original epoxy resin. The sprayed material, based on the epoxy resin and alumina mixture, increases the alumina ratio to control electrical displacement changes and reduce surface accumulation; the final layer on the surface remains the original epoxy resin and alumina mixture, thus maintaining the surface hardness of the insulator.

[0028] When the polishing process of an insulator causes hard particles in the insulator matrix to protrude, such as alumina particles in a basin-type insulator, local electric field distortion occurs in the middle of the epoxy resin particles and at the interface with the most concave area of ​​the polishing. This results in a significant increase in the electric field strength. Figure 1 As shown, because the dielectric constant of the epoxy resin matrix is ​​higher than that of the gas side, the electric displacement in the matrix is ​​generally higher than that on the gas side, and the surface charge density on the gas side is generally negative, meaning that the insulator surface generally accumulates negative charges. However, locally enhanced electric field strength amplifies the electric displacement on the gas side, potentially making it higher than that on the matrix side. Therefore, positive charges often accumulate on the polished insulator surface. The opposite polarity of the charges creates a high potential difference and distorted electric field on the insulator surface, increasing the likelihood of local discharge and flashover.

[0029] To reduce the electric displacement difference between the two sides of the polished insulator surface, and taking into account the fact that the dielectric constant of the protruding alumina particles on the polished surface is larger than that of the epoxy resin matrix, in Figure 1In the polishing zone, a filler with a dielectric constant between 3 and 10 is sprayed onto the polishing zone using methods such as magnetron sputtering.

[0030] In summary, to address the problem of uneven charge accumulation on the surface of polished basin-type insulators, which leads to localized high potential differences and high distorted electric fields causing partial discharge, a step-type repair material based on a uniform charge treatment method was developed. A surface repair device for polished insulators was then constructed to repair the polished insulators while maintaining the surface hardness of the insulators.

[0031] In this embodiment, the recessed area on the insulator surface after polishing was selected. Given that the micron-sized alumina particles protrude more than the epoxy resin after polishing, a stepped repair was performed on the insulator at the recessed height. Assuming the dielectric constant of the insulator substrate is 3, during the multi-step repair, starting from the surface side of the recessed substrate, dielectrics with dielectric constants of 8, 5, and 3 were sprayed using methods such as magnetron sputtering. The repaired surface height was less than or equal to the original surface height.

[0032] from Figure 3 It can be seen that when using stepped repair, after under-height repair or equal-height repair, the change in electrical displacement at the interface between the repair medium and the SF6 medium is much smaller than that in pure epoxy repair. According to formula (7), the low electrical displacement difference results in less charge accumulated on the surface of the insulator, and the charge distribution on the surface of the insulator is more uniform, reducing the risk of partial discharge.

[0033] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for repairing the surface of a polished basin-type insulator based on uniform charge treatment, characterized in that, Implement the following steps: The first step is to use a 3D scanner to determine the micron-level morphology of the insulator as a sample reference before polishing. The accuracy of the 3D scanner is 20μm to 100μm. The second step is to polish the protruding parts or impurities of the insulator and compare them with the morphology detected by the 3D scanner to form a 0-2mm depression in the polished area. The third step is to use a 3D scanner to re-determine the morphology of the insulator and compare it with the sample to determine the depth h of the polishing depression; The fourth step is to apply a working voltage to the center conductor of the insulator. After the power is turned off, the surface charge measurement device of the insulator is used to determine the surface charge distribution pattern M1 and the surface charge value Q1 of the insulator. The fifth step is to calculate the difference in electric displacement between the inner and outer normals of the insulator surface after polishing, based on the adsorption and accumulation effect of space charge after the dielectric polarization under AC conditions, and then obtain the surface charge value Q2 of the insulator. Step 6: Determine the number of repair steps and the dielectric constant of the sprayed material based on the surface charge value Q2 of the insulator. The number of repair steps in the polished area can be adjusted according to the process. During repair, a mixture of epoxy resin and alumina with a high proportion of alumina (not less than 80%) needs to be sprayed first. The thickness of the multiple sprays may be the same or different. In the final sprayed epoxy resin and alumina mixture layer, the proportion of alumina is the same as the proportion K of the original alumina in the repaired insulator. The sprayed material is a mixture of epoxy resin, alumina and curing agent, and the dielectric constant of the mixture is between 3 and 10. Step 7: Apply the working voltage to the center conductor of the insulator again. After power is cut off, use the insulator surface charge measuring device to determine the insulator surface charge distribution pattern M3 and the insulator surface charge value Q3. Then, based on the new insulator surface charge distribution pattern M3, repeat step 5 to calculate Q'2 under the new distribution pattern. Compare Q'2 and Q3. If the error between Q'2 and Q3 is less than 10%, the repair is complete. Otherwise, repeat steps 2 to 7. The calculation process for Q2 in the fifth step is as follows: In an electric field environment, the motion of gas-side charge carriers depends on the Coulomb force acting on the particles, while the diffusion of charge carriers is determined by the uniformity of their concentration. The dynamic change of positive charge carrier concentration can be expressed by the generation, recombination, and migration of positive and negative ions, as shown in formulas (1) to (2): （1） （2） In the formula, ∂ n IP / ∂t represents the ion pair formation rate; D + , D − These are the diffusion coefficients of positive and negative ions, respectively; k r The recombination coefficient of positive and negative ions; n + , n − These represent the concentrations of positive and negative ions, respectively. b + , b − These represent the migration rates of positive and negative ions, respectively. E Electric field strength; According to Einstein's equations, we can obtain... D + / − = b + / − kT / e ,in e For electron charge, k Boltzmann's constant, T Ambient temperature; Since most free electrons in highly electronegative gases attach to gas molecules, forming negative ions, and neglecting the effects of temperature on gas pressure and field emission from electrodes, we can assume that the charge carriers in the gas are only positive and negative ions. The recombination coefficient of these positive and negative ions... k r From Langevin's principle, we can derive: （3） In the formula ： ε The dielectric constant of the insulating gas; Based on the charge accumulation process on the insulator surface, the current density on the insulator side and the gas side at the gas-solid interface can be used as an important boundary condition at the insulator-gas interface, as shown below: （4） （5） In the formula, J I , J G Current densities on the insulator side and the insulating gas side, respectively; γ 2 represents the solid-side bulk conductivity; E n2 , E n1 These are the normal components of the electric field strength at the gas-solid interface on the insulator side and the insulating gas side, respectively. The charge accumulation at the gas-solid interface is as follows: （6） （7） In the formula, σ s is the surface charge density; n The normal vector of the medium surface; D 1. D 2 represents the electric displacement vector on the solid and gas sides; The charge that causes the change in electric potential and electric field distribution can be obtained by the Poisson equation, as shown in formulas (8) and (9): （8） （9） In the formula, ρ It is the charge density of freely moving ions and electrons; The formula (1)-(9) are inputted into the electric field analysis software as the constraint and control equations, so that the normal component of the electric displacement on the interface between the gas side and the base side of the insulator surface is calculated, and the difference of the normal component of the electric displacement, i.e. the surface charge density σ is obtained s As shown in the formula (7); Then the surface charge density σ s Substituting into formula (10), the surface charge value Q2 of the insulator is obtained: （10） In the formula, S is the tip area of ​​the instrument probe of an electrostatic potentiometer or nanocoulometer that can test the surface charge of an insulator.

2. The method for repairing the surface of a polished basin-type insulator based on uniform charge treatment according to claim 1, characterized in that, In the fifth step, Q1 and Q2 are compared. If the error of the values ​​of Q1 and Q2 is less than 10%, the number of repaired stair layers and the dielectric constant of the corresponding sprayed material are determined. If the error is greater than 10%, the scanning angle of the 3D scanner needs to be readjusted, and steps two through five are repeated.

3. The method for repairing the surface of a polished basin-type insulator based on uniform charge treatment according to claim 1, characterized in that, In the sixth step, the sprayed repair layer is multi-layered, wherein the proportion of alumina in the sprayed repair layer is K to 80%, the proportion of alumina in the first layer is greater than 80%, and the proportion of alumina in the last layer is K. The closer to the polished recessed surface, the higher the proportion of alumina in the sprayed repair layer; the sprayed repair material is not higher than the original insulator surface height.

4. The method for repairing the surface of a polished basin-type insulator based on uniform charge treatment according to claim 1, characterized in that, In steps four and seven, the insulator surface charge measuring device uses an electrostatic potentiometer or a nanocoulometer. During measurement, a stepper motor or lead screw device is used to control the probe of the measuring device to move on the insulator surface, directly or indirectly obtaining the insulator surface charge distribution patterns M1 and M3 and the insulator surface charge values ​​Q1 and Q3.

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