Research On Surface Charge Suppression Method Of Disc Insulator Based On Zoning Coating

As a key component of Gas Insulated Switchgear(GIS)and Gas Insulated transmission Line(GIL),epoxy insulator plays the role of electrical insulation and mechanical support.Under the long-term of DC electric field,the spacer surface will accumulate the charge,leading to the reduction of flashover voltage,which seriously affects the insulation safety of electrical equipment.Hence,it is necessary to study the inhibition method of surface charge accumulation on the insulator surface.In this paper,the disc insulator was selected as the experimental object,a zoning coating method to inhibit the charge accumulation was proposed by numerical simulation.Combined with experiments,the inhibition mechanism of zoning coating on the charge accumulation was analyzed,and the effectiveness of this method was verified,which provides a new way for charge suppression and electric field regulation of epoxy insulator in GIS/GIL.The main work of this paper is as follows:1.Based on the surface charge measurement platform of real size disc insulator,the behavior of typical surface charge accumulation under negative DC voltage was studied.According to the measured results,a zoning coating method to inhibit the charge accumulation was proposed.The method was that high conductivity coating was coated in the non-planar area of insulator surface and low conductivity coating was coated near grounded electrode,nonlinear conductivity coating was applied to the planar region between the two.2.The electro thermal coupling multi physical field simulation model of real disc insulator was established.The numerical simulation was carried out by COMSOL multiphysics software,and the optimal area and parameters of zoning coating was established.The inhibition mechanism of zoning coating on the charge accumulation was analyzed.The results showed that the charge was mainly accumulated in the nonplanar region of the insulator.Under the negative voltage,with the increase of surface conductivity,the charge density in the non-planar region first decreased and then increased,and the accumulated charge changed from negative to positive.Zoning coating could significantly inhibit the charge accumulation and reduce the surface electric field intensity.With the increase of the central conductor temperature,the negative charge accumulated in the non-planar region increased and the inhibition performance of zoning coating decreased.3.The scaled downsized disc insulator and coaxial electrode system were designed.According to the simulation results,epoxy nanocomposites coatings with different conductivities were prepared for uniform and zoning coating respectively.The effects of high conductivity,low conductivity and zoning coating on the pattern of the charge was discussed.The inhibition effects of zoning coatings on the charge deposition in the presence of linear metal particles was analyzed.It was shown that the coating with high conductivity would increase the heteropolar charge injection near the grounded electrode,the coating with low conductivity would increase the homopolar charge accumulation in the non-planar region,and the zoning coating could inhibit the charge accumulation in the non-planar region of the insulator and the charge injection of the grounded electrode,so as to reduce the charge density,which verified the inhibition effect of zoning coating on charge accumulation.When there was the metal particle,heteropolar charge speckles were significantly accumulated in the non-planar region,and the charge density of the insulator was still effectively suppressed after zoning coating.