Simulation Study On The Potential And Electric Field Distribution Characteristics Of Insulators Along The Surface Under Sand And Dust Environment

In the strategic context of "West-East Power Transmission" in our country,a large number of transmission lines need to pass through the northwest region.However,the northwest region has sparse vegetation,and desertification has intensified in recent years,leading to frequent occurrences of sandstorms.Sandstorms have severely affected the safe operation of the transmission lines.The sand weather not only accelerates the deposition of sand on the insulator surface but also transforms the pure air surrounding the insulator into a mixture of air and suspended dust,forming a strong sandstorm electric field in the space.The change in the operating environment of the insulator affects the distribution of surface potential and electric field along the insulator,posing a risk of flashover.Therefore,studying the distribution changes of surface potential and electric field along the insulator in transmission lines under sandy environments can provide theoretical references for related research on insulators in sand environments.This article focuses on the XP-70 suspension porcelain insulator and the FXBW4-110/100 suspension composite insulator commonly used in transmission lines.The insulators in a sandy environment are divided into two categories:insulators with sand deposits on the surface and insulators in a suspended dust environment.Using the finite element method based on electrostatic field analysis,the simulation models for insulators with sand deposits on the surface and for the XP-70 suspension porcelain insulator string in a suspended dust environment were established using finite element simulation software.The air domain boundaries were defined using the artificial truncation method to transform the infinite domain into a finite one,enabling the solution of the surface potential and electric field distribution along the insulator string.Additionally,an infinite element domain was set up to address the far-field dissipation issue of the electric field.For the simulation model of insulators with sand deposits on the surface,the three-dimensional sand deposition model of the insulator was replaced with a twodimensional axisymmetric model,taking advantage of its symmetry to significantly improve computational efficiency while preserving accuracy.Regarding the simulation model of the porcelain insulator string in a suspended dust environment,due to the large number of suspended dust particles in the air,which cannot be computed and solved by conventional computers,a simplified model of the complete model was created by utilizing the axisymmetric characteristics of the insulator model and the operability of mesh partitioning.This reduced the computational workload to 1/180 of the complete model,resulting in a significant improvement in computational efficiency while maintaining accuracy.finite element simulation software was employed to analyze the distribution characteristics of surface potential and electric field along the insulator caused by sand layer coverage and in a suspended dust environment.Finally,maintenance recommendations for insulators in sandy environments were proposed.The distribution of potential and electric field along the surface of an insulator is dependent on its geometric shape and the characteristics of the surrounding medium.At the junction between the upper and lower surfaces of the porcelain insulator umbrella skirt and the hardware,there will be localized peaks in electric field intensity.The sand layer deposited on the surface of the insulator skirt does not affect the potential but reduces the field strength at the skirt covered by sand,and the reduction is independent of the sand layer thickness but dependent on the position of the individual insulator within the string.With an increase in the sand layer thickness,the field strength at the junction between the upper surface of the porcelain insulator skirt and the hardware initially increases significantly,then decreases to a stable value.The magnitude of the field strength at this junction is also related to the position of the individual insulator within the string.When there is a sand-free zone within the sand layer covering the insulator surface,the field strength at the sand-free zone increases,and the magnitude of the increase is related to the position of the individual insulator within the string,the thickness of the sand layer,and the width of the sand-free zone.Suspended electrically neutral sand particles slightly elevate the surface potential and electric field along the porcelain insulator,and the degree of elevation is proportional to the particle size and concentration of the sand particles.When the sand particles around the porcelain insulator are charged,there is a significant distortion in the surface potential and electric field,and the extent of distortion is related to the particle size,concentration,and charge-to-mass ratio of the sand particles.When the porcelain insulator is in a mixed sand particle environment,the distortion amplitude of its potential and electric field is significantly affected by the charged sand particles’charge within the sand,and the suspended charged sand particles are an important cause of the distortion in the surface potential and electric field along the porcelain insulator.