Transient Electric Field Simulation Of Basin-type Insulator And Analysis Of Its Effect On Surface Flashover

Due to the advantages of its small occupied area and good insulation performance, Gasinsulated switchgear has been massively applied in substation construction. But GIS canproduce metal particles in the process of product and transport or in the operation process ofthe mechanical wear of moving parts in the actual operation, When these metal particles existon the basin-type insulator that is relatively weak of insulation performance in GIS, the localelectric field will be concentrated and distorted under the voltage, which causes partialdischarge or flashover, affecting the normal operation of GIS. So it is very important to studythat surface electric field distribution of insulator existing metal particles to the insulationperformance and flashover of basin-type insulator.According to the actual product structure of800kV basin type insulator, the3D structuremodel of basin-type insulator was established in this paper. The electric field distribution ofbasin-type insulator existing metal particles of different size and position was analyzed byusing FEM, while the lightning impulse voltage, VFTO and power frequency voltage wereimposed respectively. In addition, the different permittivity and anisotropy of medium to theeffect of the electric field distribution was analyzed. The electric field distribution ofbasin-type insulator, the normal and tangential electric field intensity along the radialdistribution curve and the maximum of electric field intensity were given about differentsituations. Compared with the flashover field strength of basin-type insulator that has no metalparticles, it can provide reference for the design of GIS.The calculated results have stated clearly: under the power frequency voltage, lightningimpulse voltage and VFTO, the maximum surface electric field strength of the basin-typeinsulator will increase with the surface field strength increased gradually of the metal particleslocated, and it increased firstly and then decreased with the increasing size of metal particles.Compared with the flashover field strength of basin-type insulator which has no metalparticles, the electric field distribution of basin-type insulator existing metal particles occursdistortion and the maximum electric field intensity along the surface of the basin-typeinsulator was more than the field strength of surface flashover, and the effect of VFTO wasmore serious than the other two kinds of voltage. Thus the surface electric field of the basin-type insulator is concentrated because of the existing of metal particles, especially thesurface electric field existed the large normal component, which is an important factor offlashover occurrence. Besides, the trend of electric field distribution of basin-type insulatorwas same when the permittivity was different, but the maximum electric field strengthdecreases with relative permittivity increasing. When the medium anisotropy was considered,the electric field distribution of the basin-type insulator was different from the isotropicmedium, the effect of electric field distribution on the basin-type insulator is bigger and withthe gap is bigger between xxand zz. So the medium anisotropy should also be considered asone of the factors to the surface flashover of basin-type insulator.