Study On The Method To Improve The Flashover Voltage Of Insulator Strings Based On The Electric Field Distribution Model

The pollution flashover accident caused by line insulator is very important to the power system.How to prevent flashover has become a hot issue in the world.A lot of researches have been done to improve the performance of insulator contamination resistance at home and abroad,most of them focus on the change of material and shape,but the study of the mechanism of flashover is relatively less.In this paper,the mechanism of pollution flashover is analyzed based on the phenomenon of insulator flashover in polluted condition,and two necessary conditions are obtained: high local field intensity and large tangential field strength.By adding a metal ring insulator can reduce the local field intensity at the iron cap and the tangential electric field of insulator surface.Reducing the local electric field intensity can reduce the discharge probability,and reducing the insulator surface tangential electric field intensity can control the development of charged particles;In this paper,we construct a 3-D model of a single chip and a single strand of the 110 kV porcelain suspension insulators based on the finite element method.By calculating the insulator surface tangential field strength under different parameters,the optimal design parameters range of metal ring has been gained.In this paper,based on the ordinary porcelain suspension insulators(XP-70)as the sample,we carry out the artificial pollution test with and without the metal ring on the insulator by solid layer method.Dry and wet flashover and pollution flashover test have been done already,and the flashover voltage has been measured.The test results show that the effect of metal ring on the pollution flashover voltage is obvious under severe polluted condition.