Research On Dynamic Flashover Mechanism And Influence Factor Of Iced Insulator

Composite insulator is widely used because of its small volume, light weight, goodtolerance, excellent shock resistance, convenient installation and other advantages. As a result,it becomes preferred insulation equipment of domestie power transmission. The long-termoperation results show that owing to the hydrophobicity of composite insulator itself, it hasgood rejection effect on rainwater and filthy and has a good ability of anti-pollution flashover.But for zones of our country’s high altitude and cold regions which are influenced by ice andsnow disaster effect all the year round, because the umbrella skirt of composite insulator itselfhas dense distribution, it is easy to make the surface area be covered with snow and ice andthen forms icicle, bridges umbrella skirt, and reduces the insulation property. As a result, itbrings huge losses to the power grid. Therefore, it is necessary for the research on the electricproperty and flashover mechanism of composite insulators after being iced.This paper takes the suspension rod composite insulator of110kV voltage grade,FXBW4-110/100model as basic simulation model, according to the position most easily toproduce local arc of composite insulator after being iced, to analyze the influence on differentdegree of icing and different umbrella skirt structure on local electric field distribution oficing composite insulator. The simulation results show that the greater icing amountof composite insulators, the more uneven potential distribution of insulator surface; theshorter of icicle, the higher of electric field strength between the clearance. When theicicle clearance is shortened to a certain distance, the discharge location on the edge of theumbrella skirt changes from discharge along surface to air clearance discharge; for thecomposite insulators of FXBW4-110/100model with different icing amount, evenly inserting3-4pieces of anti-icing umbrella sheds can play an important role in better optimizationfunction to the local electric field.At the same time, according to the position prone to generate local arc after compositeinsulator being iced, analyze the generation mechanism of icing composite insulator’s local arcand the effect on the electric arc’s occurrence on the spatial distribution of the electric field,from the angle of microscopic particles motion.The final draw: the generation of local arc duesto the electron impact ionization and distortion of electric charge produced by two ionization on the space electric field, thus push forward the development of streamer and break down airclearance; the shorter of air clearance between icicle, the shorter of the required arcdevelopment time, and the more intense of the collision of particles; in the process of arcdevelopment, the electric field strength of arc column region is high, and has effect on electricfield distribution of the area nearby. When the arc runs to the surface of icicle, the electric fieldintensity is2-3times of the initial time.The large of the voltage and pressure, the faster of thearc development;The value of the voltage affects the electric field strengththe entire of the arcarea,and the level of the atmospheric pressure affects the maximum of the electric field only inthe arc area.