Study On Local Arc Microcosmic Development And Influence Factors Of Composite Insulator Pollution Flashover

Composite insulators are widely used in power transmission because of their light weight and excellent performances of pollution flashover resistance.But in serious environmental pollution and high altitude areas,the composite insulator is also easy to be accumulated dirt to form conductive pollution layer.The thermal effect of leakage current causes the surface to form a dry area to emerge surface discharge or local arc generation,and the local arc development to flashover causes the power system accident.Therefore,it is of great significance to study the formation and development of local arc of composite insulators flashover.The FZSW-10/4 model pillar composite insulator is researched in this dissertation.An artificial contamination experiment of insulator based on the equivalent salt deposit density method is conducted,and the measured discharge inception voltage and flashover voltage and the process of local arc formation to complete flashover are taken as the initial condition of macro simulation.A 2D electric field simulation model of insulator surface covered by dry area and residual pollution layer was established here.The influence of different distribution of contamination on insulator surface and different salt conductivity on the distribution of the local electric potential and electric field,which taken as the initial condition of microscopic simulation model are comparative analyzed.According to the experimental results of the location of the local arc and the simulation results of the macroscopic electric field and potential,a microscopic simulation model of pollution flashover local arc,which based on Obenaus flashover discharge model,Boltzmann electron diffusion equation,Maxwell-Stefan mass transport equation and Poisson equation is established,and 43 kinds of reactions,such as electron impact ionization,excitation,elastic collision,adsorption and neutral particle collision are considered.The formation mechanism of local arc is revealed from the view of microscopic particle motion,and the effects of salt density,dry zone temperature,dry area length and dry area initial electron density on the micro parameters of the flashover local arc are comparative analyzed.The result shows the local arc generation position and the power function relation between corona inception voltage,flashover voltage and equivalent salt deposit density of FZSW-10/4 composite insulator,the influence of different pollution distribution on the surface of umbrella skirt and filthy conductivity on the local electric field and electric potential,the relationship between the salt density of pollution layer,the temperature of dry area,the length of dry zone and the sheath electric field strength and the arc column microscopic parameters.A theoretical basis for the micro development of flashover local arc of composite insulators is provided.