Flashover Voltage Prediction Of Icing Polluted Insulator Based On Dynamic Double Arc Model

With the rapid development of china’s industry and agriculture,the environmental pollution problem is getting more and more worse,which increases the degree of insulator surface pollution in the process of power transmission,and drops the flashover voltage of iced polluted insulator.Compared with traditional glass and porcelain insulators,composite insulators have better electrical performance,anti-pollution flashover ability and mechanical strength,so they are widely used in transmission lines.However,when the composite insulator surface is covered with ice,the pollution is easy to adhere to the ice layer,and the flashover voltage will be greatly reduced.According to statistics,the external insulation problem caused by pollution and icing is the most serious.There are a lot of researches have been done by internal and external scholars on flashover voltage prediction model and flashover mechanism of iced polluted insulators,which reduces the probability of transmission line insulator ice flashover accident to a certain extent.However,the existing static arc flashover voltage prediction model can not calculate the dynamic changes of arc characteristic parameters in the process of insulator flashover.Circuit formula is used in existing dynamic arc flashover voltage prediction to calculate residual resistance,which has certain limitations.Therefore,it is of great significance to study the flashover mechanism and flashover voltage prediction of composite insulators in the environment of pollution and icing.In this thesis,based on fxbw4-10 / 100 suspension composite insulator,the flashover test of iced insulator was carried out by the method of iced water conductivity.The starting position of local arc and the dynamic process from local arc appearing until developing into the surface flashover were recorded,and the flashover voltage variation law of iced insulator under different pollution degrees was obtained.The test results show that during the flashover process,the position of insulator arcing and the number of local arc and the relationship between flashover voltage and conductivity of iced water.Secondly,the flashover simulation model of icing polluted insulator was established by using gas dynamics model and Comsol multi-physical field coupling module was used for numerical solution where the boundary conditions and simulation calculation parameters were obtained from icing pollution flashover test.The dynamic processes of temperature field,potential and electric field on the insulator surface were obtained by simulation.The influence of the conductivity of iced water and the length of ice free zone on the surface flashover were studied.Finally,based on the Obenaus theory,the dynamic double arc model of iced insulator was established.The dynamic change process of arc parameters with time under DC voltage was calculated by self-programming with Comsol simulation results,and the flashover voltage of polluted insulators covered with ice was calculated.The model predicted results were in good agreement with the results of icing flashover test,which verified the accuracy of the prediction model.The research work of this thesis provides a certain theoretical guidance for the research of composite insulator icing pollution flashover,and has a certain engineering value for China’s ice flashover early warning.