Simulation Study On Corona Discharge Characteristics Of Insulators On The Contact Wire

With the rapid development of Chinese economy,the atmospheric environment is getting worse.Most of overhead contact nets are exposed in the natural environment,and the surface of the insulators in overhead contact nets can easily accumulate dirt to form a conductive dirt layer,which can lead to local field distortion and corona discharge.This has a negligible impact on the safe operation of the catenary circuit.At present,the results of research on corona discharge still have problems of single object,single content and single model.For the existing problems,the insulators in overhead contact nets is selected as the research object,and the contact net insulator fluid-chemical mixed numerical model is established.Macroscopically,the changes of field strength,average electron energy,and other energy during the discharge were studied,and the distribution of various particles in the discharge process was studied microscopically,and the influence of external factors on the corona discharge was studied.It provides a theoretical basis for the safe operation of the contact network circuit to prevent insulator corona discharge.The main points of the paper are as follow:In recent years,with the continuous expansion of Chinese railway scale,the problems encountered by the insulators of the catenary have also increased.The QBG-25 rod insulator used in the contact network was used as the research object,and a simulation model was established under the two conditions of surface cleaning and fouling of the insulator in overhead contact nets.According to the principle of electrostatic field combined with finite element calculation software,the distribution of the electric field along the surface is simulated and the results are analyzed.Laid the foundation for follow-up work.Second,in order to study the characteristics of corona discharge of insulators in overhead contact nets,the biaxial symmetry of the model was simplified.Based on the traditional fluid dynamics model,the Boltzmann equation is added to solve,and then 33 reaction equations such as electron impact ionization,elastic collision,adsorption,and neutral particle collision are combined.A two-dimensional numerical model of corona discharge for insulators based on hydromechanics combined with chemical reactions was proposed.The transient data from corona onset to corona onset at 30 ns was calculated using numerical simulation.The dynamic distribution of electric field intensity,electron number density,electron temperature,and positive ion number density during the corona discharge of the insulator was analyzed.When the gas medium is constant,the corona discharge is related to the pressure and density of the gas.According to the geographical conditions in China,the appropriate atmospheric pressure variation range was determined,and the influence of atmospheric pressure on corona discharge of insulators in overhead contact nets was analyzed.There are many factors that cause the electron agglomeration on the surface of the insulator.The initial electron density is changed,and the change rule of corona discharge characteristics of the insulator in overhead contact nets is summarized.