Study On The Relationship Between Insulator Leakage Current And Environmental Factors In The Contact Line

With the rapid development of electrified railway in China,the passenger lines,"four vertical and four horizontal",have been put into operation.The operation faults of electrified railway line are mostly caused by defective insulations.When the insulator's surface pollution has accumulated to a certain extent and encounters bad weather conditions(such as fog,drizzle,etc.),the insulator's insulation performance reduces.Thus the pollution flashover accident is very prone to take place,bringing serious loss to the railway operation.Insulator leakage current contains not only a wealth of feature information,but also have a close relationship with their surface contamination.Analysis the status information of catenary insulator through detection of its leakage current,establish an evaluation model that contamination condition of insulator,and judge the catenary insulator surface contamination.This reference has been provided for pollution flashover of insulator cleaning in actual operation.In this thesis,the characteristics of the insulation leakage current are analyzed,and the pollution flashover's mechanism and process is introduced.Besides,based on the insulator's detection method and test scheme home and abroad,a reasonable insulation leakage current detection platform is built.Moreover,aiming at denoising the leakage current,the improved EMD method is proposed.In this thesis,two testing signals,a simulation signal a the actual signal,are analyzed by the traditional EMD and the improved EMD method.The results show that the improved EMD method has good denoising effect and can be used for the analysis of leakage current.In addition,the leakage current is influenced by many factors,this paper selects three important factors,namely,the operating voltage,temperature difference and fog,to study the influence of these three factors on the leakage current.The results show that under the allowed operating voltage,leakage current's maximum value and effective value can be linearly related to the variation of the operating voltage.Temperature difference has impact on the time of achieving the leakage current's maximum value.Large temperature difference can short the time,but the leakage current's maximum value is almost the same.Fog has a certain effect on leakage current characteristics.When the other conditions are the same,the greater the mist concentration,the greater the leakage current value is.So pollution flashover accidents in the fog should be particularly prevented in the line operation.