Insulation Aging Process Analysis And State Evaluation Of High Voltage Cable Of EMU

The on-board high-voltage cable of EMU is the only channel for train energy transmission,the deterioration of its insulating layer is the main reason for its function failure.The increase in the service life of on-board high-voltage cables of EMUs has led to the aggravation of the deterioration of the insulation system of on-board high-voltage cables,it brings great hidden dangers to the safe and stable operation of the train.Therefore,explore the aging process of the insulation layer of high-voltage cable of EMU and realize the evaluation of aging state of high-voltage cable insulation of EMU can not only provide guidance for the daily maintenance of the EMU,but also avoid the potential safety hazards of the EMU in the power transmission link,moreover,it can help the maintenance personnel correctly identify the aging degree of on-board high-voltage cable,so as to select the corresponding maintenance strategy,reduce the probability of misjudgment and the cost caused by excessive maintenance.In order to master the residual insulation capacity of on-board high-voltage cables of EMUs after service and eliminate potential safety hazards in train power transmission,this paper takes the on-board high-voltage cable of 30 KV EMU with different service life as the research object,focusing on the evaluation of insulation aging state of on-board high-voltage cables of EMUs after service,the following researches and work contents are mainly carried out:Firstly,referring to the relevant test standards,the insulation performance test platform of on-board high-voltage cable is built,and the relevant electrical performance test and mechanical performance test are carried out smoothly.Secondly,based on the parameter results of on-board high-voltage cable insulation performance with different service years obtained from the above tests,the variation trend of each insulation performance characterization parameter is analyzed,the micro mechanism behind the macro change trend of each characterization parameter in the process of insulation degradation is discussed.Finally,four grades of insulation aging state evaluation of vehicle high-voltage cable are proposed,the semi trapezoidal method is used to normalize and forward the test data,the correlation analysis method is used to analyze the correlation of the preset 11 characteristic parameters,and 9 characteristic parameters are selected as the reference object of the evaluation model,the probability evaluation model of insulation aging state of vehicle highvoltage cable with eigenvalue-probability conversion based on the combination of subjective method and objective method is established,fitting the aging state probability distribution results of vehicle high-voltage cable insulation with different service years,the service life intervals corresponding to the four aging states are obtained.After verification,the results show that the insulation of on-board high-voltage cables in service for 7 and 12 years is in the dominant probability interval of "poor" state,which is consistent with the state interval divided by the proposed evaluation method,which verifies the effectiveness of the method.