Insulation Condition Assessment,prediction And Reliability Evaluation Of XLPE Cable

With the development of economy and power system,the network size becomes larger and the amount of electric transmission and transformation equipment increases significantly,so the safe operation of them is an essential issue.Once the equipment brake down,it brings tremendous jeopardize to the safety of network and loss of finances.Therefore,effective and accurate state assessment becomes more important.Meanwhile,accurate prediction can prevent the occurrence of operation failures and help technical staff to take corresponding measures previously to ensure the safe work of the power system.The dissertation adopts an evaluation model based on an evidence reasoning approach combined with the fuzzy theory and an accurate approach based on grey-Markov error back-stepping model to predict states.Fianlly,Weibull distribution is employed to analyse the reliability of XLPE cable.In order to improve assessment accuracy,this dissertation proposes an insulation evaluation model based on an evidence reasoning approach combined with the fuzzy theory,which obtains weights of each parameter objectively and construct the distribution of belief function with uncertainty effectively.What is more,accurate prediction can effectively protect equipment from failures and the main drawbacks of solely using the grey model or the Markov theory for state prediction are the demand for large amount of data and low prediction accuracies.This dissertation proposes an model to predict states of the equipment.Then,Weibull distribution is used to compute the reliability of XLPE cable considering the results of state assessment.Firstly,it introduces the domestic and overseas research status in state assessment and prediction area,also relevant theories and models.According to the cable maintenance guidance and the features of XLPE cable,main parameters for condition assessment are presented,then the relevant condition evaluation algorithms are presented.Subsequently,on the base of the above,the state prediction model is constructed.Relevant data is cited to verify the effectiveness of the proposed theories and models.Finally,this dissertation studies the failure model of XLPE cable and structure the reliability assessment model by failure statistic data.