Prediction Of OCS Reliability Under Under Lightning And Fog-haze Weather

Overhead contact line system(OCS)is an important part for traction power supply system of electric railway.OCS,characterized by non-backup and exposed outdoor completely,is more vulnerable to external environment factors,such as lightning,fog-haze and strong wind.Among these external factors that can influences the reliability and safety performance of OCS seriously,lightning and fog-haze are most important factors.Therefore,it is indispensable to explore the natural characteristics of lightning and fog-haze and model OCS trip-out subject to two weather conditions.In order to solve the above two problems effectively,two aspects of works are carried out in this thesis.Firstly,the trip-out probability of OCS in lightning weather is calculated and the reliability of OCS system under lightning weather is predicted based on lightning strike data and recorded OCS lightning trip-out events.Besides,combined with fog-haze parameters and OCS insulator flashover records,this thesis predicts the reliability of OCS insulator in foghaze weather.Firstly,this thesis analyzes the reliability indicators of OCS and calculates the reliability of the OCS system under different maintenance modes.This thesis uses fault mode effect analysis(FMEA)method to obtain the significant factors that can influence OCS’s reliability seriously,namely lightning and fog-haze.Secondly,aiming at the prediction problem of OCS reliability under lightning weather,this thesis proposes a prediction method of OCS trip-out probability and reliability under lightning weather.Based on the obtained the actual lightning data,the probabilistic lightning model is established to characterize the nature of lightning occurrence.Then the lightning data is divided into various basic time unit.The density-based spatial clustering of applications with noise(DBSCAN)is applied to cluster lighting strike data within each basic time unit.Finally,combined with electric geometry model(EGM)and predicted lightning strike data,the lightning trip-out probability and reliability of whole OCS are expressed analytically.The actual lightning weather data and recorded lightning trip-out events of OCS are used to verify the feasibility of the proposed method.Finally,aiming at the prediction problem of the reliability of OCS insulators under foghaze weather,this thesis proposes a prediction method of reliability of OCS insulators under fog-haze weather.This thesis investigates the characteristics of fog-haze weather that affects the insulator flashover of OCS comprehensively.Then this thesis utilizes the COX proportional hazard model to achieve the significant factors associated with insulator flashover.A dynamic prediction method of OCS insulator reliability is proposed.Finally,the optimal maintenance strategy of OCS insulation based on cost minimization is given.The actual foghaze weather data and recorded fog-haze trip-out events of OCS are used to verify the feasibility of the proposed method.Based on the above investigation,this thesis puts forward suggestions on fault prevention and maintenance for OCS under lightning and fog-haze weatherand provides a valuable insight for improving the reliability performance of OCS,which are of great significance to the operation and maintenance of OCS.