Reliability Analysis And Maintenance Strategy Optimization Of Key Equipment Of Subway Train Signal System

The task of urban rail transit is to transport passengers safely and efficiently.Metro signal system,as a vital control system,has significant functions such as directing train operation,achieving wireless communication and so on.Thus,train signal system should have high reliability to ensure safe and reliable operation of the train.Compared to high-speed rail,subway trains run at a lower speed and have shorter distance between stations.Metro trains need to start,speed up,decelerate and brake in a short time and these processes have to be implemented with high frequency everyday,which leads to high operation and maintenance costs.Therefore,optimal maintenance strategy for subway signal system is required.This thesis summarizes current research status of reliability and maintenance for subway signal system at home and abroad,and closely combines the realistic situation of metro operating company to conduct the following research.(1)Underground train signal system is divided into two major subsystems,the on-board signal system and the ground signal system.Combined with the big data analysis method,data mining and visualization are performed on the fault data of different operating lines in the field,in order to explore different fault sub-classes,failure mode,cause of failure,impacts of failure.In addition,data fitting method is used to explore the regular pattern of failure interval.Based on above data analysis results,we have a better understanding of failure situation and effects of signal system.Then,the failure mode effect and criticality analysis(FMECA)method is used on the on-board signal system,which includes failure level partition,mode failure rate calculation,hazard matrix calculation,etc.A FMECA form is established in the end.(2)Based on the fault data recorded by the subway operating company and the FMECA analysis results,this thesis calculate the value of estimated reliability characteristics of the on-board controller.What's more,we draw time-dependent function graphs of reliability indexes and perform comparative analysis.Then,we draw fault trees for the on-board signal system of different operating lines and perform qualitative and quantitative analysis.Based on the fault trees,Bayesian network analysis is introduced to perform the conversion of fault tree to Bayesian network.Assuming the case of system failure,we design an algorithm to inference and calculate the posterior probability of root nodes.Based on these results,we can identify the signal equipmentthat has a greater probability of affecting the system failure,and provide a basis for finding the key equipment of the signal system(3)Extract the ground signal system data,which cause serious impacts,for data splicing,aggregation and preprocessing.And perform data visualization of ground signal system from different dimensions.Draw the fault tree of ground signal system to identify the importance of each equipment.Based on fault tree,the Monte Carlo Simulation method is used to plot the reliability and unreliability time-dependent functions.At last we calculate the reliability indexes of overall signal system,combined the ground and on-board signal system analysis results.(4)Investigate the existing maintenance strategies of the subway operating company and summarize the status of maintenance.Using EXAKT modeling and optimization tool,based on statistical and decision models such as proportional hazard model(PHM),cost decision models,etc.,to study the two-objective optimization maintenance strategy of subway signal systems considering both risks and costs.Take the on-board controller as a case to optimize the maintenance strategy,establish a condition-based model(CBM)to determine the optimal failure risk level,which can minimize the maintenance cost and ensure that the risk of failure is at a low level.Through the research in the above aspects,more intuitive fault regular patterns and characteristics,reliability status and weak links of the train signal system were shown to the maintenance department of the subway operating company.In addition,we formulate more reasonable and optimized maintenance strategies for the realistic operation and maintenance,improving the system service capability and cutting back maintenance costs.