Research On Reliability And Safety Evaluation Method Of On-board Equipment Of CTCS-3+ATO System

With the rapid development of China’s high-speed railways,the CTCS-3+ATO system that adds ATO(Automatic Train Operation)functions to CTCS-3(Chinese Train Control System)is an important node for high-speed railways to move towards high-quality intelligence and high-level automation.It has also become the development trend of intelligent high-speed rail.Under this background,the on-board equipment of C3+ATO system is the core technical equipment to ensure the safety of train operation and realize the automatic train operation.If the dangerous side faults occurred,it will endanger the safety of operation and cause serious accidents,such as rear-end collision,rollover or derailment.Therefore,the research on the reliability and safety of C3+ ATO system on-board equipment is great significant to improve the design,improve the maintenance level of daily operation,and reduce maintenance cost.Due to the on-board equipment of C3+ATO system is affected by various working conditions,insufficient epistemic level,many random factors and lack of sample data,the operation of components are uncertain.During the actual operation,due to external environmental factors such as vibration and temperature,the performance of the components will be degraded to a certain extent,that is,there are several intermediate states between normal operation and complete fault.Additionally,the redundant configuration of on-board equipment increases the possibility of common cause failure.In response to above problems,the main research contents of this thesis include:(1)On the premise that the function and structure of on-board equipment of C3+ATO system are analyzed,the research is carried out on the uncertainty problem.Combined with evidence theory and fuzzy set method,the interval of component fault probability is described.Then,the advantage of failure logic between components can be described intuitively by using tree model,and the system fault tree and T-S dynamic fault tree analysis model are established.Due to the computational complexity of tree model analysis methods,fault trees and T-S dynamic fault trees are mapped into static evidence network and DTEN(Discrete Time Evidence Network)analysis models.The reliability of on-board equipment of C3+ATO system is evaluated by comprehensively considering the problems such as uncertainty,dynamics,common cause failure,degradation scene and task time discretization.(2)Components of system will show a certain degree of unequal importance in the analysis process.In this thesis,the algorithms based on static evidence network and DTEN are used to obtain the importance measures and sensitivity of each component.Through analysis and identification of weak links in the system,high-risk events that further impact system reliability are identified.The analysis results provide a theoretical basis for the formulation of daily maintenance strategies.(3)Aiming at the performance degradation of the on-board equipment components of C3+ATO system,a multi-state transition model based on Markov is established.The polymorphism problem is solved by DTEN analysis,and the influence of different maintenance strategies on the reliability of C3+ATO system on-board equipment is compared.By analyzing the reasons that cause different redundant structures to be in dangerous states,a quantitative model of dangerous failure rate based on dynamic evidence network is established to evaluate the safety of C3+ATO system on-board equipment.The results provide a theoretical basis for the selection of redundant strategies,and analyze the impact of various parameters in the quantitative model on security.