Research On Common Cause Failure Analysis Method For Safety Computer

In recent years,with the rapid development of high-speed railway,safety computer as the core of control system,its reliability and safety has been focused and become one of the hot-spots of scholars in various fields.Redundancy structure can improve the reliability and safety of safety computer.The commonly used redundancy structures include hot-standby,2-out-of-3 and double 2-vote-2 and so on.At present,when the researchers analyze the reliability and safety of system,it is usually assumed that each model are independent,such hypothesis can bring great convenience to a certain extent.However,it does not consider the impact of common cause failure on the reliability and safety of the system in engineering application,so it lacks practical value.This thesis introduces the structure of safety computer in the field of rail transit and its performance evaluation theory.Aiming at the problem of the common cause failure,this paper makes some research on the analysis process,analysis methods of safety computer,its probabilistic estimation model and its defense measures.With the full consideration of working principle and actual operating conditions of the safety computer,the thesis makes a further research on common cause failure combined with the related knowledge of Markov process ordinary differential equation and system safety theory.Considering there may exist common cause failure problem for double 2-vote-2 system,using Markov model method,a new proposed partition idea of double 2-vote-2 system in which common cause failure,repair rate and diagnostic coverage are considered.Then the reliability and safety of the system are analyzed based on the new proposed partition idea.The simulation experiment results demonstrate that the proposed partition idea is effective.Under the same conditions,the reliability and safety of the system are analyzed and simulation for hot-standby and three-vote-two system.Finally,The simulations of hot-standby and2-out-of-3 system are compared with double 2-vote-2 system simulation results.The compared simulation result shows that the safety of double 2-vote-2 system is the highest between three redundancy structure in which common cause failure are considered.