基于PDS的铁路信号冗余结构危险失效概率计算方法

在铁路信号领域的安全评估中常采用IEC61508中的方法计算产品的每小时危险失效概率(Probability of a Dangerous Failure Per Hour,PFH),但该方法所面向的工业控制系统同铁路信号地面控制系统间存在差异性,且计算过程针对共因失效的分析较少。采用PDS(挪威语缩写,代表安全仪表系统的可靠性)方法定量计算铁路信号冗余结构的PFH,首先分析铁路信号系统典型的3种冗余结构,然后通过引入结构修正因子CMOON改进β参数模型,以区分共因失效对不同冗余结构PFH影响的不同,接着根据3种冗余结构的工作特点构建系统可靠性框图,并给出不同冗余结构通用的PFH计算公式,最后以实验数据进行仿真,结果显示,与采用IEC61508中的方法相比,本文的方法更加注重共因失效对PFH的影响程度,符合现场设备的实际使用情况。

Computing Method of Dangerous Failure Probability of Redundancy Structures of Railway Signal Based on PDS

The method of IEC61508 is often used to calculate the Probability Of Dangerous Failure Per Hour(PFH)of products in the safety assessment of railway signal system.However,the standard is more suitable for industrial control systems,and such systems are different from ground control system of railway signal.Furthermore,the analysis of common cause failure needs more research.In this paper,the PFH of redundant structures of railway signal is quantitatively calculated by means of PDS(a Norwegian acronym for reliability of safety instrumented systems)theory.Firstly,three typical redundancy structures of railway signal system are analyzed.Secondly,the parameter model is improved by introducing the structural correction factor to distinguish the influence of common cause failure on different redundant structures’PFH,then the reliability block diagrams of these three redundancy structures are built by analyzing their working characteristics.Meanwhile,the general PFH formulas for different redundant structures are given.Eventually the simulation results obtained from experimental data show that,compared with the method in IEC61508,the proposed method addresses more on the effect of common cause failure on PFH.