基于FTA和DTMC快速构建安全控制系统

Rapid Design Method for Safety Control System Based on FTA and DTMC

以恒压供水控制系统为例提出了一种快速构建安全控制系统的方法.首先对所设计系统的基本结构采用故障树法(FTA)进行故障定性分析,据此确定并完善系统总体结构和主要功能,然后对该系统硬件结构进行基于离散时间马尔可夫链(DTMC)的可靠度计算,最后根据可靠度求出失效率(PFD),再查功能安全标准中的PFD和功能安全评估等级(SIL)关系表确定SIL.研究表明:在系统分析和设计阶段充分考虑控制系统的功能安全,有利于提高控制系统的可靠性和开发效率.

Taking constant-pressure water supply control system as an example, the paper presents a method for designing a safety control system rapidly. First, the basic structure of the designed system is qualitatively analyzed based on fault tree analysis （FTA） to determine and improve the system＇s general structure and main functions. Second, the hardware reliability of the system is calculated based on DTMC. On the basis of that, the probability of failure design （PFD） is obtained. Finally, the safety integrated level （SIL） is determined based on the relationship table between PFD and SIL. The research indicates that full considering control system＇s functional safety during system analysis and design is favor of improving control the reliability and exploiting efficiency of the system.