双冗余控制器的失效状态分析及面向高可靠度的设计

Failure analysis of dual redundant controllers and designs for high reliability

冗余控制器广泛应用于核动力设施控制等对可靠度有特殊要求的场合。为有效提高双冗余控制器的可靠度,该文首先通过状态分析获得其全面的状态转移图,明确了影响可靠度的2种典型情况:"双主"冲突造成的整机失效和备机失效造成的冗余功能丧失。其次,针对上述2种情况提出了基于双通信链路的冗余切换方案和从机状态报告机制,以有效避免失效状况的发生。最后,基于Markov链建立了描述双冗余控制器可靠度的理论模型,并依据该模型对冗余控制器在改进前后的可靠度进行了分析评估。评估结果表明:所提方案可将冗余控制器的失效率降低近3个数量级。

Redundant controllers are widely used in control systems of nuclear-powered facilities requiring high reliability. The reliability of dual-redundant controllers is improved by analyzing the controllers＇ possible working states in a state transition diagram. The two critical circumstances where the reliability is impaired are failures caused by dual-master collisions and the loss of redundancy resulting from the failure of a stand-by unit. To avoid these critical circumstances, this paper presents a redundant controller scheme with dual dedicated communication paths using heartbeat double checking and slave reporting. A Markov-chain model was developed to evaluate the reliability of redundant controllers and the effectiveness of this scheme. The results show that this redundant controller design significantly improves the reliability with a three orders of magnitude reduction of the failure rate.