Reliability of IEC 61850 based substation communication network architecture considering quality of repairs and common cause failures

Mission-critical IEC 61850 system architectures are designed to tolerate hardware failures to achieve the highest reliability performance.Hence,multi-channel systems are used in such systems within industrial facilities to isolate machinery when there are process abnormalities.Inevitably,multi-channel systems introduce Common Cause Failure(CCF)since the subsystems can rarely be independent.This paper integrates CCF into the Markov reliability model to enhance the model flexibility to investigate synchronous generator intra-bay SCN architecture reliability performance considering the quality of repairs and CCF.The Markov process enables integration of the impact of CCF factors on system performance.The case study results indicate that CCF,coupled with imperfect repairs,significantly reduce system reliability performance.High sensitivity is observed at low levels of CCF,whereas the highest level of impact occurs when the system diagnostic coverage is 99%based on ISO 13849-1,and reduces as the diagnostic coverage level reduces.Therefore,it is concluded that the severity of CCF depends more on system diagnostic coverage level than the repair efficiency,although both factors impact the system overall performance.Hence,CCF should be con-sidered in determining the reliability performance of mission-critical communication networks in power distribution centres.