Multi-state IEC-61850 Substation Communication Network based on Markov partitions and symbolic dynamics

Abstract

Abstract Substation Communication Networks (SCN) make the digitalisation of power distribution centres possible. In recent times, combinatorial analysis methods are used to evaluate the reliability and availability of IEC-61850 based SCNs. Although the approach is conceptually simple and easy to use, it does not incorporate imperfect repairs that often occur during the system’s useful life and diagnostic coverage. Hence, reduced system performance is experienced for this reason, which is worsened by digital-based systems that require unique expertise to support and maintain the system. In this paper, the reliability and availability of multi-state IEC-61850 based SCN is modelled using structure-function and Markov process to incorporate imperfect repairs and system diagnostic coverage. Thereafter, the impact of repair efficiency on the system’s reliability performance and its dynamical behaviour is investigated in the context of Markov partitions and linear dynamical systems incorporating matrix similarity concepts. The case study results demonstrate that the system’s reliability performance based on mean system state transitions is highly dependent on the level of quality of repairs (viz. repair efficiency and diagnostic coverage) on the system. The results also indicate that the mean state transitions are very sensitive to low repair efficiency levels observed from the eigenvalues’ response to incremental repair efficiency. Hence, the quality of repairs cannot be ignored for mission-critical substation communication networks.