State Space, substation layout, topology I. NOMENCLATURE SAS Substation Automation Systems GOOSE Generic Object Oriented Substation Event

Abstract-This paper focuses on the reliability evaluation of modern substation automation systems. Such systems include both physical devices such as lines, breakers, and transformers, as well as cyber devices (switches, intelligent electronic devices, and cables) and belong to a broader class of cyber-physical systems. We assume that the substation utilizes IEC 61850 standard, which is a dominant standard for substation automation. Focusing on IEC 61850 standard, we present the failure modes and analyze their effects on the system. We utilize reliability block diagrams for analyzing the reliability of substation components (bay units) and then use the state space approach to study the effects at the substation level. The results of our analysis provide critical input to evaluating the reliability of the substation and the effects of substation failures to the rest of the power system. Index Terms—Cyber-physical system, IEC 61850, reliability