Formal reliability and failure analysis of ethernet based communication networks in a smart grid substation

Secure and continuous operation of a smart grid substation mainly depends upon the reliable functioning of its communication network. The communication system of a smart substation is typically based on a high performance Ethernet communication network that connects various intelligent embedded devices, such as Intelligent Electronic Devices (IED) andMerging Units (MU), to ensure continuous monitoring, automation and efficient demand response of the smart substation. Traditionally, Reliability Block Diagram (RBD) and Fault Tree (FT) methods are used to develop reliability and failure models for these communication networks by considering the failure characteristics of their substation intelligent embedded devices and other components, like transformers and circuit breakers. These resulting reliability and failure models are then analyzed using paper-and-pencil methods or computer simulations, but they cannot assure accuracy in the analysis due to their inherent limitations. As an accurate alternative, we propose a methodology, based on higher-order logic theorem proving, for conducting the formal RBD and FT-based reliability and failure analysis of smart substation communication networks, respectively. This paper also describes a sound transformation of smart grid FT models to their equivalent RBDs - a well-known method to reduce the complexity of FT-based failure analysis. Some ML-based tactics have been developed to automatically compute the reliability and failure probability of smart grid substations for practical purposes.