Reliability Analysis of Transformer Protection System in Smart Substation

The reliability of relay protection in smart substations is of great significance. However, the current research methods for relay protection reliability have certain limitations. Solely using reliability block diagram (RBD) methods cannot provide a sufficient amount of reliability indicators. Furthermore, research on the reliability of duplicated protection has not taken the impact of the independence between redundant configuration components into account. Based on the specific technical implementation of transformer protection in smart substations, this paper proposes a reliability evaluation method based on reliability block diagram and the Monte Carlo method. This method is used to obtain reliability indicators such as system unavailability, failure frequency, and mean time to failure. A comparative analysis is conducted between single transformer protection and dual transformer protection, and the component importance of secondary equipment in the transformer protection system is provided. The effectiveness and practical significance of the proposed method are verified through numerical examples.