A Framework for Multi-Level Reliability Evaluation of Electrical Energy Systems

This paper proposes a framework for multi-level reliability evaluation of electrical energy systems. Reliability, independent of the criteria (deterministic or probabilistic) used to measure it, is often treated as a binary variable, i.e, the system is considered to be reliable if it meets some intended function and unreliable otherwise. This binary approach is appropriate in systems with a single intended function or in which degraded performance is not allowed. Electrical energy systems are highly distributed and have multiple functions, i.e., deliver power to different loads. Furthermore, electrical energy systems are dynamic, both in operational conditions and physical structure, which has an additional impact on system performance, and therefore on reliability. In this context, the paper presents multiple levels of reliability and defines the concept of degraded performance for power systems work. The proposed multi-level reliability evaluation framework explicitly models both structural and operational uncertainty. It will become increasingly important as user-based reliability considerations become more prominent in electric power systems.