Toward Reaching a Consensus on the Concept of Power System Resilience: Definitions, Assessment Frameworks, and Metrics

The electric power system plays an integral part in the well-being of the modern society. Because of climate change, the ageing power system infrastructure is under threat due to the ever-increasing intensity and frequency of high-impact, low-probability (HILP) events. Although, in most cases, these events are area-specific, the impact of such events, if unaddressed, can lead to cascading failures. Therefore, it is vital for the grid of tomorrow to not only be reliable but also be resilient in view of the broad inter-dependencies. Despite being a widely researched topic, the applicability of the concept of resilience, especially in power systems terms, is not a straightforward task due to the lack of consensus on a consistent definition, or a set of robust metrics. This paper starts with an analysis of different definitions, frameworks, and metrics related to resilience proposed by multiple researchers and research organizations which is then followed by determination of the damage cost and risk associated with an extreme event which is pivotal in resilience enhancement decisions. We then present two case studies: 1) for determining the customer damage cost that underpins the increase in customer cost as a result of major event, 2) for estimating the risk index of the network that helps support resilience-oriented decision making. We also summarize some of the guidelines and standard practices followed by electric utility companies concerning extreme weather events in terms of preparedness and recovery actions, resilience improvement plans, etc. Moreover, to ascertain the improvement in the grid resilience indices, as a result of resilience enhancement application, a case study (Case Study 3) that evaluates three resilience improvement techniques is presented.