Identification, visualization and reduction of risk related to HILP events in power systems

High Impact Low Probability (HILP) events in the power system can have severe consequences for society. The concept of power system resilience has recently been applied to study such events. The paper discusses the definition of a HILP event and proposes a complimentary approach to studying power system resilience. This approach considers the probability of a scenario occurring and the subsequent consequences. The article further proposes methods to identify, communicate and subsequently reduce the probability of such events happening. The applicability of the methods is exemplified through a case study using the Roy Billinton Test System (RBTS) and 25 years of historical weather data. The results show that the method can be used to illustrate high-risk HILP events to support operational resilience planning, and how a developed resilience contribution measure can be used to prioritize grid hardening efforts.