Impact chains’ analysis for making resilient the distribution system, CIGRE 2022 Kyoto Symposium

Climate changes make the high impacts of disasters more probable than in the past. The power grid is one of the critical infrastructures extremely vulnerable to severe weather events. Indeed, the distribution system is the part of the power grid directly connected to the people, and this makes urgent the planning of ad hoc supply restoration strategies. Indeed, the distribution system is the weakest portion of the electric infrastructure (for many reasons, e.g., it is mainly radially operated, and the interruption of one path often does not allow restoring the service in the isolated area). In the last years, the development of strategies for adapting the infrastructures to the risk of extreme events has become a hot research area to pursue. Still, most studies involve the transmission system only (e.g., big electric highway). Nowadays, the distribution system cannot be disregarded, and the lack of design tools able to find metrics or resilience indexes that may help managers consider the trade-off between resilience and cost needs to be covered. The paper proposes a framework for evaluating the resilience in a distribution network serving a given geographical area. Such framework exploits the impact chains’ analysis that, starting from specific hazards (e.g., windstorms, earthquakes, etc.), assesses the exposure and vulnerability of the portion of the understudy network with the aim of evaluating the final risk. In the paper, options that make the distribution system stronger (i.e., hardening the network), bigger (i.e., increasing the number of redundant paths), or smarter (i.e., by adopting non- network measures that exploit Smart Grid technologies) will be hypothesised and measured with suitable indicators. Results derived by testing the methodology on a case study demonstrate the effectiveness of the model suitable for planning applications.