Impact chains’ analysis for making resilient the distribution system

Climate changes are making extreme weather events capable to cause disasters and stop the delivery of vital services more frequent. The power system is an example of a critical infrastructure extremely vulnerable to such weather events. The distribution system feeds the nal uses of energy and its disservices immediately impacts people and enterprises. Furthermore, the reliability indicators of power distribution are not as good as in the generation or in the transmission systems for reasons that span from the weakly meshed topological structure to the still limited use of automation, even though many countries are obtaining fast improvements with the use of advanced fault location, isolation and service restoration systems. In recent years, developing 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, but nowadays the distribution system cannot be disregarded. The lack of design tools that may help managers consider the trade-off between resilience and cost in distribution systems needs to be covered. The paper proposes a framework for evaluating the resilience of a distribution network serving a given geographical area. Such a framework exploits the impact chains’ analysis that, starting from specic hazards (e.g., windstorms, earthquakes, etc.), assesses the exposure and vulnerability of the portion of the understudy network to evaluate the nal risk. Making the distribution system stronger (i.e., hardening the network), more reliable (i.e., increasing the number of redundant paths), or smarter (i.e., by adopting non-network measures that exploit Smart Grid technologies) are the options analysed with suitable indicators. The test of the methodology on a case study demonstrates the applicability of the model in distribution planning.