Operational Planning Strategies for Improving the Resilience of Electricity Distribution Systems Supplying Critical Loads

Electric energy is indispensable for the majority of human activities. Some of them are more critical than others, and their proper, secure, and safe functioning strictly depends on the continuity of electrical service. Power systems may suffer from extreme climate events that are becoming more frequent than in the past. During such events, the supply of electrical energy to critical customers can be interrupted for a prolonged time if the system does not withstand the disaster and the operators are not ready to react (e.g., by developing a proper defense strategy in advance). The capacity of a power system to withstand (or at least to reduce the impact of) extreme events is called the resilience of the system, and it is also related to the capacity of the operators to put in place measures of defense. This paper proposes a methodology for electricity distribution network resilience appraisal. The tool aims to assess a risk index that is useful for defining strategic defense plans for reducing damages and quickening the recovery of the standard conditions of the grid in case of extreme climate events. This goal can be obtained only by considering many aspects, such as the extension of the affected area, the number of customers to be recovered, the number of available crews that can work simultaneously, the difficulties in reaching specific sites, etc. Special attention is paid to the presence in the territory of critical loads (i.e., hospitals or other essential services) that should be first recovered. A real-scale application is proposed to demonstrate the validity of the approach.