A Methodology for Resilience-oriented Planning in the Italian Transmission System

The increasing frequency and extension of extreme weather events in the last few years require transmission grid planning and operation approaches able to cope with these challenges, thus increasing system resilience. In this regard, initiatives have been launched by transmission and distribution system operators worldwide, often to comply with specific requirements set by regulators. This paper describes a risk-based resilience assessment methodology jointly developed by the Italian TSO and RSE aimed to capture the benefits for system resilience against extreme weather events, brought by grid hardening interventions, with a focus on the two most impacting threats for the Italian transmission system, namely wet snow and wind. The final objective is to support cost-benefit analyses in resilience-boosting plans, as required by the Italian energy regulating entity to all electric utilities. An important target is to include climate change modelling in grid planning, together with the typical planning drivers i.e. security of supply, market efficiency and renewable integration. The case study, focused on a portion of the grid, demonstrates the good matching between the outage return periods calculated for the overhead lines and the actual failure rates derived from historical datasets, as well as the effectiveness of the cost benefit analysis in prioritizing the hardening interventions in case of the two analysed threats.