Evaluation of the resilience

Evaluation of the resilience of the electrical grid to environmental and seismic disruptions

One of the most important Italian distribution system operators (DSOs), Enel-owned e-distribuzione, commissioned CESI to analyse the capacity of the grid to cope with natural disasters such as floods, landslides and earthquakes – and provide continuity of service, which is a strategic priority for the company.

The aim was to predict and prevent the dangers that can threaten this vital infrastructure by deepening the knowledge of which network components were potentially exposed to such hazards and how the hazards affect them, together with a definition of hazard intensities and probabilities.

The study analysed existing national natural hazard maps and produced:

• A hazard index for floods, landslides, and earthquakes for all the grid’s main strategic structures (1,800 HV/MV substations, 200 MV/MV substations, 350,000 MT/BT substations and 500 remote control centres)
• Rating of substations based on this new hazard index, to plan more detailed seismic vulnerability investigations

After developing a seismic risk framework focused on primary equipment cabins, operational centres and satellite centres, the study aimed to evaluate the seismic vulnerability of the main structures and structural components at priority sites. We defined a seismic vulnerability checklist and carried out 28 surveys on equipment boxes throughout the country.

The final stage, which is ongoing, assesses the seismic vulnerability of priority buildings at e-distribuzione’s plants that are located in earthquake- prone regions. As well as identifying the seismic risk for key assets, this stage will also identify the most commonly-used construction types adopted throughout the country through analysis of existing design documentation and site-specific investigations of structures and ground foundations. The assessments are being carried out using a Finite Element Modelling approach.