Knowledge of the geological forces that may affect critical components of the power system (PS) is essential for ensuring safe operation, identifying risks, and proposing improvements.
In 2021, experimental investigations were carried out to determine characteristic parameters regarding the response of soils to seismic forces, in terms of local seismic amplification, for two areas in Campania: the Sarno (SA) and Solofra (AV) regions, which host strategic PS infrastructure. For each site, the experimental measurement set was processed to obtain the local seismic amplification function expressed in terms of frequencies of interest for seismic engineering (from 0.5 to 10 Hz). Structures with natural frequencies within the typical range of seismic frequencies can exhibit significant amplification of ground accelerations, leading to increased mechanical stresses and deformations. These aspects are crucial for the generation, transmission, and distribution of electrical energy, as seismic motion effects can create critical issues in service delivery during emergencies.
Once the threat was defined, the vulnerability aspects of PS components were analyzed, represented by 2 voltage transformers and 2 current transformers, through experimental and numerical modeling to determine fragility functions. Numerical modeling, calibrated based on experimental tests on a shaking table, allowed the estimation of fragility functions for the components, assuming both rigid and alluvial soil conditions, in line with results from experimental geophysical acquisitions and processing. To accurately reproduce realistic site conditions, transformer fragility was evaluated considering a configuration with supporting tubes at the base.
To characterize the investigated sites seismologically, study the effects of seismic intensity on the territory, and define soil response spectra according to both current Building Regulations and appropriate amplification relationships valid for Italy, the catalogs and maps of the seismic application GISEQ developed in System Research were updated, considering the CPTI15 catalog and the seismic classification map of Italy.
A multi-hazard analysis was then conducted, considering various geological threats that may impact PS structures and infrastructure, and evaluating the influence of each on different components. For one site, additional studies on landslide hazard were conducted, with particular reference to collapse-type landslides.