Severity Factor and Reliability Trend Evaluation of the Italian Transmission Lines

Transmission system is the core of the electrical network since it provides the connection between loads and generators in the whole grid. It is well known that transmission lines are the weakest element of the grid, and their outages could represent a high loss from an economical point of view and in term of continuity of the supply. As a result of its transparency policy, the Italian transmission system operator provides the data of the outages occurred on the grid. An analysis of the severity of the outages of the different component classes from 2008 to 2021 is carried out. The employment of Severity Factor highlights the prioritization of the components monitoring. It is well known that the overhead transmission lines (OHTL) are the weakest element of the grid characterized by a high failure rate. A traditional reliability, availability and maintainability study has been carried out on the line failures over the 14 years of observation and the same analysis is carried on the different voltage subpopulation to check which is the weakest class that has to be carefully monitored. Furthermore, the Severity Factor has been employed for the identification of the transmission network criticalities and the enhancement of the related maintenance activities.