Statistical Analysis of Exceptional Events: The Italian Regulatory Experience

In the analysis of reliability performance of distribution utilities, as well as in continuity of supply regulation, criteria are needed for separating normal operation data from exceptional events. In recent years a number of statistical methodologies has been proposed for this purpose. We present here the new methodology that was adopted by the Italian regulatory authority at the beginning of 2008. The decision is supported by a statistical analysis of the number of faults on the medium voltage (MV) and low voltage (LV) networks, for each six-hour time interval in a three year time span, for different provinces and distribution companies. The new methodology is employed in the reward and penalty mechanisms that regulate the SAIDI, SAIFI, and MAIFI indicators and, with some original provisions, also in the Guaranteed Standard on maximum restoration times.