The data used for this analysis, which are recorded by the national PQ monitoring system QuEEN [16] on the 400 most representative Italian high-voltage/medium-voltage substations, refer to the voltage dips that occurred in Italy during the year 2012, and they are gathered in four groups corresponding to four different territorial zones. The choice of the following four areas has been performed because they represent different grid interconnection degrees with a wide area voltage regulation [17]: