Statistical analysis of transient events monitored in an electrified subway system

A statistical analysis has been performed in order to characterize overvoltage events recorded in the subway system of Rome during a power quality monitoring activity. The subway system is supplied by the public network at 20 kV through five service entrances. The recorded transients have been characterized by the maximum peak value, the peak-to-peak superimposed oscillations and the duration of the transient. The origin of each transient has been identified so that it has been possible to classify the overvoltages in two major groups, whose statistical figures could be assessed.