Voltage transient measurements in a distribution network correlated with data from lightning location system and from sequence of events recorders

Measurement units of high-frequency voltage transients have been specifically developed and installed at three different busses of an Italian medium voltage (MV) feeder, mainly composed by overhead lines and located in a rural region characterized by a high ground flash density (4 flashes/km2/yr). Several of the recorded voltage transients in the period from March 2007 to August 2008 are correlated with specific events detected by the Italian lightning location system (LLS) CESI-SIRF and with sequence of protection operations recorded by the utility's data acquisition system. The paper presents the analysis of these correlated events. Moreover, the paper compares some voltage transient measurements with the computer simulation results obtained by a detailed LIOV-EMTP model of the MV feeder response to indirect lightning strokes. The aim of the paper is to provide elements useful to solve the problem of correlating line faults with lightning events.