Performance analysis of lightning overvoltage on medium voltage distribution lines equipped with covered conductors

This paper gives the performance of lightning overvoltage due real lightning discharges that have occurred in distribution power lines equipped with covered conductors. Evaluation and simulations are based on real lightning data collected from the Finnish Meteorological Institute (FMI) from 1998 to 2008. The presented feeder is an overhead distribution line with a covered conductor subjected to indirect lightning strokes to ground and direct lightning strokes to a line support. Evaluation of induced overvoltage from indirect stroke to the line is analyzed with MATLAB. With the Electromagnetic Transient Program (EMTP), simulations of lightning strokes are performed with different lightning current characteristics. All cases are considered with the modelling guidelines for fast transients as specified in some lightning literature. Simulations are made to compare the resulting overvoltages and energy absorptions of surge arresters for all the analyzed cases.