Effect of the multi-grounded neutral on the lightning induced voltages in an overhead power line

Abstract

This paper analyzed the effect of the multi-grounded neutral on the peak values and waveforms of the lightning induced voltages (LIVs) in an overhead power distribution line. The results show that the LIV waveforms observed close to a neutral grounding point are smooth, while those observed around the mid-point between two consecutive grounding points are oscillatory. The waveform oscillations are reduced with reducing the spacing between grounding points, increasing the distance between the strike and the line, and increasing the value of ground resistivity. For a first negative stroke, these oscillations can be neglected if the distance between the strike and the line is higher than 50 m and the spacing between grounding points is shorter than 200 m. It is also shown that, under certain conditions, the indirect lightning flashover rate of a line with multi-grounded neutral can be assessed from the peak-values of the LIVs of a single wire above ground.