Effects of transmission line tower grounding improvements on its lightning performance

Improvement of transmission line tower grounding is of particular importance for the line service quality. The tower transient impedance is a key parameter for the prediction and estimation of transmission line performance under abnormal conditions including lightning strikes. In this paper we compare the impulse impedance to the low frequency resistance of the tower by evaluating their respective effects on back-flashovers estimation. Based on real-case scenarios of grounding system configurations the critical current is computed and analysed to estimate the gain in the tower-footing grounding system design.