Effect of shielding and grounding on lightning performance of 23kV distribution feeders

This paper presents a study of the behavior of distribution feeders against lightning, where the magnitude of the surge caused by this phenomenon is calculated. The feeder model and the lightning phenomena have been implemented in the electromagnetic transients program ATP-Draw. The magnitudes of the surges are obtained by numerical simulations in this program. Simulations were performed for cases where the lightning impacts the wire-guard or the phase conductor. A sensitivity study to establish the parameters that influence the maximum values of the surge is also performed. The model is applied to a rural distribution line in southern Brazil, where very often lightning causes insulation failure and power cuts. The results show how to improve the feeder protection in order to enhance the level of system reliability.