A simple approach to improve lightning performance of an uprated substation

Abstract

This paper presents a simple method to minimize lightning surges entering an uprated or compact substation. A severe lightning stress is caused by a backflashover in close proximity to the substation. Feasibility of uprating is based on the surge arrester technology available at present. However, some aspects of line design offer opportunities in reducing frequency and severity of lightning surges imposed on the substation. The tower surge response adds an inductive 'overshoot' only during the front of the stroke which reduces considerably during the tail. If backflashover does not occur before reflections from adjacent towers arrive, it is unlikely to occur at all. Use of guys and underbuilt ground wires in the limiting distance will produce reflections with larger magnitude and reduce the effective surge impedance of the tower. This would not only reduce backflashover frequency but will also minimize crest and duration of surges entering the substation.