A randomised leader progression model for backflashover studies

Abstract

AbstractInsulation coordination models are an essential part of power system studies and are used to determine the risk of damage to plant during abnormal conditions such as those experienced when lightning strikes the power system. One model used to predict the performance of an overhead line when hit by lightning examines the likelihood of a backflashover; the breakdown of an insulator coordination gap due to a rise in tower potential in comparison to a phase conductor. A backflashover model has many components that must be accurately modelled including the lightning strike, the tower, the shield wire/phase conductors, the insulator coordination gaps and the tower earthing system. Of all of these, the only two significant challenges are the accurate modelling of the insulator coordination gaps and the tower earthing system (the soil ionisation mechanism in particular). This paper focuses on the simulation of the insulator coordination gap for which available models range from a simple voltage controlled switch to the more complex leader progression model (LPM). The paper details the use of experimental data to produce a modified LPM in which certain model parameters are randomly varied. The development of this model using laboratory data is detailed, as is the effect that using this model has on the results of two insulation coordination studies that relate to backflashovers. Copyright © 2007 John Wiley & Sons, Ltd.