Modeling of surge corona on line conductors: application to lightning surge analysis

Surge corona effects on propagating surge overvoltages on line conductors is of great importance for assessing the lightning performance of transmission lines. However, modeling of surge corona is a formidable task due to the stochastic nature of the involved inception and growth processes, greatly affected by the line geometry, overvoltage waveform, conductor surface conditions, as well as atmospheric and weather conditions. This study presents a model for evaluating surge corona inception and growth on overhead line conductors. The model accounts for the stochastic nature of surge corona by yielding probability distributions for its inception characteristics and by discriminating between the different modes of surge corona inception and growth. The surge corona model is implemented in a finite-difference time-domain (FDTD) algorithm for assessing the attenuation and distortion of traveling surges on overhead line conductors. FDTD simulation results compare well with measurements reported in literature on propagation characteristics of surge overvoltages as they vary with travel distance along test overhead lines.