Voltages Induced on an Overhead Wire by Lightning Strikes to a Nearby Tall Grounded Object

摘要

The aim of this study was to identify conditions under which the presence of tall strike object can serve to increase or decrease lightning-induced voltages on a nearby overhead wire. We examined the ratios of magnitudes of lightning-induced voltages on the overhead wire for the cases of strikes to a tall object and to flat ground as a function of distance from the lightning channel d, current reflection coefficients at the top of the strike object (rho)_(top) and at the bottom of the strike object (rho)_(bot), the current reflection coefficient at the channel base (in the case of strikes to flat ground) (rho)_(gr), and the return stroke speed v. Lightning-induced voltages were computed using the finite-difference time-domain (FDTD) method. The transmission line (TL) model was used to find the distribution of current along the lightning channel and the strike object. The ratio of magnitudes of lightning-induced voltages for tall-object and flat-ground cases increases with increasing d (ranging from 40-200 m), decreasing (rho)_(bot) (<1), decreasing (rho)_(top) (<0, except for the case of (rho)_(bot) velence 0), and decreasing v (