Measurement of Induced Current on Overhead Line Very Close to Triggered Lightning and Analysis of Return Stroke Velocity on the Current

In this study, lightning-induced currents due to a triggered lightning with a strike distance of 8 m were measured at an unenergized 200-m overhead line. The characteristics of the coupling current excited by four return strokes were analyzed in time and frequency domains, respectively. Moreover, a 3-D finite-difference time-domain (3-D FDTD) model was built to calculate the coupling current, which was verified by comparing the simulation results against the recorded data. The influence of the constant return stroke velocity and the variable velocity on the coupling current was analyzed by using the 3-D FDTD model. The results indicate that the lightning-induced currents on the overhead line are significantly affected by the nonmonotonically variable return stroke velocity.