FDTD Simulation of Lightning Surges on Overhead Wires in the Presence of Corona Discharge

A simplified model of corona discharge for finite-difference time-domain (FDTD) computations has been applied to analyzing lightning surges propagating along overhead wires with corona discharge. The FDTD computations simulate the experiments of Inoue and Wagner . In Inoue´s experiment, a 12.65-mm radius, 1.4-km-long overhead wire was employed, and in Wagner ´s experiment, a 21- or 25-mm radius, 2.2-km-long overhead horizontal wire was employed. The critical electric field on the surface of the 12.65-mm-radius wire for corona initiation is set to E₀ = 1.4, 2.4, or 2.9 MV/m, and those for 21- and 25-mm-radius wires are set to E₀ = 2.2 and 2.1 MV/m, respectively. The critical background electric field for streamer propagation is set to E_cp = 0.5 MV/m for positive voltage application and E_cn = 1.5 MV/m for negative voltage application. The FDTD-computed waveforms (including wavefront distortion and attenuation at later times) of surge voltages at three different distances from the energized end of the wire agree reasonably well with the corresponding measured waveforms. Also, the FDTD-computed waveforms of surge voltages induced on a nearby parallel bundled conductor agree fairly well with the corresponding measured waveforms.