Modification in Waveform of Traveling Pulse Voltages Due to Corona Production Along Transmission Line

A very short pulse voltage traveling on a corona transmission line producing streamer coronas is subjected to a time-dependent distortion of its waveform owing to energy consumption by coronas. In the case of a wire-to-duct corona transmission line, only negative streamers appear from the edges of a corona wire. On the other hand, in the case of a wire-to-wire corona transmission line, where the positive wire is located parallel to the negative wire with a considerably small gap, positive streamers also appear when the applied pulse voltage is sufficiently high. The first (negative) streamer is launched from the negative wire at the leading part of the pulse crest voltage, while the second (positive) streamer is emitted from the positive wire at its rear part. The negative streamers in both cases produce a small distortion in the leading part of the crest, whereas the positive streamers cause a large dip in the succeeding region of the voltage waveform. Corona loss is estimated from these modifications in the waveforms for both negative and positive streamers. The other factors to cause waveform modifications are also studied. These are the skin effect enhanced resistance loss to lower the rising rate of pulses and the electromagnetic coupling between the wires.