Analysis of VHF-wideband Impulsive Electromagnetic Noises from Power Distribution Lines

Abstract

Impulsive electromagnetic noises, generated by electrical discharges on power distribution lines, are mainly responsible for wide-band disturbances to communication systems. In this paper, the impulsive noises emitted from various discharge sources are analyzed. We employed a non-contact measurement system using the VHF wide-band antenna, which permits not only the waveforms of electromagnetic pulses but also the timing of pulses. By using this system, we measured the pulses generated by applying high voltage upon the discharge sources. The characteristics of a single pulse waveform are analyzed by digital signal processing techniques, which are Fourier and wavelet transforms. Moreover, the time-sequential pulse-height patterns of pulses are investigated. The pulse-height and pulse-repetition of both positive and negative pulses are discussed associating with the mechanism of discharge. It is shown that the results are useful to classify the kinds of discharge sources and assess the condition of insulators in distribution systems.