Field tests of the traveling wave based protection for ungrounded distribution network

A typical radial ungrounded distribution network model is set up in the 10kV true type distribution network fault simulation laboratory. Through a series of single-phase-to-ground fault tests, the zero sequence and three-phase voltage and current waveforms of traveling wave and power frequency are obtained. Wavelet multiresolution analysis is used to decompose the current and voltage traveling waves. The local modulus maxima of the wavelet transform can extract the polarity of the initial traveling wave. These waveforms prove that the current traveling wave magnitude is much more significant than power frequency current. Besides, the tests also prove that the initial zero sequence current and voltage waves in the faulty feeder are reverse in polarity.