A new method to detect single-phase fault feeder in distribution network by using S-transform

Traveling wave consists of the frequencies ranging from tens of kHz to hundreds of kHz in distribution network with single-phase fault, S-transform is implemented to detect the fault line in distribution network from the tens of kHz high frequency transient component of the fault traveling wave. The moment depending on the maximum component in the highest frequency row of the S-transform magnitude matrix of zero modal bus voltage corresponds to the real mutation moment of zero modal bus voltage. Then the moment of the first fault traveling wave front is calibrated and recorded as the beginning moment of single-phase fault occurrence. At this moment, the phases of initial current traveling wave front detected by TA at the protection relay device between fault line and sound lines are opposite. The S-transform is implemented to fault zero modal currents. The argument difference of the highest frequency row between fault line and sound line is 180o after fault, which makes fault line detectible. The proposed method detects the phase characteristics of traveling wave signal from the level of relatively low high-frequency transient component, which can not only reduce the requirements of traveling wave acquisition and processing speed, but also enhance the capacity of high resistance tolerance and anti-noise ability. The simulation results verified the feasibility and validity of this method.