A Novel Method for Accurate Estimation of the Point-On-Wave of Inception and Recovery of Voltage Dips

This paper presents a method based on the use of the energy of a difference signal, the disturbance signal, computed in the time-domain cycle by cycle subtracting the voltage samples of the first cycle of a voltage dip record from the rest of the cycles of the record, for accurate detection and estimation of the point-on-wave (POW) of inception and recovery of a voltage dip. The energy of the difference signal is ideally null when the signal is in stationary state and presents a significant increase in the case of a sudden variation of the voltage waveform, as is the case of the transition segments at the beginning and the end of a fault induced voltage dip. The paper studies the performance of the method as a function of the magnitude, duration and POW of inception of a voltage dip using semi-synthetic voltage dip records, showing a maximum error in the estimation of the POW of only three voltage samples in the case of voltage dips of lower magnitude starting at fundamental zero crossing.