High impedence fault detection using low - order pattern harmonic detection

High Impedance Arc-Type Faults (HIF) on Meshed Electrical DistributiodUtilization networks are characterized by an intermittent Arc-type nature and low-level of the fault currents. The detection of low-level ground-currents using any conventional over-current or ground fault type relays is both difficult and sometimes inaccurate. [ 1-71. The Arc-nature of all (HIF) faults, being intermittent in nature, characterized by very low level fault current is also rich in low harmonic content and high frequency noise spectra that identify and fingerprint any existence of Arc hazardous HIF faults. High Impedance Arc-Type faults are safety hazard to Humans, Live stocks and Electric Utility Personnel. If left undetected for hours, weeks, and possibly months can prove fatal to humans and animals at typical current level of 50 milliampere or above. The need to find a simple, fast and accurate detection scheme using only time domain substation voltage and current signals (few cycles) at the feeder is the motivation for this novel Pattendshape Based Recognition and Identification approach. Other techniques by the first author [8-101 encompass Neutral Residual harmonics, excursion harmonic-vector, frequency-based nonlinear transformations, Artificial Neural Network and this new concept of the Harmonic PattemsPhase Portraits (HPP-Concept) introduced in this paper. Other detection algorithms are based on Fourier Transform and search methods [I I].