Impulse response analysis of a real feeder for high impedance fault detection

A high impedance fault is an abnormal event that occurs in distribution feeders. Owing to its nature it cannot be detected by conventional protection. A technique for high impedance fault detection is presented in this work. The method consists in injecting an impulsive signal in the feeder followed by the monitoring of its response. High impedance faults are detected by comparisons between the feeder response operating in normal condition and that under fault condition. In the event of a high impedance fault the feeder response becomes different from that of normal switching operations. Although the difference in the feeder response for these cases can be very small, the presented technique recognizes them as different events. The validity of the method is supported by the results of tests performed on a 13.8 kV real feeder presented in the paper