Novel signal processing techniques for fault detection and location in HV subtransmission and transmission lines

It is well known that fault induced high-frequency components contain unique information about the fault distance. However, fault waveforms for medium-distance lines are very complicated due to relatively small wave-transit time and the existence of a number of discontinuities. A homomorphic signal processing technique has been applied to extract the necessary information for fault distance estimation. A decision-maker has been designed to correlate the extracted information with the system properties. The operating time can be made very fast, less than 10 ms, but is presently restricted to 20 ms; faster than this is quite unnecessary for HV subtransmission lines. The algorithm covers a wide range of fault resistance, from dead faults to very high resistance faults of the order of a thousand ohms and even for the case of broken conductors