Design and implementation of a systematically tunable high impedance fault relay

A practical relay algorithm for detecting High Impedance Fault (HIF) is proposed, in which an operational procedure in conjunction with a novel computational algorithm is proposed that has solved the problem of determination of HIF relay's settings, in order that both dependability and security are maintained. In addition, these settings can be tuned according to the changes in the feeder conditions, e.g. topology and load amounts. The discrimination is based on the existence, steadiness and randomness of harmonic energy content of the current waveform. The proposed algorithm is implemented on a DSP. Applying the data for HIF from field tests and for other similar phenomena from simulations has resulted in acceptable security and dependability for the proposed method. (C) 2010 ISA. Published by Elsevier Ltd. All rights reserved.