Computer based harmonic simulation and testing for microprocessor-based phase distance relay with phase locator

The effect of harmonics on the operation of microprocessor-based phase distance and ground directional overcurrent relay and fault locator is addressed. The testing facility consists of a computer-based three phase harmonic source, programmable three phase voltage and current amplifiers, and a digital-to-analog interface board. The software generates the harmonics and detects any trip action by the relay. Extensive experiments are performed in which the relays are subject to a matrix of distortion frequencies, magnitudes, and phases. The results of these experiments are discussed, and suggestions on the applications of the relay are given.<>