A morphological filtering algorithm for fault detection in transmission lines during power swings

This paper presents a new algorithm for transmission line distance relaying, tolerant to power swings. The distinction between a short circuit and power oscillation is accomplished with the use of a morphological transform. With this feature it is possible to detect the dc short circuit component that presents a different waveshape during power swings. To show the effectiveness of the proposed technique, computer simulations have been carried out on ATP (Alternative Transient Program). Several faults including different frequency oscillations have been considered. The proposed methodology detect faults in very small times, even under the worst-case scenarios such as balanced faults during power swings.