New algorithm to detect balanced three phase fault during power swing on transmission lines with communication links

Distinguishing a balanced three phase fault from a power swing is difficult since both have similar characteristics. In this paper a new algorithm to detect three phase faults during power swings is proposed. The algorithm is based on separating the power swing blocking (PSB) schemes into two distinct schemes, namely PSB1 and PSB2. The first scheme (PSB1) is dedicated to blocking of zones 2 and 3, whereas the second scheme (PSB2) is dedicated to blocking of zone 1. Every relay send signal to the other relay, then coordination is applied between relays at both ends of protected transmission line using communication link. The proposed algorithm increases the reliability and speed of distance protection to detect three phase faults during power swings.