A proposed busbar protection scheme immune to the impact of outflow current during internal faults

This paper describes a proposed busbar protection scheme immune to the impact of the outflow current during internal faults based on the combination of magnitude and phase angle comparisons. The effective relay performance is achieved by implementing the phaselet approach and the adaptive digital mimic filter. The performance of the proposed scheme is extensively analyzed for different fault conditions on a breaker and a half bus substation to ensure its proper response during internal, external and evolving faults. Tests are carried out to investigate the impact of the circulating current, CT saturation, fault inception angle and high fault resistance. ATP simulations ensure that the proposed scheme can fulfill all busbar protection requirements within quarter cycle operation time and is not affected by the outflow current during internal faults.