Ground fault currents in unit generator transformer at various voltage and transformer configurations

Abstract

Single line to ground fault (SLGF) is the most frequent fault probable to occur in an electric power system. The effect of ground fault is determined by voltage transformer and transformer configurations. In this paper, the simulation showed the performance generator within the SLGF at various transformer configurations. Simulation was conducted in DIgSILENT PowerFactory 14.0. and the results were analyzed, presenting comparison of the fault impact at various transformer connections. The model of transformer connection for each side (primary and secondary) used were Y, Yn, Z, Zn and ? . The Y, Z and ? secondary side of transformer configuration were utilized to block the single line to ground fault at the generator bus. It was clearly shown that the SLGF at the generator bus was highly dependent upon the type of the transformer configurations used during the ground fault at the secondary side of transformer.