After the analysis and comparison of the present singleline to ground (SLG) selection techniques
this paper proposes a novel transient approach based on the mathematical morphology for the SLG selection. It consists of two steps: the combined morphological filter is first developed to filter noise in transient zerosequence voltages and currents in order to reduce the impact of noise on the selection
and the proper morphological structure elements are then applied to detect transient break points for selecting the grounded line. The simulation results show that the proposed approach can overcome the deficiency of low signal noise ratio with features of easy implementation and fast speed. The faulted line can be detected fast and accurately by choosing proper morphological structure elements.