Fault line selection for single-phase earthed fault based on injected active component

Concerning the current situation of fault line selection of single phase earthed fault in small-current grounded system,plus with analysis of the advantage and disadvantage of currently used in line selection techniques,a method which makes use of neutral point resistant to discriminate the fault line and the normal line during the single-phase earthed fault is proposed in this paper. When the single-phase earthed fault happens, a resistance will be connected at the neutral point in order to provide the post-fault system with zero sequence current´s active component ,which is considered as the criterion for fault line selection.At the last part of this paper the system is modeled by simulation software PSCAD,and the simulation result shows this method works effectively and improve the accuracy of the line selection.