Novel fault location methods for ungrounded radial distribution systems using measurements at substation

•A new fault location method for ungrounded radial system is developed.•Direct short-circuit analysis is adopted to determine the fault location.•The new method is independent of source impedance.•The method is accurate, and insensitive to measurement errors and load variations.

This paper describes novel fault location algorithms for ungrounded radial power distribution systems utilizing voltage and current measurements at substation. Two types of fault location approaches, using line to neutral or line to line measurements, are presented. It's assumed that network structure and parameters are known, so that the during-fault bus impedance matrix of the system can be derived. Then node voltages at substation can be expressed as a product of bus impedance matrix and current injection at substation, from which fault location can be estimated. Evaluation studies based on a 16-bus ungrounded radial distribution system have been performed and it has been demonstrated that accurate fault location estimates can be achieved by both types of methods.