  Feeder identification is indispensable for distribution networks to locate
faults at a specific feeder, especially when measuring de-vices are
insufficient for precise locations. For the high imped-ance fault (HIF), the
feeder identification is much more compli-cated and related approaches are
still in the early stage. This paper thoroughly and theoretically reveals the
features of dif-ferent feeders when a HIF happens at the resonant grounded
neutral (RGN) network, which is the most challenging condition for feeder
identification. Firstly, the diversity of nonlinearity existing in HIFs is
explained from the aspect of energy. Then, the differences of nonlinearities of
zero-sequence currents between healthy and faulty feeders are deduced
theoretically. Variations of the detuning index and damping ratio that exist in
industries are both considered. Afterward, these theoretical conclusions are
verified by the HIF cases experimented in a real 10kV system. Finally, based on
the theories, we discuss about why the existing approaches are not reliable
enough, and suggest some improve-ments.
