  Diagnosis of high impedance fault (HIF) is a challenge for nowadays
distribution network protections. The fault current of a HIF is much lower than
that of a normal load, and fault feature is significantly affected by fault
scenarios. A detection and feeder identification algorithm for HIFs is proposed
in this paper, based on the high-resolution and synchronous waveform data. In
the algorithm, an interval slope is defined to describe the waveform
distortions, which guarantees a uniform feature description under various HIF
nonlinearities and noise interferences. For three typical types of network
neutrals, i.e.,isolated neutral, resonant neutral, and low-resistor-earthed
neutral, differences of the distorted components between the zero-sequence
currents of healthy and faulty feeders are mathematically deduced,
respectively. As a result, the proposed criterion, which is based on the
distortion relationships between zero-sequence currents of feeders and the
zero-sequence voltage at the substation, is theoretically supported. 28 HIFs
grounded to various materials are tested in a 10kV distribution networkwith
three neutral types, and are utilized to verify the effectiveness of the
proposed algorithm.
