A fault section detection method using ZCT when a single phase to ground fault in ungrounded distribution system

A single line to ground fault (SLG) detection in ungrounded network is very difficult, because fault current magnitude is very small. It is generated by a charging current between distribution line and ground. As it is very small, is not used for fault detection in case of SLG. So, SLG has normally been detected by switching sequence method which makes customers experience blackouts. A new fault detection algorithm based on comparison of zero-sequence current and line-to-line voltage phases is proposed. The algorithm uses ZCT installed to ungrounded distribution network. The proposed in this paper algorithm has the advantage that it can detect fault phase and distinguish a faulted section as well. The simulation tests of proposed algorithm were performed using Matlab Simulink and the results are presented in the paper.