Analysis on performance of zero sequence signal based single phase ground fault detection method to identify line broken fault

Single phase ground (SPG) faults detection method based on zero-sequence signal (ZSS) are widely used in non-effectively grounded distribution networks. However, their performance in detecting single phase line broken (SPLB) faults is not yet clear. This paper studies the potential dead zone when ZSS-based SPG fault detection method is used to detect SPLB faults. Firstly, equations for the steady-state zero sequence voltage (ZSV) on both sides of the fault point under various SPLB fault conditions are derived. Next, the dead zone of the start-up criterion based on steady-state ZSV is studied. Subsequently, the zero sequence networks under different SPLB fault conditions are built, and then the relation-ship between transient ZSV and zero sequence current (ZSC) under different SPLB fault conditions is analysed and the dead zone of transient ZSS-based SPG fault detection methods for SPLB faults identification is examined. Finally, PSCAD simulations are performed and the accuracy of the theoretical analysis is validated.