Classification of Fundamental Ferroresonance, Single Phase-to-Ground and Wire Breakage Over-Voltages in Isolated Neutral Networks

This paper proposes a simple and effective method for classification of fundamental ferroresonance, single phase-to-ground and wire breakage over-voltages. In isolated neutral networks, power frequency over-voltages due to ferroresonance, single phase-to-ground and wire breakage may exist for a long time, and have very highly similar voltage features. If the improper suppression operation is applied due to incorrect identification, the accident is likely to worsen further. In this paper, the voltage and current features of these faults are analyzed, and a new effective classification criterion for fundamental ferroresonance and single phase-to-ground based on zero sequence current is proposed. A comprehensive identification method based on voltage, current and zero sequence current features is proposed, which is feasible and promising for real applications.