Selective ground-fault protection using an adaptive algorithm model in neutral ungrounded power systems

The selective ground-fault protection is greatly valued for the safe and reliable operation of power systems. In order to eliminate the effect of zero-sequence current transformer´s phase character on selective ground-fault protection devices, this paper proposes a new adaptive principle of selective ground-fault protection, and gives an algorithm model of action criterion based on the half-wave Fourier algorithm. The simulation results show that this criterion will possess very good selectivity to ground faults