A phase selection element for zero sequence current differential protection

A phase selection method for zero sequence current differential protection was proposed in this paper. In the first, electrical quantities characteristics of different ground faults were analyzed. Then zero sequence differential current was used as reference value and sizes of sequence differential currents and zero sequence differential current were compared to identify fault phase. Phase differential current was used to identify healthy phase of two phases to ground faults, theory analysis and simulation results show that the phase selection criterion can identify fault phase correctly and is not affect by load current and fault resistance. It is more sensitive than zero sequence current differential protection.