A Synchrophasor-Based Line Protection for Single Phase-Ground Faults

Synchrophasor measurement data enhances the transmission line protection. This paper proposes an improved line protection against single phase-ground faults using synchronized phasor data. This algorithm prevents the relay mal-operation caused by high fault resistance. This algorithm calculates the phase difference between relay point voltage and fault point voltage based on the relation between negative sequence of relay point current and fault point current. After, the calculated phase difference between relay point voltage and fault point voltage will be compared with set point voltage phase referred from the relay point voltage phase. The fault detection action will be taken according to a certain phase difference relation between fault point voltage and set point voltage. This method is then applied to a practical single machine single line system. The results show that the suggested algorithm could determine in-line faults accurately with less computational time. It also has proved that this method is immune to the fault resistance, system conditions.