A Method of Impedance Differential Protection for DG Grid-Connected Line

Traditional overcurrent protection loses its selectivity, while the existing current differential protection suffers serious sensitivity degradation due to the high data synchronization requirements. A new impedance differential protection method for Distributed Generation (DG) grid-connected Line is proposed. The method makes use of fault variation components to calculate the measured impedances on both sides for DG grid-connected line, and then constructs protection criterion. Finally, the performance of the proposed protection is validated by constructing a 10kV DG grid-connected line through PSCAD. The simulation results prove that faults could be effectively identified under the condition of various fault types and locations through the proposed protection.