A novel distance protection algorithm in frequency domain based on parameter identification

In this paper, a novel distance protection algorithm in frequency domain is introduced. Based on the R-L model of transmission lines, this algorithm is derived from the linear equations which are obtained in fault condition network and O-module network for single-phase-to-earth fault. Considering that transformers usually ground directly in high voltage power systems, a linear equation with three coefficients is deduced based on the inductive O-sequence system impedance. Theoretical analysis and simulation results prove that the algorithm is accurate when faults happen at the remote terminal and it will get a positive fault distance error when faults happen around the remote terminal. This phenomenon shows that the algorithm effectively prevents overreach action of distance relays. Meanwhile, this algorithm has a high ability of anti-resistance and is expected to form a new distance protection.