This paper proposes a new design for high-performance digital distance relay. It is equipped with a dedicated decaying dc component estimation algorithm and a new method for compensation of ground fault resistance. The proposed relay algorithm can estimate and eliminate the dc decaying component from fault current signals within one cycle from the fault instant. Then, it uses fast Fourier transform to extract accurate phasor quantities of fault currents. Also, an innovative algorithm for compensation of fault resistance is introduced. The later technique is based on supposing a virtual distance relay at the other end of the line. Using the preliminary estimation of the apparent relay-to-fault impedance at both sides, the unknown fault resistance and its related error are determined. Hence, this error can be compensated in computing the actual relay-to-fault impedance. Many test cases are performed under different fault locations and several values of ground fault resistance to confirm the efficacy of the proposed relay.
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