This paper investigates study the influence of a fault resistance on the performance of a digital distance protection installed on a transmission lines, it is well known that augment of fault resistance can cause seriously overreach or underreach to distance relay depending on the different operational situations of power system, To compensate the magnitude and phase error of the apparent impedance, This algorithm uses the angle of an impedance deviation vector ( ). The impedance correction algorithm for ground faults has been employed by the Fault Resistance Compensation Block (FRCB) to compensate fault resistance effect.

Artificial neural network technique using Matlab/Simulink software is trained to determine the suitable value of an impedance deviation angle for the FRCB, In order to minimize the estimated impedance error of a distance relay. The results of simulation showed that compensated scheme relay performance are acceptably improve and the impedance estimated by relay is close to the actual value via FRCB with ANNS. So the performance of distance relay is much more reliable and accuracy.

Key Words: - Distance protection, Fault resistance, Artificial neural network