New distance relay compensation algorithm for double-circuit transmission line protection

A new zero sequence compensation method is proposed to correct the impedance, estimated by distance relay during the single-circuit operation of double-circuit transmission lines. In the new approach, zero sequence current of the adjacent line is not required for compensation. The new scheme is non-pilot and therefore does not require any communication link. Simulation results verify the dependability and security of the new approach. The over-reach problem, caused by mutual coupling, during far-end faults, is completely resolved by the new method.