Enhanced differential protection algorithm for tapped transmission lines

In the paper new algorithm enhancing performance of the current differential protection for tapped transmission lines is presented. In order to find an optimal solution various disturbances that may be the sources of unbalance of differential signals are discussed. The newly developed protection except differential current itself employs also negative-sequence and zero-sequence signals calculated from differential currents. The proposed scheme has been thoroughly tested using signals generated for a power system model prepared in ATP-EMTP software package. The new algorithm proved to be very effective in elimination of the problems observed in tapped lines configurations.