A Novel Boundary Protection for Series-compensated Transmission Lines

This study proposes a novel boundary protection for the series-compensated transmission lines, on the basis of the R–L differential-equation algorithm using the least square method and the theory of equal transfer process of transmission lines. This method takes the series capacitor (SC) as a boundary. The relative position of the fault with respect to the SC can be determined according to the fitting error of the least square method. This proposed protection method only uses one-terminal measurement, and the protection reach can be expanded to the total length of the series compensated line. The overreaching problem of the conventional distance relay in the series compensated transmission lines can be effectively overcome. A variety of PSCAD/EMTDC simulation tests show the validity of this new method.