Fault locating for inhomogeneous multiple-circuit transmission lines with shared towers

This paper describes the principle of an on-line fault locating scheme for multiple-circuit transmission lines with some shared towers and hence featuring inhomogeneous zero-sequence coupling and the possibility of cross-country faults. It uses the comprehensive positive-negative-sequence components of the voltage and current un-synchronously sampled from two ends of individual lines. A simple fault locating function is derived from transmission line equations without using any iteration and fault type recognition. It can be applied to long transmission lines and has avoided the effect of any zero-sequence mutual coupling between multiple circuits. PSCAD simulation shows that the fault locating scheme is insensitive to the network configuration, prefault load current, fault resistance, fault type and fault inception angle as well as system source impedance. It is further shown that the proposed scheme can locate cross-country faults between circuits regardless of the voltage levels of the transmission lines involved.