A technique for estimating transmission line fault locations from digital impedance relay measurements

A technique is presented that is suitable for estimating locations of shunt faults. The estimates are reasonably accurate even if the fault resistance is substantial and the transmission line is connected to energy sources at both terminals. The technique uses post fault fundamental-frequency voltages and currents measured at the two line terminals. The measurements need not be synchronized, and the source impedances are not used by the estimation procedure. The mathematical development of the technique is presented. Sample test results using simulated fault data are included.