In this paper, fault location on three-terminal and tapped transmission lines without requiring line parameters is presented, which mitigates the effect of line parameters variations due to weather and loading conditions on fault location accuracy. For three-terminal lines, a fault location method is presented which utilizes post-fault measurements of all three terminals. For tapped lines, two methods are presented. The first one uses post-fault measurements of the main two terminals. The second one needs one cycle of pre-fault measurements at main terminals as well. Synchronized transient-based measurements are used in methods proposed in this paper. In all presented methods, the fault location problem is converted to an optimization problem and then solved to find the line parameters and the accurate location of fault. The simulations are carried out by ATP/EMTP software and the presented algorithms are executed by MATLAB. Simulation results assess the effects of fault resistance, type and inception angle on the accuracy of presented methods. Further discussion is also provided on the impacts of synchronization errors, noisy measurements, and nonresistive faults.

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