New fault location scheme for four-circuit untransposed transmission lines

This paper introduces a new fault location scheme for two-terminal four-circuit untransposed transmission line using synchronized measurements. The current phasors at both line terminals and the voltage phasor at only one terminal are needed to formulate the fault location equation. The proposed scheme is developed based on theory of transmission lines and expansion of Taylor series for the distributed line model parameters. The mutual coupling between all phases and the untransposition of the line are considered to obtain precise results. The faulty phases are determined using Kirchhoff's current law (KCL) and all fault types including normal shunt and inter-circuit faults can be located. DIgSILENT Power Factory software is used to simulate the power system and the fault location calculations are carried out using MATLAB. The proposed scheme is investigated under different fault locations, fault inception angles, fault types, and fault resistances. The influence of soil resistivity variation, measurement and synchrophasors errors, errors in line parameters, various line lengths, non-linear time-varying arc resistance, and complex fault impedance is also investigated. The simulation results confirm the validity of the fault location scheme for all test cases.