This article proposes a fault location algorithm for double-circuit transmission lines compensated by a generalized unified power flow controller (GUPFC) in the phasor analysis domain. The suggested algorithm is able to locate the fault point in three stages at each circuit of a double-circuit line equipped with a GUPFC between two terminals. The first stage determines the faulty section with respect to the location of the GUPFC using the positive sequence voltages of two terminals of the line. In the second stage, the faulty circuit among the circuits of the double-circuit line is identified through analysis of sequence components of the line currents at the terminals. After determining the faulty section and faulty circuit of the line, the fault location is calculated at the third stage with high accuracy based on the analysis of synchronous current and voltage phasors that rule the circuitry equations in the GUPFC compensated double-circuit transmission line. Finally, the equations required for determining the fault location for 11 types of faults in these lines are presented based on the distributed parameter model of the line in sequence components considering the coupling between the two lines. The considered GUPFC, based on the detailed model method, is modeled along with the test network inMATLAB/Simulink. Moreover, the presented algorithm is programmed in MATLAB software for evaluation and test. The obtained simulation results verify the accurate performance of the presented algorithm under different fault conditions
