The conventional fault location algorithm cannot be directly applied to the series compensated transmission lines because of the nonlinear characteristic of the metal oxide varistor(MOV)installed with the series capacitor(SC)in parallel. For this reason

this paper presents a fault location algorithm for the series-compensated double-circuit transmission lines based on the distributed parameter model. The algorithm is divided into two subroutines according to the fault position relative to the left or right side of the series compensator. For each subroutine

the voltages of the series compensated devices are eliminated according to the features that the sequence voltages calculated from local and opposite buses are equal at the fault point. Since the transition resistance is pure resistant at the fault point

the fault location equation can be created according to the boundary condition of the fault sequence current. The proposed algorithm does not use the equivalent model of series compensated device and is not affected by the nonlinear characteristic of MOV. In addition

there is no need to predict the location of the series compensation device relative to the fault point

nor is there any pseudo root elimination problem. The simulation and calculation results of EMTDC/PSCAD and MATLAB have verified the proposed algorithm.