A practical fault phase selection scheme for untransposed double-circuit transmission lines on the same tower

Double-circuit transmission lines are usually untransposed within short distance, in which case the fault characteristics will be significantly different from the ideal transposition cases. In this paper, based on the analysis of fault characteristics of the untransposed double-circuit transmission lines on the same tower, a practical fault phase selection scheme is proposed to identify various fault types. Firstly, on the base of six-sequence component, the voltage, current and phase angle information are used to classify the faults into single line faults, same phase cross-county faults and different phase cross-county faults. Then, for each of the three categories, the specific fault phase is selected according to the current phase information. The simulation results of PSCAD given in this paper illustrate that the scheme proposed can withstand a greater degree of asymmetry of lines and identify all the fault types accurately.