Parameter set selection for untransposed double-circuit lines considering trade-off between parameter number and modelling accuracy

This paper proposes a selection of a parameter set for untransposed double-circuit transmission lines on the same tower. From the features of corresponding impedance and admittance parameters under different line symmetry assumptions, the number of unknown parameters in the complete 6×6 parameter matrices of the double-circuit lines is corresponding reduced. The validity of various ways to reduce the number of parameters is evaluated across varied scenarios, including differing transmission line lengths, different tower structures, and different external fault locations. By evaluating the computational errors of remote end voltages and currents from the local terminal, a selection of parameter set that maintains modelling accuracy within an acceptable error tolerance can be determined. Simulation results demonstrate that certain off-diagonal elements in the impedance and admittance parameter matrices can be approximated as equal without significantly compromising computational precision.