Circulating Currents in Paralleled Untransposed Multicircuit Lines: I - Numerical Evaluations

The current unbalance in a 50O-kV double-circuit and a 138-kV triple-circuit, paralleled and untransposed transmission line is analyzed comprehensively. This paper establishes that the magnitudes of individual circuit current unbalances due to currents circulating between the paralleled circuits are more significant than the net through system unbalance. Since the former were not considered in previous investigations, the criteria established there for proper phase configurations is shown in this paper to lead to maximum circulating current unbalance. The influence of series capacitor line compensation is also shown and the ramifications of these unbalances are discussed and evaluated on a present worth of annual loss basis.