Circulating Currents in Paralleled Untransposed Multicircuit Lines: II - Methods for Estimating Current Unbalance

The current unbalance in a 500-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 resulting from 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 circulatimg 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.