New configuration constraints to reduce unbalance in hexagonal double-circuit transmission lines

Abstract

Mutual impedances of transmission lines are not equal due to unequal spacing between conductors which creates problems like circulating current in double circuit lines. In this paper, the authors introduce novel configurations constraints for hexagonal double circuit arrangement that will achieve equal mutual impedances without transposition. Principal results of such arrangement are uncoupling between positive, negative and zero sequence networks, minimizing negative and zero sequence unbalance values, and increasing line loadability. Impact of adding one and two ground wires on the proposed configuration is also evaluated.