Minimization of three-phase line imbalances by proper positioning of earth wires

Usual untransposed three-phase overhead lines are, by nature, unbalanced structures. For phase-conductors protection against lightning most of these lines include in their configuration one or two grounded earth wires. The presence of these wires naturally leads to a modification of line parameters and concomitantly to an alteration of the line imbalance. In this paper we analyze how the imbalance depends on the earth wires position; more specifically, our goal is to find out whether an optimal positioning for the earth wires exists such that line imbalance minimization can be achieved. Application examples provided in the paper focus on horizontal line configurations