Simplified approach for estimating current unbalances in e.h.v. loop circuits

Electromagnetic and electrostatic unbalances due to the omission of transposition of transmission lines have been treated rather thoroughly, even though separately, in the literature. As e.h.v. lines become longer, and operating voltages are increased, it becomes evident that the line-charging currents are growing to the same order of magnitude as normal load currents. Consequently, it is often necessary to consider the effect of both line-charging and load currents in causing negative- and zero-sequence components of line current. When the total line is composed of sections with different cross-sectional configurations, the rigorous analysis becomes quite formidable. Therefore, a simplified equivalent circuit for an untransposed transmission-line section is proposed which relates more directly to familiar methods of circuit analysis. An important aspect of this method is that it brings out clearly the nature of the unbalance problem and thereby facilitates extrapolation, via good engineering judgement, to more complex networks.