Comparison between single-circuit overhead transmission lines based on line costs and loadability

Previous papers by the same authors have compared traditional and alternative solutions for singlecircuit overhead transmission lines, by considering threephase AC lines as the former, non-conventional four-phase AC lines and monopolar HVDC lines as the latter. This paper merges into one two separate benchmarks that were made as a function of line length, i.e. the economic comparison at given transmission power and the loadability comparison under the constraints of thermal limit, voltage drop, losses, static and transient stability. In this way, the comparison is ultimately performed about the “per-unit-ofcarried- power” costs of the different solutions, thereby correlating the various expense items (per-unit length line investment, losses costs, reliability costs and so on) to the actual transport capability of each selected single-circuit overhead transmission line at every line length of interest.