Technical-economic comparison between three and four-conductor bundled 380 kV OHLs

Aim of the present paper is assessing the technical-economic comparison between three-conductor bundled (3B) and four-conductor bundled (4B) 380 kV overhead transmission lines (OHLs). In both cases, the widely used standard ACSR 31.5 mm is taken as the base conductor. Increasing the number of conductors with respect to the commonly used 3B improves the transport capacity, which can be properly represented in terms of loadability, i.e. the maximum allowable power that can be transmitted for an assigned value of the line length. The consequent higher power limit can be very useful in reducing transmission congestions and, thus, wind-generated energy curtailment that currently is not negligible in Southern Italy, promoting the integration of renewable energy. Moreover, reducing congestions has positive effect in relieving the differences in terms of zonal prices of the electric energy, bringing a further economic benefit for the system. The paper addresses these items performing a technical-economic comparison between a 3B and a 4B 380 kV OHL, assuming basically the same load diagram for both solutions.