AC and/or DC substantial power upgrading of existing OHTL corridors

The ever increasing difficulty to find new right of ways (ROW) for the construction of overhead transmission lines (OHTL) is forcing the study of possible alternatives for substantial power upgrading of existing AC line corridors. One possible solution is to modify existing OHTLs without major new construction. The authors discuss the two main methods of modification. Conversion of both double circuit and single circuit HVAC lines to bipolar and monopolar lines respectively; and substitution of both double circuit and single circuit old HVAC lines with new compact EHV lines having horizontal V assemblies and with the possible reutilization of existing tower location. The upgrading possibility offered by the above methods is analyzed with due considerations to the various design criteria relevant to conductors, structural/insulation/losses/environmental effects