Reduction in sub-transmission loss using underground power cables

Traditionally overhead lines have always been a common medium to deliver power from remote generation plants into urban power loads. These loads can be situated at long distances, as far as hundreds of kilometres. This traditional delivery method has come at a huge cost which is in the form of transmission losses. Overhead transmission losses consist of real and reactive power, this reactive power is proportional to the length and load of the transmission line. Therefore more reactive power is generated. With the advancement in cable technology, various transmission cables were designed with a major objective of reducing transmission losses to further enhance transmission capacity. Despite all the effort and energy that is spent by cable manufacturers and their R & D departments, utilities still do not recognise that savings in transmission losses is a good enough incentive to start undergrounding. However, utilities should realise that combined benefits can outweigh the cost tag associated with undergrounding. This paper investigates sub-transmission losses occurrence in existing overhead lines. It further develops a small underground sub-transmission network using Paladin design (EDSA) software. Real and simulated data are presented to show the savings in sub-transmission losses using underground cables as compared to the overhead lines. In addition, other major benefits of undergrounding will be highlighted throughout the paper.