Conductor optimisation for overhead transmission lines

Conductors make up for about a third of the cost of an overhead transmission line. Power losses in lines account for the bulk of the transmission system losses, which in South Africa is about 1100 MW at peak load. These are critical economic factors which needs careful analysis when selecting a conductor for a new overhead line, which will be in operation for an excess of 25 years. Choosing a larger conductor configuration will have higher up front capital costs, but this may lead to lower overall life cycle cost. A process needs to be followed to optimally choose a conductor and tower configuration. This paper presents the novel procedure which has been formulated to optimise the selection of the conductor and tower configuration from an overall system point of view. The paper also highlights the significance of incorporating planning and load forecast considerations, power quality constraints, voltage collapse studies, line performance studies, corona and audible noise, induction and transposition studies, and life cycle cost of maintenance for the different options; in the optimisation algorithm. The methodology end result of an actual case study is presented to demonstrate the effectiveness of the proposed procedure. The paper provides a valuable guide to assist with the selection of conductor and tower configurations for new overhead transmission lines