Evaluating opportunities for increasing power capacity of existing overhead line systems

Abstract

Re-tensioning and/or re-conductoring are considered the most popular cost-effective ways to increase the efficiency of power capacity of an existing aerial line. The identification of the most beneficial method requires ampacity and sag calculations to consider all the system factors that influence its performance. A holistic methodology for calculating conductor ampacity and sag at any temperature and power frequency when different conductors are implemented onto a pre-specified overhead line structure is used to illustrate how the properties of the conductors allow opportunities for thermal and voltage uprating on existing overhead line systems. This is achieved through a comparative analysis of the electrical and mechanical behaviour of conductors of different technologies and sizes on a 33 kV wood pole system. The analysis focuses on normal operating temperatures for novel conductors that can operate at elevated temperatures to avoid the increase in losses, and also allow the comparison with conventional conductors in order to identify potential benefits for the investigated overhead lines (OHL) system.