ITEE Innovation Expo 2008 : Project Details

Optimum utilization of 11kV feeder

Abstract

Most problematic area in the distribution network are the 11kV feeders. ENERGEX Limited splits South East Queensland into three areas; CBD, urban, rural. The urban and rural areas are predominantly constructed with overhead feeders, while the CBD have them all underground. Having the lines overhead, has much greater potential in having a fault due to geological reasons such as wind, lightning and tree branches short-circuiting the feeders.

The aim of this thesis was to optimise an 11kV network specified by ENERGEX Limited. The substation was simplified and modelled into seven main feeders. Every feeder was optimised using three distinct methods. The main devices used to optimise were fuses and reclosers. Other alternative methods included tree trimming, animal protection and the application of cover conducting (CCT).

The most optimised final improvement for the provided substation was approximately 60%, at $470,000. After this optimising process, it was found fuses were most efficient when installed in the middle of the feeder, whereby the number of customers on either side of the device is approximately even. The recloser was found to be most efficient when placed in the beginning of the feeder, whereby it shielded the rest of the feeder beyond the installation by decreasing the failure rate by a third. Using these findings and more, an Optimising Topology was formed and applied to a fictional village connected to the substation. By using this topology, a 99% improvement was made on the network at an initial cost $122,000 with a 10 year investment estimated to be $374,000.