The Williamtown/Medowie load area, located south of Port Stephens, includes the suburbs of Medowie, Campvale and Williamtown, and is supplied by Williamtown zone substation (ZS). The area is large and characterised by small townships, featuring low and medium density housing separated by national parks and undeveloped land. Williamtown Airport, which provides domestic airline services for the Newcastle region, is also located in this area.
Demand in the Medowie load area under peak conditions exceeded 12MVA in 2010. The 11kV supply to the area at the time was constrained under system normal conditions. Significant load growth was also expected as further residential subdivisions were proposed for the Medowie load area. The preferred network solution is the construction of a new Medowie ZS.
A demand management (DM) screening test completed in September 2010 concluded that it was not considered reasonable to expect that it would be cost-effective to postpone the building of a new 33/11kV ZS at Medowie. However, it was found to be cost effective to reduce the load above the licence level of two 11kV feeders (34989 & 34983) prior to commissioning of the new ZS. The investigation report can be found here.
Ausgrid successfully reduced the load at risk by 5.062MVA in summer 2011/12 and summer 2012/13 (by 93% and 92% respectively).
It was found that reinstating a single relocatable generator on the site could cost effectively achieve sufficient peak demand reduction to completely remove load above the licence level in summer 2013/14. An additional benefit expected from the installation of generation is the improved opportunities for switching the network around if unplanned outages occur or planned outages are needed for work.
A project close-out report will be developed in coming months to reflect on the benefits of having completed this project and any lessons learnt.