To provide power supply security for Auckland’s CBD, national grid operator Transpower and local Auckland distribution utility Vector initiated the construction of two new substations. Aurecon, as lead design consultant, was responsible for the key aspects of design and technical construction support for the substations.
Construction took place on a small 3500m2 CBD site which was shared with an existing Vector substation. The existing substation provides a vital source of power supply to Auckland’s CBD and had to be maintained as operational throughout construction. The site was also bounded by a large multi-storey hotel on one boundary.
The new Transpower substation at Hobson Street forms a vital link in the upgrading of their 220 kV grid to cater for growing power demand in the north of Auckland and beyond into Northland, a key link in Transpower’s NAaN grid upgrade project. The use of Vector’s Penrose to Hobson St tunnel as an essential part of the new supply route, allowed both Transpower and Vector the opportunity to at the same time reinforce Vector’s supply into the CBD by the provision of a new Transpower 220/110 kV Grid Exit Point (GXP) into Vector’s existing Hobson St 110/33/22 kV substation.
The confined site, fire and blast issues, high voltage power and complex temporary works meant that safety in design and innovation were core considerations. The design saw innovative technical solutions developed to counter fire suppression, pressure relief and oil containment issues for placement of traditional outdoor type transformers in an indoor environment.
Spatial and geometric modelling was used to integrate the new building structures with existing structures, which included critical deep and shallow cable tunnels. This included the individual 3D modelling of main cable routes with prescribed minimum cable radii to ensure installation fit.
The substation development represents one of the most complex substations developed in New Zealand to date. It has formed a vital link in the upgrading of the 220kV grid which caters for the growing power demand and network diversity through Auckland and to the North.