Electricity Asset Management Plan 2019-2029
144
Vector Limited://
works with NZTA roading projects making the project significantly more expensive than Option 1 Option 8: Install a new supply through Kaipara Flats from a new GXP near Tauhoa. The distance is similar to Option 1, and it avoids SH1. There is no opportunity for shared civil works with NZTA roading projects. The need for a new GXP makes the project significantly more expensive than Option 1 Option 9: Upgrade the existing lines. Upgrading the existing subtransmission circuits will provide extra capacity and defer the installation of a third subtransmission circuit (Option 2) for 4 years. However, these lines are mostly on private property without easements, and the cost and feasibility of an upgrade is not certain – the lines may need to be completely rebuilt. Even under a very optimistic cost estimate, the NPV of the return on this option is poorer than Option 2 without deferral Warkworth and Snells Beach substations. Establishing a zone substation at Omaha reduces the 11kV load these two substations, freeing up capacity for further growth. Omaha will also sectionalise two long 11kV feeders improving the resilience while reducing SAIDI, and improve voltage performance on the more remote rural sections of the Warkworth network Option 2: Build a second 11kV circuit to Matakana. This option will supplement the capacity to Matakana but will place the extra load onto the 11kV network advancing the reinforcement of Warkworth and Snells Beach substations. The original plan for this feeder was for a second circuit on the existing Matakana overhead line, but this is mostly on private property without easements and may not be feasible. A new overhead line following the road would cost nearly as much as option 1. An underground circuit would cost more. Option 1: new zone substation at Warkworth South. To relieve the forecast capacity constraints at Warkworth substation and provide supply diversity a new substation is proposed at Warkworth South. Omaha substation will defer this solution. Option 2: upgrade the capacity at Warkworth substation: Warkworth substation is located 3km from the load centre so any additional capacity installed here would need be supplemented by new 11kV cables to convey the capacity into Warkworth. Further it lacks the diversity offered by an additional zone substation (Option 1). Including feeder reinforcement, this option more expensive than Option 1 A new NZTA link road is proposed connecting SH1 and Matakana Rd at Warkworth. We intend to install a new feeder in this new road when constructed. New commercial load is proposed on Sandspit Rd necessitating the reinforcement of the Sandspit Rd 11kV feeder 11kV feeder upgrade – Puhoi: Connecting the Kaipara and Satellite feeders has the potential to save 0.8 SAIDI-min per annum 11kV feeder upgrade – Tomorata feeder: Linking the Te Hana and Tomarata feeders will save approximately 1 SAIDI minute per year Option 1: Omaha zone substation. Growth in the Matakana/Omaha area is increasing the load on
Rejected
$3M Rejected
Warkworth and Snells Beach substations are approaching capacity.
$2.7M Selected
$2.5M Rejected
Load growth in Warkworth is exceeding the capacity of Warkworth substation
$8.9M Selected
Rejected
11kV security shortfall at Snells Beach and Warkworth
$1.7M Selected
SAIDI reduction initiatives
$0.7M Selected
$0.3M Selected
Made with FlippingBook - professional solution for displaying marketing and sales documents online