Electricity Asset Management Plan 2019-2029
143
Vector Limited://
A new zone substation is planned for Omaha to capture the growth in the Matakana and Omaha areas, while improving network resilience by shortening 11kV distribution feeders (Omaha – new zone substation). To address the forecast demand increase for Warkworth and to reduce the dependence on Warkworth substation, a new zone substation is planned for Warkworth South (Warkworth South – new zone substation). We have two 11kV feeder upgrade projects planned, one at Snells Beach and the other at Warkworth (Matakana Link Rd). Two additional 11kV feeder reinforcement projects have been included to improve network resilience of the network (Puhoi and Tomorata).
TARGETED OUTCOMES
CUSTOMER EXPERIENCE
SAFETY
RELIABILITY
RESILIENCE
OPERATIONAL EFFICIENCY
CYBER SECURITY AND PRIVACY
OPTIONS ASSESSMENT For major projects, i.e. above $4M (level to be confirmed), include the following in this section: Technical feasibility, economic analysis, OPEX and CAPEX costs, net present value or net present cost, service levels, risks, etc.
DESCRIPTION
DISCUSSION OF OPTION
ESTIMATED COST (NPV IF APPLICABLE)
STATUS
Forecast capacity constraints on the subtransmission circuits between Wellsford and Warkworth
Option 1: Install ducts for future subtransmission circuits. NZTA are undertaking a safety improvement programme that will enable us to install cable ducts along SH1 from Wellsford to Warkworth, sharing the cost of traffic management and civil works. The ducts will be populated with subtransmission cables when capacity limits are met on the existing overhead circuits (Option 2) Option 2: Install a subtransmission cable from Wellsford to Warkworth in the ducts installed on Option 1. This will also require a rebuild of the 33kV switchgear at Wellsford. Option 3: Install a subtransmission cable from Wellsford GXP to Wellsford zone substation: This will increase the capacity to both Wellsford zone substation and Warkworth (Option 2) Option 4: Upgrade the 33kV switchboard at Wellsford zone substation: The installation of additional subtransmission circuits to Wellsford (Option 2) will initiate an upgrade of the 33kV switchboard at Wellsford Option 5: Implement DSM measures to reduce load. Network batteries have been installed at Snells Beach substation and in Warkworth township to reduce the maximum demand on the subtransmission lines. A project to upgrade the load control across the Warkworth region (see below) will be implemented in 2020/21. This will enable non-critical load shifting into off-peak periods. These three measures will defer the investment of Option 2 Option 6: Defer installation of the ducts as proposed in Option 1 until the additional subtransmission circuit is needed. The cost of the installing the ducts in the completed highway with median barrier is estimated to be more than double that of Option 1 due to loss of benefits arising from the shared works Option 7: Install a new supply along the SH1 motorway from Silverdale GXP. Silverdale is further away from Warkworth, and there is no opportunity for shared civil
$21.2M Selected
$7.6M Selected
$7.6M Selected
$2.0M Selected
Batteries already installed
Selected
Load control $3.8M
$25M Rejected
Rejected
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