Waikato and Upper North Island Voltage Management

Under Delivery
Waikato and Upper North Island Voltage Management

The decommissioning of thermal generation plants in Otahuhu, Southdown and Huntly, alongside the retirement of the Huntley coal generation plant in 2022 will cause voltage management issues in Waikato and the Upper North Island. Transpower, the owner and operator of the National Grid, is exploring the potential solutions to maintaining voltage stability.

Transpower is proposing investing in a range of projects. These will be divided across two stages of work.

Phase One: installation of a grid stability device at Transpowers Hamilton Substation, and
Phase Two: installation of a second grid stability device at Otahuhu.

Key Dates

Oct 2020 Major Capex Proposal approved by New Zealand Commerce Commission
Nov 2020 Construction commencement: Phase One
May 2023 Expected Construction Completion: Phase One
2023 Expected Construction Commencement: Phase Two
2025 Expected Construction Completion: Phase Two

Funding contributions

User charges

Transpower is making the capital investment on the project, and has received New Zealand Commerce Commission's approval in recovering cost through user charges.


Procuring Agency: Transpower


Dec 2019 Transpower submitted major Capex Proposal.
Oct 2020 The New Zealand Commerce Commission has approved Transpower's capital expenditure proposal, allowing cost recovery of up to NZ$143 million of investments to manage voltage stability in the region.
Nov 2020 Transpower announced it will commence work on Phase One, which is estimated to take 30 months and be ready for commissioning by winter 2023 with a cost of NZ$60 million. The need and timing of Phase Two is to be reviewed when there are confirmed changes to either the output from Huntly or demand for electricity in the Waikato and Auckland regions.
Jan 2023 Transpower announced their decision to progress the $55 million Phase Two of the project and deliver a second STATCOM at the Otahuhu substation. Transpower will partner with Hitachi Energy to manufacture, install and commission the device.
Estimated Total Cost
Procurement approach
Unconfirmed |
New Zealand |
Project pages