National Grid (New Zealand)
In a news release in January 2012, the Commerce Commission reported that Transpower was planning to invest $5 billion over the next 10 years in upgrades of critical infrastructure.
Electricity was transmitted at 3.3 kV over a 13-mile (21 km) route to Rotorua, and was used to drive sewage pumps, and some public buildings including five thermal baths.
[6] The first major transmission line in the North Island was constructed in 1913-14, connecting the Horahora hydro station to Waikino to meet the power requirements of the stamp battery 5 miles (8.0 km) further on at the Waihi gold mine.
[7] The first major transmission line in the South Island was constructed by the government as part of the Coleridge hydro station development and was commissioned in 1914.
Two transmission lines operating at 66 kV carried the power from Coleridge over a distance of 65 miles (105 km) to Addington in Christchurch.
[8] Following World War I, regional networks began to develop using 110 kV transmission lines to connect towns and cities with remote hydroelectric schemes.
The State Hydro-electric Department was established in 1946 to oversee the development of electricity generation and transmission to meet rapidly growing demand.
Nelson and Marlborough were the last regions to join the national grid system when a transmission line between Inangahua and Stoke was completed in 1956.
The HVDC Inter-Island was also upgraded by increasing the operating voltage of the lines, replacing the original Cook Strait submarine cables and installing a new thyristor pole in parallel to the existing mercury arc valve converter equipment to double its capacity to 1240 MW.
Many of the grid assets were approaching the end of their useful life, and at the same time had to carry higher loads than previously experienced to meet the demands of a growing economy and population.
[16] The North Island Grid Upgrade (NIGU) between the southern Waikato region and central Auckland was a large and controversial transmission project.
There were strong protests against the proposed transmission line during the initial planning and regulatory approval process from those most directly affected.
Many individuals and communities living near the proposed route expressed concerns about the visual impact of the line, possible health effects, and the devaluation of their properties.
Cabinet Minister Pete Hodgson used powers under the Resource Management Act to "call in" Transpower's proposal, because of its national significance.
A further grid upgrade project was completed to increase supply security to central Auckland, the North Shore, and further afield to Northland.
[18] This project involved building a new 220 kV cross-harbour underground cable link between Pakuranga, Penrose, Hobson Street (Auckland CBD), Wairau Road (North Shore City), and Albany.
In October 2021, Transpower submitted a resource consent application to the Taupō District Council to build a series reactor on the Wairakei to Whakamaru A line at Ātiamuri.
The 220 kV grid supplies major loads at Dunedin, Invercargill and Tiwai Point, from generation at Roxburgh and Manapouri.
The scope includes:[23] The new interconnection at Gore was constructed during 2017-2018 [24] On 30 November 2009, Transpower submitted Part V of the 2009 Grid Upgrade Plan (2009 GUP), Lower South Island Renewables Investment Proposal, with approval sought for up to $197 million.
At the time of submission, it was expected that a large amount of new renewable generation would be commissioned in the Lower South Island within the next few years.
[26] In 2019, Transpower restarted the remaining upgrade work on lines in the Clutha and Upper Waitaki area to enable more northwards power transmission in this region.
HVDC was chosen for the inter-island connection because it is a more practical and economical solution for long distance transmission, particularly where significant lengths of cable are required.
