Waikato and Upper North Island Voltage Management Investigation

Region Map
Auckland population
1.5 M
...and increasing
Thermal generation decom. since 2012
Improved voltage support
to meet Auckland's needs

Latest updates

5 November 2020: Transpower will commence work on the first phase of its Waikato Upper-North Island Voltage Management (WUNIVM) project which will see the installation of a grid stability device at Transpower’s Hamilton substation costing approximately $60m.

The work is needed to manage potential changes in either generation or demand in the region.

Read Transpower's media release and information on the investigation into transmission alternatives


23 September 2020: The Commerce Commission has given approval to Transpower for its Waikato Upper-North Island Voltage Management (WUNIVM) major capital expenditure proposal. GM Grid Development John Clarke says the team will now take time to consider the Commission’s final decision and the current market environment, before deciding next steps.

Read Transpower's media release

Read the Commerce Commission's media release 

The application and accompanying documents can be found in the downloads section below.


A need to investigate

Since 2012, over 1000 MW of generation capacity has been decommissioned in the Waikato and Upper North Island regions. This generation reduction coupled with the actual and expected demand growth in the Waikato and Upper North Island raises significant voltage stability risks. The potential loss of the two remaining Huntly Rankine units further increases this risk.

The critical risks are transient under - and over-voltage events that could cause voltage collapse if not managed. Efficient voltage management is essential to the reliable delivery of power.

What are the potential solutions

There are many ways of supporting voltage such as by using capacitors, synchronous condensers, statcoms and SVCs, but potentially also demand response and generation solutions.  Moreover, the issue is complex and a portfolio of different assets – at various locations and commissioned at different times – rather than a single asset solution is needed. 

After three years of in-depth analysis, we are proposing a mix of reactive power devices and a demand management scheme. We detail our progress in our consultation documents, accompanying reports and updates, which can be found below.