Invitation to Comment: Draft Security of Supply Assessment

Closing date for submissions 5pm 8 June 2022 

Transpower, as the system operator, is responsible for publishing the medium-term security of supply assessment (SOSA) annually. This assessment provides a 10-year assessment (2022 to 2031) of the balance between supply and demand in the New Zealand electricity system.

Its purpose is to inform risk management and investment decisions by generators, other market participants, and investors.

COVID-19 Response

We have a comprehensive emergency response plan in place to maintain system security and services to Aotearoa New Zealand. We will be using our usual channels for industry communication during this time and will use this webpage to publish updates or additional COVID-19 related information.

HVDC 2020 Outage FAQs

We have listed below common questions we have received from industry along with our responses. We will continue to update this section and share with participants any updates.


Can you please provide further clarification of the HVDC limits during the HVDC 2020 outages?

System Operator Response, 8 August 2019:

Conflict of Interest

Transpower as an SOE carries out a role of great significance and value in managing and maintaining New Zealand’s national electricity grid and in co-ordinating the power system. Transpower’s position as system operator and as grid owner puts it in a position whereby our decisions can materially affect the interests of electricity market participants.  Conflicts of interest may arise in the performance of Transpower’s functions.


The following is a list of agreements the system operator has in place with other parties covering step change and local quality.



Local Quality Agreements

Transpower as the system operator has agreed to publish the transitional LQA agreement that parties entered into just before the EGRs became effective in 2004.

This was intended to negate the need for a rule change under the EGRs. Publication of this agreement and the schedule will considerably improve transparency for Asset Owners on the voltage profiles that we manage for agreed parts of the grid.

Load Forecasting


Transpower as system operator prepares a forecast of demand at conforming grid exit points (GXPs) for each trading period. This information is a key input into the market schedules; in particular, the Week-ahead Dispatch Schedule (WDS), the Non-Response Schedule (NRS) and the Price-Responsive Schedule (PRS).

Load Forecast Methodology

The process and methodology we use to prepare the demand forecast is made available to the Electricity Authority and to the public.

HVDC Transfer

Latest Data

Following two graphs show HVDC transfer data, "Today's HVDC Transfer" shows the half hourly snapshots taken from our SCADA information.  The "HVDC weekly summary" is updated daily between 11:00am and noon daily and shows 1/2 hourly transfer snapshots for the last 8 days.