System operator

The system operator co-ordinates electricity supply and demand in real time, in a manner that avoids fluctuations in frequency and disruption of supply.

About the system operator

The system operator determines the optimal combination of electricity generators and reserve providers for each half-hour trading period. The system operator then instructs generators on when and how much electricity to generate, and manages any events that cause the supply-demand balance to be disrupted.

The system operator also carries out planning and investigations to ensure that electricity supply can meet demand, and system security can be maintained during future trading periods.

Who is the system operator?

Section 8 of the Electricity Industry Act 2010 mandates that Transpower is the system operator. Part 7 of the Code sets out the critical processes and functions of the system operator.

Joint development programme

The Electricity Authority has a strategic joint development programme with the system operator (as per clause 7.7 of the Code) that is updated annually. The 2023-28 programme involves a range of projects related to service maintenance and enhancement.


Operational reports provide information on the system operator's performance and system performance. The reports include compliance with the Code, project updates, ancillary services, system events and frequency fluctuations.

Service provider agreements

Our service provider agreements set out the specific functions and processes that the system operator must perform.

Annual review

We review and assess the performance of the system operator each financial year. The system operator also undertakes an annual self-review and assessment of its performance against principal performance objectives.