This requires maintaining a continuous (second-by-second) balance between electricity supply from generators and demand from consumers, while ensuring that appropriate reserves are available to manage any system events.

To do this the system operator determines the optimal combination of 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 investigations and planning to ensure that supply can meet demand and system security can be maintained during future trading periods.

Section 8 of the Electricity Industry Act 2010 mandates that Transpower is the system operator.

System operator website(external link)

Most of system operator’s critical processes and functions are set out in Part 7 of the Code. Our service provider agreement with the system operator sets out a wider range of the functions and processes that the system operator must perform.

  • Relationship Charter between the Electricity Authority and System Operator

    RelationshipCharter-EAandSO.pdf (PDF, 49 KB)

    Transpower and the Authority agreed a relationship charter confirming that the joint objective of both parties is the long-term benefit of consumers.

    Last updated: 17 August 2016

  • Annotated System Operator Service Provider Agreement v2.0

    Annotated-System-Operator-Service-Provider-Agreement_v2.0.pdf (PDF, 1.2 MB)

    System operator service provider agreement (SOSPA) - 2016
    Transpower and the Authority have agreed a variation to the SOSPA as a result of the 5-year review. The varied agreement takes effect 1 July 2021.

    Last updated: 02 June 2021