Scheduling and dispatch

Backup procedure if primary dispatch system fails

Asset Owners are required under Part 8, Schedule 8.3 Technical Code C (4) to have a primary and backup means of voice communication between the control room of the asset owner and the system operator.

If normal dispatch systems fail, the system operator will utilise the primary or secondary voice communication means to dispatch generation instructions to asset owners.

Published schedules

The system operator publishes a number of schedules on WITS to provide market participants an overview of what the inputs to the power system are leading up to real time. All the schedules produced in the Market System are listed in the summary document, with the inputs to each schedule and what information is published.

Constraint information is included in the schedules. The Constraint Overview document provides a summary of all the types of constraints used in the Market System, why and where they are used and also provides examples of their use.

Standby residual check

The Standby residual check (SRC) determines:

  • whether there are enough energy offers to meet demand after the loss of the largest risk (energy shortfall)
  • whether there are enough energy and reserve offers to meet demand after the loss of the largest risk and schedule reserves to cover the new risk (capacity shortfall).

The SRC information is available to registered Market Participants on WITS.  WITS displays a graph indicating when there is a shortfall situation. The data from the graph is also available.

SPD model

The New Zealand power system is modelled for the purposes of Scheduling, Pricing, and Dispatch as a national set of nodes and branches connecting those nodes.

The SPD diagram represents those nodes and branches, but does not provide any information on injection (generation) off-take (demand) on those nodes, or the power flow on the branches.

The Node names are defined by a seven-character alphanumeric code that links to the standard three-letter substation abbreviation and the node voltage (in kV) and bus number. For full names and geographic area, refer to the abbreviation list.

​For further information on dispatch services or the SPD model contact us at [email protected]


The New Zealand power system consists of the North Island Power System and the South Island Power system connected by a 1040 MW HVDC link between the two islands.

NIPS and SIPS are an electrical representation (single line diagrams) of the New Zealand Power system. These diagrams are intended to give an overview of the New Zealand power system and therefore show only the electrical connections on the system. 

Substation and Power Station names are shown by three letter codes. For full names and geographic area, refer to the Standard Site Abbreviation list.

NIPS6.pdf (PDF 145.42 KB)
SIPS6.pdf (PDF 103.25 KB)

Substation map

The Substation Locator Map shows the geographical location of the substations, power stations and transmission lines.