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Scheduling & Dispatch

Published Schedules

The System Operator publishes a number of schedules on WITS (Comit) to provide market participants with 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.  Constraint Overview document provides an summary information of all the types of constraints used in the Market System, why and where they are used and also provide examples of their use.

Reserve Adjustment Factors

For a Contingent Event (CE) where there are insufficient offers and/or reserve offers in the current trading period the System Operator uses CE reserve adjustment factors (RAFs) to maintain a dispatchable SPD solution. The following CE RAFs can be used 0.8, 0.6, 0.4, 0.2 and 0.

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 COMIT. COMIT displays a graph indicating when there is a shortfall situation. The data from the graph is also available.

Related Information

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.

The System Operator makes available branch information data for the EMarket Offer Tool in the following two csv files.

For further information on dispatch services or the SPD model contact us at system.operator@transpower.co.nz

NIPS and SIPS

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 and overview of the New Zealand power system and therefore show only the electrical connections on the system. These diagrams do not provide any information on loads, generation capacity or equipment rating.

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

Substation Map

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