WEM Dispatch

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Overview

The Dispatch APIs give access to the full range of available data input to and output from the Wholesale Electricity Market Dispatch Engine (WEMDE) for every Dispatch Interval, including:

  • Forecasts, offers, and constraint equations

  • Facility Dispatch Instructions

  • The full facility schedule, showing the quantities allocated to each individual facility 

  • Market prices 

  • Information on interventions and/or real-time adjustments made to the dispatch process.

This data corresponds to the definition and requirements of Section 7.13: Settlement and Monitoring Data of the WEM Rules.

Dispatch API collection

Data availability 

In the WEM, AEMO runs the central dispatch process to determine the dispatch instructions that are sent to facilities to enact physical dispatch over the upcoming five-minute dispatch interval. For clarity, AEMO refers to this as the primary dispatch interval. 

In parallel, AEMO also runs a series of dispatch solutions to determine and publish the market schedules: forecasts of dispatch outcomes using the best available information at the time. 

There are three market schedules that run over different time horizons: 

Market schedule 

Horizon

Run frequency 

Dispatch

Each five-minute dispatch interval for two hours (24 intervals total)  

Every five minutes  

Pre-dispatch 

Each 30-minute pre-dispatch interval for 48 hours (96 intervals total)  

Every 30 minutes  

Week-ahead 

Each 30-minute pre-dispatch interval for seven days (336 intervals total)  

Daily 

At intervals where multiple market schedules kick off, the runs will initially overlap, as shown below: 

Data flows and types 

The following diagram shows a simplified version of the data flow through the dispatch system and the Settlement and Monitoring Data API (labelled Dispatch API in the diagram) in context. 

For every dispatch interval or pre-dispatch interval: 

  • AEMO’s dispatch systems assemble a case file containing all information needed to run the dispatch algorithm 

  • WEMDE produces a solution file, containing all output information of the market solution. 

 

The following table shows the data types used in the dispatch system: 

Data Type 

Description

Publication Frequency 

Dispatch instruction 

Dispatch instructions are MW (megawatt) output instructions (or MW cap instructions) created by the market dispatch engine and available every five minutes for the primary dispatch interval for energy and essential services 

The current interval, referred to as the primary dispatch interval 

Case file 

Case files contain the various inputs used by the dispatch engine to determine a solution. Case files contain information such as price quantity pairs, ramp limits, and availability for all facilities 

Created for each dispatch or pre-dispatch interval in a market schedule 

Made available prior to 12:00 noon, the first business day after the relevant trading day 

Solution file 

Dispatch solutions are produced by a successful solve of the market dispatch engine and contain scheduling information for all facilities. Information includes:  

  • Dispatch targets/caps 

  • Dispatch forecasts (demand + IMGs) 

  • Cleared ESS quantities 

  • Prices (Energy + ESS) 

  • Constraint information (including when binding/violating) 

Created for each dispatch or pre-dispatch interval in a market schedule 

Made available within five minutes of any dispatch interval, or 30 minutes of any pre-dispatch interval 

Trading Day Report  

A trading day report is a summary of calculations that are derived from the solution data, including: 

  • Congestion rental 

  • Facility and network risk 

The trading day report is available after the relevant trading day has finished 

One report created each trading day 

Made available prior to 12:00 noon, the first business day after the relevant trading day  

Case file 

Dispatch solutions, case file data, and trading report process 

The following diagram illustrates the process for dispatch solutions, case file data, and trading report:  

  1. AEMO exposes multiple GET end points for the dispatch data 

  2. Participants invoke the GET endpoint to get the dispatch data details 

  3. AEMO returns the most relevant dispatch data details for the endpoint requested 

Dispatch instruction process 

The dispatch instruction process is shown below: 

  1. AEMO exposes one GET and one ACKNOWLEDGE end point for the dispatch instruction solution 

  2. Participants invoke the GET endpoint to get the dispatch instruction details 

  1. AEMO returns the most recent dispatch instructions details 

  2. Participants invoke the ACKNOWLEDGMENT endpoint to send the dispatch instruction acknowledgement