ST PASA Replacement project

The ST PASA Replacement Project involves a comprehensive review of the Pre-dispatch (PD) and Short Term (ST) PASA methodology, exploring the development of a system that will serve the NEM now, and into the future. 

This page provides information and updates on the progress of this project. 


PD and ST PASA are the core systems used by AEMO and electricity industry stakeholders to identify and manage risks to power system security and reliability over the next seven days.

The PD and ST PASA systems were designed when most of the generation in the NEM was supplied from large thermal units connected to the transmission network.  An assessment of the current systems noted that:

  • The power system is rapidly changing due to the advent of emerging technologies, such as battery storage, virtual power plants (VPPs), and distributed energy resources (DER), and the current systems are unable to model these technologies.
  • The systems are also unable to incorporate improvements in the modelling of intra-regional network issues, sharing of reserves across different regions and the allocation of energy-limited resources.
    As a result, AEMO is exploring a redevelopment of the PD and ST PASA systems.

Requirements Gathering and Proposed High Level design

In December 2019, AEMO engaged Intelligent Energy Systems (IES) & Steve Wallace Advisory (SWA) to consult widely with industry to gain broad insights into how the industry currently uses the PD and ST PASA information, and understand requirements from these systems going forward. The consultation included both one-on-one discussions and a workshop where the current issues and potential requirements were discussed with a variety of stakeholders.

The slide pack presented at the workshop and a summary of the workshop can be viewed:

Please note that this slide pack has been prepared by IES and SWA and the summary document summarises discussions at an industry workshop with stakeholders.  They do not necessarily reflect the views of AEMO or any particular participant.

Using a range of information, including stakeholder input, IES & SWA developed a set of business requirements and a proposed high-level design for the new PD and ST PASA systems.

These business requirements can be viewed:

AEMO is currently working through the recommendations provided by IES & SWA and will provide regular updates to industry over the coming months as this work progresses.

Industry Update

AEMO will be conducting five workshops between April and August 2022 to provide stakeholders and AEMO the opportunity to discuss the technical concepts of the ST PASA Replacement Project in more detail ahead of its formal consultation on the ST PASA procedure and guidelines.

The workshop plan can be viewed here:

AEMO holds regular industry workshops where it provides updates on the progress made to date on the project and seeks feedback from the stakeholders. The slide pack presented in these updates can be viewed here:

Any questions or comments regarding this project should be directed to

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