Projected Assessment of System Adequacy (PASA)

The Projected Assessment of System Adequacy or PASA is the principal method of forecasting the adequacy of the power system to stay within the reliability standard. The National Electricity Rules requires AEMO to prepare PASA in two-time frames:

1. Short Term PASA (ST PASA) covers 6 trading days from end of the trading day covered by most recent pre-dispatch schedule with a half hourly resolution; and
2. Medium Term PASA (MT PASA) covers 24 months from the Sunday after the day of publication with a daily resolution.

AEMO also prepares Pre-Dispatch PASA (PD PASA) that covers the next trading interval until the end of the next trading day.

Short Term Projected Assessment of System Adequacy (ST PASA)

In May 2022, the AEMC made the National Electricity Amendment (Updating Short Term PASA) Rule 2022 (Amending Rule) to introduce greater flexibility to the short term projected assessment of system adequacy (ST PASA), revise some ST PASA definitions and obligations and require the commencement of the new ST PASA Procedure from 1 July 2025.

The ST PASA has the following objectives:

• Provide information to the market on the expected level of short-term capacity reserve and allow the market to respond to the power system needs. 
• Provide a benchmark for AEMO to intervene in the market through the reserve trading provisions of the National Electricity Rules, and then commit extra capacity (either scheduled generation or loads) into the spot market.

The Reliability Standard Implementation Guidelines (RSIG) contain information on how AEMO administers ST PASA process.

For more information on the ST PASA process, please refer to the following related documents: 

AEMO is currently conducting a comprehensive review of the PD and ST PASA methodology, exploring the development of a system that will serve the NEM now, and into the future.

Medium Term Projected Assessment of System Adequacy (MT PASA)

MT PASA assesses the adequacy of expected electricity supply to meet demand across the two-year horizon through regular assessment of any projected failure to meet the reliability standard. This assists Registered Participants and other stakeholders making decisions about supply, demand and transmission network outages over that period.

Each week participants must submit forecasts of availability to AEMO for the next 36 months, commencing from the first Sunday after the latest MT PASA run. These forecasts form the basis of the MT PASA report that will be produced the following week.

The MT PASA process description and the Reliability Standard Implementation Guidelines (RSIG) contain information on how AEMO administers MT PASA process.