Market Notices

Change Number: CHG0109708

Notification issued to: Market Notice
Notification Type: Initial
Change Type: Normal
Service/ Component: Electricity Market Management System
Change Title: EMMS Production Systems will be transferred to the alternative datacentre for maintenance activities .
Change Start Date & Time: 22/05/2026 08:00:00
Change End Date & Time: 27/05/2026 17:00:00
Outage Start Date & Time: 26/05/2026 18:00:00
Outage End Date & Time: 26/05/2026 19:00:00
Environment: Production

Participant Impact and Requirements: EMMS Production Systems will be transferred to the alternative datacentre for maintenance activities.
o Please note that this activity is being performed between 18:00 to 19:00 AEST on 26th May 2026.
o During the window, delivery of FPP calculations through the participant data model may be delayed at various points.
o The Market Portal Services will be intermittently unavailable at this time.


Support Information:
Report any impacts to the AEMO Information and Support Hub or call 1300 236 600.
Please refer to https://aemo.service-now.com/participantportal?id=pp_services_status for any planned/unplanned maintenance activities.

Change Number: CHG0110233

Notification issued to: Market Notice
Notification Type: Initial
Change Type: Normal
Service/ Component: Identity Service (IDS)
Change Title: Identity Service Site Transfer
Change Start Date & Time: 26/05/2026 09:00:00
Change End Date & Time: 26/05/2026 18:00:00
Outage Start Date & Time:
Outage End Date & Time:
Environment: Production
Participant Impact and Requirements: Identity Service is used by multiple systems for user authorisation and authentication.
Identity Service is mostly used by the following systems:
*MSATS
*APIs (EMMS, GBB, MSATS)
*WEM
*Internal / Markets Portal Services
*NOS
*AMP

Identity Service may cause users to experience few session issues for logins initiated between 18:00 to 18:15 Market Time on 26/May/2026.
Internal / Market Portal Services will have an outage due to EMMS site transfer activities carried out in parallel, under a separate change.

Support Information:
Report any impacts to the AEMO Information and Support Hub or call 1300 236 600.
Please refer to https://aemo.service-now.com/participantportal?id=pp_services_status for any planned/unplanned maintenance activities.

AEMO ELECTRICITY MARKET NOTICE.

Update - Non-credible contingency event - NSW region - 17/05/2026

Refer AEMO Electricity Market Notice 144112

At 1327 hrs the Upper Tumut Units 1, 2, 3 and 4 were made available to return to service.

The cause of this non-credible contingency event has been identified and AEMO is satisfied that another occurrence of this event is unlikely under the current circumstances.

AEMO will not reclassify this event as a credible contingency event.

Manager NEM Real Time Operations

The MTPASA results published on 19 May 2026 identifies no Low Reserve Conditions.

MTPASA informs the market of potential reliability issues to allow the market to respond in the first instance, potentially avoiding the need for any AEMO intervention.

For further information on MT PASA, please refer to:
https://www.aemo.com.au/Electricity/National-Electricity-Market-NEM/Data/Market-Management-System-MMS/Projected-Assessment-of-System-Adequacy.

For more information about how AEMO implements the reliability standard, please view the Reliability Standard Implementation Guidelines (RSIG) available on AEMO's website at https://www.aemo.com.au/energy-systems/electricity/national-electricity-market-nem/nem-forecasting-and-planning/forecasting-and-reliability/reliability-standard-implementation-guidelines.

This notice supersedes Market Notice 144070 published on 12 May 2026.

Forecasting

AEMO

AEMO ELECTRICITY MARKET NOTICE

NON-CONFORMANCE NSW1 Region Monday, 18 May 2026

AEMO has declared the following unit as non-conforming under clause 3.8.23 of the National Electricity Rules:

Unit: BW02
Duration: 18/05/2026 11:35 to 18/05/2026 11:40
Amount: 41 MW
Constraint: NC-N_BW02

Auto-generated on behalf of Manager NEM Real Time Operations

AEMO ELECTRICITY MARKET NOTICE

The Forecast LOR1 condition in the QLD region advised in AEMO Electricity Market Notice No. 144111 is cancelled at 1015 hrs 18/05/2026.

Manager NEM Real Time Operations

AEMO ELECTRICITY MARKET NOTICE

NON-CONFORMANCE QLD1 Region Monday, 18 May 2026

AEMO has declared the following unit as non-conforming under clause 3.8.23 of the National Electricity Rules:

Unit: TARBESS1
Duration: 18/05/2026 06:00 to 18/05/2026 06:05
Amount: -23 MW
Constraint: NC-Q_TARBESS1

Auto-generated on behalf of Manager NEM Real Time Operations

AEMO ELECTRICITY MARKET NOTICE.

Non-credible contingency event - NSW region - 17/05/2026

At 2317 hrs the Upper Tumut Units 1, 2, 3 and 4 tripped.

AEMO did not instruct load shedding.

AEMO has not been advised of any disconnection of bulk electrical load.

The cause of this non credible contingency event is not known at this stage.

Manager NEM Real Time Operations

AEMO ELECTRICITY MARKET NOTICE

The Forecast LOR1 condition in the QLD region advised in AEMO Electricity Market Notice No. 144108 has been updated to the following:

[1.] From 1700 hrs 18/05/2026 to 1900 hrs 18/05/2026.
The forecast capacity reserve requirement is 1194 MW.
The minimum capacity reserve available is 1014 MW.

Manager NEM Real Time Operations