Semi-Scheduled units are constrained down (or off) reasonably regularly in QLD and in some other regions for System Strength reasons:

• This is normally done through constraint equations
• So it’s the need for AEMO to issue a Direction today (Tuesday 29th September 2026), even if for just a limited period that makes this event noteworthy.

We noticed internally that the AEMO had issued 3 x Market Notices in short succession early this afternoon:

1)  MN145402 at 14:21 (NEM Time) titled ‘Direction – QLD region 29/09/2026’

2)  MN145399 at 14:22 (NEM Time) titled ‘Direction – Qld region to Powerlink to disconnect Mt Emerald Solar Farm’ (noting a bit of a glitch in the title)

3)  with MN145405 at 14:42 (NEM Time) correcting as follows:

‘——————————————————————-
MARKET NOTICE
——————————————————————-

 From :              AEMO
To   :              NEMITWEB1
Creation Date :     29/09/2026     14:42:43

 ——————————————————————-

notice ID               :         145405
Notice Type ID          :         MARKET INTERVENTION
Notice Type Description :         Reserve Contract / Direction / Instruction
Issue Date              :         29/09/2026
External Reference      :         Update Direction – Qld region to Powerlink to disconnect Mt Emerald Wind Farm 

——————————————————————-

 Reason :

 AEMO ELECTRICITY MARKET NOTICE

 Update Direction – Qld region to Powerlink to disconnect Mt Emerald Wind Farm
Refer to AEMO Market Notice 145399

 In accordance with section 116 of the National Electricity Law AEMO is issuing a direction to Powerlink.  For the purposes of the National Electricity Rules this is a direction under clause 4.8.9(a1)(1).

 Direction issued to:  Powerlink at 1400 hrs 29/09/2026
Required actions: Disconnect Mt Emerald Wind Farm from the network at 1400 hrs 29/09/2026
Services provided: N/A
Circumstances necessitating the Direction: System Strength
Circumstances necessitating the Direction additional detail: intervention is required to maintain the power system in a secure operating state
Expected duration:  until further notice.

 Powerlink does not incur any civil monetary liability for a relevant action taken in accordance with this direction unless the action is taken in bad faith.

 Manager NEM Real Time Operations

 ——————————————————————-
END OF REPORT
——————————————————————-’

This action was reversed a little later:

4)  MN145403 at 14:58 (NEM Time) as follows:

‘——————————————————————-
MARKET NOTICE
——————————————————————-

 From :              AEMO
To   :              NEMITWEB1
Creation Date :     29/09/2026     14:58:09

 ——————————————————————-

 Notice ID               :         145403
Notice Type ID          :         MARKET INTERVENTION
Notice Type Description :         Reserve Contract / Direction / Instruction
Issue Date              :         29/09/2026
External Reference      :         Cancellation: Direction issued to Powerlink to disconnect Mt Emerald Wind Farm

 ——————————————————————-

 Reason :

 AEMO ELECTRICITY MARKET NOTICE

 Cancellation: Direction issued to: Powerlink to disconnect Mt Emerald Wind Farm 

 Refer to Market Notice 145405

 Direction is cancelled from: 1500 hrs 29/09/2026

 Manager NEM Real Time Operations

 ——————————————————————-
END OF REPORT
——————————————————————-’

5)  MN145404 at 14:59 (NEM Time) titled ‘Cancellation – AEMO Intervention Event – QLD region 29/09/2026’

Nothing further, at this point.

PS1 briefly with ‘next day public’ data

It’s now Wednesday morning 30th September 2026, so (with the advantage of the ‘next day public’ data set) we can include the ‘Unit Dashboard’ widget snapshot at 08:10 (NEM time) looking back to yesterday to see more about MEWF1:

There’s much to see, here, but the main points being that:

1)  The unit was already constrained off prior to the direction … there were 3 different constraint equations involved (don’t have time to delve into them here)

2)  So the reason for the Direction was (I’m guessing) that the AEMO (and/or Powerlink) wanted the inverters out of service at the site, not just powered down.