Two bouts of >2 hours of Non-Conformance at Aldoga Solar Farm on Sunday 12th October 2025

Yesterday, we noticed AEMO issue MN129565 at 12:30 on Sunday 12th October 2025 as follows:

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

From :              AEMO
To   :              NEMITWEB1
Creation Date :     12/10/2025     12:30:27

——————————————————————-

Notice ID               :         129565
Notice Type ID          :         NON-CONFORMANCE
Notice Type Description :         Details of Non-conformance/Conformance
Issue Date              :         12/10/2025
External Reference      :         NON-CONFORMANCE Region QLD1 Sunday, 12 October 2025

——————————————————————-

Reason :

AEMO ELECTRICITY MARKET NOTICE

NON-CONFORMANCE QLD1 Region Sunday, 12 October 2025

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

Unit:      ALDGASF1
Duration:   12/10/2025 10:15 to 12/10/2025 12:30
Amount:     337 MW
Constraint: NC-Q_ALDGASF1

Auto-generated on behalf of Manager NEM Real Time Operations

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

Later in the day (on Sunday 12th October 2025), AEMO issued MN129567 at 16:20 as follows:

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

From :              AEMO
To   :              NEMITWEB1
Creation Date :     12/10/2025     16:20:29

——————————————————————-

Notice ID               :         129567
Notice Type ID          :         NON-CONFORMANCE
Notice Type Description :         Details of Non-conformance/Conformance
Issue Date              :         12/10/2025
External Reference      :         NON-CONFORMANCE Region QLD1 Sunday, 12 October 2025

——————————————————————-

Reason :

AEMO ELECTRICITY MARKET NOTICE

NON-CONFORMANCE QLD1 Region Sunday, 12 October 2025

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

Unit:      ALDGASF1
Duration:   12/10/2025 14:05 to 12/10/2025 16:20
Amount:     1 MW
Constraint: NC-Q_ALDGASF1

Auto-generated on behalf of Manager NEM Real Time Operations

——————————————————————-
END OF REPORT
——————————————————————-‘

With respect to the first bout, a run of 2-hours-and-15-minutes is longer than many instances for a run of Non-Conformance for any unit … so (coupled with a few other reasons*) I thought I would have a quick look, with the benefit of ‘Next Day Public’ data

*  Other reasons include:

1)  The unit is a relatively new addition to the Queensland region, and I’d not looked at it before

2)  A 337MW is a sizeable (sustained!) Non-Conformance for any unit.

3)  With the version 9.14 upgrade to ez2view released just last week, I was curious to see how clearly it would show a trend of Non-Conformance like that.

Here’s a snapshot of the upgraded ‘Unit Dashboard’ widget in ez2view:

With this image we can see the following:

First period (beginning 09:50 on Sunday 12th Oct 2025)

In the first period, we can see that the large negative Dispatch Error begins in the 09:50 dispatch error – when the spot price (-$11.18/MWh) drops below the bid price for the unit (-$11.10 at the RRN) and so the unit is ‘economically curtailed’.

In this case (from this time):

1)  The Target for the unit is 0MW

2)  But the unit continues to generate:

(a)  In the 09:50 dispatch interval, producing 143MW – meaning a Dispatch Error of -143MW;

(b)  Which increases in the following dispatch intervals:

i.  to a peak of –337MW at 10:15,

ii.  before the ‘NC-Q_ALDGASF1’ constraint is invoked and bound.

So that means that the 6 dispatch intervals (09:50 to 10:15) will have seen the grid consuming between 143MW and 337MW surplus generation, meaning an additional upwards pressure on frequency:

1)  remembering what happens when Supply ≠ Demand

2)  though we note, in the 4-hour time range for frequency yesterday that:

(a)  The frequency did see a spike to 09:50 (i.e. at the end of the first dispatch interval with the surplus generation);

(b)  But frequency did not keep rising … which suggests that other units assisted (through PFR and also via Regulation FCAS) to act against the rogue output from Aldoga Solar Farm.

Second period (beginning before 14:05 on Sunday 12th Oct 2025)

In the second period, the ‘NC-Q_ALDGASF1’ constraint was applied from 14:05 (NEM time) for the 14:10 dispatch interval … so that means the deviations occurred in the 6 dispatch intervals before that (i.e. to work through the AEMO’s Non-Conformance logic).

However these were not large, in this instance.