About the short (planned) outage at Tarong unit 2 on Monday 21st September 2026

Yesterday we were involved in a discussion with others about what happened at Tarong unit 2 on Monday 21st September 2026:

• Remembering that this is a sibling to the Tarong unit 3, which is on a long planned outage currently (there are a few coal units on long planned outages as part of ‘outage season’ before summer).
• So we take a quick look here, via two snapshots in ez2view v9.20 (the recent upgrade to the software).

Firstly via the ‘Bids & Offers’ widget, we show the past 3 days of operations:

We see the unit was offline around sunrise on Monday 21st September 2026 and back online for the evening peak (and a later period of Fixed Load on Tuesday 22nd September 2026) for ‘Stack Testing’.

With a combination of the ‘Forecast Convergence’ widget (looking at Availability in earlier ST PASA market data submissions), and ‘Constraint Sets Gantt’ widget we can see that:

• this short outage was planned in advance (since last Thursday 17th September 2026);
• and seems related to both of the highlighted constraint sets relevant to Tarong unit 2:
  • firstly, the  ‘F-Q_TARONG#2_ZERO’ constraint set (which affects FCAS from Tarong unit 2); and also
  • the ‘Q-TR_TG_842’ constraint set (which affects ENERGY from Tarong unit 2).

Will just leave this here, as another example of two-shifting operations at coal units in the NEM …

Interestingly, given the Gantt chart shows scheduled invocation of constraint sets containing constraint equations relevant to any/all of the 4 x Tarong A station units:

• We see a similar situation looming next week (starting Monday 28th September 2026 for 5 days) for Tarong unit 3:
• with both:
  • the ‘F-Q_TARONG#3_ZERO’ constraint set; and
  • the ‘Q-TR_TG_843’ constraint set.
• but in this case, the unit’s already offline.