Managing bids during the market suspension on 23 March 2026

The market suspension for the NSW region lasted from interval 11:45 to 18:30.

We have a collection of articles about the the event on WattClarity.

One feature of a market suspension is the possibility for suspension pricing, which happened in this case. AEMO’s website provides the following:

Spot prices and FCAS prices in a suspended region continue to be set in accordance with NER rule 3.9 where AEMO considers it practical and reasonably possible to do so, and central dispatch is continuing under rule 3.8. Otherwise, prices will be based on the relevant Market Suspension Pricing Schedule developed and published in accordance with NER clause 3.14.5(e).

For the 23rd of March, the declaring market notice informed Participants that suspension pricing would apply.

Another aspect of a market suspension is that bidding and dispatch will continue if deemed practical and possible. AEMO’s website advises:

Bidding and dispatch will continue in accordance with NER rule 3.8 where AEMO considers it is practical and reasonably possible to do so. Where possible, dispatch instructions will be issued electronically via the automatic generation control system. Otherwise, AEMO may issue dispatch instructions in any other form that is practical in the circumstances.

Information received by WattClarity indicated that the automatic generation control system in NSW was not operable. Yet it appears to WattClarity that bids continued to be processed for dispatch.

Hence our look into rebids on the day.

Overview of rebids

With this chart we consider how energy offers of the NSW units might have coincided with Suspension Pricing and how this might have been managed by Participants.

In the chart below there is one dot for each rebid, placed at the time of the offer. Each row is a unit, grouped by fuel type.

• Higher frequencies of dots for a unit suggest auto-bidding systems are in use.
• Isolated dots might represent manual rebidding.
• Gaps are periods when no rebid was issued.

Some unit rebidding patterns

1. Some units were frequently rebidding before the suspension; stopping soon after the start of the suspension; issuing one rebid after the suspension when spot prices had resumed.
2. Others exhibited no clear change until well into the suspension period.
3. No clear change in pattern among thermal and hydro resources. For example, gas units look to be manually rebid with no change in pattern evident.
4. Some units frequently rebidding before the suspension; continue that way through out the majority of the suspension duration (e.g. until 16:30); no material change in rebidding throughout the suspension.
5. Most battery storage units tended to halt or alter rebid frequency soon after the start of the suspension; resumed near the end of the suspension period.

Suspension prices

Suspensions prices for the suspension period ranged from 44 $/MWh to 100 $/MWh, thereabouts.

Blue box denotes the suspension period on March 23, 2026.