This evening’s news that there’s a week or two’s delay to the return to service of the 3 workable Callide units took on additional meaning this evening when we witnessed again a string of both:
(a) Market volatility in the QLD region; and
(b) A repeat of low IRPM (Instantaneous Reserve Plant Margin) levels right across the NEM … and particularly in the QLD + NSW ‘Economic Island’ formed as a result of constrained transfers* into NSW from VIC.
* These constraints (and the price separation that has resulted) are quite topical, given the approval of the ‘Project EnergyConnect’ link between SA and NSW with the assistance of some debt financing from the CEFC.
Noting that I’d already posted about how ‘Prices spike on Sunday 30th May with low NEM-wide IRPM’ only 2 days ago, let’s quickly cover what happened this evening:
(A) Market volatility
There were four discrete dispatch intervals with extreme (i.e. >$10,000/MWh) pricing:
1) The 17:20 dispatch interval for QLD and NSW … only one in the 17:30 trading period.
2) The 17:35 dispatch interval for QLD and NSW … only one in the 18:00 trading period.
3) The 18:20 dispatch interval for QLD and NSW (see below) … only one in the 18:30 trading period.
4) The 18:40 dispatch interval for QLD and NSW … only one in the 19:00 trading period.
… at the time of publication, at least!
(B) Low NEM-wide IRPM
The lowest point this evening was 13.68% for the 17:50 dispatch interval. See here in a snapshot of this from NEMwatch v10 taken at the time:
(C) Low IRPM for the QLD+NSW ‘Economic Island’
The lowest point this evening was 8.63% for the 18:20 dispatch interval. Here’s a snapshot of this from NEMwatch v10 taken at the time:
(D) Trip of Darling Downs Power Station
It’s not every time that we see this happen, in that the AEMO telegraphed ahead of time that it might happen – with Market Notice 86375 published at 10:15:17 this morning:
——————————————————————-
MARKET NOTICE
——————————————————————-
From : AEMO
To : NEMITWEB1
Creation Date : 01/06/2021 10:15:17
——————————————————————-
Notice ID : 86375
Notice Type ID : RECLASSIFY CONTINGENCY
Notice Type Description : Reclassify contingency events
Issue Date : 01/06/2021
External Reference : Reclassification of a Non Credible Contingency Event: Loss of multiple generating units QLD region – 01/06/2021
——————————————————————-
Reason :
AEMO ELECTRICITY MARKET NOTICE
Reclassification of a Non Credible Contingency Event: Loss of multiple generating units QLD region – 01/06/2021
Due to a technical issue at the power station AEMO has reclassified the simultaneous loss of multiple generating units at Darling Downs Power Station as a credible contingency event.
Constraint Set invoked: Q-DARLING_DOWNS_N-2
The constraint set contains equations with the following interconnector on the LHS
N-Q-MNSP1
NSW1-QLD1
T-V-MNSP1
Duration: 01/06/2021 10:15 hrs until further notice
Manager NEM Real Time Operations
——————————————————————-
END OF REPORT
——————————————————————-
Readers should note that, whilst there are multiple generating units onsite at Darling Downs (it’s a CCGT but I forget its exact configuration) it is represented in the NEMDE systems as only a single DUID (i.e. DDPS1) – this is not the only unit where this type of things happen:
Wind Farms and Solar Farms are all like this, as are some other gas and liquid fired units, and hydro units (particularly the Snowy) are particularly confusing (and have changed through history)!
Then at 17:28:31 (the same day) the AEMO published Market Notice 86383 alerting the market that this new ‘Single Credible Contingency’ had indeed occurred:
——————————————————————-
MARKET NOTICE
——————————————————————-
From : AEMO
To : NEMITWEB1
Creation Date : 01/06/2021 17:28:31
——————————————————————-
Notice ID : 86383
Notice Type ID : POWER SYSTEM EVENTS
Notice Type Description : Emergency events/conditions
Issue Date : 01/06/2021
External Reference : Non-credible contingency event – QLD region – 01/06/2021
——————————————————————-
Reason :
AEMO ELECTRICITY MARKET NOTICE.
Non-credible contingency event – QLD region – 01/06/2021
At 1713 hrs 01/06/2021, all generating units at Darling Downs Power Station 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
——————————————————————-
END OF REPORT
——————————————————————-
Here’s how the trip looked in ez2view (a pre-release copy of v9), Time-Travelled a couple hours earlier back to the 17:15 dispatch interval:
Remember that, with Time-Travel:
(a) We are ‘same day’ so can’t see things like Targets, Bids and Private Constraints; but
(b) Widgets like the ‘QLD Schematic’ and ‘Gen Change’ and ‘Notifications’ now show end-of-interval FinalMW values … hence show the unit tripping off 2 minutes prior to the end of the interval.
I’ve annotated the image to note that, whilst there had not been volatility to that point, the envisaged volatility later in the evening will have been helped along by the trip of DDPS1. To illustrate this, here is the ‘Forecast Convergence’ widget in ez2view Time-Travelled forward to 18:00 but looking back to 17:15 to see how prices progressed from that time:
We see that the price spiked for the 17:20 dispatch interval (which would be partly due to ramp rate constraints + also possibly rebids), but also at 17:35 (in the next trading period).
(E) Volatility to continue for next couple weeks
Let’s wait to see whether the issues at Darling Downs PS can be resolved quickly … and whether the ‘single credible contingency’ risk can be lifted.
With Kogan Creek still limping along with a tube leak (PS1 – offline before 22:05), and 3 x Callide units delayed RTS – it may well be (as I noted here on Twitter and here on LinkedIn earlier this evening) that it could be volatile most evenings for the next couple weeks?
————–
PS2 DDPS1 back in service
The AEMO issued Market Notice 86402 following the Return-to-Service of the unit with a piece of good news:
________________________________________________________________________________________________
Notice ID 86402
Notice Type ID Emergency events/conditions
Notice Type Description MARKET
Issue Date Tuesday, 1 June 2021
External Reference Update – Non-credible contingency event – QLD region – 01/06/2021
________________________________________________________________________________________________
AEMO ELECTRICITY MARKET NOTICE.
Update – Non-credible contingency event – QLD region – 01/06/2021
Refer AEMO ELECTRICITY MARKET NOTICE MN 86383
At 1845 hrs the Darling Downs Power Station was returned 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
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