On Thursday (25th May 2023) AEMO released their Scheduling Error notification (incident number 54) confirming they had incorrectly scheduled three of the Liddell units into one of their systems, post the Liddell shutdown, which caused price spikes across the NEM and forwards market on the morning of 1st May 2023.
As has been widely documented the last three Liddell units came offline on the 24th of April (Unit 4), 26th April (unit 2) and finally unit 1 on the 28th of April. This should have flowed through to the systems within the AEMO dispatch engines, however due to an error this was not the case, and the market was affected by the error between midnight and midday on the 1st of May 2023.
The error was cause by a mismatch of data used within the systems which feed the NEMDE (NEM Dispatch Engine) used by AEMO, whereby one part of the system removed the units from 00:01 on the 1st May. However, a separate part of the NEMDE’s data feed system, which controls the constraints still included the Liddell units at their “initial values” i.e. 500MW, not their real value of zero.
When the equations within the constraint tried to equalise, there was a “drop” of 1500MW on one side of the equation from the first interval on the 1st May 2023.
To rectify this AEMO reduced flow coming from Victoria into NSW and around 173MW of generation was dispatched down.
Prices reacted as expected with 6 periods between midnight and 6am having prices between $2,771.58/MWh and $2,964.04/MWh and increasing the daily average price by around 30% to an average of $288.86.
With a marketplace reacting to every cough of a power station, especially in the days following the Liddell closure the added constraint was enough to also strengthen the forwards market with the Q323 close price rising $5.50/MWh on the day in comparison to the day before across QLD, Vic and NSW and even SA was affected with an $8/MWh increase on the previous days close.
This strength continued into the next few weeks as outages came into the mix, a tube leak delaying the return to service of Bayswater 2 to the 3rd May, Kogan Creek, Eraring 2 and Tarong taking outages, the return of Callide being delayed and an unexpected interest rate hikes putting additional pressure on the market. Speculators were quick to act trading the spread between states thus increasing prices across the NEM.
This reactionary sentiment is one we feel will remain for a while, with the spot market quickly correcting however the futures continue to hold value down the curve.