‘Market Demand’ in TAS drops by 151MW on Wednesday 12th March 2025

A quick article to record this alert triggered by the ‘Notifications’ widget in ez2view at 12:00 (NEM time) on Wednesday 12th March 2025:

This notes the ‘Market Demand’ in Tasmania dropping by 151MW across a 5 minute Dispatch Interval (or ~15% of what the total was beforehand).

Now, Tassie is a bit ‘unique’ in the NEM in a number of ways – including the fact that there are 4 big industrial loads that oftentimes account for well more than half of the aggregate demand in the region.

1)  In the trend of demand below, we can see a number of step changes over the past 12 hours … though 151MW clearly the biggest.

2)  So my first guess is that one of them switched off for some reason (possibly coupled with other things – they are not all >150MW).

But it might also have been to do with the storms ripping through Tasmania today as we see from all the reclassifications in the ‘Market Notice’ window within NEMwatch:

PS1 Non-credible contingency event

Coincident with me hitting publish (at ~12:26), the SMS alerts in ez2view notified me of this Market Notice containing ‘bulk electrical load’:

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

From : AEMO
To : NEMITWEB1
Creation Date : 12/03/2025 12:24:04

——————————————————————-

Notice ID : 125554
Notice Type ID : POWER SYSTEM EVENTS
Notice Type Description : Emergency events/conditions
Issue Date : 12/03/2025
External Reference : Non-credible contingency event – TAS region – 12/03/2025

——————————————————————-

Reason :

AEMO ELECTRICITY MARKET NOTICE.

Non-credible contingency event – TAS region – 12/03/2025

At 1158 hrs the Sheffield George Town No. 1 220kV Line and the Sheffield George Town No. 2 220kV Line 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
——————————————————————-‘

… so this may well be related.

PS2 AEMO notes 43MW of bulk electrical load disconnected at ~12:00

At 13:24 the AEMO published the following MN125556:

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

From : AEMO
To : NEMITWEB1
Creation Date : 12/03/2025 13:24:46

——————————————————————-

Notice ID : 125556
Notice Type ID : POWER SYSTEM EVENTS
Notice Type Description : Emergency events/conditions
Issue Date : 12/03/2025
External Reference : Non-credible contingency event – TAS region – 12/03/2025

——————————————————————-

Reason :

AEMO ELECTRICITY MARKET NOTICE.

Non-credible contingency event – TAS region – 12/03/2025

At 1200 hrs the Sheffield – Burnie No. 1 220kV Line, Sheffield – Burnie 2 110kV Line and the Ulverstone – Emu Bay 110kV Line tripped.

AEMO did not instruct load shedding.

AEMO has been advised that 43MW of bulk electrical load has been disconnected.

The cause of this non credible contingency event is not known at this stage.

Manager NEM Real Time Operations

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

PS3 AEMO notes 96MW of bulk electrical load disconnected at ~12:00

At 14:12 the AEMO published the following MN125561:

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

From : AEMO
To : NEMITWEB1
Creation Date : 12/03/2025 14:12:35

——————————————————————-

Notice ID : 125561
Notice Type ID : POWER SYSTEM EVENTS
Notice Type Description : Emergency events/conditions
Issue Date : 12/03/2025
External Reference : Update – Non-credible contingency event – TAS region – 12/03/2025

——————————————————————-

Reason :

AEMO ELECTRICITY MARKET NOTICE.

Update – Non-credible contingency event – TAS region – 12/03/2025

Refer AEMO Electricity Market Notice 125555

Updated elements: Sheffield George Town No. 1 220kV Line, Sheffield George Town No. 2 220kV Line plus 40 MW load loss at Nystar and 56 MW load loss at Temco.

Manager NEM Real Time Operations

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

… as noted in the above, this followed MN125555 which was published earlier at 12:58 as follows:

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

From : AEMO
To : NEMITWEB1
Creation Date : 12/03/2025 12:58:00

——————————————————————-

Notice ID : 125555
Notice Type ID : POWER SYSTEM EVENTS
Notice Type Description : Emergency events/conditions
Issue Date : 12/03/2025
External Reference : Update – Non-credible contingency event – TAS region – 12/03/2025

——————————————————————-

Reason :

AEMO ELECTRICITY MARKET NOTICE.

Update – Non-credible contingency event – TAS region – 12/03/2025

Refer AEMO Electricity Market Notice 125554

The cause of this non credible contingency event is not known at this stage.
AEMO is not satisfied that this non credible event is unlikely to re-occur.
AEMO has therefore reclassified this event as a credible contingency event until further notice.

Region: TAS

Elements: Sheffield George Town No. 1 220kV Line and Sheffield George Town No. 2 220kV Line
Duration: 1300 hrs 12/03/2025 until further notice
Constraint set(s) invoked: T-GTSH_N-2

Manager NEM Real Time Operations

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