About the ‘S-HUBG’ and ‘S-HUWT’ constraint sets, and yesterday’s network outage on Yorke Peninsula

We noted earlier that ‘ElectraNet experienced multiple faults on the transmission network Friday 14th March 2025 impacting power supply to the Yorke Peninsula’ and, in that article, noted the invocation of two constraint sets:

• The ‘S-HUBG’ constraint set … which is now no longer invoked; and
• The ‘S-HUWT’ constraint set … which remains invoked.

For our future reference I’ve included this collage of ez2view widgets, with the ‘Constraint Set’ widget at the top – as at the 14:55 dispatch interval (NEM time) on Saturday 15th March 2025:

With respect to the above:

1)  We see that the ‘S-HUBG’ constraint set:

(a)  Was invoked yesterday through until yesterday evening … but something’s changed in the AEMO records in the EMMS so the end time of this component of the outage is a little imprecise.

(b)  We also see that this constraint set contains the ‘S-SNWWF_0’ constraint equation, which would have ‘constrained off’ (i.e. to 0MW) the output of Snowtown Wind Farm over this period of time.

2)  We see that ‘S-HUWT’ constraint set:

(a)  Currently looks set to continue until 18:00  (NEM time) this evening; and

(b)  At the time of writing, contains the ‘S>HUWT_BWPA_RHBR-T’ constraint equation that is bound with a significant Marginal Value:

i.  suggesting some other VRE is being constrained down.

ii.  though we’re not going to look, at this point.

That’s all for now…