What happened to the ‘N::N_DTKV_2’ constraint equation leading to whiplash on VIC1-NSW1 interconnector on Sunday 18th June 2023

Yesterday evening we posted a short note about ‘Whiplash on VIC1-NSW1’ that occurred form the 17:00 to 17:05 dispatch interval.

With the use of the ‘Constraint Dashboard’ widget* in ez2view and the benefit of ‘next day public’ data I’ve time travelled back to both dispatch intervals in the snapshots below

* note for ez2view clients (following a query from one of our clients last week about this) you will need to as a minimum be on v9.5.1.216 … but preferably
(a)   v9.6.1.99 (if your local EMMS is still v5.0 or v5.1) or
(b)  at least v9.7.1.25 (if your local EMMS has been upgraded to v5.2).
We will be switching off older versions shortly.

Yesterday we highlighted that VIC1-NSW1 was limited on export in both instances by the ‘N::N_DTKV_2’ constraint equation …

… this is one Constraint Equation that is part of the Outage on the Dapto to Kangaroo Valley 330kV line (i.e. line 18her) discussed here last week, and currently underway (currently invoked in the ‘N-DTKV_18_WG_CLOSE’ constraint set).

So let’s use the ‘Constraint Dashboard’ widget  time-travelled back to Sunday 18th June at 17:00 and take a closer look…

17:00 Sunday 18th June … with Dispatch Target flow 1,043MW north (VIC to NSW)

Here’s a view of the first dispatch interval shown … where Target Flow on VIC1-NSW1 interconnector was +1,043MW at the maximum of the export limit:

This snapshot (click to open in larger view) has been annotated to highlight a number of things, especially with respect to:

1)  The Uranquinty gas-fired units have spare capacity … particularly at Unit 4 (more on this later).

2)  The TUMUT3 hydro unit has a lot of spare capacity.

17:05 Sunday 18th June … with Dispatch Target flow 1,000MW south (NSW to VIC)

Moving forwards to 17:05 we see a significant change with respect to TUMUT3, and also (subsequently) with VIC1-NSW1:

In this snapshot, we see volume shifted downwards to the –$1,000/MWh Market Price Floor by Snowy Hydro for the TUMUT3 unit … which then (especially because of the large ROCUP rate, not shown here) is preferred over the (comparatively ‘more expensive’) supply from VIC over the VIC1-NSW1 interconnector.

More to come as time permits…