Interconnector Watch

SA1 stands out as the key price outlier at 170.44 $/MWh — more than double VIC1's 81.31 $/MWh — and the two SA-bound interconnectors explain why. Heywood (V-SA) is carrying 466 MW eastward-to-west into SA and is binding at its export limit of 466.22 MW, meaning it is fully saturated in the SA import direction. Murraylink (V-S-MNSP1) is simultaneously binding at its export limit of 170.64 MW, also flowing VIC-to-SA. Both SA interconnectors are therefore at their respective ceilings simultaneously, with no residual capacity to deliver further imports into SA. That transmission constraint is the direct mechanical cause of SA's price premium over VIC: the marginal cost of serving additional SA load cannot be arbitraged away while both links are fully loaded.

VIC1-NSW1 (VIC-NSW interconnector) is carrying a modest 30.1 MW northward from VIC into NSW, well within its 435 MW export limit and not binding. The NSW1-QLD1 (QNI) shows -51 MW, indicating 51 MW net flow from QLD into NSW against the NSW1 reference direction — also unconstrained relative to its -149 MW import limit. These two links are operating with substantial headroom, and the corresponding price spread between NSW (84.79 $/MWh), VIC (81.31 $/MWh), and QLD (85.53 $/MWh) is tight, consistent with unimpeded cross-border arbitrage keeping the three regions close to price convergence.

Basslink (T-V-MNSP1) is carrying effectively zero flow (0 MW) between TAS and VIC, leaving TAS to price independently at 96.24 $/MWh — notably above VIC's 81.31 $/MWh. With Basslink idle, that 15 $/MWh spread persists uncorrected. The most recent constraint notices relating to Basslink — multiple lightning-driven reclassifications of Tasmanian transmission circuits through 11 April, including the Farrell–Tribute, Farrell–John Butters, and Farrell–Mackintosh 220/110 kV lines — have all been resolved and the associated constraint sets revoked by 13 April. There are no active binding constraints on T-V-MNSP1 at present; the zero flow reflects dispatch outcomes rather than a hard limit. The Nullarbor DC link (N-Q-MNSP1) carries a negligible 0.96 MW and is unconstrained.

The negative settlement residue notices for QLD-to-NSW (NRM_QLD1_NSW1, active 13 April, subsequently cancelled the same day) and NSW-to-VIC (NRM_NSW1_VIC1, active briefly on 10 April) are both resolved. No active negres constraints are currently operating on any interconnector. The dominant market structure for today is therefore the SA island effect created by simultaneous binding on both Heywood and Murraylink, while the eastern mainland corridor from QLD through NSW to VIC operates with ample transfer capacity and compressed regional price spreads.