Interconnector Watch: Sunday 21 June 2026

South Australia is the standout story this interval, with SA1 sitting at $3,130.31/MWh against Victoria's $159.27/MWh — a $2,971/MWh spread that directly reflects constrained import capacity into the state. Both SA interconnectors are affected by active network outages. The Roseworthy–Templers 132 kV line outage (constraint set S-TPRS invoked at 0930 AEST yesterday) and the ongoing X3 Balranald–Buronga 220 kV rating change have together tightened limits on both Murraylink (V-S-MNSP1) and Heywood (V-SA). Murraylink is binding at its import limit of -158.14 MW, flowing from SA into Victoria — the reverse of what you'd expect given SA's price spike, and a sign that the constraint equations are overriding what the price signal would otherwise incentivise. Heywood is exporting 88.89 MW into SA and sitting at its export limit, meaning no additional Victorian supply can reach SA through that corridor either. With both links at their constrained limits, SA's price has no relief valve.

QNI (NSW1-QLD1) is the other binding interconnector this interval, locked at its import limit of -590 MW, flowing from Queensland into New South Wales. The binding constraint is holding QLD1 at $116.27/MWh while NSW1 clears at $132.08/MWh — a modest $15.81/MWh spread consistent with the link being at capacity in the Queensland-to-NSW direction, with no additional northward headroom (export limit sits at just -24.07 MW on the QLD side). Directlink (N-Q-MNSP1) is flowing -48.16 MW southward from QLD into NSW, well within its -113.3 MW import limit and not binding. However, Directlink's controls remain unavailable until further notice (constraint set I-CTRL_ISSUE_TE active since 18 June), restricting AEMO's ability to dispatch it as a dispatchable tool, which reduces flexibility on this corridor and compounds QNI's binding position.

VIC-NSW (VIC1-NSW1) is flowing -443.55 MW from Victoria into NSW against an import limit of -443.55 MW — it reads as at-limit but is flagged non-binding, suggesting the constraint equation is not actively cutting into dispatch this interval even though the flow equals the stated import limit. Watch this corridor: with NSW demand at 8,744 MW and Victoria at 6,473 MW, any tightening of this limit would quickly translate into NSW price uplift. Basslink (T-V-MNSP1) is flowing 64.26 MW from Tasmania into Victoria, sitting at its import limit on the Tasmanian export side but flagged non-binding and well short of its 261.6 MW export capacity — the APD A2 500/220 kV transformer outage (constraint set F-I_ML_APD_LOAD, active since 10 June) continues to constrain this link's northern headroom. Tasmania at $79.28/MWh remains the cheapest region on the NEM, with the price discount to Victoria ($159.27/MWh) indicating Basslink's limited capacity is preventing full arbitrage. The net picture across the NEM today is one of fragmented regional markets: SA is effectively islanded at a price premium by