Interconnector Watch: Thursday 20 August 2026

Two interconnectors are binding right now: Basslink (T-V-MNSP1) is flowing 206 MW from Tasmania into Victoria, exceeding its nominal import limit of 157 MW under the current constraint configuration, and Murraylink (V-S-MNSP1) is flowing 164.5 MW from Victoria into SA against an 83 MW import limit. Both are constrained by the network outage on the Tailem Bend to South East No.2 275 kV line in SA, which tripped at 1415 hrs yesterday and has invoked four constraint sets (S-BC_CP, S-SE_VC1_BC-2CP, S-SECB6611_10_BC-2CP, S-TBSE) touching all five mainland interconnector links.

Heywood (V-SA) is exporting 170.82 MW from Victoria to SA, sitting right at its export limit with no headroom, while Murraylink adds a further 164.5 MW in the same direction — combined interconnector support into SA of over 335 MW. This is consistent with the price spread: SA sits at $101.02/MWh against VIC1 at $55.52/MWh, a $45.50/MWh differential that's holding despite both links running at or above nominal limits into the region. Basslink's Tasmania-to-Victoria flow of 206 MW is also pushing well past its stated import limit, reflecting the technical limitation constraint (I-VT_000) that AEMO flagged on 18 August — Tasmania's $39.03/MWh price against Victoria's $55.52/MWh shows the arbitrage still isn't fully closed even with elevated flow.

QNI (NSW1-QLD1) is flowing 468.58 MW from QLD into NSW, well inside its 1210 MW import limit, with NSW1 at $77.29/MWh against QLD1 at $72.50/MWh — a modest $4.79/MWh spread that doesn't require binding transfer capacity to resolve. Directlink (N-Q-MNSP1) is flowing a light 17 MW from QLD to NSW, subdued by the ongoing control-availability issue flagged on 14 August, which has held it well short of its 70.9 MW export limit. VIC1-NSW1 is flowing 400.42 MW from Victoria into NSW, close to its 390 MW export limit, reflecting Victoria's low price drawing NSW demand and reinforcing the $21.77/MWh VIC-NSW spread.

The SA transmission outage remains the dominant driver across the grid today — it's binding two separate interconnectors simultaneously and elevating SA's price premium. With Heywood already maxed on export and Murraylink also constrained tight, any further loss of transfer capacity into SA would likely see the SA1 price separate further from the rest of the mainland. Traders should watch AEMO's Network Outage Scheduler for restoration timing on the Tailem Bend line, as its return to service would relax all four active constraint sets and likely narrow the VIC1-SA1 spread.