Interconnector Watch: Thursday 21 May 2026

At 06:35 AEST, the Queensland-New South Wales Interconnector (QNI) is the sole binding constraint across the NEM. QNI is exporting 534.61 MW from NSW into Queensland — sitting exactly at its import limit of -534.61 MW — meaning the interconnector is fully congested in this direction. This binding condition is directly reflected in the regional price spread: NSW clears at $125.25/MWh while Queensland sits $26.44/MWh lower at $98.81/MWh. Absent the constraint, arbitrage flows would compress that spread; instead, QLD is effectively isolated at the margin from higher-priced NSW supply.

The VIC-NSW interconnector (Heywood's northern counterpart) is carrying 523.85 MW northbound from Victoria into NSW, utilising 38.5% of its 1,360.44 MW export capacity — well clear of its limit and not binding. This flow is consistent with Victoria's $110.50/MWh price sitting below NSW's $125.25/MWh, with the interconnector providing meaningful arbitrage. Heywood (V-SA) is flowing 102 MW from SA into Victoria — a reversal of the more typical VIC-to-SA direction — at 19% of its 536.43 MW import capacity. SA's $103.44/MWh price undercuts Victoria's, which explains the westward-to-eastward pull. Neither interconnector is binding.

Murraylink (V-S-MNSP1) remains severely curtailed following an unplanned outage at the Redcliffs converter station first notified on 16 May, with constraint set I-ML_ZERO still active. The interconnector is carrying just -9 MW (SA to VIC direction), essentially at zero — consistent with the outage notice and well within its nominal ±89 MW capability. Basslink (T-V-MNSP1) is at a dead stop, flowing 0 MW between Tasmania and Victoria. Tasmania clears at $105.18/MWh against Victoria's $110.50/MWh, a $5.32/MWh spread that would ordinarily attract northbound flows, but Basslink's zero flow suggests either an operational restriction or scheduling decision this interval.

An active constraint notice (V-SMTX_F_R, issued 20 May) covers the South Morang F2 500/330 kV transformer outage, scheduled to clear at 17:00 AEST today. This constraint set directly caps transfer limits on VIC1-NSW1, V-SA, V-S-MNSP1, and T-V-MNSP1 simultaneously. Traders should watch for limit relaxation on VIC1-NSW1 and V-SA post-17:00 AEST, which could shift the VIC-NSW flow pattern and compress the NSW-VIC price spread. VicGrid's separately noticed increase in Victoria's maximum generation contingency size from 600 MW to 750 MW provides marginally more headroom for dispatch in south-west Victoria under outage conditions — relevant context for any afternoon position changes after the South Morang transformer returns to service.