VIC1 experienced sustained negative pricing at −$0.55/MWh across two consecutive 5-minute intervals (16:30–16:35) on 18 September 2026, following a period of near-zero pricing. The event occurred during a period of high wind generation (approximately 3,481 MW combined) and brown coal baseload (2,041 MW), with minimal flexible gas generation available.
The negative pricing was driven by a binding constraint (F_T+LREG_0050) with a marginal value of approximately $89.85/MWh, indicating a transmission or voltage constraint was limiting the market's ability to dispatch lower-cost generation or absorb available supply. With high renewable output combined with inflexible brown coal generation and no CCGT or OCGT capacity available to modulate output downward, the market required negative pricing to incentivise demand response or curtailment of marginal plant to resolve the constraint violation.
Causal analysis generated by gridIQ's synthesis model from live AEMO market data: dispatch prices, generation mix, interconnector flows and market notices in the interval surrounding the event.