VIC1 experienced sustained negative pricing of -$0.55/MWh across two consecutive dispatch intervals (15:30 and 15:35) on 19 September 2026, following a period of near-zero pricing. The negative pricing occurred during a period of high wind generation (approximately 5,520 MW combined) and moderate brown coal output (2,096 MW), with minimal gas and solar contribution.
The negative pricing reflects an oversupply condition where the marginal cost of generation adjustment fell below zero, likely driven by the high proportion of wind generation which has zero or near-zero marginal operating costs. The binding constraint F_T+LREG_0050 maintained a consistently elevated marginal value (ranging from 26.82 to 27.64 $/MWh) across the periods leading to negative pricing, indicating that system management requirements created downward pressure on the wholesale price despite the constraint's positive shadow price, consistent with a situation where renewable generation curtailment or rapid ramping constraints forced the dispatch to preserve inflexible generation.
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.