A major binding constraint (N_QPSFB_L_9INV) with an exceptionally high shadow price of $811,907/MWh became active in NSW1 during the evening of 27 July 2026, coinciding with elevated region reference prices ranging from $82.95 to $101.10/MWh. The constraint remained binding across multiple settlement intervals as the system managed a generation mix dominated by black coal (6,169.68 MW) alongside substantial renewable and storage contributions.
The extreme shadow price on the binding constraint indicates severe physical congestion or a critical network limitation that significantly restricted generation flexibility in NSW1 during this period. The high marginal value suggests the constraint was actively limiting power flows and forcing the dispatch of higher-cost generation to meet demand, with the binding constraint acting as the primary price-setter rather than supply-demand balance, thereby explaining the sustained elevation of regional reference prices above typical levels.
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.