A high-value binding network constraint, F_S+SETB_L1, was recorded in the NEM with a peak shadow price of $990/MWh, indicating significant congestion on the South Australian transmission network around the South East to Tailem Bend corridor. The constraint appeared across multiple dispatch intervals with shadow prices of $990, $208.27, and $15.20, suggesting a period of sustained but easing network pressure. A related constraint, F_S++SETB_L60, and a frequency regulation constraint (F_T+RREG_0050) were also binding concurrently, pointing to broader system stress in the region.
The F_S+SETB_L1 constraint family relates to thermal limits on the South East to Tailem Bend transmission lines in South Australia, and elevated shadow prices of this magnitude are typically driven by high renewable generation in the South East of SA (particularly wind) attempting to export into the main SA grid, exceeding the physical transfer capability of that corridor. The concurrent binding of the F_S++SETB_L60 constraint (a 60-second pre-dispatch variant) suggests the congestion was anticipated and persistent rather than a sudden spike, likely reflecting sustained wind output in the region. The presence of the frequency regulation constraint F_T+RREG_0050 may indicate that AEMO was also managing system strength or inertia concerns in Tasmania or South Australia simultaneously, compounding the dispatch complexity in that part of the NEM.
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.