Wednesday, 24 September 2008
Market Outcomes: Tasmanian region saw a high energy price of $2161.53/MWh at trading interval (TI) ending 17:30hrs on Wednesday, 24 September 2008. The sum of all Frequency Control Ancillary Service (FCAS) prices reached a maximum of $7784.26/MWh at the same trading interval. Energy and Frequency Control Ancillary Service (FCAS) prices for the remaining NEM regions were not materially affected.
Principal Contributors: An unplanned outage of the Basslink interconnector which tripped from a target of 89MW when flowing in the Victoria to Tasmania direction at 16:55hrs. As a result, both raise and lower FCAS requirements dispatched within Tasmania increased. Binding FCAS capability limits caused the dispatch engine (NEMDE) to reduce the MW targets of negatively priced generation to allow them to supply FCAS.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Saturday, 20 September 2008
Market Outcomes: Queensland region experienced a high energy price of $1683.24/MWh at TI 08:00hrs on Saturday, 20 September 2008. Energy and Frequency Control Ancillary Service (FCAS) prices for the remaining NEM regions were not materially affected by the event.
Principal Contributors: The high energy price of $10,000/MWh in Queensland region at DI 07:55hrs coincided with the interval when a step change of 111MW was introduced to the rating of the Calvale to Wurdong (871) 275kV transmission line (reduced to 737MW) in accordance to the advice by the relevant TNSP. As a result, binding constraints contributed to change in some generation and interconnector flow targets while some other generators were limited by their ramp rates.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during this event.
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