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Spinning reserve (margin peak and off peak), load rejection reserve and system restart (cost_LR)

Spinning reserve is generation capacity that is held in reserve but ready to respond quickly if another generator suffers an unexpected outage. This helps maintain an uninterrupted supply of electricity to customers. Margin Peak and Margin Off-Peak parameters are used in the Ancillary Service settlement calculations to compensate Synergy for the costs it incurs in providing spinning reserve.

The value of the Ancillary Service Cost_LR parameter covers the payment to a market generator for the costs of providing the Load Rejection Reserve Service and System Restart Service.

The “L” component in the "Cost_LR" parameter relates to Load Rejection Service. This ancillary service is used to maintain power system reliability in the event of an unforeseen reduction in customer demand.

The “R” component in the “Cost_LR” parameter relates to System Restart Service. This ancillary service is used to restore power to the electricity system in the event of a localised or system-wide blackout.

Synergy is the default provider of the Spinning Reserve and Load Rejection Reserve Ancillary Services in the Wholesale Electricity Market in the South West Interconnected System. Multiple generators provide the System Restart Service.

The ERA must determine the margin values and cost_LR parameters to apply in 2023/24 by 31 March 2023.

This is the ERA’s final determination for spinning reserve and load rejection reserve. The determination will cover the three months from 1 July 2023 to 1 October 2023, when the new Wholesale Electricity Market design is scheduled to commence. At this point spinning reserve and load rejection reserve will be replaced by frequency control essential system services with prices set through real-time markets.  


Date Documents File type
30-Mar-23 Determination
Adobe PDF 5 MB

20-Jan-23 Issues paper
Adobe PDF 5 MB

Public submissions

Date Documents File type
20-Feb-23 Synergy
Adobe PDF 189 kB

Page last updated: 30 Mar 2023