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Local Energy Market Dispatch Issue Corrected

March 17, 2022

A modelling deficiency in the IESO’s energy market dispatch software resulted, under certain conditions, in the over-dispatching of roughly 50 MW of generation. For comparison, the IESO regularly dispatches more than 15,000 MW to help meet Ontario’s energy needs. The impact of this deficiency began in December 2017 and was identified as part of the IESO’s ongoing reviews of market activity in 2021. The issue has been corrected as of December 1, 2021 via a software update.

While IESO analysis determined that market clearing prices were not affected, the deficiency did result in the payment of additional congestion management settlement credits (CMSC) to some generators. The IESO’s modelling indicates the issue resulted in $100,000 – $600,000 per year in additional CMSC payments.

As soon as the concern was identified, the IESO moved to correct the deficiency in the software. The IESO continues to review the matter along with any additional controls that may be required to prevent similar issues in the future. Moving to a single schedule market, as planned under the IESO’s Market Renewal Program, will help ensure dispatch anomalies such as this are more visible and can be addressed in a timely manner.

Many processes and tools support the IESO’s efforts to maintain the reliability of Ontario’s electricity system. The energy market dispatch software helps determine which generating resources are needed at any given moment.

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