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Independent review of the IESO's Dispatch Scheduling and Optimization, and Day-Ahead Calculation Engine

June 16, 2016

A 2016 review of the IESO's Dispatch Scheduling and Optimization (DSO) and Day-Ahead Calculation Engine (DACE) processes and procedures were completed without qualifications. During the review period, there was nothing that came to the attention of the audit firm PricewaterhouseCoopers which would indicate that the dispatch algorithms were not operating in accordance with the relevant market rules. The full reports are available at DACE Review and DSO Review.

The review included an examination of both the DACE and DSO tools. The DACE tool is the software program that runs the day-ahead dispatch algorithm and is used to optimize day-ahead schedules over a 24-hour period for energy and operating reserves. The DSO tool is the software program that implements the dispatch algorithms, calculates market clearing prices and formulates dispatch instructions for generators and loads. The DSO tool finds an optimal outcome every five minutes by integrating market and reliability priorities. Accurately calculated prices and precise dispatch instructions ensure all Ontario electricity consumers are well served.

The PricewaterhouseCoopers review approach was extensive and included, but was not limited to:

  • Understanding applicable market rules and related processes and procedures
  • Control Room observation
  • Development and execution of automated screening tests
  • Base case and save case testing
  • Comparison of DSO tool input/output data to DSO save case and IESO website

As part of its review, PricewaterhouseCoopers identified the need for a number of non-material market rule amendments to clarify several formulas related to DSO and DACE calculations. These corrections will form part of a future Market Rule Amendment package for review by the IESO Technical Panel.

This is the sixth independent review of the DSO since the market opened in Ontario and the first review of DACE. "The result of the 2016 review reflects the IESO's continued commitment to ensure that systems and processes allow for the optimal unit commitment and dispatch of electricity in Ontario for all consumers" said Chief Operating Officer, Kim Warren.

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