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Sector Participants > Engagement Initiatives > Engagements > Updates to Performance Requirements Market Rule Appendices 42 and 43

Updates to Performance Requirements: Market Rule Appendices 4.2 and 4.3


Like most other jurisdictions in North America, Ontario has a long history of transmission-connected generation facilities producing electricity and supporting grid reliability. With increased penetration levels of distributed energy resources (DERs), that picture is changing. Complicating matters is the fact that existing Market Rules in Ontario have no specific performance requirements for DERs or load displacement units (LDUs) units with an installed capacity less than 10 MW, or facilities with total aggregate generation of less than 50 MW.

In practical terms, that means these generation units may connect to the electricity system without having the ability to provide the necessary support for reliability, in particular, following transmission system disturbances. The IESO’s 2019 Operability Assessment identified potential concerns related to increased penetration of DERs and made recommendations to improve the performance of DERs to support reliability during and immediately following specific transmission system disturbances. The assessment also showed a need to clarify performance requirements for inverter-based generation units, as existing requirements are tailored for conventional generators.  Inverter-based generators behave differently than conventional generators, as highlighted in the NERC industry recommendations and event analysis reports following the system disturbances in California.

The IESO proposes to update Appendices 4.2 and 4.3 to improve the performance of DERs and mitigate the concerns identified in the Operability Assessment, to clarify the performance requirements for inverter-based resources, and to ensure the IESO Market Rules are consistent with the newly released NERC PRC-024-3 and CSA 22.3 no.9 standards. The proposed changes are also intended to align the performance requirements with on-site validation testing processes and requirements. The IESO is seeking feedback from stakeholders on these proposed updates to the performance requirements in Market Rule Appendices 4.2 and 4.3. All comments and enquiries on this engagement can be directed to

Schedule of Activities

Timing Engagement Activity Webinar Registration and Recordings

June 30, 2021


Final Engagement Summary Report


April 21, 2020

Stakeholder feedback on the proposed updates to Market Rule Appendices 4.2 and 4.3

IESO Response to Stakeholder Feedback


March 31, 2020

Public Webinar

Recorded Presentation

August 2019

Technical Panel Presentation


August 2019

Stakeholder feedback on materials and issues discussed at the July Energy Storage Advisory Group

  • Advanced Energy Management Alliance(AEMA)
  • Hydro One
  • Kelvin Thermal Energy
  • OPG
  • Storage Power Solutions

IESO Response to Stakeholder Feedback


July 2019

Energy Storage Advisory Group

  • Communication
  • Presentation
  • Draft Market Rules: Grid Connection Requirements
  • Feedback Form

Recorded Presentation

June 2019

Market Operation Spring Awareness Session