Changes to Net-Demand Uncertainty Requirement Calculation Methodology in Flexible Ramping Product effective trade date 8/14/24

Effective trade date Aug. 14, 2024, the determination of the mosaic net-demand uncertainty requirement, utilized in the California ISO Flexible Ramping Product (FRP), will undergo a change within the historical data utilized to form the mosaic requirement, from a rolling set of sample days (currently 180 days) towards a symmetric sampling scheme. Symmetric sampling will split the total sample days between two ranges: the last 90 days in the historical set and the forward 90 days minus 1 year. The FRP requirements for each participant may vary in reference to previous trade dates. The anticipated magnitude of changes is described further in the documentation below, as changes are variable across participants. Participants are encouraged to review the documents in preparation of the change. Note, another notice will be posted on August 12.

A change has been made to the Market Operations Business Practice Manual (BPM): Appendix N to reflect the change of historical net-demand uncertainty information.

Further details of this change can be found in the following referenced documentation:

• Market Operations BPM
• 29, 2023 Market Surveillance Committee (MSC) presentation
• 7 2024 Board of Governors presentation

Contact information

Please contact ISO Customer Services at 916-608-7320 with any questions.