Proposed Revision Request Detail Help
PRR Life Cycle*********Closed
PRR Details
Title Clarification on Number of Historical Days Used in the Mosaic Quantile Regression
Date Submitted 1/24/2024 8:34 AM
PRR Category A
Priority Normal
Owner Martin, Michael (CAISO)
Status Closed
Status End Date 5/14/2024 11:59 PM
Related BPM Market Operations
BPM Section Appendix N
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Existing Language

​See Attached

Proposed Language

See Attached​

Reason For Revision

For Flexible Ramp Requirements, the ISO uses a technique called Mosaic Quantile Regression. This technique incorporates both histograms and quantile regression models to estimate uncertainty based on historical data. It was initially set at 180 days but is now configurable.

Click here to view the Recommendation Details for this PRR
BPM PRR Submitter

Martin, Michael (CAISO)
Modified BPM language proposed by the PBM Chnage Management Coordinator

Approved as submitted.

Identification of the authorship of comments


Approve the BPM PRR as submitted

See FAQs in the announcement of this PRR
Statement of apparent requirements of the BPM PRR

Priority and rank for any BPM PRR requiring a CAISO system change

Proposed effective date(s) of the BPM PRR

Other recommended actions

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Final Decision

Approve original
Stakeholder Comment

Answered questions on implementation, see Announcements

Effective Date


Adopt the recommendation as originally issued

FAQs on 1552:

Q. When is this PRR being implemented?
A.  After the PRR is approved and CAISO will communicate with the market participants in the MPPF and/or market notice.

Q. When the CAISO will stop using day types in the histogram and mosaic methods other than 180 days of historical data?
A. CAISO will communicate changes through the MPPF or MSC.  Should a change be necessary from the communicated 180 days, then CAISO will submit a new PRR.

Q. Is there a process the CAISO will follow when deciding whether to use something other than 180 days of historical data? 
A. The CAISO considers:
o When a significant enhancement is identified, changes to FRP may occur after internal review and external communication.
o The main metrics monitored for FRP performance are coverage and requirement. Coverage describes the fraction of intervals in which the FRP requirement was at or greater than realized uncertainty. Requirement is the average of requirement values over the period of analysis. The goal is to provide target coverage and where possible minimize average requirement. Currently, our review focuses on these two metrics.
o The PRR change significantly enhances coverage metrics toward target across all BAAs. You can see the impact to BAAs in the following presentation deck
o The ISO continues to evaluate enhancements to performance metrics, especially those that will further highlight and account for reliability or awareness

Posted On - 2/23/2024 3:26 PM
Impact Analysis
Impact Analysis not available.
Initial Comments
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Recommendation Comments
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