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Proposed Revision Request Detail Help
PRR Life Cycle*****Stakeholder Meeting on Recommendation****
PRR Details
PRR #
1656
Title Clarifying Nature of Work for generation outages related to distribution utility limitations
Date Submitted 11/21/2025 1:31 PM
PRR Category B
Priority Normal
Owner Das Gupta, Dinesh (CAISO)
Status Stakeholder Meeting on Recommendation
Status End Date 1/27/2026 11:59 PM
Related BPM Outage Management
BPM Section Section 3.4  Nature of Work Attributes for Generation Outages
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Existing Language

​See Attached​

Proposed Language

See Attached​​

Reason For Revision

Clarify that distribution-level market-participating resources with generation outages due to limitations set by the distribution utility unrelated to transmission or distribution equipment outage should use the “ambient due to fuel insufficiency" nature of work.​​

Add 12/23: This PRR was driven by questions on distribution-level charging constraints. The PRR is relevant to all storage resources with limitations to charging abilities that are unrelated to transmission or distribution equipment outages.


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

Das Gupta, Dinesh (CAISO)
Modified BPM language proposed by the PBM Chnage Management Coordinator

​Approve as modified. 

Identification of the authorship of comments

Wellhead Power eXchange, Independent Energy Producers Association, PG&E, CESA, Six Cities
Action

Approve the BPM PRR as modified.

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

Announcements
No Announcements has been posted for this PRR.
Impact Analysis
PRR 1656 Impact Analysis Form.doc    
Notes:
Initial Comments
PRR 1656 EXTERNAL PRR 1656 Wellhead Comments.msg    
Submitted for:
Colin Orloff
Market Analyst
Wellhead Power eXchange

Please see the Wellhead Comments on PRR 1656 Update below:

Wellhead opposes using the “Ambient Due to Fuel Insufficiency” nature of work for charging limitations on distribution resources on a sub-transmission (>50 kV) line. Specifically, those resources whose charging restrictions are caused by an N-1 transmission condition, and not a resource issue or congestion. In these conditions the Transmission Induced nature of work is the correct cause.
 
Resources with transmission interconnections are not subject to RAAIM penalties when their charging restriction are due to a N-1 condition, as they are allowed to use the “Transmission Induced” nature of work. We don’t see a valid reason that distribution resources under the same conditions should be treated differently.
12/10/2025 7:14 AM
Logged By - Williamson-Duffney, Joseph (CAISO)
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Submitted for:
Dinesh Das Gupta
Policy Developer
CAISO

The “Transmission Induced” nature of work generator outage is “to be used if Transmission equipment outage curtails a generator output, or distribution equipment outage in the case of distribution-connected generator,” as outlined in Outage Management BPM § 3.4. The “Transmission Induced” nature of work does not apply unless there is an outage on transmission or distribution equipment under the current nature of work definition.  This PRR proposes no edits to the “transmission induced” nature of work purpose. 
Resources with transmission interconnections are allowed to use the “Transmission Induced” nature of work only if equipment failure on the transmission system drove the charging restriction.  Distribution-level resources can also use the “Transmission Induced” nature of work only if equipment failure on the transmission or distribution system drove the charging restriction. Charging constraints related to the level of service agreed upon by the resource, even if modeled after an N-1 contingency, are not related to a transmission or distribution equipment outage that materialized. 
12/16/2025 3:33 PM
Responded By - Williamson-Duffney, Joseph (CAISO)
PRR 1656 CAISO PRR_BPM Modification_IEP Comments Final.pdf    
PRR 1656 EXTERNAL IEP Comments on PRR #1656.msg    

Submitted for:
Sara Fitzsimon
Policy Director
Attorney at Law
Independent Energy Producers Association

RE: Dinesh Das Gupta, PRR #1656
The Independent Energy Producers Association (IEP) writes to respectfully protest the Proposed Revision Request (PRR) #1656, “Clarifying Nature of Work for generation outages related to distribution utility limitations.” IEP is California’s oldest trade association representing the interests of independent power generators, owners, and operators, including those with hybrid and storage resources at the sub-transmission level. IEP opposes the change proposed in PRR #1656 because it inadvertently subjects generators with storage and hybrid resources to Resource Adequacy Availability Incentive Mechanism (RAAIM) penalties.
A generator at the sub-transmission level does not have control over the activities of the distribution utility and may be artificially forced into outage during high-load seasons until and unless a congestion management system (CMS) is put into place. Until a CMS system is in place, the generator with hybrid and storage resources is not allowed to charge during seasons of overall increased load under the assumption that an N-1 is taking place. Such restriction occurs even with sufficient power, “fuel”, on the system for charging—for example charging during the summer when the duck curve is at the bottom. With a CMS, a resource’s charging capability will be governed automatically to ensure that operations are curtailed in the event of an equipment failure. However, the placement of a CMS system is dependent on the distribution utility. Under this proposed PRR, a generator awaiting a CMS system will suffer RAAIM penalties for an outage labeled “ambient due to fuel insufficiency,” even though the resource could charge sufficiently and avoid an outage but for the assumption that there is a transmission outage and an N-1 event has occurred.
As such to the extent the CAISO continues to pursue this change, the proposed language should be revised as follows (highlighted changes below): PO BOX 1287 • SLOUGHHOUSE, CA 95683 • OFFICE: 916-448-9499 • WWW.IEPA.COM

This additional change would ensure that the resource does not suffer from lost revenue from a restriction on charging outside the generator’s control and a RAAIM penalty fee, meant to encourage generators to mitigate potential outages.
Additionally, With the RAAIM incentive program up for debate at the California Public Utilities Commission’s Resource Adequacy proceeding (R.25-10-003) and the CAISO’s own Resource Adequacy Modeling and Program Design initiative development of an unforced capacity mechanism (UCAP), RAAIM’s relevance might soon diminish. To ensure generators who have proactively partnered with their distribution utility to install a CMS system are not penalized, and to maintain consistent outage tracking, generators who experience outages due to limitations set by the distribution utility should not have to report an outage as “ambient due to fuel insufficiency,” subjecting them to penalties that won’t elicit behavior change. Rather, IEP respectfully requests the outage be reported as a “transmission outage.”
We appreciate your consideration of our protest, and we look forward to continued engagement.
12/10/2025 7:12 AM
Logged By - Williamson-Duffney, Joseph (CAISO)
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Submitted for:
Dinesh Das Gupta
Policy Developer
CAISO

The “Transmission Induced” nature of work generator outage is “to be used if Transmission equipment outage curtails a generator output, or distribution equipment outage in the case of distribution-connected generator,” as outlined in Outage Management BPM § 3.4. The “Transmission Induced” nature of work does not apply unless there is an outage on transmission or distribution equipment under the current nature of work definition.  This PRR proposes no edits to the “transmission induced” nature of work purpose. Routine charging constraints faced by distribution-interconnected storage assets are not related to materialized transmission or distribution equipment failures.
CAISO does not believe this outage should be reported as a “transmission outage” because the generator, not transmission, is on outage. 
This PRR does not modify the Resource Adequacy Availability Incentive Mechanism (RAAIM) exemption status of existing natures of work. 
12/16/2025 3:33 PM
Responded By - Williamson-Duffney, Joseph (CAISO)
CAISO did not explain the details of removal of a distribution limitation. Can CAISO clarify the actions available to market participants when a distribution limitation ends and the periods to which they apply? Does this language apply in exactly the same way as other forced/planned outages?
12/9/2025 4:28 PM
Logged By - Alan Meck (PG&E)
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Submitted for:
Dinesh Das Gupta
Policy Developer
CAISO

This language applies in the same way as other nature of works for generator outages.
12/16/2025 3:34 PM
Responded By - Williamson-Duffney, Joseph (CAISO)
_EXTERNAL_ Comment on PRR 1656.msg    
Storage Design and Modeling 9-29-25 Working Group Comments.pdf    
Storage Design and Modeling November 12 Workshop Comments.pdf    
The ISO has received written comments from Don Tretheway from GDS Associates representing CESA. Please see 3 attachments.
12/9/2025 2:38 PM
Logged By - Hines, Nicole (CAISO)
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Submitted for:
Dinesh Das Gupta
Policy Developer
CAISO

The “Transmission Induced” nature of work generator outage is “to be used if Transmission equipment outage curtails a generator output, or distribution equipment outage in the case of distribution-connected generator,” as outlined in Outage Management BPM § 3.4. The “Transmission Induced” nature of work does not apply unless there is an outage on transmission or distribution equipment under the current nature of work definition.  This PRR proposes no edits to the “transmission induced” nature of work purpose.  As CESA states in comments, routine charging constraints faced by distribution-interconnected storage assets are not related to materialized transmission or distribution equipment failures.
The driver behind routine charging constraints faced by distribution-interconnected storage assets is the agreement between the distribution utility and the resource upon interconnection. The “Technical Limitations not in Market Model” nature of work generator outage is to “provide notification that resource is unavailable due to technical limitations not captured in the CAISO market model and that result in infeasible dispatches because they are inconsistent with the resource’s design capabilities,” as outlined in Outage Management BPM § 3.4.  Resources agreed to interconnect with a level of service where the distribution utility can issue charging constraints as needed to ensure delivery of load.  These limitations are consistent with the “resource’s design capabilities,” and therefore the “technical limitations not in Market Model” nature of work does not apply. 
CESA did not include why they believe the PRR is incomplete in its public comment.  In response to CAISO follow-up, the commenter mentioned to CAISO that they believe the BPM PRR is incomplete because it does not list the “impacts and benefits of the suggested changed on the CAISO Market structure, CAISO operations, and Market Participants, to the extent that the submitter may know this information,” as stated in BPM Change Management BPM § 2.4.  This PRR does not makes changes to CAISO Market structure, CAISO operations, or Market Participants.
12/16/2025 10:30 AM
Responded By - Williamson-Duffney, Joseph (CAISO)
The description of the purpose for this PRR states that it is intended to clarify that distribution-level market participating resources with generation outages due to limitations set by the distribution utility that are unrelated to transmission or distribution equipment outages should use the “ambient due to fuel insufficiency” nature of work classification.  However, the PRR language changes shown at page 23 of the attachment to the PRR do not seem focused on resources at the distribution level, and the PRR does not explain why limitations set by the distribution utility should be characterized as “fuel insufficiency.”  The Six Cities request that the CAISO provide more explanation regarding applicability of the PRR revision (e.g., whether limited to distribution-level resources or not) and the basis for characterizing limitations set by distribution utilities as fuel insufficiency.
12/9/2025 12:53 PM
Logged By - Bonnie Blair (Cities of Anaheim, Azusa, Banning, Colton, Pasadena, and Riverside, CA)
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Submitted for:
Dinesh Das Gupta
Policy Developer
CAISO

This PRR was driven by questions on distribution-level charging constraints.  This PRR applies to all storage resources with limitations to their charging abilities, including distribution-level charging constraints.
12/16/2025 10:30 AM
Responded By - Williamson-Duffney, Joseph (CAISO)
Recommendation Comments
Engie comments on PRR 1656.docx    
We received written comments from Margaret Miller on behalf of Engie on 1/9/26. Please see attached.
1/12/2026 10:36 AM
Logged By - Madrigal, Radha (CAISO)
We have received the below comments from Colin Orloff on behalf of Wellhead Power eXchange on 1/8/26.

“Wellhead continues to oppose using the “Ambient Due to Fuel Insufficiency” nature of work for charging limitations on distribution resources on a sub-transmission (>50kV) line. Specifically, those resources whose charging restrictions are caused by an N-1 transmission condition, and not a resource issue or congestion. Under these conditions the Transmission induced nature of work is the correct cause code.
One of the primary justifications CAISO has continued to use is that the resources impacted by this change chose As-Available and as such chose to be subject to this classification. The issue with that justification is that it just isn’t accurate. The idea that a restriction on the charging capability of a resource because of a N-1 condition, would be subject to RAAIM penalties was never considered.

The primary reason it was never considered is because resources interconnected to the transmission system under these same conditions are not subject to RAAIM and there was no justification or expectation that these resources should be treated any differently. To date we haven’t gotten a justifiable reason as to why these resources should be treated differently.

A secondary reason RAAIM penalties for Charging Restrictions wasn’t considered is due to the nature of original agreement. The original agreement was for As-Available charging managed by an automated system (Contingency Management System, CMS). Static charging tables were only going to be used during times when the CMS system could not for one reason or another properly manage current conditions. The CMS system is currently expected to go live in 2027 at which point these very outages become modeled by a system and therefore no longer necessary to ensure the market correctly manages these resources. Penalizing resources now when the very same situation a year from now won’t even be considered by the RAAIM system is illogical.

Ultimately, this process has revealed a disconnect in understanding by all parties as to the implementation and justification for this PRR. Wellhead believes it to be in the best interest of all parties for this PRR to be withdrawn at this time and for this discussion to be continued in a stakeholder initiative until justification is agreed upon.”

Colin Orloff
Market Analyst
Wellhead Power eXchange
 
1/8/2026 3:24 PM
Logged By - Madrigal, Radha (CAISO)
Fullmark_Energy_PRR_1656_Comments_Final.docx    
Fullmark Energy (also known as Hecate Grid LLC) opposes PRR 1656.
1/8/2026 2:06 PM
Logged By - Tosin Kasali (Fullmark Energy)
PRR 1656 Terra-Gen Comments.docx    
We have received written comments from Siddhant Srivastava on behalf of Terra-Gen on 1/8/26. Please see attached.
1/8/2026 2:03 PM
Logged By - Madrigal, Radha (CAISO)
CAISO_PRR1656_Strata_Comments_01082026_Final.docx    
Strata welcomes the opportunity to provide input on PRR 1656. Our comments are focused on ensuring that outage classifications reflect the operational realities of the transmission system, particularly where charging restrictions are driven by transmission outages—whether actual or assumed. Our comments on the proposed changes can be found in the attached word document. 
1/8/2026 11:54 AM
Logged By - MichaelRuss (Strata Clean Energy)
CESA Comments on PRR 1656 - Distribution Charging Limitations.docx    
We have received written comments from Donald Tretheway on behalf of CESA on 1/8/26. Please see attached.

CESA Supplemental Question/Comment received 1/9/26: A distribution interconnected storage resource with a static charging table has established standing outages to manage the charging constraint.  If storage resource’s SOC is 100%, why would it be subject to RAAIM penalties when it cannot charge because the resource was charged when there were no charging limitations?
1/8/2026 10:49 AM
Logged By - Madrigal, Radha (CAISO)
Attachments