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Proposed Revision Request Detail Help
PRR Life Cycle*****Stakeholder Meeting on Recommendation****
PRR Details
PRR #
1634
Title Clarification on generation outage nature of work to include curtailment due to plant configuration parameters
Date Submitted 6/30/2025 9:14 AM
PRR Category B
Priority Emergency
Owner Jin, Licheng (CAISO)
Status Stakeholder Meeting on Recommendation
Status End Date 8/12/2025 11:59 PM
Related BPM Outage Management
BPM Section Section 3.4
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Existing Language
​See attachment
Proposed Language
​See attachment​
Reason For Revision
​​To help scheduling coordinators to pick the correct nature of work in their outage submission. The curtuailment due to plant equipment/plant configuration elements should be reported in the plant trouble category. 
Effective 6/30/2025
 
Click here to view the Recommendation Details for this PRR
BPM PRR Submitter

Jin, Licheng (CAISO)
Modified BPM language proposed by the PBM Chnage Management Coordinator

​Approve as submitted

Identification of the authorship of comments

PG&E and CESA
Action

Approve the BPM PRR as submitted

Approve as submitted
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 Impact Analysis Form_06302025.doc    
Notes:
Initial Comments
CAISO response for PG&E Comments:
The intent of the language is to cover generation derate due to plant control setup (for example, limitation on co-located solar/battery output). The correct nature of work should be Plant Trouble. There is no impact on the current transmission induced NoW. Any transmission component caused limitation is under the Transmission Induced NoW.

CAISO Response for CESA’s comments:
This BPM clarification outlines the ISO's current approach to reporting outages. The Plant Trouble category addresses reductions in dispatchable capacity due to imminent equipment failure. In some instances, protective equipment designed to prevent unit failure may reduce dispatchable capacity. This reduction is linked to plant failure as it is necessary to prevent a larger unit failure. This BPM revision does not replace the broader discussions on modeling and optimization issues for storage resources. For the topics that are currently discussed in the policy stakeholder process, it will continue to be discussed through that process.
For any transmission component caused generation limitations, the transmission induced NoW should be used and there is no impact by this PRR.
7/23/2025 4:17 PM
Logged By - Hines, Nicole (CAISO)
2025-07-15-CESA-PRR1634-Comments v2 (final).pdf    
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California Energy Storage Alliance (CESA) Comments on CAISO PRR 1634
CESA is concerned that the proposed changes to the definition of the Plant Trouble nature of work go far beyond a simple clarification and fundamentally change how and in what instances resource operators may now be required to use this field. The reason provided is that it will “help scheduling coordinators to pick the correct nature of work in their outage submission” but there is no indication that scheduling coordinators are currently picking an incorrect nature of work nor was there a public process to determine that this new definition is appropriate and correct. Furthermore, the reasoning CAISO provides for its change to the definition does not provide sufficient justification for a change that may have broader implications than CAISO’s immediate intent. CESA requests CAISO provide a more detailed background and justification for the change so that stakeholders can appropriately review the change.
CAISO submitted a Proposed Revision Request (PRR) to update its Outage Management Business Practice Manual (BPM) on June 30, 2025. The PRR re-defines the “Plant Trouble” nature of work as follows:
• Plant equipment fails or is in danger of imminent failure resulting in a curtailment of dispatchable capacity. This category also covers curtailments of dispatchable capacity caused by plant equipment or plant configuration element(s) whose purpose is to mitigate risk of harm to the plant and/or interconnected transmission equipment.
The current Plant Trouble definition is focused on facility equipment failures. This means that the field applies when equipment at the facility is either operating or in danger of imminently operating inconsistent with its design criteria. Resource operators use the field to reflect when true equipment failures either derate or remove a facility from service.
CESA is concerned that the new language, not limited to instances of immediate or imminent equipment failure, could be interpreted to expand the definition to include instances where facility equipment is operating within its design criteria or instances when the transmission or distribution system equipment (not at the control of the resource operator) limits resource operation. Furthermore, CESA is concerned that the new definition may inadvertently capture normal operations scenarios for energy storage

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resources (such as dispatch nonlinearities). In other forums,1 CAISO is actively discussing
resource model changes to ensure that the market optimization accurately represents
normal resource operating criteria, recognizing that these instances ideally should not
require resource operators to submit outages.2 If the Plant Trouble nature of work is
applied inappropriately, due to an overly broad definition, its use may mask root issues at
the transmission and distribution level that should be discussed in a public stakeholder
process to explore all policy interactions.
CESA recommends CAISO provide a more detailed background and justification for the
proposed change so that stakeholders can appropriately review and provide relevant
comments on the change.

1 CAISO Storage and Modeling Initiative, Issue Paper & Straw Proposal on Outage Management, Nonlinearity, and
SOC Clarification, March 27, 2025

2 Stakeholder comments on the March 27, 2025 Issue Paper & Straw Proposal indicate strong support for
nonlinearities being RAAIM exempt until CAISO can implement fixes to its resource models.

Comment submitted by:

Perry Servedio
Senior Project Manager
Power Supply Planning
direct 916-246-1587
cell 916-945-6502
perry.servedio@gdsassociates.com
7/14/2025 3:26 PM
Logged By - Williamson-Duffney, Joseph (CAISO)
PG&E would like clarity on a scenario where the last added phrase “and/or interconnected transmission equipment” would come in play when selecting Plant Trouble as a Nature of Work (NoW). With this added language, are there scenarios where CAISO believes a Plant Trouble NoW should be utilized over a Transmission Induced NoW?
7/14/2025 2:50 PM
Logged By - Elizabeth Lopez (PG&E)
Recommendation Comments
20250812 CESA PRR1634 Comments v1.pdf    
August 12, 2025
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California Energy Storage Alliance (CESA) Comments on CAISO PRR 1634
CESA is concerned that the proposed definition of the “Plant Trouble” nature of work is inconsistent with CAISO’s own explanations provided in response to prior comments. In its PRR responses, CAISO stated that plant trouble should apply to equipment failures or protective actions taken to prevent plant equipment failure, and that any limitations caused by transmission components should be logged under the “Transmission Induced” category. However, the proposed definition still includes curtailments taken to protect interconnected transmission equipment—contradicting CAISO’s stated intent and creating the risk that outages will be misclassified. As CAISO stated at the last BPM Change Management meeting, Scheduling Coordinators (SC) can seek individualized clarifications on the usage of nature of work fields directly from CAISO. The current definition will cause some SCs to seek clarifications on whether an outage should be Plant Trouble or Transmission Induced and would therefore cause inconsistent usage across all SCs. To ensure accurate and consistent outage reporting, the definition must be revised to remove references to transmission equipment and clearly limit “Plant Trouble” to issues related to facility equipment.
CAISO provided two responses to CESA’s prior concerns within the text of the PRR but has not updated the proposed definition accordingly. First, CAISO stated:
“The intent of the language is to cover generation derate due to plant control setup (for example, limitation on co-located solar/battery output). The correct nature of work should be Plant Trouble. There is no impact on the current transmission induced NoW. Any transmission component caused limitation is under the Transmission Induced NoW.”
Second, CAISO stated:
“This BPM clarification outlines the ISO's current approach to reporting outages. The Plant Trouble category addresses reductions in dispatchable capacity due to imminent equipment failure. In some instances, protective equipment designed to prevent unit failure may reduce dispatchable capacity. This reduction is linked to plant failure as it is necessary to prevent a larger unit failure. This BPM revision does not replace the broader discussions on modeling and optimization issues for storage resources. For the topics that are currently discussed in the policy stakeholder process, it will continue to be discussed through that process. For any
August 12, 2025
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transmission component caused generation limitations, the transmission induced NoW should be used and there is no impact by this PRR.”
CESA appreciates these further clarifications but is still concerned that the proposed Plant Trouble definition continues to reference curtailments to protect transmission equipment in light of CAISO’s statements. The PRR re-defines the “Plant Trouble” nature of work as follows:
• Plant equipment fails or is in danger of imminent failure resulting in a curtailment of dispatchable capacity. This category also covers curtailments of dispatchable capacity caused by plant equipment or plant configuration element(s) whose purpose is to mitigate risk of harm to the plant and/or interconnected transmission equipment.
Considering CAISO’s statements, the definition must be further modified to remove reference to interconnected transmission equipment, as such outages should clearly be logged as Transmission Induced. CESA recommends the following modification to the proposed definition:
• Plant equipment fails or is in danger of imminent failure resulting in a curtailment of dispatchable capacity. This category also covers curtailments of dispatchable capacity caused by plant equipment or plant configuration element(s) whose purpose is to mitigate risk of harm to the plant and/or interconnected transmission equipment.
Furthermore, CAISO should clarify that the intent of the Plant Trouble nature of work remains focused on facility equipment failures. This means that the field applies when equipment at the facility is either operating or in danger of imminently operating inconsistent with its design criteria.

Perry Servedio
Senior Project Manager
Power Supply Planning
direct 916-246-1587
cell 916-945-6502
perry.servedio@gdsassociates.com

8/13/2025 6:38 AM
Logged By - Williamson-Duffney, Joseph (CAISO)
Attachments