Comments on Draft final proposal

Short-long start unit definitions update

Comment period
Feb 24, 10:00 am - Mar 03, 05:00 pm
Submitting organizations
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Submitted 03/03/2022, 12:48 pm


Jerret Fischer (

1. Provide your organization’s overall position on the Short-long Start Unit Definitions Update draft final proposal:

Salt River Project Agricultural Improvement and Power District (SRP) appreciates the opportunity to comment on the Short-Long Start Unit Definitions Update initiative. In general, SRP supports simplifying and aligning definitions for resources in both the Tariff and Business Practice Manuals (BPMs) and would appreciate additional clarification.

2. Please provide a summary of your organization’s comments on the Short-long Start Unit Definitions Update draft final proposal:

SRP appreciates the responses and clarifications the CAISO provided with respect to Short-Long Start Unit Definitions Update issue paper. However, SRP requests additional clarification. To better understand whether the proposed changes will impact SRP’s operations, we are requesting clarification on two items in the draft final proposal:


  • SRP requests clarification on the differences between how the startup time condition (hot, warm, or cold) is used in both the Day Ahead Market (DAM) and Real-Time Market (RTM) software. SRP requests the CAISO confirm SRP’s understanding that the market software for the RTM can distinguish between hot, warm, and cold starts and choose the appropriate time when determining if the resource is startable, despite the definition being tied to a cold start.


  • Please provide clarification for Section 34.6. The Tariff language states, “Once per hour, near the top of each Trading Hour, immediately after the FMM and the RTUC for the same interval is completed the CAISO performs an approximately five (5) hour Short-Term Unit Commitment (STUC) run using SCUC and the CAISO Forecast of CAISO Demand over a 270-minute time horizon to commit Medium Start Units and Short Start Units, with Start-Up Times greater than the time period covered by the RTUC described in Section 34.3.”  SRP requests that the CAISO address whether the term “Start-Up Times” should be changed to “Cycle Times” to reflect the time that is considered for commitment decisions.
3. Provide your organization’s comments on the proposed WEIM designation for this initiative:

SRP supports the CAISO’s Joint Authority decisional classification on the basis that both the EIM and the day-ahead market will be impacted by the outcome of this initiative.  As CAISO staff noted at the January 26, 2022, initiative webinar, amending the Short Start and Long Start definitions will impact and align the definitions in the EIM and day ahead market.


SRP appreciates the CAISO’s consideration of these comments.

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