Comments on draft tariff language

1. Please provide a summary of your organization’s comments on the Energy Storage Enhancements draft Tariff language.

PG&E’s comments could be summarized as follow:

• PG&E requests the CAISO to replace the current draft tariff language for the reliability enhancements with the language from the final proposal that the state of charge will account for a fraction of the regulation awards in the previous interval and explain the multiplier to be applied will be defined in the BPM (section 8.4.1.1).
• PG&E requests the CAISO to clarify how the CAISO would distinguish between an ED to hold SOC and an ED to reach an SOC (section 11.8.4.2.1).
• PG&E requests the CAISO to clarify where the “registered Charging Constraints” will be defined (section 34.13.3).

2. Please submit any additional edits or suggestions in redline.

Section 8.4.1.1 Regulation

In the draft tariff language, the CAISO proposed the following language: “Consistent with the requirements of this Section, the CAISO will use all reasonable efforts to commit, schedule, and dispatch Non-Generator Resources providing Regulation while recognizing the impact of Regulation Awards on their State of Charge in the Day-Ahead and Real-Time Markets.”

In the final proposal, the CAISO proposed “This formula illustrates that state of charge, in any interval, is a function of the state of charge in the previous interval, the energy dispatch instructions during the previous interval and a fraction of the regulation awards in the previous interval. The proposal notes that only the fraction ?? of the full amount of regulation will factor into the state of charge for the next interval in the real-time or day-ahead market. This multiplier will be specified in a business practice manual and may be updated as analysis drives updates of actual regulation awards and impacts to state of charge” (page 11 of the final proposal).

PG&E requests the CAISO to replace the current draft tariff language with the language from the final proposal that the state of charge will account for a fraction of the regulation awards in the previous interval and explain the multiplier to be applied will be defined in the BPM.

Section 11.8.4.2.1:

PG&E requests the CAISO to clarify how the CAISO would distinguish between an ED to hold SOC and an ED to reach an SOC. It is PG&E’s expectation that an NGR can only receive ED to hold SOC instructions when its current SOC is at the specified level. The draft Tariff language suggests that an NGR can receive ED to hold SOC instructions when its SOC might be below the specified level. It should be made clear that any ED instructions to charge or discharge should follow existing Tariff rules regarding Settlements and Bid Cost Recovery (BCR).

Section 34.13.3:

PG&E requests the CAISO to confirm whether the Charging Constraint is a Y/N parameter and where that is stipulated (e.g., Masterfile or otherwise). PG&E also suggests CAISO use a different word than “registered Charging Constraint” and use instead Charging Constraint as defined in the Masterfile or [specified where].

1. Please provide a summary of your organization’s comments on the Energy Storage Enhancements draft Tariff language.

The Cities of Anaheim, Azusa, Banning, Colton, Pasadena, and Riverside, California (the "Six Cities") have limited comments regarding the draft tariff language for the Energy Storage Enhancements initiative, as outlined in the attached.

2. Please submit any additional edits or suggestions in redline.

Please refer to the attached redline.  

1. Please provide a summary of your organization’s comments on the Energy Storage Enhancements draft Tariff language.

See attached a redlined version of the draft Tariff language with comments included on specific sections. We have a few categories of comments:

• Vistra noticed that some of the proposed redlines overreach beyond the board approved policy, but we believe this is unintentional and have provided suggested changes that will correct for this issue.
• Vistra noticed the CAISO provided some redlines on the  Section 34.11.1 System Reliability Exceptional Dispatches that are unnecessary and may confuse entities. CAISO has authority to issue hold State of Charge Exceptional Dispatches, and no Tariff or Policy change was needed for this element. The settlement changes is the newly approved functionality being added with ESE proposal. We recommend removing these revisions with the exception of adding "all types of" language to Generating Units for clarity.
• In general, we prefer Tariff Amendments conform as closely as possible to existing structure and terminology in the Tariff and have proposed changes to result in a more consistent Tariff.
• We beleive that there was insufficient detail on some of the redlines and added language to better conform to level of detail that the Tariff normally provides.

We are happy to discuss these proposed revisions to the draft with CAISO staff at your earliest convenience.

2. Please submit any additional edits or suggestions in redline.

Vistra review was a cursory review of what was provided by CAISO, and we preserve the right to offer additional suggestions. For instance, we noticed that there are no Tariff changes to introduce a rule that would limit the operating range of storage resource(s) that can be awarded regulation in day-ahead to no more than two-thirds its operating range.

This day-ahead market proposal was the critical piece that allowed the CAISO to move forward with a proposal to not require energy bids in the day-ahead market and instead the CAISO proposed that:

"The proposed rules will not require bids in the day-ahead market from the storage resource, but ancillary services will not be awarded in the day-ahead market that cannot accommodate the required energy bids in the real-time market."

This was a gap that we noticed but do not have suggested additions at this time. We ask the CAISO to address this in the next iteration of its Draft Tariff language.