PSC: Improvements to Attachment Y Retirement Process (PAC-2022-1) (20220607)

PGR supports revisions proposed to Attachment Y, especially revisions to increase the time required for notice, studies, and other associated processes under Attachment Y. However, we would encourage MISO to ensure that any proposed enhancements to the Attachment Y (especially those associated with timing) be closely coordinated with potentially impacted market and Tariff processes, e.g., the interconnection process and associated interconnection services (including Surplus Interconnection Service) and the ARR/FTR processes, as well as the average timing for commercial operation of appropriate replacement capacity.

Wolverine supports MISO’s efforts to improve the transparency and effectiveness of its Attachment Y suspension/retirement planning process. Keeping the lights on is paramount and MISO’s Attachment Y planning process is one of several and significant options of accomplishing. Therefore, in addition to MISO’s proposed changes presented to the Planning Subcommittee Committee on June 6, 2022, Wolverine requests MISO work with its stakeholders (including the MISO States) to include a resource adequacy analysis as part of the Attachment Y planning process. In support of Wolverine’s request, several presentations and statements over the past few months identify that there is a close correlation between retirements and resource adequacy that needs be maintained and considered. These include:

1. MISO’s 2022/23 Planning Resource Auction results that identified the entire MISO North/Central region is short of meeting its capacity reserve margin driven by growing load and more retirements of accredited capacity than additions of accredited capacity,
2. MISO’s April 28, 2022 Summer Readiness that showed potential for emergency conditions due to lack of capacity,
3. The June 10, 2022 OMS/MISO Survey that showed the shortfalls of the 2022/2023 PRA are expected to continue in future planning years,
4. The IMM’s June 14, 2022 presentation to MISO’s Markets Committee of the Board of Directors that indicated the MISO’s markets need to slow down the retirements to avoid the use of more frequent emergency situations, or even worse load shed,
5. MISO’s June 16, 2022 Reliability Imperative presentation to the Board of Directors that identified an increasing risk of emergency situations due to more retirements of accredited capacity (largely controllable) than additions of accredited capacity (largely intermittent) coupled with growing load, and
6. The June 9, 2022 letter from certain MISO States that requested enhanced collaboration between MISO, the states, and other entities responsible for resource adequacy such that MISO has the right markets and planning processes in place whereby “MISO must…ensure resource retirements are properly and holistically studied before states finalize their decisions.”

The Environmental Sector submits the following comments in relation to MISO’s proposed improvements to the Attachment Y Retirement Process (PAC-2022-1): 

General Comment:

• As the current retirement process for the Rush Island generators shows, we agree that additional time will help MISO and stakeholders better consider alternatives to resolve significant impacts connected to proposed generator retirements. 

Regarding Advance Notice: 

• While our preference is for a more expedited timeline for generators whose proposed retirement only presents de minimis impacts to the grid, we understand that MISO needs sufficient time to pinpoint impacts in studies. We appreciate that the degree of such impact can vary greatly from resource to resource, depending on local conditions and necessary studies. We generally support MISO in extending advance notice to one year for generator retirements. 

Regarding the Quarterly Study Kickoff:

• Given the staffing limitations that MISO must manage and the workload to complete an Attachment Y study, we support MISO’s proposal of a quarterly study kickoff process.

Regarding Additional Stability Studies: 

• We support MISO’s judgment in requesting additional time in the Attachment Y process for stability studies which are known to take longer than power flow and other studies. 

Regarding Mitigation Practices: 

• We support MISO in not permitting load shed as an acceptable Attachment Y constraint mitigation practice. Generator interconnection projects cannot mitigate constraints with load shed. MISO’s effort toward consistency is appreciated. 

Regarding Confidentiality:

• MISO should use the smallest type of zone (e.g. LRZ’s) possible when publishing generator retirement information. If LRZ’s are too small and risk a reverse-determination of which specific generator any such retirement information may refer to, MISO should consider using subregional groupings (e.g. South, Central, etc.). These grouping types may even be combined so that some subregions have information published at the LRZ level and that other subregions publish at the subregional level, so long as such subregional publication is accompanied by a finding that publication at the LRZ level would indirectly risk jeopardizing confidentiality requirements. The overriding goal should be to publish the most detailed information possible without indirectly ceding confidentiality requirements. 

• Since access to OASIS is limited, and since such limitation creates asymmetric access to information among stakeholders, MISO should provide additional, non-sensitive SSR information on retirements across its footprint that might only otherwise be available on OASIS. Doing so will help relevant stakeholders who do not have access to OASIS better help MISO resolve any potential SSR issues in a more timely manner.

Entergy Operating Company feedback on Proposed Improvements to Attachment Y Retirement Process (PAC-2022-1)

June 21, 2021

During the June 7, 2022 Planning Subcommittee (PSC) meeting, MISO discussed proposed improvements to the Attachment Y Retirement Process.  Stakeholders were asked to provide feedback on the proposed improvements, and in response, the Entergy Operating Companies[1] (Entergy) provide the following comments. 

Entergy agrees that improvements in the generator retirement process are needed process to address the challenges associated with increasing retirements and appreciates MISO’s efforts to do so.  Regarding the proposed changes:

Additional analysis:

Entergy supports performing stability analysis as part of the Attachment Y process, but also recommends considering transient and voltage stability analysis as appropriate, such as if the generator/plant is in a load pocket.  MISO’s analysis should also consider any EMT or short circuit studies to determine the impact of weak grid issues created from the retirement of large synchronous generation.

MISO should take into consideration Local Planning Criteria for Attachment Y analysis.

Units in the study area that are in suspension should be studied with and without that generation.

Extended advance notice period:

Entergy supports extending the notification period.

Quarterly study kickoffs:

Entergy supports MISO performing these studies on a quarterly basis but would like further consideration of evaluating retirements in the same area collectively either in addition to or instead of studying these retirements individually, as this approach would more appropriately reflect system conditions following announced retirements and would avoid issues that could arise from coordinating the results of individual studies performed at the same time, relative to mitigation requirements. 

The grouping of multiple retirements would also support the evaluation of overall system stability.  As the generation mix evolves to more invertor-based machines, the need for stability studies will be increasingly more important. 

Additional clarity is also needed on how retirements included in the quarterly studies will be incorporated in other study processes.

Reviewed mitigation practices:

The Attachment Y process should not rely on dropping load as mitigation for NERC TPL contingency events.

Updated confidentiality terms:

Additional detail is needed on the information MISO intends to share and with whom.  It is important to retain a high level of confidentiality on retirement requests until the unit owner has confirmed the intent to retire the unit. 

MISO needs to perform generator retirement studies together when there are several retirements which are in proximity to each other rather than one at a time, since several retirements in the same area affect each other.

The Attachment Y process, suspensions, and retirement process is broken as far as future MTEP models are concerned.  There are several units which have publicly announced retirements modeled online in future MTEP models.

ITC supports MISO’s efforts to improve the Attachment Y Notification Changes as outlined in the June 7th presentation at the Planning Subcommittee meeting.  We note that it would make the most sense to group the quarterly studies by including all the generators within a geographical/electrical area instead of studying each one separately.  Studying each one separately creates a potential gap between the individual study results and the cumulative effect of the multiple retirements in an area which would likely not be caught until the next planning study (MTEP and/or TPL).  Grouping retirements together would also help MISO manage workload, resulting in fewer overall individual studies. 

While ITC supports MISO’s proposed move to a requirement of at least 1 year of advance notice for an Attachment Y, we believe that a requirement of 18 months would be better because it would allow for more time to develop alternatives and mitigation efforts and aligns better with the TPL requirements.  ITC also supports MISO’s move to incorporate stability studies into the Attachment Y process.  The grouping of studies for multiple retirements of generators, discussed above, is also useful for the evaluation of the combined effect on system stability.  As the generation mix moves from synchronous machines to more invertor based machines, the need for stability studies is going to become increasingly more important.  In addition, ITC also supports reducing overall reliance on load shed as a mitigation option and increasing visibility into requested retirements by modifying the confidentiality requirements.

Consumers Energy understands MISO's presentation and desire to make changes to the Attachment Y process. We hope to learn more about these changes and more detail over the next two PSC meetings and the eventual policy discussion at the August PAC meeting. With this in mind CE would like MISO's thoughts on the questions or additional detail requested directly below:

MISO is adding 6 months of additional studies that are more in depth. It would be good to know the expected cost estimates for future studies these changes are going to create. For example, what if Consumers Energy were to ask for a study one year in advance but later decide to retract/rescind a retirement date, how much would that be expected to cost and is there added value with the more granular study?  Our subject matter experts assume there will be major cost increases and a tightening on our decision making of whether to pursue a study or not for a potential retirement. Maybe a tiered approach to study levels/depth of detail paired with a level of commitment to retire?

On a secondary note and just to reaffirm our understanding from the original presentation, there are concerns with the level of visibility to the public when we are exploring potential retirements.  Consumers Energy will certainly want to retain a high level of confidentiality on our requests for study and appreciates MISO's understanding and support of this position moving forward.

DTE appreciates the effort led by MISO to improve the Att Y process. Here are some comments for considerations. DTE will continue to wok with MISO  and other stakeholders to improve this process. 

• Advance Notice Proposal
  • DTE would support 1 year advance notice from the effective date.  Not 1 year from the start of the study.
• Quarterly Study Kickoff

-          Clarity on how MISO will include retirements in the Quarterly study and overall process. For example, will MISO use the QOL study models used for determining the conditional generator quarterly limits?  What about the temporary operational outages?

-          Does MISO plan to perform the studies on each retirement request individually or it will be a group of retirement generators included in the model and one study will be performed every quarter?

-          How does MISO plan to prioritize the retirement requests in the studies. For example, if there are retirement requests for multiple generators in a quarter, will MISO maintain a priority order based on the individual requests or based on the quarters?

-          How would MISO plan to include transient and voltage stability studies into the quarterly studies?

• Additional Stability Studies
  • Clarity on frequency and scope and if studies will be optimized to control additional costs. Perhaps consider a MW threshold. 
• Mitigation Practices
  • Clarity around their proposal to “Reduce reliance on load shed as a mitigation option”. For example, will there be metrics around how many instances of load shed are allowed? How will the goal to reduce reliance on load shed be reconciled with Planning Criteria and Nerc standards which allow for load shed?
• Confidentiality
  • Clarity on visibility into Att Y requests?
    • What information will be shared and with whom.

The capacity value of the resource needs to be also considered in Attachment Y requests.  Of course, resource adequacy SSR considerations will need a different cost allocation than traditional transmission-related SSR allocations.

Ameren would like to submit the following feedback regarding Attachment Y process improvements

1. Ameren supports performing stability analysis as part of the Attachment Y process, apart from this Ameren also recommends considering Voltage stability analysis if the generator/plant is in a load pocket. MISO can consider a MW threshold for voltage stability analysis.
2. The analysis should also consider any EMT or short circuit studies to determine the impact of weak grid issues created from the retirement of large synchronous generation.
3. MISO should take into consideration Local Planning Criteria for Attachment Y analysis.
4. Ameren recommends the Attachment Y process should not rely on dropping load as mitigation for NERC TPL P0 – P7 contingency events.
5. Another item to consider in the study process is that any units in the study area that are in suspension mode should be studied with and without that generation. MTEP cases are typically dispatch with suspended generators in the far out models which could mask any reliability issues.

WEC Energy Group understands and agrees with MISO that the submission rate for suspension/retirement requests is increasing and there is a need to evaluate both thermal and stability implications of suspension/retirement.  Increasing the Attachment Y advance notification from 26 weeks to 52 weeks is one option to provide more time for in-depth studies.  We note that resource owners often utilize the Attachment Y-2 study process to obtain indicative information related to a suspension/retirement.  While non-binding, Attachment Y-2 provides valuable study information that is applicable to a timely-submitted Attachment Y request, significantly shortening the Attachment Y study time line.  WEC Energy Group recommends that in addition to increasing the notification time from 26 to 52 weeks, an optional path is provided for those resource owners that utilize the Attachment Y-2 study process immediately prior to an Attachment Y submission with a 26 week advance notification.

WEC Energy Group also recommends a one-year transition period for the increase in advance notification so that existing suspension/retirement plans are not affected.  As an example, if the 52 week notification period is in effect on January 1, 2023, an Attachment Y submittal with a suspension date prior to January 1, 2024 will have a 26 week notification period.  An Attachment Y submittal with a suspension date after January 1, 2024 will have a 52 week notification period.