RASC: Hybrid Resource Accreditation (RASC010) (20210310)

Feedback to the RASC March 2021 Hybrid and Surplus Interconnection Resource Accreditation Presentation

The organizations submitting these comments appreciate the progress that MISO has made since the February 2021 presentation and believe that MISO’s proposed accreditation approach is an improvement. However, many details remain unclear, and additional examples across more hybrid resource use cases is warranted. We recognize and fully support MISO’s desire to develop a near-term solution for hybrid accreditation and support the approach of not making the perfect solution the enemy of a good solution. We hope MISO will take this feedback in earnest and work with stakeholders to develop a workable solution that provides market participants certainty for hybrid resource accreditation.

To date, MISO’s examples appear to show that MISO is proposing to allocate a portion of secured interconnection service to each component of a hybrid resource. This approach fails to recognize that a hybrid resource, distinct from co-located but separate resources, will be optimized by the MP behind the POI to maximize capability, particularly during times of reliability risk.

Framework for Determining Hybrid and Co-Located Resource Accreditation Processes

We suggest MISO adopt a comprehensive framework to identify the key variables that will lead to differences in how hybrid resources of various fuel types and designs, and co-located resources, will be accredited. MISO should then provide additional examples to aid collaboration with stakeholders in thinking through the various resource combinations and approaches for accreditation. This approach will keep the conversation organized and provide much-needed clarity.

First, evaluate if there should be different accreditation approaches for hybrid resources (single CPNode behind the POI) versus co-located resources (multiple CPNodes behind the same POI), including how deliverability requirements will be imposed.

Second, differentiate between accreditation for new resources and accreditation for existing resources.

Third, consider if the MP’s market participation model choice (Generation Resource, DIR, or SER Type II) impacts accreditation approach.  There is considerable design heterogeneity possible within hybrid resources, even of the same fuel types. For example, a solar + storage hybrid could vary in design with respect to the MW size of the solar array and storage capability relative to the injection limit at the POI, the relative MW size of the storage component to the solar component, and the duration of the storage component. Based on current discussions within the MSC, we expect the MP to choose the participation model appropriate for the design of the hybrid resource and that based on those choices, the hybrid resource will be treated comparably to other resources using that participation model. So we raise the question here, should hybrid resource capacity accreditation be based in part on the model through which it chooses to participate in the market?

Finally, evaluate each of these scenarios for technology pairings expected to enter the market in the near-term: Solar or wind + storage, Gas + storage, Gas + wind + solar. The table below graphically captures this approach. As noted in the stakeholder presentation to the MSC in March 2021, not all participation models are likely suitable for all use cases, so we’ve proposed a narrowed set of examples below needed to inform a robust stakeholder discussion.

Please note we have omitted co-located resources from this table as we believe the co-located resources would be accredited separately and by fuel type with NRIS allocated to each component for the purposes of accreditation at the MP’s direction.

As a starting point, how would capacity accreditation be calculated for a hybrid resource combination with the following assumptions?

Assumptions: 

• 100 MW NRIS
• 100 MW Nameplate Wind
• 75 MW Nameplate Solar (assume that performance data shows 70% capacity during peak hours)
• 40 MW Nameplate CT

• Would the order of the resources matter for the resource accreditation?
• Does it make any difference how the resources are controlled behind the interconnection, for example if there is automated controls in place to limit the total output of the resources? 
• Will deliverability curves differ by season once the seasonal construct is implemented?
• In addition, would it make sense after one year to create a deliverability curve for the solar + wind resource instead of each separately?

Additional Questions Stakeholders Seek MISO’s Perspective On:

• Will MPs with resources connecting to the MISO transmission system via the surplus interconnection process have the choice to participate in MISO’s market as a single-node Hybrid Resource or as multi-node Co-Located Resources?
• How will hybrid resource accreditation work with multiple components of the same fuel type (i.e. solar + solar hybrid or short-duration battery + long-duration battery hybrid)?
• Would MISO’s approach differ between a battery with a 4-hour duration and a 12-hour duration as a component of a hybrid resource?

Thank you for the opportunity to submit this feedback and we look forward to further collaboration.

On behalf of:

Alliant

Apex Clean Energy

Duke Energy

Entergy

Fresh Energy

Great Plains Institute

NextEra Energy

Southern Renewable Energy Association

Xcel Energy

Clean Grid Alliance Hybrid and Surplus Accreditation Comments

       Clean Grid Alliance appreciates that MISO has requested comments on its evolving proposal for accreditation of hybrid and surplus interconnection generators. While MISO’s adjustments to its proposal from its presentation at the February RASC are an improvement, MISO has still not provided analysis to show that the original proposal from January is not reasonable or sufficient.  CGA urges MISO to revert to this original proposal presented at the January RASC, which showed a simple approach of adding the UCAP values of the hybrid or surplus resources and capping the total UCAP value at the NRIS (or firm transmission service) level.  If not, we request that MISO provide a detailed explanation, with examples, showing why this simpler approach is not reasonable.

       The March proposal does not sufficiently consider the diversity of generation profiles that exist between the resources that make up a hybrid.  MISO also does consider that the generation owner or market participant has every incentive to make the most efficient use of its firm transmission capacity to provide as much capacity to the market during peak hours as is possible.  For instance, in a wind and solar hybrid, the two resources have different generation profiles both daily and seasonally, thus there should not be as much overlap of the output of the two resources as is suggested by the method MISO has proposed, which essentially splits the firm transmission service between the two resources.  If storage is added to a gas resource, the storage resource would be operated when the gas resource is not as cost effective, or when it is not available due to an outage.

       MISO’s latest proposal also adds significant complexity to the administration of determining the hybrid or surplus accreditation of each resource.  The use of deliverability curves with a seasonal construct, especially a four season construct, adds significantly more complexity and work for MISO and the market participants.  Each hybrid resource will have a deliverability curve for each season and for each wind or solar resource in the hybrid.  And these deliverability curves will change each year as new historic output data is incorporated into the curves for each specific resource. If a deliverability curve is ultimately used, it may be more appropriate to develop a curve for each specific hybrid resource combination rather than the individual resources that make up the hybrid.  This would better reflect how the hybrid resources are operated together in each instance.

       It seems to us that, in addition to the issues raised above, MISO’s proposed approach also breaks down in certain situations.  For example, in a hypothetical gas/storage hybrid, with a 100 MW gas plant that has a 5% EFORd, the gas plant would be assumed to “consume” 100% or 100MW of the NRIS service in order to receive 95 MW of capacity credit.  But this does not leave any NRIS capacity for the storage resource, which we can reasonably expect would be operating when the gas plant is on a forced outage.  If MISO continues with its current proposal, we request that MISO provide more examples of how its approach would work with a variety of different hybrid/surplus resource combinations (i.e., gas/storage, gas/wind, wind/solar, solar/storage, etc.). 

       If MISO stays with its proposed approach of splitting the firm transmission service between the resources in the hybrid or surplus situation and maintains the use of deliverability curves, MISO should let the generation owner or market participant decide how to allocate the firm transmission service between the resources, and this decision should be allowed for each season in a seasonal capacity construct.  However, CGA strongly urges MISO to revert back to its original accreditation proposal for hybrids and surplus interconnection resources, as it is the simplest approach and seems to best account for the diversity of generation profiles and the incentives of market participants to optimize the use of their firm transmission service.

Respectfully submitted by Natalie McIntire on behalf of Clean Grid Alliance.

Alliant Energy appreciates the updated examples on slides 8 and 9, however we still have concerns, especially with the uncertainty around future deliverability curves for solar.

MISO needs to show specific ERIS and NRIS amounts relative to total ICAP.  For example, MISO could show what would be seen in the MISO MECT Tool for hybrid resources.  In particular, we want to understand what ERIS amounts may be converted to UCAP with firm transmission service. 

WEC Energy Group agrees with MISO's examples of accreditation for hybrid and surplus interconnections presented at the March 10 RASC meeting.  It is very important to maintain the capacity value of each resource within a hybrid or surplus interconnection agreement, subject to NRIS and firm transmission service deliverability.

Regarding the three questions posed by MISO to refine the accreditation of hybrid and surplus resources, it is our belief that a generation interconnection with more than one resource behind the CPNode will have performance data by fuel-type (including those with a single inverter - DC coupled).  That data will allow for the separate accreditation of each resource and recognition of the shared NRIS and firm transmission service of the interconnection.

The anticipated dispatch of hybrid and surplus resources is dependent on the resource types behind the interconnection and the operational strategy of the owner.  The MSC is currently investigating different participation models for hybrid and surplus resources.  The RASC should not develop any rules or procedures that would limit the ability of a resource to provide services to the market or that would influence the following issues under discussion at the MSC:

1. (SER Type II and Generator) Expand intra-hour offer update flexibility based on DIR Forecast Maximum Limit
2. (DIR ) Clarify that existing DIR Forecast Maximum Limit processes will account for storage operation of DIR-hybrids
3. (Generator) Refrain from imposing a “forecast independence” requirement.
4. (DIR and Generator) Clarify that hybrids may use virtual demand bids to schedule grid charging in Day Ahead and evaluate reliability implications
5. (All Models) Enable Ramp Rate offers for both individual components and the combined hybrid
6. (All Models) Clarify partial outage capabilities/registration updates
7. (SER Type II ) Confirm/expand market product and make-whole payment eligibility