In the December 2 meeting of the Planning Subcommittee (PSC) feedback was requested on Wind and Solar Dispatch Assumptions in MTEP Models, specifically:
Comments are due by January 14.
Transmission Owner Sector Feedback on Wind and Solar Dispatch Assumptions in MTEP Models
January 14. 2021
In the December 2, 2021 meeting of the Planning Subcommittee (PSC) MISO requested feedback on Wind and Solar Dispatch Assumptions in MTEP Models, specifically:
and
The MISO Transmission Owners Sector[1] appreciates the opportunity to provide feedback to the information and recommendation presented by MISO in the responses to these questions below, in the context of MISO’s recommendation to make no changes to the MTEP21 assumptions for MTEP22.
Does annual monitoring of Wind/Solar output and potential impact on future reliability provide useful information?
Yes. As the resource mix in MISO’s footprint rapidly evolves, having a formalized annual process to evaluate the appropriate dispatch assumptions and the method by which they are established for the TPL study scenarios is important for ensuring that the grid supports serving load reliably with the resources available on the system and dispatched in MISO’s markets.
What additional data and format may be helpful?
Due to the rapid increase across the MISO footprint in the capacity of battery storage devices seeking to interconnect to the MISO system either directly or through an aggregator and the reliability benefits of storage identified in MISO’s Renewable Integration Impact Assessment (referenced in MISO’s December 2021 PSC Presentation on this topic), the Transmission Owners agree with the comments of other stakeholders at that meeting that suggested including battery dispatch in MISO’s annual wind and solar dispatch assumption evaluation. The TOs recommend battery storage be evaluated as both standalone resources and as part of hybrid resources.
The Owners appreciate the benefits of maintaining consistency in solar and wind dispatch assumption data from year to year but stress the importance of MISO’s MTEP studies appropriately evaluating both typical system conditions and stressed yet credible planning scenarios, as required by NERC planning standards.
In considering MISO’s proposal to maintain MTEP21 dispatch assumptions for wind and solar in MTEP22 models, the comments below reflect the Owners’ interest in ensuring that the planning assumptions used in MISO’s reliability studies appropriately capture the broadest possible range of credible dispatch and load conditions that can be expected to occur within the TPL planning horizons used in MTEP and Generator Interconnection (GI or DPP) studies.
Solar penetration will certainly increase going forward within the planning horizons studied in MTEP and GI studies. MISO’s Future system reliability planning studies should be modeling solar dispatch, and the coincident dispatch of wind and solar in order to effectively plan for system reliability as penetration levels of intermittent resources increases and traditional generation decreases on the system:
Unlike traditional generation, wind and solar will vary at any time of day or season particularly across a footprint as large as MISOs, irrespective of load levels assumed in each planning scenario so, for purposes of system reliability, MTEP Planning models must represent the bookends of intermittent generation output “under likely and possible dispatch patterns” described in Attachment FF: Section II.A.1, cited in MISO’s December 2021 PSC presentation. In addition to capturing a range of credible dispatch scenarios, NERC TPL guidance also requires that a “more severe” planning scenario be included and identified as such.
More data and analysis is needed to:
(See slide 3 in MISO’s December 2021 PSC Presentation, posted at: https://cdn.misoenergy.org/20211202%20PSC%20Item%2005b%20Annual%20Review%20of%20Wind-Solar%20dispatch%20assumptions%20in%20MTEP%20Models606785.pdf). See also the attached wind and solar duration curves.
MTEP model scenarios should include base case models based on historical and industry data as well as four sensitivity models based on bookends of wind and solar dispatch assumptions (representing low/low; low/high, high/high, and high/low wind/solar dispatch). These bookends should be based on 16 data points within the MISO footprint with a system average applied to the footprint. Although MISO explains in the PSC presentation that solar performance data on the MISO system is not included due to a limited number of installed solar units, actual performance data on MISO’s system is not required to evaluate whether the current dispatch assumptions appropriately capture the bookend planning wind and solar dispatch scenarios recommended by the Owners.
Rather than relying on installed solar capacity in MISO to produce sufficient operating history on which to evaluate appropriate solar dispatch capacity assumptions, MISO could use a source like NREL’s geographic solar output data as a point of comparison to the appropriateness of assumptions used in MTEP21 for MTEP22. In its evaluation of whether changes to current assumptions would more appropriately represent the required TPL planning scenarios, MISO should also consider the rate of increase in solar and wind penetration in its queue and being installed within MISO each year, relative to each other on an LRZ basis in evaluating.
MISO’s TPL (MTEP) studies should capture the bookends represented by the following cases, as appropriate:
Of these scenarios, the “more severe scenario” should continue to be one of the cases used for DPP studies along with a scenario where wind and solar are both dispatched at 100% output of their capacity. While the Transmission Owners recommend these new scenarios, we understand that they will need to be implemented in MTEP for 1-2 passes to understand how the system performs prior to implementing them in the DPP studies.
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Clean Grid Alliance Comments on Wind and Solar Data Monitoring
Presented to the Planning Subcommittee
January 14, 2021
Clean Grid Alliance appreciates the opportunity to provide input on the valuable topic of wind and solar data monitoring. In particular, MISO has asked stakeholders for feedback on two questions that we will respond to in these comments:
Question: Does annual monitoring of Wind/Solar output and potential impact on future reliability provide useful information?
Clean Grid Alliance Response:
CGA supports annual monitoring of Wind/Solar output, as reliability needs of the MISO system are changing, along with the change in mix of generation. We believe it is prudent and necessary for MISO to continue monitoring and reporting, and would ask that battery storage and hybrid projects also be included in future reports.
During the December 2nd meeting of the PSC, a stakeholder raised a concern regarding solar being dispatched at 50% in peak MTEP models, noting that solar will likely dispatch at closer to full capacity in Summer peak conditions. Clean Grid Alliance strongly agrees, and notes that solar in generator interconnection models, and per BPM 15, is dispatched at 100% in peak models. Our understanding has been that MTEP and DPP dispatch were to be aligned. Without this alignment, and with a higher dispatch value in DPP studies than in MTEP, constraints in MTEP will be masked and subsequently shifted to DPP studies where the burden for mitigation is put on generators. We ask that MISO address this concern at the next PSC meeting.
Question: What additional data and format may be helpful?
Clean Grid Alliance Response:
It would be useful if MISO did more than just aggregate all of its footprint together in looking at wind and solar data, and presented more granular data in local resource zones, to increase accuracy. Having this additional data and information will allow MISO to be more informed in making decisions based on reliability assessments.
Finally, we suggest that MISO look at the impact of DER on these values in the future. With the upcoming Order 2222 compliance in April, more DER will come online causing load and peak values to shift. MISO had mentioned that last year around 100 new DERs came online, which is not insignificant, and will only increase over time. It would be valuable for MISO (next year and ongoing) to present load and generation data, identifying any shifts due to DERs. In the interim, we believe it would be helpful for MISO to perform modeling simulations based on patterns to date of DERs, to better predict and adapt to the coming changes.
We appreciate MISO’s consideration of these comments and look forward to the follow up on this important topic.
Sincerely,
Rhonda R. Peters, Ph.D.
Technical Consultant for Clean Grid Alliance
As noted during the Dec 2, 2021 PSC meeting, current penetration levels of solar resources are not indicative of future conditions, especially in the 5 and 10 year models. As the penetration of solar resources increases, WEC Energy Group anticipates the need to model solar within the summer peak models at output levels greater than the current assumption of 50%. The default capacity credit of solar is not indicative of the anticipated output of those resources during the summer (gross) peak hour. During a hot and sunny summer day, solar resources are expected to generate closer to their nameplate rating and studies are needed to ensure those resources are able to reliably serve load.
MISO should calculate monthly wind and solar demand and energy for each LRZ. These data can then be aggregated to all of MISO. This will take some effort but is necessary for good reliability planning with increased renewable penetration. Only in this way can accurate wind and solar capacity values be calculated,
MISO should also take into account the effects of DER solar on the load curve and the future capacity value of solar, As more DER solar is added, the net load peak shifts later in the day decreasing the capacity value of all solar installations (without storage).