In the November 29, 2022, meeting of the Planning Advisory Committee (PAC), MISO presented an updated recommendation for dispatch of storage in MTEP and DPP studies as well as supporting draft BPM-015 language. Stakeholders were asked to review and provide feedback.
Comments are due by January 6.
Key Capture Energy ("KCE") is a developer, owner, and operator of standalone battery storage projects. KCE appreciates the opportunity to provide feedback on MISO's proposed BPM-015 redlines to the Fuel Type Dispatch Table. KCE continues to strongly support removing the discharge case of +100% for storage from the Shoulder Peak Dispatch. This case is inconsistent with the real-world operation of storage in response to low load conditions and wholesale market pricing signals.
Regarding the charging case in the Shoulder Peak Dispatch, if MISO keeps the charge case of -100%, KCE agrees that interconnection customers should be allowed to establish charging limits in lieu of incurring network upgrades to mitigate system constraints. However, because MISO states that a GIA does not grant Transmission Service, and the interconnection customer will need to request Transmission Service in order to charge from the Transmission System, KCE proposes that any charging limitations identified in GI studies should be removed if the subsequent TSR process does not indicate that the applicable system constraints related to charging are triggered.
Regardless of MISO’s decision on whether to maintain or eliminate the charge case, KCE urges MISO to move forward expeditiously with removing the discharge case prior to the initiation of DPP 2022.
Finally, KCE suggests one editorial/clarifying change to the following sentence on slide 6, footnote 9, to maintain consistency with MISO’s 841 filing: “Transmission Service is required to charge from the Transmission System for ESRs, except when dispatched to provide Regulating Service or Down Ramp Capability; the GIA does not grant Transmission Service.”
KCE thanks MISO for their work on this important issue.
SoftBank Energy (SB Energy) appreciates the opportunity to provide feedback on the topic “Dispatch of Storage in DPP and MTEP Studies” currently being discussed at the Planning Advisory Committee (PAC). Please consider the below comments:
SB Energy would like to thank MISO for the opportunity to comment.
Charging scenarios should not be studied in the Definitive Planning Process (DPP) as long as Transmission Service Requests (TSRs) are required to utilize the transmission system for charging the battery storage facilities since a DPP study of charging would not grant any transmission rights and would not grant the ability to charge.
NextEra views the justification for studying charging in DPP was that the TSR process as inadequate. It is not the role of the DPP process to be overly stringent to compensate for issues stakeholders have with unrelated processes. As long as the TSR process is the route for obtaining the rights to charge, it should be the avenue of studying the impact of charging.
Invenergy appreciates the time and attention that MISO staff has put toward aligning storage and hybrid dispatch modeling assumptions with the expected behavior of the asset. Invenergysupports the intent and the direction of these changes but offerone additional critical consideration.
Invenergy urges MISO to distinguish between short duration and long duration storage, as these two assets have fundamentally different behavior.
Invenergy agrees with the proposal that stand-alone storage be dispatched at 0% during shoulder peak, as short-duration storage would have little incentive to discharge during shoulder peak-like periods with low load, high generation, low energy prices. The nature of short-duration storage would necessitate that it behaves similarly during shoulder-peak in both a hybrid and stand-alone configuration. However, the proposed dispatch assumptions have storage dispatching at 100% during shoulder-peak in a hybrid configuration, which is reasonable if the storage component were long-duration (multi day) and/or if the intended dispatch is to firm asset 24/7, as presented in MISO’s most recent presentation (data courtesy of Clean Grid Alliance and Form Energy), but this is not a reasonable dispatch for short-duration storage. The intended dispatch for storage in this example is to firm the hybrid asset and is not necessarily responding to a price signal to dispatch, meaning it will still dispatch during off-peak hours to fill the gaps left by the intermittent renewable asset.
However, NREL has shown that PV hybrids with short duration storage would behave nearly identical to separate PV and storage systems, responding to the peak signal as expected. Boththe standalone and hybrid storage charge during periods of low energy prices and discharges during periods of high energy prices corresponding to typical periods of high demand and low supply. This further confirms that hybrids with short duration storage should follow the same dispatch methodology as standalone storage. (Source: Denholm et al., “The evolving energy and capacity values of utility-scale PV-plus-battery hybrid system architectures”, Advances in Applied Energy (2021))
The differences in capabilities between long and short duration storage result in different behavior and thus should be modeled with their own assumptions. A lack of this distinction may result in long-duration standalone storage to be under-modeled at shoulder or a short-duration hybrid configuration to be assumed to dispatch during hours where it will have no incentive to do so.
As the proliferation of storage resources accelerates in the coming years, accurate modeling will become an increasingly important component of maintaining reliability.
Invenergy would ask MISO to consider the following dispatch methodology:
As a placeholder delineation, Invenergy might offer that short-duration storage have 10 hours or less and anything longer belong-duration .
While acknowledging that this discussion may be out of scope for this change, Invenergy would ask MISO to walk through the reasoning behind needing to acquire TSR as load if storage will be studied to be charging during shoulder peak.
Clean Grid Alliance Comments on Dispatch of Storage in DPP and MTEP Studies
January 6, 2023
Clean Grid Alliance appreciates the opportunity to comment on the Dispatch of Storage in DPP and MTEP Studies. We strongly support MISO’s proposed change to remove storage dispatch in the Shoulder Study and encourage its quick implementation for the 2022 DPP cycle as proposed. Data shows that stand alone storage does not inject power in the Shoulder period. Studying it in planning as if it does has prevented storage from being installed in the locations it is needed most - to alleviate congestion. The proposed change to storage dispatch is similar to previous dispatch changes MISO has made to other fuel sources to align planning studies with real time operations for more accurate study results. The proposal to remove storage injection in the Shoulder study has been discussed for over a year and half in the MISO stakeholder process and has broad support among diverse stakeholder groups. We encourage MISO to finalize this change as soon as possible.
MISO has also proposed to make clarifications to battery storage withdrawal in the Shoulder DPP study. While we support MISO’s BPM 15 clarification that energy storage will not be required to fund costly Network Upgrades related to charging, we question whether other loads are being held to same standards as energy storage in being studied for withdrawal both through a Transmission Service Request (TSR) and in the Generator Interconnection (GIP) process. While we do not seek to hold up the current proposal, we encourage MISO to consider how to better align the two process, including 1) allowing a subsequent TSR study to remove any limitations that might be put on storage in the DPP process, and 2) whether loads that do not seek to inject but only withdraw power, could equally be subjected to rate limitations in the TSR process, as are being imposed in the Generator Interconnection Process for load withdrawals.
The Environmental Sector appreciates MISO’s ongoing attention to storage dispatch assumptions in the MTEP and DPP studies and this opportunity to provide feedback on MISO’s current proposal.
1) We strongly support MISO’s proposal to remove storage dispatch in the Shoulder Study and encourage its quick implementation for the 2022 DPP cycle. Studying storage as if it injects power in the Shoulder period when the data indicates it does not has led to unnecessarily high Network Upgrade costs for storage projects, particularly in congested areas where storage’s arbitrage capabilities would be most valuable. The proposed change to storage dispatch is consistent with previous dispatch changes MISO has made for other fuel sources to align planning studies with real time operations, resulting in more accurate study results. MISO’s proposal has broad stakeholder support, and we encourage MISO to finalize this change as soon as possible.
2) MISO should consider limiting the study of storage withdrawals to the TSR process or, at a minimum, allow TSR studies to adjust or remove limitations imposed through the DPP process. The BPM language MISO has proposed to address withdrawal in the Shoulder Study is an improvement over the current process, and we support MISO’s clarification that energy storage can reduce its rate of charge rather than pay for costly Network Upgrades to address a reliability issue. However, we have concerns over MISO’s proposal to continue studying withdrawals in the GIP process when storage withdrawals are also studied in the TSR process.
Studying storage withdrawals in both the GIP and TSR processes puts storage on unequal footing with other load withdrawals. Other loads are not studied for withdrawal both through a TSR and in the GIP process, and therefore do not have ramp rate or other limitations applied in the GIP process while also being required to go through the TSR process where additional upgrades can be assigned. This unequal treatment creates barriers to storage deployment, and we encourage MISO to consider the utility and fairness of this practice. Studying storage withdrawal and addressing any study gaps through the TSR process alone may be more appropriate to ensure storage is treated similarly to other load withdrawals. At a minimum, MISO should allow for TSR study results to supplement DPP withdrawal study results and, where applicable, remove or adjust any limitations placed on projects in the DPP process.
3) MISO should move quickly to implement these changes. The proposed changes will improve the accuracy of MISO studies, have an immediate and meaningful impact on the ability of storage to connect, and help unlock the benefits of storage, including resource adequacy and congestion relief, to the MISO system. For these reasons, MISO should prioritize the implementation of these changes in time to be applied to the 2022 DPP study group.
Thank you
The MISO Environmental Sector
SunEnergy1 appreciates the opportunity of providing feedback.
SunEnergy1 believes that MISO needs to work out more details regarding battery charging study implications and how GIA will document it. It is OK if the charging study serves as pre-study that future TSR study can refer to (potentially avoid a re-study). It is not OK if it creates a withdraw limit for the battery. That essentially creates an inconsistent treatment between battery and other load additions -- while battery withdraw has to pass GI study, other new load withdraws don't have to pass GI.
We look forward to working with MISO further on this topic.