During the February 8, 2022, Planning Subcommittee (PSC) meeting, MISO discussed framing the dispatch of storage in MTEP and DPP. MISO requested stakeholder feedback on is this issue limited to stand alone batteries dispatch in DPP and MTEP.
Please provide feedback by March 1.
WEC Energy Group agrees with the comments of ATC on this issue The dispatch assumptions for Battery Energy Storage Systems (BESS) within MTEP and DPP models is not limited to just stand-alone BESS. The issue includes the dispatch of BESS that are within co-located and Hybrid resources. WEC Energy Group also agrees with ATC that the framing of the issue should include consideration of an exemption from the generic dispatch assumptions in cases where the BESS use case is documented and dramatically differs from the generic assumptions.
Alliant Energy appreciates MISO taking up the issue of storage dispatch in MTEP and DPP studies. As noted in previous comments to MISO, Alliant Energy strongly supports this effort and believes that improvements to the way that storage is modeled will better align siting decisions for storage with the value that storage can provide to the MISO system. We also continue to support the previous requests made by CGA to:
1) Revise energy storage dispatch in MTEP and DPP models to remove unrealistic operating scenarios
2) Accommodate the need for limited dispatch studies in MISO’s generator interconnection process so energy storage can be deployed to address transmission needs, which it is unable to do today
3) Capture energy storage asset capabilities in models to reflect the storage technologies seeking interconnection today as well as into the near future with long-duration storage
Our concern again is that MISO’s current study dispatch methodologies for energy storage are not consistent with how these resources will operate. This difference between storage dispatch in MTEP and DPP models and the actual dispatch during operations could prevent valuable grid functions and services from being made available on the MISO system. As it stands now, the interconnection of a very flexible resource like storage can be more challenging than the interconnection of intermittent resources. MISO should ensure its planning is working to enable the benefits flexible resources like storage can provide.
In addition, we believe that the issue does not just apply to stand alone batteries but also applies to hybrid or collocated batteries. Given the increasing need for flexible resources in the MISO footprint Alliant Energy believes it is worth the time and resources to focus on improving MISO’s modeling of storage and its ability to interconnect in multiple forms.
NextEra Energy appreciates the opportunity to provide feedback about the dispatch assumptions used to study standalone batteries in the DPP and MTEP. NextEra has vast experience with battery storage in a variety of applications, including colocated, hybrid, and standalone applications in a variety of US markets. Evidence from CAISO and other regions shows that batteries are typically discharging at their full available capacity during peak load conditions. During shoulder periods, batteries are often idle or charging. We analyzed publicly available five-minute operational data from batteries in CAISO to understand the operational behavior of batteries (see attachment). The data set includes the dispatch of batteries under standalone and colocated configurations from June 2021 until February 2022. The green lines display the daily operation of the CAISO battery fleet. The red line is the average of the green lines. In the attached image there is a clear diurnal pattern that reflects the market prices and system conditions.
Based on the publicly available data from CAISO and NextEra’s first-hand experience with standalone batteries, we recommend that MISO MTEP and DPP studies assume batteries are discharging at 100% during peak conditions and are turned “off” during shoulder conditions. This approach is consistent with requirements outlined in the Generator Interconnection Business Practice Manual (BPM) 015. That BPM indicates that storage assets that would like to charge from the grid must submit a transmission service request. To accommodate that request, batteries are studied under a variety of dispatch assumptions that supersede the requirements of MTEP and DPP.
3/1/2022
National Grid Renewables Comments on MISO Storage Dispatch Assumptions
National Grid Renewables thanks MISO for responding to stakeholder concerns about storage dispatch assumptions. Accurate dispatch assumptions will enhance long-term planning and generator interconnection by more accurately identifying upgrades based on a more realistic dispatch of storage resources.[1] National Grid Renewables appreciates the opportunity to comment on the scope of this assessment and provides the following feedback.
As an initial matter, the scope of this initiative should include both stand-alone storage and hybrid facilities. Hybrid resources have distinct operating profiles relative to stand-alone storage and both should be considered to maximize the benefits of this exercise as both types of resources are significantly present in the queue; as of February 20th, 2022, there were approximately 15,000MW of hybrid resources and 14,000MW of battery storage in the MISO queue.
National Grid Renewables believes it is reasonable to assume that energy storage will be sited close to transmission constraints. Modeling facilities accordingly in long-term planning scenarios reflects the ability of the resources to capture the respective market and charging opportunities depending on system conditions. These assumptions reflect logical behaviors for these facilities and enhance long-term planning by more accurately reflecting the reliability and economic benefits of realistic operational modeling of the resources. This trend is also reflected in the current MISO queue of co-located and hybrid resources. These assumptions should be reflected in the development of storage dispatch assumptions as well.
To effectively implement changes to storage dispatch assumptions, MISO should outline the “several modes of operation”[2] they intend to incorporate in this assessment and explain how and why they were chosen.[3] This will enable MISO to benefit from stakeholder feedback; although MISO dispatches resources, stakeholders develop operational plans to capture highest value based on expected system conditions and this feedback will enable MISO to fine tune the modes of operation ultimately adopted in this exercise so they are as accurate as possible – which, again, will enhance the effectiveness and efficiency of the long term transmission planning process.
[1] For generator interconnection purposes, although there is potential benefits to accurately modeling stand-alone storage and hybrid facilities based on realistic dispatch assumptions, these resources must be modeled at 100% of nameplate (or other relevant value) on-peak to ensure the resources receive injection/interconnection rights equal to their full capability as reflected in the interconnection requests. Any changes resulting from this review must ensure requested interconnection rights are respected in the modeling.
[2] Storage modeling is complex and will require iteration to achieve a useful, accurate set of assumptions. National Grid Renewables encourages MISO to allow time for stakeholder feedback on the substantive changes of this assessment, not just the scope.
[3] In a long term planning process, modes of operation should include storage offering into multiple/different ISO/RTO markets.
After a few months of preliminary discussion, MISO is soliciting feedback on the scope of studying the dispatch of stand-alone storage. Though MISO has previously recognized the "unique flexibility" of storage and acknowledges that hybrid resources benefit from study flexibility, in its solicitation for feedback, MISO asserts that special NRIS dispatch studies for storage are not necessary because NRIS dispatch studies are "fuel agnostic."
Invenergy disagrees that current dispatch studies for storage are sufficient. The behavior of storage is fundamentally different from any other generation on the grid and should thus be studied differently.
Unlike any other resource, storage provides both demand AND supply services to the grid. The Network Resource Integration Service Studies operate with the underlying assumption that the studied resource's impact on the grid is defined by its dispatch. However, storage also charges, the impacts of which are not considered in a dispatch study.
MISO's assertion that current NRIS studies are sufficient because "NRIS dispatch is fuel agnostic" fails to acknowledge that storage is not a generating resource, but a balancing resource. Storage does not run on fuel like traditional baseload or even intermittent resources. Their value does not lie in providing the grid with new generation, but rather smoothing peaks and easing congestion.
Regarding the framing of Stand-Alone Storage dispatch discussions, Invenergy urges MISO to consider a new type of NRIS study for stand-alone storage. If storage is studied through current NRIS, MISO will (1) inaccurately account for the impact of batteries on neighboring resources, (2) incorrectly model power-flow on the grid, and (3) insufficiently compensate storage resources for the smoothing and congestion alleviation services they provide.
Stand-alone storage is an essential technology to maintain reliability on the Grid of the Future and Invenergy asks MISO to expeditiously leverage the stakeholder process in development of accurate dispatch assumptions.
WPPI Energy appreciates the opportunity to provide feedback on the framing of the issue of dispatch storage. Based on MISO's presentation, we expect more detailed discussion of potential solutions to take place in future meetings.
We see the issue as potentially applicable to all battery storage resources in MISO. We focus here on the generation interconnection process,
We are concerned that, as currently implemented, battery storage is modeled in interconnection studies in a way that makes it appear to have system impacts at least as severe as other generation, and more severe to the extent that re-charging mode has material impacts. We see this as inappropriate, since we expect battery storage to be dispatched in a way that tends to alleviate congestion. We also see this as a potentially serious problem to the extent it poses a hurdle to increased interconnection of storage resources, which we expect to play an important role in accommodating an expected much higher penetration of intermittent resources in the future.
Comments to the PSC on Dispatch of Storage in MTEP and DPP Studies
March 1, 2022
The Environmental Sector appreciates the opportunity to provide comments on dispatch of battery storage in MTEP and DPP studies. We agree with MISO’s clarification that the objective of this current effort is to eliminate or revise storage dispatch downward in the ERIS shoulder case of the fuel dispatch table for Energy Storage in Business Practice Manual 15. Currently storage is dispatched at 100% in both the Peak and Shoulder ERIS cases, but does not operate in that manner in the Shoulder case, leading to unnecessary upgrades and high costs for projects to interconnect. Revision of storage dispatch to 0% in the shoulder case would address this problem.
This topic was first introduced to the PSC in June 2021, with a request to expedite. We appreciate and support MISO’s stated intention at the Feb 2022 PSC to make a proposal/recommendation at the April PSC meeting, based on available operational data.
ATC thanks MISO for providing the opportunity to provide comments on this item.
We believe that the issue of dispatch of storage in DPP and MTEP studies that was discussed at the last PSC meeting does not just apply to stand alone batteries but may also apply to hybrid or collocated batteries. We note that it is important to recognize when hybrids resources make the decision to charge or not charge from the transmission system (as they will require a Transmission Service agreement if they charge from transmission system). Transmission Owners will need to know which storage resources are or are not charged from the transmission system for dispatch in MTEP studies, which MISO should track (maybe as part of the resource naming convention). Also, for MTEP studies, the maximum charging rate at any time should also be communicated especially if the storage owner will limit charging because of operational limitations or economic reasons.
As part of the scope of this item, we also recognize that market-based storage devices may have other use cases that may not follow the typical dispatch outlined in in BPM-015 or from the MISO Reliability Planning Model Data Requirements & Reporting Procedures document.[1] The generic dispatch assumptions may suffice when the storage use case is not known, but there could be some leeway given if the use case would prove inconsistent with the general dispatch assumptions (MISO would need an exception process). We also agree that as operational data becomes available, additional consideration should be given to allow for other dispatch options. We also note that MTEP and DPP study objectives are different, therefore modeling assumption differences could be reasonable, but should be noted and tracked.
[1] See Table 5.1: Potential BESS and Hybrid Plant Study Dispatch Scenarios from NERC IRPWG’s Performance, Modeling, and Simulations of BPS-Connected Battery Energy Storage Systems and Hybrid Power Plants guideline.
Via Electronic Mail
February 24, 2022
Thompson Adu
MISO Planning Subcommittee Liaison
Email: tadu@misoenergy.org
RE: Dispatch of Storage in MTEP and DPP Studies
Dear Mr. Adu,
Key Capture Energy (“KCE”) is a developer, owner, and operator of standalone battery storage projects. Founded in 2016, KCE has 54 MW (five projects) of standalone battery projects in operation in New York and Texas. KCE has 220 MW of storage projects currently in construction and a development pipeline of over 3 GW, including 700 MW located in MISO.
KCE would like to thank MISO for investigating dispatch of storage in MTEP and DPP studies, as proposed at the MISO Planning Subcommittee Meeting on August 10, 2021[1]. Per our letter from August 25, 2021, we strongly support this effort and believe that improvements to the way that storage is modeled will better align siting decisions for storage with the value that storage can provide to the MISO system[2].
Consistent with our verbal feedback at the February 8th PSC meeting, our primary point of concern is MISO’s current practice of dispatching storage under worst-case conditions during low load shoulder periods in the ERIS steady state modeling. This approach does not reflect the real-world operation of storage in response to wholesale market pricing signals, as illustrated by battery operational data KCE has compiled from projects operating in ERCOT and CAISO. A more appropriate dispatch for batteries during the shoulder case would be 0%.
We commend MISO for investigating this issue and respectfully urge MISO to move forward with a recommendation on storage modeling improvements at the upcoming April PSC.
Sincerely,
/s/ Danny Musher .
Danny Musher
Director, Market Design
Key Capture Energy, LLC