In the October 19, 2022, meeting of the Planning Advisory Committee (PAC), MISO presented a proposal and draft BPM language for dispatch of storage in MTEP and Definitive Planning Phase (DPP) studies. Stakeholders were invited to submit feedback.
Comments are due by November 9.
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 strongly supports the change to the Shoulder Peak Dispatch of storage from +/-100% to 0%. Consistent with data assembled by KCE and shown at the April PSC, this fuel dispatch assumption more accurately aligns with real-world operation of storage in response to low load conditions and wholesale market pricing signals. KCE would like to thank MISO for proposing this change, which we expect will better align siting decisions for storage with the value that storage can provide to the MISO system.
Transmission Owner Feedback on Dispatch of Storage in MTEP and DPP Studies
November 9, 2022
The MISO Transmission Owners[1] (Owners or TOs) appreciate MISO’s presentation at the October 19, 2022 Planning Advisory Committee meeting on the issue of Dispatch of Stand Alone Storage Resources in the DPP, and proposed changes to the current dispatch assumptions in DPP Studies. The Owners support the overall objective of dispatching these resources in the DPP as they are likely to be operated, and the feedback below is in support of that objective.
The Owners agree that the operational data from ERCOT and CAISO referenced by MISO supports the MISO’s determination that studying a +100% dispatch case in the shoulder peak period for storage is not consistent with operational expectations and is not needed in the DPP. However, the Owners are concerned with the potential reliability impacts of MISO’s proposal to eliminate the study of storage in the charging mode (i.e., elimination of -100% dispatch) in the Shoulder Peak scenario, which charging from the Transmission System is most likely to occur based typically lower energy prices.
MISO has suggested that the potential Transmission System impacts of charging an energy storage resource from the transmission system will be evaluated through the Transmission Service Request process, necessitated by Order 841’s requirement that transmission service charges apply to the withdrawal of energy from the transmission system for later resale in the wholesale market. The Owners, however, do not believe that the current TSR process is sufficient to cover all necessary reliability studies under FAC-002, TPL-001 and Local Planning Criteria; in particular, the Owners are concerned about voltage stability issues that could result from the instantaneous withdrawal of energy from the transmission system energy that are not studied in the Transmission Service Request evaluations. These concerns are the basis for three recommended modifications to MISO’s proposed revisions to the BPM-015 provisions relating to the evaluation of energy storage resources in the DPP:
6.1.3 Storage Charging from the Grid
If a storage interconnection application indicates that it will charge from the grid, it will be modeled at its default maximum charging capability in the DPP Shoulder Peak charging case as shown in Table 6.1. For system constraints that appear only in the DPP Shoulder Peak charging case, lowering the battery charging rate(s) could be considered as a feasible mitigation option if accepted by the developer and local TO. If a lower charging limit is identified, it would be considered as the charging operating limit cap for the GIA.
3. Revise or remove Footnote 9 to Table 6-1:
“Storage requests need Transmission Service if they will be charging from the Transmission System; GIA does not grant Transmission Service. In order to obtain any type of Transmission Service for charging from the Transmission System, the IC will have to seek service as a Transmission Customer.”
This language, as currently stated, may confuse rather than clarify requirements for withdrawing energy from the transmission system, which always requires procurement of Transmission Service, regardless of the resource type. Such withdrawals have typically been by Transmission Owners through Load Interconnection studies that establish new Points of Delivery to which Transmission Service can be requested, but energy storage resources are a new type of load, which have thus far been studied through the GIP.
While there are other options for evaluating the potential system impact of an energy storage resource charging from the Transmission System, the Owners believe that continuing to evaluate these impacts through a charging scenario in DPP studies would be the most efficient means of doing so at this point, though additional discussion may be warranted going forward.
Invenergy supports the proposal to model storage dispatch at 100% in Peak models and 0% in Off-Peak models as well as the timeline for prompt implementation. These new storage dispatch assumptions will more closely approximate battery operation than the status quo. Invenergy appreciates MISO’s work to refine these assumptions to create a clearer picture of the future grid and facilitate stakeholders in their decision making.
ENVIRONMENTAL SECTOR COMMENTS ON 20221019 PAC ITEM 5C REGARDING STORAGE DISPATCH
The Environmental Sector supports MISO's proposed change to BPM 15 that removes storage dispatch in the Shoulder model/study for stand-alone storage. Operational data supports this change, which will enable more accurate modeling of storage in planning studies.
The Environmental Sector also supports MISO's proposed implementation of this change in MTEP 23 and the Definitive Planning Phase (DPP) 2022.