CARMEL, Ind. — MISO hopes to mete out different reserve margin obligations to its load-serving entities as it sees bigger perils on the horizon.
The grid operator says because of shifting and growing risks to the system, its reliability requirement should be reallocated among LSEs based on periods that contain the highest reliability risks. Today, MISO divvies up its planning reserve margin requirement (PRMR) based only on LSEs’ 50/50 load forecast for its coincident peak.
MISO instead would like the PRMR spread among load-serving entities based on historical load during MISO’s set of predefined risky hours that already are used to gauge capacity accreditation values.
At a Jan. 15 Resource Adequacy Subcommittee meeting, MISO’s Neil Shah said the RTO would look back one year to get an idea of historical load. The RTO first mulled using three years of historical load data but said a one-year lookback should be sufficient in an era of expanding load.
Shah said the demand uncovered in MISO’s loss of load expectation study — which is used to set the PRMR — diverges from the demand it sees in its capacity auctions. He said MISO’s probabilistic modeling “observes risks at load levels that are much higher than 50/50 coincident peak load.”
A recalibration of the PRMR distribution should remove a “misalignment” between LSEs’ obligations and the load LSEs are consuming at the times of highest need on the system, Shah said.
Shah said MISO hopes to make a filing with FERC on LSEs’ PRMR values sometime in 2025 after workshopping the proposal with stakeholders.
MISO also said portioning out the PRMR to LSEs based on demand during system risk will line up with its recently approved resource accreditation, which accredits resources based on their availability during risky hours. (See FERC Approves New MISO Probabilistic Capacity Accreditation.) MISO originally considered including a PRMR reallocation as part of the early 2024 capacity accreditation filing to FERC but later decided to hold off and make a separate filing.
