US Midcontinent ISO defends efforts to help neighbors during December storm

Midcontinent Independent System Operator is defending its decision to deploy its load modifying resources to help its neighbors during the December 2022 storm after stakeholders questioned whether it was fair to ask for load reduction to benefit another region.

MISO's emergency operating procedures permit the grid operator to deploy LMRs to assist neighbors that are in a comparable or worse condition, John Harmon, director of market administration at MISO, told a Feb. 28 meeting of the MISO Reliability Subcommittee.

"It is pretty clear the procedures allow us to do that," Harmon said. But more clarity may be needed for unusual scenarios, he said. MISO has tasked the subcommittee with reviewing the procedures for deploying LMRs as one of its action items after the storm.

MISO exports

MISO consistently exported power to its southern neighbors during the December storm, with maximum exports nearing 5 GW, MISO staff told the subcommittee during a Jan. 17 meeting.

MISO was not at risk of insufficient capacity during the weather event, but it still used its emergency procedures and access its LMRs so it could help its neighbors who were shedding load, staff said during the January meeting.

MISO's neighbors were consistently at Energy Emergency Alert level 2 or EEA level 3, MISO staff said. EEA 2 means that a balancing authority is using all available generation and is implementing demand-side management. EEA 3 means that firm load shed is imminent or in progress.

At the time, some MISO stakeholders raised concern about the use of LMRs during the winter weather event. LMRs did not sign up to support non-firm market exports, Chris Plante, a regulatory and policy manager at WEC Energy Group, said at the Jan. 17 meeting. More clarity is needed on when LMRs are called on to support exports, he said.

Storm action items

In response to this concern, MISO has assigned the subcommittee to take another look at the procedures for LMR deployments.

The subcommittee will review emergency operations procedures pertaining to LMR deployments and curtailments of non-firm exports, including energy emergency alert levels, according to a presentation discussed at the Feb. 28 meeting.

The subcommittee will also consider six other action items related to the storm, including reviewing the process to change the regional directional transfer limit between MISO Central and MISO South, reviewing the load forecasting process for opportunities for improvement, and reviewing unit commitment practices for gas-fueled generators for forecasted high-risk operating days.

The subcommittee is also slated to conduct an analysis of resource performance by fuel type and outage cause, describe lessons learned and action items to improve communication of alerts to market participants, and compare the scheduled and actual imports and exports.

The action items respond to a wide range of issues raised during the January meeting. For instance, abnormally high load forecasting errors occurred due to a lack of historical data for similar extreme conditions in December, according to a MISO presentation. Members of the subcommittee also raised concern that MISO did not call on gas-fired generators soon enough for them to procure gas before the holiday weekend.