NEW ORLEANS — MISO may have to delay its first seasonal capacity auction after FERC issued a show-cause order Friday for the RTO’s capacity ratio that it must publish ahead of the auction.

FERC ordered MISO to either update an unforced capacity to intermediate seasonal accredited capacity ratio that it uses to gauge anticipated supply or explain why it shouldn’t have to. (See MISO Issued Show-cause on Seasonal Capacity Auction Values.)

Executives said this week the order will hinder MISO’s ability to conduct the seasonal auction on time.

Staff reported that a software error counted previously excused generation outages against capacity accreditation, resulting in smaller capacity values than expected. While they corrected individual ratios for multiple units, they did not update a summary systemwide ratio. The RTO said it didn’t have time to rework the systemwide data point before it conducts the 2023/24 planning resource auction.

“It will likely mean an ultimate delay in our auction,” Zak Joundi, director of resource adequacy coordination, told the Board of Directors’ Markets Committee Tuesday.

Joundi said MISO expects to publish auction results in mid-May, about a month behind schedule.

The four seasonal auctions that were to be conducted concurrently in early April are the grid operators first stab at using a seasonal capacity framework.

Joundi said FERC’s order was “hot off the presses” and that staff was still reviewing the commission’s directive. He acknowledged that members and staff might be disappointed by the delay, but the ratio must be recalculated.

“I understand that there are a lot of folks in the room that have done a lot of work,” he said.

“We’re going to comply with what FERC tells us and get this auction run as quickly as possible,” MISO Independent Market Monitor David Patton said.

Patton had alerted the RTO late last year that it was artificially inflating seasonal capacity requirements because it assumed generators on planned outages were offering capacity. (See IMM: Faulty Assumption in MISO’s Seasonal Auction Design.)

“A little bump in the road here, but you’re a leader in this area, and I commend you,” MISO director Tripp Doggett said, referencing the seasonal auction.

WEC Energy Group’s Chris Plante said the potential delay and revised ratio shows that the stakeholder community may have been justified in urging MISO to delay the auctions for a year and to use its normal annual method for the 2023/24 planning year.

“I think there’s a lesson to be learned here, and that’s stakeholders are experts in this process alongside MISO,” he said.

Staff used mounting reliability risks outside the summer peak as evidence that they needed to get a jump on dividing capacity contributions and requirements by season.