MISO’s Independent Market Monitor has expressed lingering dissatisfaction with NERC’s Long-Term Reliability Assessment, even with potentially corrected values.  

Monitor David Patton said though NERC would rerun the numbers on its assessment regarding MISO’s risk, it appears MISO will be downgraded only to an “elevated risk” from “high risk,” which he said he still disagrees with.  

NERC in June said it would rerun the numbers on expected risk for MISO after the IMM discovered an inconsistency in the assessment. NERC apparently used unforced capacity values for MISO when calculating a margin that it ultimately compared to an installed capacity requirement. (See MISO IMM Blasts NERC Long-term Assessment, Says RTO in Good RA Spot.)  

Patton said NERC is likely to call out MISO for elevated risks for a few more summers despite the RTO maintaining an approximate 17% installed capacity requirement that more than covers forced outages during peak summer demand hours.  

Patton said he believes reliability assessments chronically undercount MISO’s interfaces, which grants it more access to imports from neighbors “than just about anybody.” 

“It has a powerful impact during emergencies,” Patton said during a July 10 Market Subcommittee meeting.  

He said even during MISO’s late June emergency declaration in a wide-ranging heat wave, there was “virtually no potential for load loss.” He said MISO’s emergency declaration didn’t escalate into load-modifying resource use and wound down after MISO was able to access the emergency ranges of generation. (See MISO Declares Max Gen Emergency in Heat Wave.) 

“If you look at our neighbors, they were all having operating reserve shortages,” unlike MISO, Patton said.  

Despite his confidence in MISO, Patton urged the MISO community to keep an eye on “four to five years out” so the footprint continues to enjoy reliable operations. He said MISO nevertheless should “keep an eye on the pace of entry” for new generation and “continue to be flexible” to slow down retirements.