FERC on Tuesday approved MISO’s plan to replace its retirement notification process with a more general three-year generation suspension period.

MISO’s proposal places all generation owners submitting an Attachment Y retirement notice into a catch-all three-year suspension period, with suspended units maintaining interconnection rights for the full three years unless they formally decide to retire (ER18-1636). Units that do not return to service after three years are presumed retired and their interconnection rights dissolved. The changes became effective July 16, 2018.

After FERC issued a July deficiency letter on the proposal, MISO said the new suspension process would still allow it to designate resources seeking suspension as system support resources needed to keep operating for reliability reasons. (See FERC Seeks Details on Proposed MISO Retirement Rules.) The RTO also explained its old suspension process wasn’t working as intended, saying that out of 77 suspensions over the last five years, only eight generators returned to service at the end of the originally designated suspension period.

For modeling purposes, MISO will treat approved suspensions as unavailable resources with no specified date of return service. MISO also said its proposal requires no notice from a generation owner should it want to change its suspension status into a permanent retirement anytime during the three years.

FERC said MISO’s proposal that modeling not anticipate suspended units will return to service “better reflects the inherent uncertainty of planning.”

” … We agree with MISO that its current requirement to provide a return-to-service date in Attachment Y Notices to suspend may at times create an illusion of certainty that does not actually exist,” the commission said.

— Amanda Durish Cook