FERC has decided it’s practical for MISO to have an almost three-year extension of the commission’s directive to implement ambient-adjusted transmission line ratings (ER22-2363-002). 

With FERC’s June 6 decision, MISO has until December 2028 to fulfill its responsibilities under Order 881. Without the postponement, the RTO would have had until July to prepare its systems to accept more varied line ratings from transmission owners. 

MISO cited vendors’ delays supplying software for the range of line ratings required under Order 881. (See MISO to Seek 3-Year Order 881 Delay for Vendor Holdups.) 

The commission said MISO “demonstrated that delays in the delivery of vendor software are beyond its control.” FERC said the extra three years are key to ensuring continuing reliable market operations.   

“We are persuaded by MISO’s argument that requiring MISO to implement interim processes could further postpone MISO’s overall compliance efforts,” FERC wrote.  

The commission accepted MISO’s explanation that its ability to test the capability hinges on having Limit Exchange Portal (LEP) upgrades in place, which has the RTO and its TOs drawing on the same limited collection of software vendors. MISO also said it needed its new market clearing engine in place before it could use the more technologically advanced LEP.  

The commission overruled the Organization of MISO States’ suggestion that the RTO could introduce AARs as much as possible in stages. It agreed with MISO that that would “ignore the interlinked nature of the software development MISO requires.” FERC said ordering staggered compliance could cause further delay.  

FERC took MISO up on its offer to make annual informational filings that describe its progress on the LEP.  

During MISO’s quarterly board meetings in March, ITC Holdings’ Brian Drumm said TOs have met regularly with the RTO on Order 881 compliance since the rule was issued. He said the TOs take seriously their duty to implement AARs, which he called no small task.  

“It’s an overlay of an entire network and information flowing back and forth,” Drumm said. TOs are “all trying to capture the attention of a very select pool of vendors.”