Conventional capacity resources in MISO will now have to prove full deliverability before collecting maximum capacity credits, FERC said last week.

The commission on Oct. 27 approved the RTO’s proposal to require capacity resources to demonstrate deliverability through firm transmission service up to installed capacity (ICAP) levels before they can convert their entire unforced capacity (UCAP) into zonal resource credits (ER20-1942).

MISO said procuring firm transmission remains optional for capacity resources, provided that they are comfortable with settling for fewer capacity credits based on their partial ability to deliver. The RTO said it plans to prorate credits. Staff have previously acknowledged that it may be expensive for some resources to secure firm transmission service up to their installed capacity levels.

The RTO used to allow capacity resources to demonstrate full deliverability based on UCAP levels — something its Independent Market Monitor has long called inconsistent with the assumptions used in the grid operator’s loss-of-load expectation (LOLE) study, which assumes that all capacity resources are fully deliverable.

Before, MISO’s Tariff required capacity resources to demonstrate capacity deliverability by having network resource interconnection service, which stipulates that the entire ICAP of the resources must be deliverable. However, the Tariff also allowed resources to demonstrate deliverability by securing energy resource interconnection service and procuring firm transmission service up to their UCAP levels, which tend to be about 5 to 10% below full ICAP levels.

FERC agreed that the second option needed to be eliminated for the sake of reliability and accurate reserve margins.

“MISO has demonstrated a disparity between its LOLE study assumptions and the deliverability requirements associated with conventional capacity resources used to satisfy MISO’s reserve requirements,” the commission said. “As MISO explains, the LOLE analysis, and therefore the resultant reserve margin and reserve requirements, assumes that a conventional capacity resource can deliver its full installed capacity level of output when it is online. Therefore, we find reasonable MISO’s proposal to require all conventional capacity resources that seek to participate in MISO’s resource adequacy construct at their full unforced capacity levels to demonstrate deliverability up to their installed capacity levels. In doing so, MISO’s proposal will provide certainty that MISO’s reserve requirements are satisfied by fully deliverable planning resources, thereby ensuring that MISO meets its reliability needs.”