By Amanda Durish Cook

CARMEL, Ind. — MISO’s Independent Market Monitor is backing the RTO’s proposal to revise its uninstructed deviation rules to allow generators to recoup a portion of make-whole payments even when their ramp rates fall short of expectations.

Monitor David Patton said last week that he now favors the “less draconian” performance-based proposal over his original recommendation from last year’s State of the Market report.

MISO’s plan would calculate a generator’s uninstructed deviation by comparing the time-weighted average of its real-time ramp rate with its day-ahead offered ramp rate, while allowing for a 12% tolerance from set point instructions. The proposal eliminates the RTO’s current “all or nothing” eligibility for make-whole payments, instead allowing generators to collect full payments when they respond to dispatch instructions at a rate of 80% or higher over an hour, while excluding payouts when performance rates fall below 20%. Units operating between those two thresholds would earn make-whole payments in proportion to performance.

The RTO currently flags generators that deviate from ramp rate dispatch instructions by more than 8% over four consecutive five-minute intervals, putting them at risk of losing day-ahead margin assurance payments (DAMAPs). The new approach would eliminate all current ramp rate requirements except for the one requiring rates of greater than 0.5 MW/minute.

Patton said MISO’s time-weighted approach provides generators greater incentive to follow their offered ramp rates than his earlier proposal requiring units to move at least half their offered ramp rate within a 20-minute grace period before being flagged and losing make-whole payments. (See MISO Tempers Dispatch Plan After Stakeholder Pushback.)

“That 15 minutes is a knife edge,” Patton said of the originally proposed 20-minute grace period before becoming ineligible for DAMAPs. “Generators motionless after 15 minutes will have to move at 100% of their ramp rate immediately to avoid exceeding 20 minutes.”

He also pointed to the benefits of performance-based partial payments.

“Over the course of an hour, generators will have a stronger incentive to perform better. If you perform reasonably well, you’ll make more money than if you don’t perform reasonably well,” he said.

Patton said MISO generators have so far been discouraged from providing a “multi-point” ramp rate that factors the time it takes to move a unit in the first few moments after firing it up. He said using an average of hourly performance will allow for nuances.

Some stakeholders agreed that it was a good idea to allow a lagging lead-time for slow-moving units but said the proposal doesn’t help wind and solar generators, which have a tendency to be flagged for excessive energy production.

Patton acknowledged that wind power may need a “special rule,” saying MISO could make “simple” changes to excessive energy flags for wind only when the excessive ramping doesn’t cause congestion.

MISO plans to continue refining the uninstructed deviation proposal through April.