PJM is planning changes to the way it estimates Tier 1 synchronized reserves after SR performance fell far short of expectations during the Sept. 10 heat spike. The RTO wants to make at least some of five proposed changes by the end of the year.

On Sept. 10, PJM received only 200 MW of Tier 1 reserves in the RFC region (the RTO excluding the Dominion zone), less than one-fifth of the 1,435 MW estimated by system operators. Members had claimed 4,000 MW of reserves, PJM staff told the Operating Committee last week.

“Wacky,” remarked one member.

Operators’ lack of confidence in reported reserves led PJM to call on a record amount of demand response on Sept. 11. Gaps are not critical most days, but referring to the stressful September event, a staff member said, “These are the days we need to worry about.” (See Big To-Do List from September Heat Wave)

If all five changes that staff has proposed had been in place, the Sept. 10 estimate would have been about 301 MW, about 100 MW above the actual response, according to Senior Reliability Engineer Chris Pilong.

Pilong said staff wanted feedback on the changes although it does not need member approval to implement them. PJM plans to “nail down” their changes at the next OC meeting, Nov. 5.

The changes being considered would:

• Cap Tier 1 estimates based on the lowest of EcoMax, SpinMax or Emergency Max. An analysis of the last 42 spinning-reserves events found less than 4% of units outperformed their EcoMax, Pilong said.
• Remove from Tier 1 estimates hydro and combined-cycle units, most of which do not respond to Tier 1 spin events because they lack required equipment such as duct burners and fuel guns. The units would still be eligible for Tier 2 assignments.
• Exclude units providing regulation from the Tier 1 estimates. Manual 12 allows such units to respond to spin events as long as they return to their regulating band within 10 minutes.
• Remove from the Tier 1 estimate any units being backed down for constraint control.
• Cap units’ Tier 1 estimates based on the degree of generator performance (DGP) modifier, which measures how units respond to dispatch instructions and estimates their future response. Staff is conducting additional analysis to determine whether to implement this change 24×7 or just during peak load periods and emergency procedures. Two committee members recommended applying this change only in emergency situations to assess its impact on reserves and shortage pricing.

Staff said the proposed changes would likely result in more Tier 2 clearing than did this summer.

Pilong said he also plans to propose rule changes to make PJM more confident it has enough of a synchronized-reserve requirement. He plans to bring the matter up at November’s meeting, taking into account the feedback he received from generator representatives.

“Market participants need to have a good feel for when PJM will be raising the SR requirement, or the triggers for it,” one generator representative said. When generators know they will be held back, he said, they won’t “chase LMP because PJM will compensate them for reserves.”