NYISO’s Management Committee voted Tuesday to revise the ISO’s Tariff to address a concern regarding the peak load forecast and minimum unforced capacity requirements for load-serving entities.

The forecast is determined using the New York Control Area’s (NYCA) highest actual hourly load in the prior calendar year adjusted to “design conditions,” which are expected to occur on a non-holiday weekday in July or August.

NYISO Associate Planning Analyst Ying Guo said the ISO was concerned about situations in which the highest hourly actual load occurs outside the “design conditions” as in 2019, when the highest actual load occurred on a Saturday in July.

The minimum capacity requirement is allocated among individual LSEs, determined by their consumption during the highest hourly actual load in the NYCA, regardless of whether that is consistent with consumption at design conditions.

The Tariff revision would require the use of the highest NYCA load hour occurring on a non-holiday weekday during July or August when calculating the NYCA peak load forecast. About 80% of the highest coincident NYCA peak load hours have occurred in July and August.

The change will ensure that each LSE’s share of the minimum capacity requirement is consistent with the design conditions used to calculate the minimum capacity requirement.

If the highest load hour occurs on a weekend or holiday, it would be adjusted to account for expected additional load that would have occurred if the highest load hour had been a non-holiday weekday. Similarly, load also would be adjusted when the highest load hour occurs outside July and August.

If the temperature is higher than the design temperature, load will be removed to reflect the expected lower load that would have occurred if the highest load hour had taken place at the “design” temperature. The ISO said the change should ensure that the incentive to reduce peak demand aligns with when the peak demand is expected to occur.

Following board approval, the changes are expected to be filed with FERC in July, with the ISO seeking an effective date in time for the 2021/22 capability year.

Dave Clarke of the Long Island Power Authority said the change “makes some sense in the short run” but asked whether the rules would need to change again if increasing solar generation transitioned the ISO into a winter-peaking region.

“If we shift to a … winter-peaking system, this wouldn’t be appropriate,” agreed Nate Gilbraith, NYISO resource adequacy and ICAP specialist. “In 10 years or so, if we need to make this change again, we will and that will be made with a whole suite of things we’d need to accommodate a winter-peaking system.”

Gilbraith said the change approved by stakeholders Tuesday “doesn’t have any administrative or coordination challenges.” But he said a project considering moving from a one-hour peak calculation to one involving five or 10 peak hours would be more complicated. “That’s why that’s a project — bigger scope,” he said.