ISO-NE reliably manages grid through August 1 capacity deficiency

ISO New England system operators used well-established procedures to balance supply and demand on the regional power system during a capacity deficiency on August 1, 2024.

Temperatures were higher than anticipated across New England during the late afternoon and early evening hours, leading consumer demand for electricity during the peak hour to be approximately 300 megawatts (MW) above forecasts from that morning.

Numerous unplanned generator outages and reductions throughout the day, including the loss of a 335 MW resource at approximately 4:44 p.m., contributed to the capacity deficiency. The specific generators are not identified, per the ISO’s Information Policy.

These factors combined to leave the region short on its operating reserve requirements beginning at approximately 4:45 p.m., leading ISO-NE system operators to declare a Power Caution for the region. This declaration allows the ISO to utilize reserve resources to balance supply and demand.

The ISO also declared an Energy Emergency Alert (EEA) Level 1, the lowest of three alert levels.

As consumer demand decreased in the evening, conditions on the system improved. The ISO canceled the Power Caution and EEA 1 declarations at 9:45 p.m. ISO New England did not issue appeals for public conservation during this event. Consumer conservation wasn’t necessary given the short duration of the event and the ability of reserve resources to make up the deficiency.

The capacity deficiency triggered the region’s Pay-for-Performance rules, which penalize resources that fail to meet their capacity supply obligations in real time, while rewarding resources that exceed their obligations. The ISO is working to estimate the penalties that will be levied.