High-outage, high-demand scenario could stress US PJM power system in summer: official

Power supplies in the US PJM Interconnection could get dangerously tight this summer if there is high demand and high outages -- a situation that would require the grid operator to rely on demand response to maintain reliability, Mike Bryson, senior vice president of operations at PJM, said May 4.

When PJM looked at the combination of unexpectedly high demand and high outages, it saw "for the first time that we would be below operating reserves for the summer," Bryson told a meeting of the Illinois Commerce Commission.

Nationally, summer temperatures are likely to be above the 30-year normal, according to the PJM presentation. The forecast is influenced by warm ocean water, which is indicative of warm summers in the past 10 years, the presentation said.

Summer scenarios

When PJM looked at just one factor -- like high demand -- there were no reliability concerns for the summer, Bryson said. The summer high-demand scenario of 162,666 MW is significantly below PJM's installed capacity of 186,540 MW.

But the grid operator decided to look at a combined high-demand and high-outage scenario in its summer forecast, after the December 2022 storm stressed the PJM system, Bryson said. "Clearly, one of the things we saw in Elliott is higher than expected generation outages," he said.

During the winter storm, PJM officials thought there would be plenty of extra capacity to meet demand. PJM called 155,750 MW of operating capacity for Dec. 23, which should have been enough to cover the peakload of 134,765 MW plus contingencies, officials said in January.

But outages were unacceptably high during the storm, PJM officials said. On the evening of Dec. 23, generation outages reached 34.5 GW, and on the morning of Dec. 24, outages reached 46 GW, or 23.2% of PJM's total capacity, according to the grid operator. Prior to the event, PJM had typically seen a forced outage rate of 5% to 10%, officials said.

During the winter storm, zonal power prices reached around $4,300/MWh on Dec. 24, PJM said. The highest December PJM West Hub daily average real-time on-peak price of $1,111.90/MWh was reached Dec. 23, according to PJM data.

MISO wind risks

Looking at weather, the Midcontinent Independent System Operator is expecting less risk this summer than last summer, Bob Kuzman, regional director for the MISO Central region, told the ICC. The grid operator expects normal to slightly above-normal temperatures in the MISO North and Central regions, he said. In MISO South, there should be a near- to slightly below-normal hurricane season, he said.

"Our meteorologists are also expecting summer 2023 to be very frontloaded again, as it was last summer," Kuzman said. Last summer, there were nine days temperatures were above 90 degrees Fahrenheit system-wide in June and July, he said.

Meteorologists are also expecting a bit of an El Nino, which could help drive below-normal wind generation, he said. There could also be more storms in the afternoon and evening, which could help reduce load on hot days, he said.

"Relatively low wind volatility but low production levels can stress some of our operations conditions as we do have a lot more wind in our system than we have had in the past," Kuzman said. MISO's summer wind forecasts tend to be off by 800-1,200 MW, and there is usually a falloff of wind output in August, he said.

There is less risk of generator outages in the summer compared to winter, but outages and derates can be expected on days with persistent heat, Kuzman said. Solar capacity is expected to hit 2.9 GW this July, which is about 1 GW higher than the summer of 2022, he said.

MISO does not yet have a summer readiness forecast, Kuzman said. The grid operator plans to discuss the results of its planning resource auction on May 19. "Until we get those results, the data is not quite there," he said.

MISO did see some risks for spring, Kuzman noted. Under a high-demand high-outage scenario, load this spring could reach 109 GW and available generation could drop to 105 GW, he said. In past years, load has peaked in May, and peakload this spring is forecast to be 100 GW, according to the presentation.