VALLEY FORGE, Pa. — PJM last week presented two deep dives into how the grid performed during the January 2024 Winter Storm Gerri, highlighting changes to how it committed generators to reduce risk. The RTO’s out-of-market actions cost $53.5 million. (See PJM: Grid Performed Well During January Winter Storm.)
Much of the discussion during a Feb. 7 presentation to the Market Implementation Committee centered on PJM’s use of conservative operations to commit generators to operate throughout the storm. PJM’s Joe Ciabattoni said conservative operations were used to maintain transmission security that could not be accomplished with the resources committed through the day-ahead market alone.
A subset of those resources whose start-up parameters would have prevented dispatchers from ramping them up and down throughout the storm as needed were given multiday commitments, as were gas-fired generators that might have difficulty procuring fuel without certainty regarding how long they would be expected to run.
Around 98,000 MW of resources were identified for conservative operation commitment Jan. 12, of which 58,000 MW received multiday commitments. Two-thirds of the committed resources were gas-fired, while just over a quarter were coal. Conservative operations peaked at 15,189 MW of resources committed Jan. 16.
Senior Dispatch Manager Donnie Bielak said fuel type was not a major focus in which resources were selected under conservative operations. PJM started by looking at which units were needed for reliability, and analysis of fuel security followed, he said.
Uplift payments between Jan. 12 and 22 totaled over $53.5 million, with over half of that concentrated on the 15th and 16th. PJM’s Lisa Morelli said there is a correlation between the number of resources operating on multiday commitments and the amount of uplift paid, but there were other contributors to the amount of uplift as well.
During an Operating Committee presentation Feb. 8, Bielak said committing resources for multiple days proved valuable to dispatchers in mitigating the risks associated with fuel insecure resources.
Bielak said PJM also modified its practice around committing gas resources to treat flexible combustion turbines as if they were inflexible. The RTO normally commits inflexible combustion turbines earlier in the day than other resources to provide additional time for them to procure fuel, which also has the added benefit of giving dispatchers more reaction time if that generator is unable to obtain gas. Bielak said PJM is considering standardizing the procedure going forward by adding triggers for when it may be initiated and transparency around how it will be used.
Senior Vice President of Operations Mike Bryson said the storm presented unique challenges, including the worst weather manifesting at the end of a holiday weekend. Instead of buying one day’s worth of gas on a weekday, generators must buy for an entire weekend — a full three days if it’s a holiday.
Gas must be purchased as a package over weekends, with the commitments largest during holiday weekends.
Michelle Bloodworth, president of coal lobby America’s Power, questioned whether using a special dispatch process for inflexible resources undermines PJM’s incentives for generator investments in fuel security and winterization. Committing them early could also suppress prices for generators that have made those investments, which she said may further weaken the incentive to perform.
Reviewing the load forecast performance, PJM’s Stephanie Schwarz said some of the underforecasting in valley periods was due to lower-than-forecast temperatures and snow cover suppressing behind-the-meter solar generation.
The number of forced outages during Gerri was significantly lower than the December 2022 Winter Storm Elliott, peaking at 16,119 MW on Jan 16. Elliott peaked at 46,124 on Dec. 24, 2022.
PJM’s Ray Lee said most outages experienced during Gerri were due to plant equipment failures, followed by gas procurement problems and freezing, which each contributed to a lesser extent than during Elliott.
More generation owners submitted real-time temporary exceptions at least 24 hours in advance of being dispatched during Gerri than during Elliott. However, PJM’s Chris Pilong said generators are still underreporting constraints. He said that throughout the storm, all pipelines reported constraints to PJM, while only 22% of generators subsequently submitted temporary exceptions.
