Arctic Blast Roiling Reliability in TVA, MISO, SPP, PJM
Credit to Author: Sonal Patel| Date: Sat, 24 Dec 2022 14:09:33 +0000
An Arctic blast felt by a large portion of North America is causing reliability turmoil within some segments in its bulk power system, forcing reliability coordinators to declare emergencies, issue conservation warnings, or curtail load.
TVA, Grappling With Demand Surge, Is Curtailing Load
Temperatures averaging the single digits across the Tennessee Valley Authority (TVA) prompted the federal corporation—a reliability coordinator—and local power companies to act proactively and take steps “to temporarily reduce power supplies to localized areas,” TVA said. “These actions may create short, temporary power outages in certain areas,” it said.
TVA has partnerships with 153 local power companies across seven states. These are “industrial customers who are assisting us to ensure the reliability of the system during what the National Weather Service has called a ‘once-in-a-generation’ storm impacting the majority of the country,” Ashton Davies, a TVA spokesperson, told POWER on Dec. 24.
The issue stems from an unprecedented demand surge. “For the 24 hours on Friday, Dec. 23, TVA set an all-time TVA record for energy delivery: 740 GWh. The previous record was 706 GWh in 2018. We also set an all-time winter peak power demand record: 33,425 MW. It is also the third-largest peak demand in TVA’s history,” she said. “Normally, during this time of year, our system manages demand of around 24,000 MWs.”
In addition to the intensified demand, “a limited number of TVA’s generating facilities did not operate as expected during this event resulting in a loss of generation,” Davies said. “Such events are part of TVA’s plans, and we have teams working 24/7 to return those units to service as soon as possible.”
Local power companies reduced their power load “at TVA’s direction” on Friday and again on Saturday morning, she said. “Each local power company is executing its own plans to minimize the impacts on the communities they serve.”
MISO Declares Generation Emergency
The Midcontinent Independent System Operator (MISO) on Dec. 23 declared a maximum generation emergency event at 5:23 p.m. and stepped it up to a Level 2 minutes later, owing to higher forced generation outages than forecasted load.
While the reliability coordinator that serves 15 U.S. states and the Canadian province of Manitoba terminated the event at 8:35 p.m., it declared “conservative operations” until noon on Dec. 24 for its central and north regions. MISO cited concerns related to “extreme cold, generation outages, and neighboring [regional transmission organizations (RTOs)] struggling to serve load.”
The Southwest Power Pool (SPP), which has members in 14 states across the central U.S., also declared an Energy Emergency Alert (EEA 1) on Friday at 8:27 a.m., ending it at 10 a.m. The reliability coordinator pointed to “effects of widespread and extreme cold,” which led to new records, it said. “SPP set a new record for electricity use during the winter season on Dec. 22, with load exceeding 47,000 MW. The previous record was 43,661 MW, set Feb. 15, 2021,” during Winter Storm Uri, an event that precipitated the worst U.S. reliability crises in recent decades.
The grid entity had previously issued a resource advisory on De. 22 for its entire balancing authority footprint in the Eastern Interconnection, anticipating its end at noon on Dec. 25. That remains in effect, SPP said.
PJM Urges Power Conservation, ERCOT Watching Demand
PJM Interconnection, a grid operator that serves 65 million people in 13 states and the District of Columbia, late on Dec. 23 also urged public in its region to conserve electricity until 10 a.m. Dec. 25. “Demand for electricity is expected to increase in the PJM region and the regions neighboring PJM because of the extremely cold weather,” it said. While the grid operator is monitoring the power supply conditions and would do everything to keep power flowing in the region, it said it would take additional steps “such as reducing voltage.”
The Electric Reliability Council of Texas (ERCOT), which has implemented several grid improvements since its Winter Storm Uri debacle, said it was closely monitoring changing weather conditions. It said in an operating condition notice on Dec. 16, it said that temperatures would meet ERCOT’s criteria of 25 degrees or lower in the Austin/San Antonio and the Dallas Fort-Worth areas between Thursday, December 22 through Monday, December 26.
The grid operator was still carefully watching conditions as peak demand shattered records on Friday. Demand soared to 74 GW Friday morning, surpassing the previous winter record of 68,871 MW during Winter Storm Uri. “This is the deepest freeze in Texas (other than Uri, when we don’t know what demand would have been without the blackouts) since electric heating jumped. That makes for lots of uncertainty in the demand forecasts,” noted Daniel Cohan, an atmospheric scientist at Rice University.
ERCOT is forecasting an ample margin tonight, but that’s assuming that tonight’s demand gets nowhere near the 73 GW from last night (which was 8 GW above expectations) despite similar temperatures. With winds slow, conditions will be tight. pic.twitter.com/VJxTIJVqYs
— Daniel Cohan (@cohan_ds) December 23, 2022
—Sonal Patel is a POWER senior associate editor (@sonalcpatel, @POWERmagazine).
Editor’s note: This story is being updated.
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