Polar Vortex Tests Resiliency of U.S. Power System
Brutally cold temperatures in the midwestern and northeastern U.S. spurred grid operator alerts as natural gas demand has surged, power prices have soared, and there have been forced generator outages.
The polar vortex, an extreme cold event characterized by back-to-back cold fronts, has so far prompted states of emergency in Wisconsin, Illinois, and Michigan. On Jan. 30, several cities reported record-breaking lows as Arctic air arrived, and dangerous snow squalls beset the Northeast. Power outages were reported across Illinois and other areas in the Midwest. On Thursday morning morning, nearly 20,000 customers in Wisconsin, Pennsylvania, West Virginia, Virginia, and New Jersey had no power, according to poweroutage.us.
More extreme conditions are expected Thursday. Minneapolis is set to break low temperature records originally set in the 1800s, and temperatures in Chicago could fall below the all-time record low of -27F. Power prices in Minnesota already jumped Wednesday to the highest in more than a year.
Grid Operators Issue AlertsGrid operator PJM, whose entire 13-state footprint has been affected by the bone-chilling temperatures, said on Wednesday afternoon that it had not seen reliability issues. But it noted cold weather alerts will remain in effect for the Western Region on Thursday. PJM's preliminary load forecast for Thursday is about 143,000 MW, "which would approach the all-time confirmed winter peak of 143,338 MW, set on Feb. 20, 2015," it noted.
The Western Region includes all or parts of Illinois, Indiana, Kentucky, Maryland, Michigan, Ohio, Pennsylvania, Tennessee, Virginia, and West Virginia. The entire PJM service area also includes all of New Jersey, Delaware, Washington, D.C., and part of North Carolina.
MISO issued a maximum generation event for Wednesday owing to "tight conditions, extreme cold weather, and generator uncertainty." It said the "reason for the Event is because of Forced Generation Outages, Higher than Forecasted Load." MISO has also urged conservative operations affecting its entire region, including the south, that extended through Thursday. Maximum Generation emergency procedures allow MISO greater flexibility and resources-such as emergency power purchases-to ensure system reliability. The conservative operation declaration urges suspension of all transmission and generation maintenance, unless it is needed for bulk electric system monitoring, control, and security.
ISO-New England, which saw challenging power system operations owing to forced outages and fuel delivery constraints last winter, said it had adequate supplies to meet consumer demand.
Today's #grid snapshot. More winter weather here in NE. More on how ISO-NE prepares for the cold weather: https://t.co/HsPmQ7e2Sc pic.twitter.com/r44A3kY13n
- ISO New England (@isonewengland) January 30, 2019
But BloombergNEF reported Thursday that Midwest gas demand surged about 50% on Wednesday over the previous two days."Nationwide demand was on track to reach an all-time high, according to preliminary data from S&P Global Platts," it said.
Generators Grapple with the Deep FreezeThe widespread cold weather impact on generators isn't yet clear, and details will likely emerge in the coming weeks.
Early on Thursday morning, Unit 2 at PSEG's Salem nuclear plant in New Jersey was manually tripped due to icing conditions, which were described as "frazil ice." The conditions required removal of four Circulating Water Pumps from service. The company told the Nuclear Regulatory Commission (NRC), however, that the "trip was not complex, with all systems responding normally post-trip."
| Prepare your Plants for Cold Weather Operations In October 2014, in response to the debilitating 2014 polar vortex event, POWER published a series of articles to help generators prepare for future deep freezes. How have your plant's cold weather strategies shifted substantially since then? Send us a line: editor@powermag.com. Prepare Your Coal Plant for Cold Weather Operations Prepare Your Gas Plant for Cold Weather Operations |
Despite its record cold temperatures, the current polar vortex event's impact on the power generation landscape appears muted compared to the "bomb cyclone," a winter storm that descended on much of the eastern U.S. from Dec. 27, 2017, to Jan. 8, 2018. That event renewed the raging debate about resiliency and prompted flashbacks of the "polar vortex," a similar deep freeze that transpired in January 2014 and was compounded by the loss of 82 GW nationwide for various reasons.
Owing to lessons learned from the polar vortex-and despite sizable retirements of baseload generation and an upsurge of variable generation-the bulk power system performed relatively well during the bomb cyclone. [This POWER infographic compares the two events.]
Last December, the North American Electric Reliability Corp. (NERC), and organization tasked with ensuring the reliability and security of the bulk power system forecast in its 2018/2019 Winter Reliability Assessment that anticipated resources in all assessment areas would meet or exceed their respective reference margins this winter.
"Generator unit winter preparedness programs continue to receive significant attention in assessment areas as a means to mitigate seasonal reliability risks," it noted. Market mechanisms had also proved a useful tool for incentivizing generator performance during extreme weather conditions.
Meanwhile, grid operators across the bulk power system were in the process of implementing strategies to promote fuel assurance and reduce risks to the power system from seasonal generator fuel supply issues. ISO New England, for example, was implementing new periodic energy assessments aimed at "providing market participants with early indication of potential fuel scarcity conditions that can help inform generator fuel procurement decisions. The new periodic assessments complement existing fossil fuel surveying and monitoring activities and natural-gas-fired generator day-ahead confirmations that are employed to promote fuel assurance in the area."
In PJM, "daily natural gas infrastructure analysis is performed to project transmission and generation reserve impacts to the PJM system from natural gas pipeline contingencies." And in NYISO, "seasonal generator fuel surveys indicate oil-burning units have sufficient start-of-winter inventories and arrangements for replacement fuel. Emergency protocols are in place for communicating electric reliability concerns to pipelines and natural gas operators during tight electric operating conditions," it said.
On Thursday morning, NERC spokesperson Marty Coyne told POWER: "The bulk power system remains stable during this severe weather situation. NERC's Bulk Power System Awareness team continues to monitor the grid and update stakeholders as necessary."
-Sonal Patelis a POWER associate editor (@sonalcpatel, @POWERmagazine)
UPDATED (Jan. 31): Adds comments from NERC
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