by Paul Ciampoli
APPA News Director
Posted January 31, 2019
A polar vortex blanketing much of the Midwest with life-threatening cold temperatures in recent days prompted power grid operators and utilities to take a number of actions in response to the deep freeze.
The PJM Interconnection implemented procedures that include the cancellation or postponement of planned maintenance outages, while the Midcontinent Independent System Operator took steps to provide it with greater flexibility and resources to ensure system reliability.
Meanwhile, individual utilities including public power utilities also did their part in responding to the polar vortex as the extreme weather resulted in power outages.
“Records have been shattered as the polar vortex unleashed the harshest cold in years on the midwestern United States during the final days of January,” wrote AccuWeather senior meteorologist Kristina Pydynowksi in a Jan. 31 post. “After the polar vortex plunged southward, temperatures plummeted under 20 below zero F from North Dakota to northern Illinois during the morning hours of both Wednesday and Thursday,” she wrote.
“In Minnesota, the low of 56 below zero in Cotton was 4 degrees from that state's all-time record, which is 60 below zero, set in Tower in 1996,” USA Today reported on Jan. 31.
On the morning of Jan. 31, nine states in the Midwest and northern New England recorded temperatures lower than the northernmost point in Alaska, Pydynowksi noted.
Illinois was among several states in the Midwest that were hit hard by the record cold weather due to the polar vortex. Illinois Gov. JB Pritzker on Jan. 29 issued a disaster proclamation for the entire state ahead of the severe winter storm.
On the morning of Jan. 31, a new all-time Illinois state record low temperature of 38 degrees below zero was likely set in Mount Carroll, Ill., reported USA Today. In Chicago, the city has been hit with a cold snap the past few days. The deep freeze resulted in record low temperatures during the morning of Jan. 31.
The Illinois Municipal Electric Agency (IMEA) noted that its operations department monitors loads and schedules electric supply to all 32 IMEA member utility delivery points 24 hours a day, 365 days a year.
When IMEA’s power services coordinators receive alarms for load losses, they will coordinate communications between the member municipality’s electric department and the transmission operator. If need be, they will alert IMEA’s managed professional association – the Illinois Municipal Utilities Association – to coordinate mutual aid.
IMEA details two incidents tied to polar vortex
IMEA on Jan. 31 noted that two incidents occurred during the recent polar vortex.
First, an IMEA member municipality experienced a citywide outage in the early morning hours of Jan. 30, but as a public power city with its own generation, the utility was able to minimize outage time to half an hour, IMEA noted.
The city in question experienced a citywide outage at 5:22 a.m. CT. A substation re-closure opened, but then re-closed as designed. Thirty minutes later, the city’s electric department manager reported he had two phases with low voltage at a different substation, and so they could not switch the load to that station, IMEA reported.
A transmission owner assured that crews were on the way to check transmission into the city. At that time, the city began using its own generation to restore power to customers and ensure local distribution system reliability in below zero air temperatures and below negative 20 wind chills.
A follow up call revealed that crews from the transmission owner were still on their way and by 8:05 the transmission owner had established a line feeding the city was indeed down, IMEA noted.
The city at this time was still generating and had no customers without power. After the transmission repairs were completed, grid power was returned to the substation at 8:42 a.m. The city continued to generate until 9:07 and then began taking power from the transmission owner.
With respect to the second incident, IMEA said that thanks to the expertise of its city utility employees, another IMEA member municipality was able to respond quickly to an early morning marked by sub-zero temperatures, limiting outage time significantly.
Specifically, in the early morning hours of Jan. 30, the city lost three poles due to weather conditions and all power to its north substation. The on-duty IMEA power services coordinator contacted the city and a transmission owner to alert all parties to the problem. The city switched its entire load to its South substation to ensure system reliability.
By 6:10 a.m., the load on the south sub began to rise and was carrying all the city’s load by 6:30 a.m. The city indicated that did not need to use mutual aid to fix the poles.
“In order to ensure that IMEA does all it can to supply the necessary power to the grid to serve its members at all times, we continue to work with our project partners and with regional and national reliability entities to assure preparation for these cold weather events at the several large baseload generation units that make up the lion’s share of the power supply in the frozen Midwest,” IMEA said.
Due to those local and regional planning efforts, there seemed to be less major large-unit outages during the vortex, the agency said. “This kept the wholesale power prices at a remarkably low market price for most of the period when the actual air temperature was less than zero for about 36 hours.”
These efforts “are complex and still require men and women at the generation sites, the transmission operators and the local distribution crews to brave the elements. Their efforts may be taken for granted by folks in their nice warm, energized homes and businesses, but it their yeoman efforts are not lost on us. We appreciate all of their planning, preparation and efforts in the toughest part of the storm,” IMEA went on to say.
PJM Interconnection and MISO
The PJM Interconnection continued to report no reliability issues as of 8:50 a.m. Jan. 31. PJM said that it had already passed its Thursday morning peak electricity usage and that the peak forecast was revised to under 140,000 MW. The Thursday evening peak was expected to reach to about 136,000 MW.
PJM said that cold weather alerts would remain in effect for the PJM footprint through 6 p.m. Friday, Feb. 1, and that it “continues to have robust reserves and does not expect to have any capacity issues at this time.”
A cold weather alert prepares personnel and facilities for expected extreme cold weather conditions, when actual temperatures fall near or below 10 degrees Fahrenheit.
PJM communicates with generator owners and tells them to be prepared to call in additional staff to get all generating units running for the morning load pickup. They must take extra care to maintain the equipment so that it doesn’t freeze in the cold weather.
During a cold weather alert, PJM also cancels or postpones planned maintenance outages to ensure the availability of resources.
MISO on Jan. 30 tweeted that it had issued a Maximum Generation Event for portions of the North and Central regions and a Conservative Operations notice for its South region until noon ET, Jan. 30.
It noted that Maximum Generation emergency procedures allow MISO greater flexibility and resources to ensure system reliability.
On Jan. 31, MISO reported that system conditions were returning to a normal state as extreme temperatures that gripped parts of the midcontinent region moderate.
MISO continued a second day Jan. 31 operating under emergency procedures as the extreme cold drove high electric demand across the RTO’s 15-state footprint.
The MISO North and Central regions came out of a Maximum Generation Event at 9:30 a.m. ET and remained in a Maximum Generation Warning until 11 a.m. ET, when it expired. The entire footprint was expected to exit conservative operations status as of 6 p.m. ET Jan. 31.
While demand was high, the system did not set a peak record. The Jan. 30 peak market system load (preliminary) was 100.9 GW – compared to an average peak load Jan. 1-Jan. 28 of 86.7 GW. MISO’s all-time winter peak was 109.3 GW on Jan. 6, 2014. Thursday’s (preliminary) peak was around 100.1 GW.
MISO said it worked closely with members and neighboring grid operators to manage reliability across the grid during this event and said its operators and its members train regularly on emergency operations.
“As a standard process, MISO will evaluate the event in the coming days to ensure the RTO captures and incorporates lessons learned as part of its commitment to continuous improvement,” MISO said.
According to the Energy Information Administration, spot prices for electricity on the morning of January 31 in PJM’s Western trading hub and MISO’s Illinois hub were $89 and $97 per megawatt-hour respectively.
Prices reached $141 in New York City and $100 in the Massachusetts hub of ISO-New England. But these were not as high as experienced last January 5, when prices exceeded $200 per megawatt-hour in PJM, ISO-New England, and the New York ISO.