Polar Vortex Reflections

Lessons learned from cold weather Maximum Generation Event of 2019

When last winter’s brutal polar vortex swing hit North Dakota and Minnesota, Todd Sailer wasn’t worried about his vehicle starting or protecting his fingers from the negative 65 wind chill.

The Minnkota senior manager of Power Supply was thinking about keeping the heat on. For everyone in the Upper Midwest.

“I don’t really remember much outside of work, because your whole day is consumed with trying to make sure that everything is in order so that you have electricity for the region,” Sailer said. “At that point, you’re really focusing on the bigger picture.”

The extreme multiday freeze of January 2019 dipped down into states that rarely realize that level of cold. The event brought several tests to the electricity supply of the North Central U.S. and Manitoba, which is managed through a working relationship between utilities and Midcontinent Independent System Operator (MISO) – a regional transmission organization (RTO) that monitors and controls the stability of the power grid.

When temperatures drop to dangerous lows, demand for power and heat goes up. At the same time, that subzero air can hinder wind generators, which make up a large part of the generation footprint. In response to these challenges, MISO declared a Maximum Generation Event across its North and Central regions.

“Basically, wind dropped off more than MISO was expecting. They knew they would have some wind generators drop off because of the cold, but they didn’t think it was going to drop that far south,” Sailer said.

The Maximum Generation Event declared for January 30-31 allowed MISO to proactively manage the region’s high load and available generation resources, as well as access additional load management, emergency power purchases and calls for public conservation.

Demand response

On Jan. 29, Sailer and his team prepared for a tough 48 hours of demand response, energy marketing and constant communication with MISO and other utilities.

“We knew,” Sailer recalls. “We were expecting that we wouldn’t have wind the next morning [Jan. 30] because of the temperatures. With our forecast, we had already planned on using demand response before MISO asked us to do it.”

With a shortfall in generated electricity, MISO called on Minnkota, Minnesota Power, Otter Tail Power Company and others to use demand response – temporarily controlling voluntary consumers’ dual-fuel heat, storage heaters, etc. – to help take some strain off the system. This was the first time in the region MISO required utilities to do so for grid reliability. It was also the first time MISO required Minnkota to run its emergency diesel generators located throughout the service area.

In addition to these procedures, MISO purchased resources from other regions outside of the Upper Midwest.

“Because they have a big-picture view of what’s going on across states, RTOs are able to manage these events much easier than individual utilities,” Sailer explained. “With Minnkota’s well-developed demand response, we were able to limit our exposure. We were actually able to add some support to the region’s neighboring utilities because we had more resources than we had load.”

Ultimately, the regional power grid remained strong and consistent through the event.

“Minnkota is a valuable partner in helping maintain reliability of the system by being prepared for extreme conditions and ensuring resources and systems are available when needed,” said Darrin Lahr, MISO external affairs.

“Our team did a great job,” Sailer said. “When you look at what we were doing and what they were managing, and all of the different things they had to communicate – with our members, with MISO, with the control center, with our staff – it went really well.”

Baseload resources

Minnkota’s baseload coal power plant in Center, N.D., became one of the stabilizing pieces of the emergency. When wind generation came in low, the Milton R. Young Station was still firing reliably.

“The plant worked well as a team with the Power Supply group to be well aware of the issue in advance and make plans to adapt to the situation,” said Craig Bleth, senior manager of power production. He added that a routine cleaning outage scheduled over the time of the bitter cold had already been moved outside of the weather window, a decision that was made a full five days before the polar vortex’s effects. “Extreme events like this demonstrate that there is no substitute for baseload resources,” he said.

“All of the resources were challenged during this event. But coal, in general, fared well, especially in our region,” Sailer said. “Our plant performed – we had no outages and, really, no limitations.”

Lessons learned

The historic cold snap presented an opportunity to mark areas for improvement in energy operations.

“MISO and its stakeholders have embarked on an effort examine our processes to make sure there are adequate resources available in times of need,” MISO’s Lahr said.

One resource that is difficult to forecast and manage is wind. As states establish more requirements for renewable energy on the system and utilities add those resources to their portfolios, more accurate wind forecasting (including the temperature threshold for wind generation) will be crucial. Otherwise, time and money will have to be invested on building up a transmission system to get electricity from other regions during times of high demand.

The Upper Midwest system also learned the value of real-time demand response. MISO has many demand response programs registered, but many are unable to launch as quickly as Minnkota’s, which can take effect within 10 minutes. For some utilities, demand response can take hours, or even days.

“Load modifying resources are something that will be more valuable as the grid gets more renewable resources,” Sailer said. MISO is looking to increase its awareness of the availability and performance of those programs during an emergency event to better harness the benefits.

MISO has already presented its findings to many entities and will continue to work with its members to build on what was learned in 2019 and during the Maximum Generation Events before it. This openness and collaboration will help maintain a reliable electricity flow for the area – and the country.

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