MISO, stakeholders float ideas to better prepare grid system for extreme weather

Midcontinent Independent System Operator is considering whether it should change the way it prepares for extreme weather, including potentially using industry and historical data to predict generation and transmission outages during different types of storms, MISO staff said March 3.

One idea to keep track of the age, condition and type of transmission lines in the MISO footprint seemed gain some traction among stakeholders attending the webcast meeting of MISO's reliability subcommittee.

"Even if you bring up all the generators it doesn't matter if the transmission line falls into the river," said Simon Mahan, executive director of the Southern Renewable Energy Association, who first raised that particular issue at the meeting.

When Hurricane Ida hit Louisiana in 2021, one of Entergy's transmission lines fell into the Mississippi River. The powerful hurricane cut power to almost 1.2 million customers across eight states, according to the US Department of Energy.

And during the 2021 winter weather event, up to 40% of installed generation capacity in MISO South was unavailable. A significant portion of these outages were due to freezing issues and fuel issues related to the storm, according to a report by staff at the Federal Energy Regulatory Commission, the North American Electric Reliability Corporation and regional entities.

Current process

MISO already has a list of steps it takes to prepare for extreme weather such as hurricanes, heat waves and winter storms, said Trevor Hines, manager of South region reliability coordination in MISO.

For instance, MISO can use a weather alert, capacity advisory, conservative system operations and maximum generation alerts, Hines said. The grid operator also communicates with transmission owners to see if there are any risks to transmission equipment or if any outages can be returned to service, he said. And the grid operator reaches out to local balancing authorities and generator operators to discuss risks to generation or load, he said.

MISO also uses generation commitments to prepare for extreme events by starting units early or starting additional units to account for unplanned outages, decreased imports and reduced wind and solar generation, Hines said. The grid operator might also start long-lead units so that it can keep quick-start units at the ready, he said.

It is critical that units provide the most up-to data generation offer data so that MISO can best commit the generation fleet, Hines said. For instance, a generator operator might change their offer because they need an additional two hours to start up when the weather goes below a certain temperature, he said. "We are only as good as the information that is being provided to us," he said.

Potential improvements

MISO is also considering whether to improve its preparation process, Hines said. One idea is to create a tool that uses historical data to determine transmission and generation failure rates during different types of events, he said. The grid operator could also create new thresholds for decision making based on the number of generators or transmission lines that are lost during an event, he said.

Mahan asked whether MISO currently gathers information on transmission type or age to predetermine which grid facilities are at risk of outage.

MISO does not currently have a repository for that type of information, Hines said. But it could be useful to know the type of structure and the wind speeds that the transmission line is designed to withstand, he said.

In a related matter, MISO is planning on improving its survey of generator fuel availability so that it is easier for generators to answer and more useful for the grid operator, said JT Smith, director of economic and policy planning at MISO. The grid operator is also weighing how to report the data and whether to collect the data year-round, he said.

"There is an effort around energy adequacy in general that we need to get our hands wrapped around and this is part of that," Smith said.