“The exercise was held from May 8 to 9, 2024, at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, and at a Federal Emergency Management Agency (FEMA) site in Denver, Colorado.”
Article refers to a PDF of the report it’s based on:
https://www.jhuapl.edu/sites/default/files/2025-04/Space-Weather-TTX-Report-Summary-v3-FINAL.pdf
If a transmissions company tried to spend money preparing for a disaster like this, their shareholders would sue them into the ground and lobby to make it illegal to acknowledge the existence of the sun.
Prior to Trump and his saboteurs getting into office, US grid operators were pretty good at planning for these events.