WASHINGTON, Jan. 17 (UPI) -- The U.S. power system in states affected by last week's sub-zero weather "generally performed reliably," the Federal Energy Regulatory Commission said.
A meteorological phenomenon called a polar vortex brought record-setting low temperatures to several states east of the Mississippi River.
Temperatures were well below zero in some areas.
The FERC issued an 18-page brief saying the energy grid in states affected by the cold spell performed well.
"The bulk power system remained stable and generally performed reliably throughout the event," it said.
PJM Interconnection, a company operating the electric grid for more than a dozen Midwest and mid-Atlantic states, said last week its grid was strained by the intense cold weather. Several natural gas-fired plants reported issues, though PJM said that represented a "relatively small percentage" of energy problems blamed on the extreme cold.
The cold snap eased late last week, with temperatures returning to a relative normal for the season.