US Eastern Electric Grid Narrowly Dodged Collapse During Storm
(Bloomberg) — The unprecedented strain on the electrical grid during December’s frigid storm was threatening to trigger cascading blackouts across the Eastern US when Duke Energy Corp. called for rolling outages in North Carolina to stabilize the system, company officials said Tuesday.
Duke cut power to about 500,000 homes and businesses the day before Christmas after freezing weather increased demand by up to 10% more than forecast while forcing multiple coal and natural gas-fired plants to reduce power generation.
The resulting imbalance in Duke’s operations contributed to problems for the entire Eastern Interconnection grid, one of the two major US power grids, and required Duke to institute outages on its own system to protect the larger grid, Duke executives said.
“If that doesn’t work, the stability of the Eastern Interconnection system is at risk,” Sam Holeman, Duke’s head of transmission system planning, said at a hearing Tuesday. “That risk comes in the form of uncontrolled loss of the system.”
After the lights came back on, North Carolina Gov. Roy Cooper asked Duke for a complete report on what went wrong and for changes to be made, prompting the hearing by the North Carolina Utilities Commission, which regulates electricity in the state.
A handful of Duke executives gave a timeline of the demand surge, power supply failures and system failures that made blackouts last much longer than the 15 or 30 minutes of which customers initially had been warned.
Holeman added that other utilities were in the same situation at the time. For example, Tennessee Valley Authority, a federal agency that supplies power in the region, was forced for the first time to institute rotating outages on Dec. 23 and Dec. 24 as demand soared to a winter record.
Just north of Duke’s territories, PJM Interconnection was doing all it could to prevent rotating outages from rolling across its 13-state network that stretches from the mid-Atlantic to the Midwest. PJM reduced exports, including additional reserves Duke was hoping to tap for the Carolinas.
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