Transmission ‘disturbance’ leaves D.C. in the dark

Source: Hannah Northey and Blake Sobczak, E&E reporters • Posted: Wednesday, April 8, 2015

Large swaths of Washington, D.C., and Maryland went dark this afternoon, halting train service, affecting the Capitol and White House, and turning out the lights on a crowded room listening to Oprah Winfrey.

A “major disturbance on the transmission system” occurred at about 12:30 p.m. in Pepco Holdings Inc.’s footprint that caused three power plants — about 2,000 megawatts — and transmission lines to shut down, according to PJM Interconnection, which operates the grid in the Midwest and Mid-Atlantic.

Pepco in a statement said it experienced a “dip in voltage” in the D.C. area caused by an “issue” with a transmission line. The utility said there was never a loss of permanent supply of electricity to customers, but the disturbance caused some customer facilities to turn to backup systems.

“We have crews onsite investigating the cause,” Pepco wrote.

PJM said the outages for customers equaled between 200 and 500 MW of power, and confirmed the problems were limited to the D.C.-Maryland area.

Robyn Johnson, public information officer with the D.C. Department of Homeland Security and Emergency Management, said an explosion at a Southern Maryland Electric Cooperative facility may have caused the outages but that the impact of the explosion “has not been 100 percent confirmed yet.”

She said only about 800 customers were experiencing outages as of 3 p.m., but noted several “high-level buildings” were affected.

“What we’ve gathered is that the power outage in D.C. resulted as a failure of equipment in the power distribution system for Pepco,” she said.

A public affairs manager for the electric co-op did not respond to requests for comment.

The outage affected federal agencies and halted train service in D.C., even triggering a blackout as Winfrey gave a speech at the Warner Theatre honoring Maya Angelou, according to Reuters.

The disturbance also prompted evacuations at the National Air and Space Museum and the National Portrait Gallery, among other museums, the Smithsonian Institution said on Twitter.

The daily press briefing at the State Department was interrupted when the lights went out, and several other D.C. institutions were forced to rely on backup power.