Washington Power Falls as Grid Adjusts to Transformer Failure

Mid-Atlantic wholesale power retreated from earlier gains as the grid found alternate supply sources to make up for a transformer failure that shut two reactors and briefly cut electricity to the White House and Capitol Hill.

Hourly spot prices surged more than sixfold in the hour ended at 2 p.m., topping $200 a megawatt-hour, before dropping to $31.20 three hours later, down $8.21 from the same time Monday, according to PJM Interconnection LLC grid data compiled by Bloomberg.

The transformer failure caused power flows to drop on transmission lines to the Calvert Cliffs nuclear plant in Maryland, triggering automated emergency systems to shut both reactors at the site, Neil Sheehan, a spokesman for the U.S. Nuclear Regulatory Commission, said by phone.

Power outages across the Washington area knocked out electricity at the State Department and briefly disrupted activities at the White House, the Capitol and the city’s tourist attractions.

The number of customers without power in the city fell to about 500 at 4 p.m. from more than 1,300 at 2 p.m. Pepco Holdings Inc., the local utility, said on its website.

“There was some volatility in the real-time market, especially in Pepco and some of the Maryland zones,” said Eric Newell, director of trading and energy management at Consolidated Edison Inc.’s ConEdison Energy unit in Valhalla, New York. “PJM has redirected the power flows and redispatched some of the power plants to overcome whatever limits were breached by the transmission failure.”

Reactor Shutdowns

The earlier price surge was probably driven by the nuclear reactor shutdowns because of the sudden drop of supply in the region, Newell said.

“There is a lot of power capacity on standby so if this had happened in the middle of a heat wave in the summer or one of the real cold spells in the winter time, it would probably have taken a lot longer to get it under control,” he said.

“The transmission grid is stable,” PJM said in an e-mailed statement. “The cause of the disturbance is under investigation.”

On-peak power at the Western hub is up 37 percent so far Tuesday at $56.41 a megawatt-hour as of 5 p.m., heading for the highest daily average since March 6. Peak-demand hours are from 7 a.m. until 11 p.m.

Generating Units

Valley Forge, Pennsylvania-based PJM, which serves more than 61 million people in 13 states from the mid-Atlantic region to the Midwest, said the transmission disturbance caused three generating units with 2,000 megawatts of capacity to trip offline. “The outages of customers equaled between 200 and 500 megawatts of power,” PJM said in the statement.

Several 500-kilovolt lines went offline, said Shiraz Akhtar, a Boston-based power analyst for Genscape Inc. The major outage among them was on a Maryland line from Chalk Point to Calvert Cliffs, the data provider said.

Both Calvert Cliffs nuclear reactors are ready to resume output, Lace Dean, a spokeswoman at the plant, said by e-mail. The plants, about 38 miles (61 kilometers) south of Annapolis, have combined nameplate capacity of 1,829 megawatts.

While power prices eased in late afternoon trading, the shutdown of those plants may contribute to price volatility in the real-time power market Wednesday, Newell said.

“I’m not seeing a whole lot of change in the market as far as power in the Pepco zone itself. It seems like a lot of traders are backing off from doing anything else.”

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