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Power Demands Strain High-Voltage Lines in Mid-Atlantic States

Posted on: Wednesday, 27 July 2005, 21:00 CDT

Jul. 28--There was electricity to spare this week to meet record demand across the region's power grid. But stress on high-voltage lines in the mid-Atlantic states yesterday afternoon prompted grid managers to take an unusual step: They ordered utilities to cut electricity voltage by 5 percent.

Utility and grid officials said the four-hour voltage reduction -- often called a "brownout" -- would not affect most residential and business customers, because it fell within the normal range of fluctuations most devices can handle. But they warned larger customers that it could affect some machinery.

"A 5 percent reduction should be unnoticeable to most people," said Ray Dotter, a spokesman for PJM Interconnection, the Valley Forge company that manages the regional grid, which serves customers in 13 states and Washington, D.C.

Ironically, the voltage reduction came as demand began to drop within PJM. But as temperatures dipped in the upper Midwest, electricity use peaked along the East Coast.

On Tuesday, Peco Energy reported a new record for peak demand. By yesterday, that record had fallen.

Tuesday's peak for Peco's 1.6 million residential and business customers was 8,329 megawatts, consumed between 4 and 5 p.m. That surpassed a record of 8,124 megawatts, set on Aug. 14, 2002.

Demand hit 8,593 megawatts yesterday between 1 and 2 p.m. Then it set another new record between 4 and 5 p.m. of 8,695 megawatts -- after the voltage reduction was imposed.

Demand was also high in South Jersey. Betty Kennedy, a spokeswoman for Atlantic City Electric Co., said the company's unofficial peak demand Tuesday appeared to surpass its previous record, set a week ago.

PJM's peak demand came between 3 and 4 p.m. Tuesday when it delivered about 135,000 megawatts, beating its previous record -- set just last week -- of 130,574 megawatts. Yesterday's demand was expected to fall below 126,000 megawatts.

Dotter said both day's peaks were well within the overall 166,000-megawatt capacity of the grid, which delivers energy from more than 1,100 power plants. PJM requires a reserve capacity of 15 percent; it never had less than 18 percent.

The problem yesterday was getting that power to East Coast customers who were still sweltering. Power lines tend to heat up and sag as they near their capacity limits, and since unplanned surges can occur, grid managers try to avoid pushing the lines' limits.

"We like to have a nice safety margin, and a voltage reduction is one way to assure a safety margin," Dotter said.

Dotter said PJM does not use the word brownout to describe the step it took, because of confusion over the term's meaning.

Peco spokesman Michael Wood was less hesitant.

"This is a brownout -- that's how people refer to it," he said.

The voltage reduction was first ordered at 1:45 p.m. in Maryland, Virginia and Washington. At 2:21, it was extended to Pennsylvania, New Jersey and Delaware. It was lifted at 5:44.

Even before, PJM asked customers to try to reduce their electricity use, especially during the peak-demand period between 4 p.m. to 7 p.m. Dotter suggested closing shades and blinds, and waiting until nighttime to use appliances such as washers, dryers and dishwashers. He also recommended turning window air-conditioners down or off when rooms are unused.

Last night, Peco was braced for possible storm damage, but only about 920 customers lost power during the heat-related peak usage. The largest outage left about 100 customers without service for nearly 12 hours in Southwest Philadelphia.

Wood said small voltage dips were a problem in some areas -- similar to the intentional reduction, and enough to make lights briefly go dim.

Wood blamed overnight temperatures that dipped only into the upper 70s, and a lack of Tuesday morning's fog and haze, for yesterday's extraordinary demand. "Today we've had intense sunlight from dawn onward," he said.

But long-term trends also play a role. Wood said that since 1993, average household use among Peco customers has climbed 21 percent.

Wood attributed the rise in demand to stable prices coupled with lifestyle changes: bigger houses, especially in newer suburbs; higher-pitched roofs that are less energy efficient; air-conditioning added to older homes; and a profileration of appliances and electronics.

"People have more DVDs, more TVs, and more computers," he said. "A lot of households even have two refrigerators."

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EXC,

Source: The Philadelphia Inquirer

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