Power Grid Main Characteristics

PJM Interconnection coordinates the movement of electricity in all or parts of 13 states and the District of Columbia in the eastern portion of the U.S., including 84,042 miles of transmission lines. PJM’s more than 1,040 members own the transmission facilities and generating units. PJM’s job is to ensure there is enough electricity for the 65 million people in the region.

PJM controls the operation of about 178,563 megawatts of generating capacity in its territory. The 1,379 generating units that make up this capacity produce electricity to meet demand.

PJM administers competitive wholesale markets for large blocks of electricity – similar to the way the New York Stock Exchange works. Our markets are Internet based. Utilities and other electricity suppliers use them to make short-term purchases of power for their customers. PJM’s markets attract alternative power sources, such as wind, to the region.

Founded in 1927, PJM Interconnection is an independent, federally regulated organization headquartered at Valley Forge, Pa.

Major Incidents and preventative measures

August 14, 2003 Blackout

About 55 million consumers in the U.S. and Canada were out of power on August 14, 2003 when a line tripped, triggering a chain reaction that led to a cascading blackout and financial losses estimated at about $10 billion. Although a dark day for the industry, it prompted widespread changes and regulatory rules that would address the root causes of the blackout, summarized as “tools, trees and training.”

However, since then the grid is getting smarter.  Advances in technology would make modern control centers—lined with walls of hi-def data displays showing real-time conditions on the grid—unrecognizable to operators a decade ago.  Today, a new wave of devices called phasor measurement units are sampling grid conditions 30 times per second, generating terabytes of data, which will one day allow automated systems to respond to problems faster than humans can think. To the grid, they represent advancements in clarity and wealth of detail similar to the differences between MRIs and X-rays.  Over 9,000 have been deployed with more on the way.

Extreme Weather

Despite the improvements made since 2003, the reliability of the nation’s electricity supply today is challenged by extreme weather in recent years, such as Superstorm Sandy and the summer derecho of 2012. Both of these events caused catastrophic damage to power lines and electrical substations.  Threats of cyber or physical attacks against the grid are ever-present.

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