Viewing a computer image similar to a weather map, transmission system operators are now able to see congestion on the high-voltage power lines that make up the United States' massive regional electricity grids. This multi-dimensional representation of power market activities is made possible by a new software tool from the Electric Power Research Institute (EPRI) called the Community Activity Room, or CAR. CAR's color graphics show the current state of wholesale power transactions and their effect on the reliability of an interconnected power grid.

“The walls, ceiling and floor of the CAR represent the limits of the space within which local and interstate power transactions can freely take place,” said the originator of the concept, Stephen Lee, EPRI's senior technical leader for grid operations and planning development. “The multiple dimensions of the CAR graphic help operators clearly visualize the impact of the numerous constraints they must consider when guiding a power system.”

Lee explained that recent changes in the North American electric power industry have caused a dramatic increase in the use of the transmission system over long distances. As a result, planners and operators are facing tremendous challenges in maintaining reliability and efficient power market operation.

CAR software helps them see the big picture of interstate traffic as well as local traffic in order to solve the congestion problems. With CAR, the walls and boundaries for wholesale power transactions are mathematically defined, and the status of the wholesale power market is represented by an illuminated point or “floating light bulb” inside of the room. Operators can monitor wholesale power market activities and direct the light bulb to move away from the walls or get back inside if forced outages of transmission lines cause the walls to suddenly move inward, leaving the light bulb outside the room's boundaries. When congestion causes the light bulb to move outside the walls, CAR provides directions for getting the system under control.