THE NEED FOR A BETTER GRID SYSTEM

Improved synchronicity: Preventive care for the power grid

President Obama in this year's State of the Union address talked about the future of energy and mentioned "self-healing power grids" -- a grid that is able to keep itself stable during normal conditions and also to self-recover in the event of a disturbance caused, for example, by severe weather.

But as the national power-grid network becomes larger and more complex achieving reliability across the network is increasingly difficult. Now scientists have identified conditions and properties that power companies can consider using to keep power generators in the desired synchronized state and help make a self-healing power grid a reality.

Designs for a better power grid could help reduce both the frequency of blackouts and the cost of electricity as well as offer an improved plan for handling the intermittent power sources of renewable energy, such as solar and wind power, which can destabilize the network.

The use of renewable energy is growing. More people will be driving electric cars, and the power grid will be delivering this energy, not gas stations. The need will be for a power grid that is more capable and more reliable. This requires a better understanding of the current power grid as well as new ways to stabilize it.

The crux of the challenge is that for the U.S. power grid to function the power generators in each of its three interconnections (Eastern, Western and Texas) must be synchronized, all operating at the frequency of 60 hertz. Out-of-synch power generators can lead to blackouts that affect millions of people and cost billions of dollars -- losses similar to those of the Northeast blackout of 2003. Having a network that can synchronize spontaneously and recover from failures in real time -- in other words, a self-healing power grid -- could prevent such blackouts.

When a problem develops in the power-grid network, control devices are used to return power generators to a synchronized state. The researchers derived a condition under which the desired synchronous state of a power grid is stable. They then used this condition to identify the parameters of the power generators that result in spontaneous synchronization. This synchronization can be autonomous, not guided by control devices.

The blackout at this year's Super Bowl was caused by a device that was installed specifically to prevent blackouts. A large fraction of blackouts have human and equipment errors among the causes. Reduced dependence on conventional control devices can improve the reliability of the grid.