The operations and planning rules for integrating variable resources aren’t the same across the electric power industry in the United States at present. Opinions are somewhat divided about what...
Demonstrating the Smart Grid
Pilot projects clarify the vision of an intelligent utility system.
not really sure what that means.
In this special report, Public Utilities Fortnightly highlights five recent initiatives, each of which clearly demonstrates one or more aspects of this quickly developing thing called the smart grid.
PNNL: Appliance Alliance
Two studies conducted in 2007 by the Department of Energy’s Pacific Northwest National Laboratory (PNNL) demonstrated that smart-home appliances will go a long way in helping utilities improve grid operations.
The first, known as the Olympic Peninsula project, garnered most of the early headlines because it was one of the first in the country to demonstrate that individual homeowners will readjust their energy-use patterns when given real-time price signals via in-home information technology.
Some 112 homeowners on the state of Washington’s Olympic Peninsula received new, two-way meters and thermostats, along with water heaters and dryers outfitted with special software that allow the homeowner to customize the devices to the desired level of comfort or economy.
Once the settings were established, the devices automatically responded to electricity price signals that were updated every five minutes. A commercial building, municipal water pumping system and a small amount of distributed generation capacity also responded to the same pricing signals.
During peak periods when electricity was most expensive, the software automatically adjusted thermostats or appliances to pre-set response limits established by each homeowner. Combining the demand response with distributed generation reduced peak-distribution loads by 50 percent. Further, participants who responded to the real-time prices reduced their peak-power use by 15 percent.
The Olympic Peninsula project yielded remarkable results, but operations professionals might be more intrigued by the second pilot—which received less public attention.
Rather than focusing on price signals, the Grid Friendly Appliance (GFA) Project demonstrated that everyday household appliances fitted with electronic controllers capable of sensing under-frequency stress on the power grid could have an equally profound effect on network operations.
PNNL developed and embedded a small electronic controller on 150 new Whirlpool clothes dryers and 50 existing residential water heaters in 150 Washington and Oregon homes to detect and respond to low-frequency stress on the grid.
The controller’s frequency threshold was set at 59.95 Hertz—high enough to recognize frequent, shallow frequency excursions of a 60-Hz AC voltage signal available at any residential outlet. The controller automatically shut off the dryer or water heater’s heating element within one-quarter of a second after a sudden drop in frequency.
The hypothesis was that an army of controllers collectively could contribute to frequency protection on the grid—typically a substation function where under-frequency relays are pre-set to shed feeder loads if low frequency thresholds become crossed.
“We turned an everyday household appliance into an ally,” says Rob Pratt, PNNL program manager for both projects. “Utilities typically maintain a 5-percent spinning reserve, and white goods like dryers and water heaters account for 20-percent of electrical demand at any point in time. If every appliance in a service territory had a controller built in, you would have what amounts to a 20-percent safety cushion. That, in theory, could help reduce a utility’s spinning-reserve requirement.”
A total of 358 under-frequency events lasting