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With advanced metering infrastructure (AMI)—smart meters—becoming widespread, utilities are exploring a range of new opportunities the devices’ advanced monitoring and control capabilities can allow. While some of these approaches—such as real-time electricity pricing and demand-response programs—require customer participation, utilities also are eyeing options that could reduce a consumer’s electricity use (and bills) without that customer turning off a single light switch or raising an air conditioner’s thermostat.
One such technique now coming to market, conservation voltage reduction (CVR), is focused on cutting the voltage delivered to individual customers. It’s a bit like attaching a low-flow showerhead to a utility’s distribution system. The trick is to lower the delivered voltage enough for noticeable demand reduction but not enough to affect connected equipment’s performance or lifespan.
“The concept has been around for over three decades, but it’s not been done in a very intelligent manner,” said Todd Headlee, director of Dominion Voltage Inc. (DVI), a subsidiary of Dominion Energy Holdings Inc., one of the nation’s largest generation and transmission companies.
Some companies, Headlee said, have just dropped the voltage with no means of monitoring for potential problems. They are relying, instead, on customer complaints to let managers know when to dial the voltage back up.
Several years ago, researchers at the Electric Power Research Institute and the Pacific Northwest National Laboratory (PNNL), along with electric utilities such as Dominion, began looking at ways to perform CVR in a more sophisticated fashion. The technology was identified as one of nine smart grid options for reducing electricity use (and related generation-plant emissions) in a 2010 PNNL report.
With the smart grid, every meter is also a sensor, capable of monitoring voltage and other basic characteristics, and reporting results back to the customer’s electric utility company. This is the critical advantage for CVR applications, according to Headlee. For example, many utilities have assumed in less-sophisticated voltage-reduction efforts that voltage will be lowest at locations farthest from a utility feeder. It turns out that voltages can drop just about anywhere in a distribution system—even at the meters closest to a feeder.
Having accurate, detailed voltage data from multiple points is important because CVR’s savings are based on the margin between the voltage delivered and the actual voltage needed. U.S. utilities are allowed to deliver voltages to single-phase residential customers in a range from 114 volts (V) to 126V (note that the 120V you see on appliances and other electrical devices is smack in the middle). The closer a utility can get to 114V, without going under that mark, the less electricity they will need to either pay for or generate.
Headlee’s company received a patent in February for its software-based approach to CVR, trademarked as EDGE. DVI is working with smart meter manufacturers to incorporate communications capabilities, allowing the units to send information to central monitoring stations. The majority of connected meters report their voltages to the monitoring station daily. However, using proprietary algorithms, the system identifies the 10 to 20 meters at highest risk for low-voltage performance and monitors their voltage status on a real-time basis. That data can automatically trigger voltage regulators, load taps or capacitor banks to add enough voltage to the connected lines to bring the ratings up to an acceptable level.
The system is attracting interest from utilities, Headlee said, not least because it is entirely software-based. Companies can leverage existing smart meters and other equipment, and this low-cost investment can lead to electricity-use reductions as high as 4 percent (compared to 2 percent reductions possible under not-so-smart approaches).
While this system remains a lower cost investment for utilities, it isn’t completely free, and figuring out how to pay for it can be complicated for potential customers. In some ways, the product presents a case study of how smart-grid technology is advancing faster than utility commissioners have anticipated. According to Headlee, 90 percent of the savings with EDGE accrue behind the customers’ meters. They use less electricity, so their bills are lower. However, since there is no physical equipment involved, some public utility commissions have been left scratching their heads, trying to work out how to incorporate such an investment into utility rate cases.
However, bureaucratic complications shouldn’t hold up adoption for long. The National Association of Regulatory Utility Commissioners currently is working on new guidelines, Headlee said. Consequently, some utilities are already moving forward with the technology. DVI has signed a deal with the Central Lincoln People’s Utility District in Oregon, and, as of late April, Headlee anticipated up to six more utilities would be signing up within the next couple months.
“This application has already risen to the short list. [It offers] energy savings that don’t impact the customer” he said.