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Smart-Grid Strategy: Why Wireless?

Radio waves deliver flexibility and security.

Fortnightly Magazine - September 2009

notably for security reasons. “Every time you utilize a public network, such as a cellphone network, you’re just opening up the number of points at which there could be an entry into the system,” says Trilliant’s Miller. This, he suggests, increases the number and types of threats. Private wireless networks, on the other hand, are easier to secure because they limit the number of entry points, and benefit from wireless cybersecurity tools created for other industries. “You don’t have to create it from scratch,” Miller says.

Arcadian Networks also is banking on private network demand, in part because of security concerns, and also because wireless smart- grid applications continue to expand and eventually will exceed the capacity of existing networks to accommodate them. “If you’re working with an unlicensed network, you don’t have the ability to manage and control it,” Solar says.

Also, while public wireless networks have expanded dramatically in the past decade, they still might not reach a utility’s entire grid. “Reclosers, voltage regulators, capacitor banks, and substations are typically distributed in difficult-to-reach areas over wide geographies,” Kantor says. “Public wireless networks lack the coverage and quality of service to be an effective solution.” And even where public networks provide adequate coverage, they might not be affordable. “Unlicensed systems can require up to 40 times the infrastructure cost of a licensed solution, dwarfing the cost of obtaining licensed spectrum,” Kantor says. “Maybe for metering, you can use unlicensed wireless. However, for the higher level applications, you need a licensed solution.”

At the same time, however, public wireless networks offer some advantages over private networks. Bandwidth is one example. “I don’t think people yet have come to terms with what the bandwidth requirements will be in the future,” says David Mohler, vice president and chief technology officer for Duke Energy. “If we are trying to remotely read meters, the bandwidth requirements will probably be fairly low. However, if we plan to deploy an intelligent infrastructure that will allow multiple queries, real-time reporting of energy consumption information, real-time correlation of data, and allow us to use distributed resources and direct load control for reserves or peak shaving, we may need a great deal of bandwidth—maybe not broadband, but certainly more than we will probably be able to get from many of the wireless deployments that we are doing today.”

For instance, in many utilities’ wireless mesh networks, a single data concentrator (radio receiver) serves as many as 5,000 customer premises. However, the maximum bandwidth at the data concentrator might be only 100 kilobits per second (Kbps). “You probably need at least half of this just to manage the network itself,” Mohler says. “I don’t think the remaining bandwidth will be sufficient to do all the things you want to do with that many customers.”

Additionally, he says public networks offer reliability levels that proprietary networks might be hard-pressed to match. “If we own the wireless network, and if a thunderstorm rolls through and takes a bunch of equipment down, our guys have to work hard to get the power back on and