Just the beginning
Beyond smart meters
Some of this capability exists today, as utilities are deploying smart meters connected to communications systems to reduce the cost of billing. Instead of paying the costs associated with utility personnel reading meters manually, metering information can be delivered to the utility directly via the communications system.
Such metering applications do not require much bandwidth, Gunther said.
“For the meters specifically, the amount of data is incredibly small, and it’s readily scaled in those networks to bring that data back,” he said. “Turn-on/turn-off signals are nothing. Meter reads hourly, or every five minutes, use very little bandwidth from the access point on down, and most of the networks scale readily.”
In addition, meter reading can be done on a best-effort basis within a network, because the data is not particularly time sensitive in relation to the overall monthly billing process.
However, other applications envisioned in the smart grid related to the health of the system need to be provided in real time to be useful.
“Many AMI [advanced metering infrastructure] networks don’t have the capability of supporting simultaneously the distribution-automation-related capabilities,” Gunther said. “It’s not that they’re not fast enough — bandwidth is less of an issue — but they’re not reliable enough or the latency is too long.”
Bender echoed this sentiment.
“It’s the control functions that really require low-latency communications from an event — a circuit breaker tripping or a tree falling down on wires — [that causes] some kind of interaction on the grid to some control device and back,” he said. “We’re talking about latency on the order of 5 to 15 milliseconds.”
While some commercial technologies deployed by carriers can meet this standard, questions about the reliability of carrier networks — particularly during a power outage — have some utilities contemplating the construction of private communications networks for their data needs.
“As these systems become more and more integral to the operation of the utility, we view that there will be an emergent network here that will be every bit as important as the public-safety, mission-critical networks,” Motorola’s Propp said, noting that nascent video applications would be the one reason that smart-grid bandwidth speeds would need to be greater than 1 Mbps in most scenarios.