Utilities have long bemoaned their lack of access to appropriate, affordable wireless spectrum for their smart grid communications networks. But this year, a handful of utilities have taken the plunge, acquiring 2 MHz of licensed 700 MHz band spectrum from private investors.
Salt River Project (SRP), based in Phoenix, Arizona, has made one of the largest purchases to date in terms of population covered. Earlier this year, SRP acquired the Phoenix-Mesa economic area (EA) license #158, which covers an estimated 4.3 million people (pop) in central Arizona.
The license includes two 1 MHz swaths of spectrum at 757 MHz to 758 MHz and 787 MHz to 788 MHz. Access Spectrum was the seller; the company, along with Columbia Capital and Beach Point Capital, is marketing similar licenses nationwide for $0.75/MHz pop (pops x MHz). This implies a price tag in the $6.45 million range for the SRP transaction.
I spoke with Ron Taylor, senior principal engineer for SRP, about the purchase and what still needs to happen for this spectrum band to meet utilities’ needs.
“We have to find the right vendors; we’re working with standards bodies right now,” he said, to develop a standard protocol. “We’re not interested in a proprietary solution; we don’t want a single point of failure.” Taylor added, “We took a bit of a risk [buying the spectrum]. Others were waiting for someone to put a foot in the water.”
Distribution Automation Is the Goal
SRP intends to use the private network to fill the connectivity gap between its substations, which are all connected by fiber, and its advanced metering infrastructure (AMI) networks. Taylor noted that they are interested in distribution automation applications like voltage control and fault location, isolation, and service restoration (FLISR), adding that it is also looking at smart inverters for solar installations and monitoring of distribution transformers and dynamic line rating applications.
When asked if 2 MHz of spectrum is enough to do it all, Taylor admitted that SRP won’t be able to do it all. “We did the math. What is smart grid? We had to trim our list,” he said. But he added, “Everything that’s critical, and even nice to have, should be accommodated for 10 years. It all fits except meter reading; that would overload our network.”
Prior to the acquisition, SRP leased the license and tested for interference with Verizon Wireless’ adjacent licenses and network. The field test validated the license for SRP’s planned purposes.
Just a Start
SRP and other utility buyers of this slim license band are hoping the vendor community can standardize around a single technology, yielding economies of scale for utilities still seeking an efficient communications strategy for high-performance-need applications in the distribution network.
But as SRP’s chief engineer pointed out, just 2 MHz really does limit the options for longer-term smart grid goals—but with no sign the Federal Communications Commission (FCC) is considering dedicated spectrum for power utilities in the near term, the availability of this contiguous, nationwide set of licenses is a start.
Tags: Distribution Automation, Grid Networking and Communications, Transmission & Distribution, Utility Transformations
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