Connecting all the dots, wirelessly
WHEN THE SOUTH CENTRAL INDIANA RURAL Electric Membership Cooperative was looking for the most efficient way to transport data from its new supervisory control and data acquisition (SCADA) and advanced metering infrastructure (AMI) systems to its microwave-based backbone network in 2007, the utility considered many options.
Utility executives knew that settling on a solution that answered only the near-term immediate need was not the way to go. Instead, the Martinsville, Ind.-based utility wanted a scalable solution that could be tweaked and used for new and innovative concepts down the road.
Own your own
With more than 34,000 customers spread over seven counties, SCI is the largest of rural Indiana's 40 electrical membership cooperatives. Yet, it operated with a small budget for the project, and knew that a wired network would not be a cost-effective solution. The utility collaborated with an engineering firm that advised it to install an IP-based point-to-multipoint network.
The consulting firm also recommended that the utility own its own network as opposed to leasing so it could define its own uses for the network. In addition, owning eliminated the need to rely on an outside third party for service and the high monthly fees they often charge.
"It made sense to put in a high-speed data network to our substations, not only to handle SCADA and AMI backhaul, but just looking out into the future for other applications," said Jack Hubbard, vice president of distribution services at South Central Indiana REMC. "At the time it seemed like there were a lot of opportunities to do more out at our substations, so it just made sense to invest in a data network."
With a network of 22 substations, most of them located in very remote locations, it was important to find connectivity that could not only carry the utility's mission-critical usage data, but also allow for other crucial functions such as connecting two-way radio system repeater sites, and supporting alarm and video security systems that SCI has rolled out since deploying the network.
Hubbard says the system has worked exactly as planned, and that the utility plans to deploy some additional features over the next several months.
"The biggest benefit is exactly as we expected-we're able to backhaul our AMI and SCADA data," said Hubbard. "And because we have connectivity at the substations, our technicians can get connected back to our internal network to get information that they need during a job, like product manuals. We've been very pleased with the reliability of the system."
Because technicians performing maintenance and other tasks can connect back to the internal network, the system has saved time and labor from driving back and forth between substations and the main office to locate information that they need during a site visit.
The next step for South Central Indiana Rural Electric involves a feeder automation pilot that is currently in its early stages. Hubbard says that the pilot calls for placing motor operators on three switches that will allow the utility to transfer three circuits between two substations.
"It's a pretty basic pilot," he said. "We'll be communicating via our SCADA system to down-line devices and those devices will actually be communicating over the data network back to our system, so it will be a separate end point besides just our substation.
"That will allow us to do switching automatically from our SCADA system as opposed to having a person at each device operating it. We can have maybe one person in the area making sure switching occurred properly. We're just focusing in on two substations but we're pretty confident we'll grow it from there."
Down the road, the utility hopes to obtain additional information from other devices like reclosers, where the data gained can provide information about load and faults that the utility can't access now. And by monitoring regulator controls, the utility hopes to undertake voltage reduction on some longer feeders that have down-line regulators.
"We'd be able to do that by communicating with the regulator and by adjusting their settings remotely," said Hubbard.
As for challenges and lessons learned, Hubbard says that because the utility is in such a rural location, obtaining line of sight hasn't always been easy due to the hilly terrain located throughout its service territory.
"Getting the line-of-sight link has been a challenge," he said. "We went through all of the engineering studies that said the system would work out of the box, and for the most part it did. But with seasonal changes like leaves on the trees, we were having some trouble communicating with some of our substations. We are looking at installing some relay points to try and get better coverage to our substations in our more rural areas."
Hubbard says not to overlook regular maintenance that the network will require: "You don't just put it in place and expect it to work for years on end."
For example, Hubbard says that after strong wind storms, utility crews often need to realign and adjust network equipment in the field to ensure that network coverage remains strong.
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