T&D World Magazine

Private Spectrum Network Strengthens Distribution Side of Smart Grid at Minnesota Electric Co-op

Wright Hennepin Cooperative Electric Association in Minnesota passed a smart grid milestone this summer, marking one year since integrating a comprehensive smart grid-enabling communications system built on a private spectrum wireless network from Arcadian Networks.

“There are many definitions of smart grid,” said Lance Hovland, VP energy distribution for Wright Hennepin. “For us, from a distribution side, smart grid means automation and communication of substation SCADA data plus advanced metering AMI/AMR to reach high levels of customer service.”

With a 700 MHz licensed wireless IP communications network connecting formerly “poor reliability” stations, Wright Hennepin now operates a fully supported communication platform for AMR and SCADA.

This hasn’t always been the case. Wright Hennepin, which serves about 45,000 electric accounts across two Minnesota counties, has explored many solutions to link widely dispersed substations. “We started out with all substations on a frame relay,” said Hovland. “When DSL became available, we converted most substations to that (along with some of our own 900 MHz wireless systems where we had line-of-sight). But there were a few areas where neither was possible. We looked for a better way.”

Hovland recalls the process: “When our generation and transmission supplier, Great River Energy, put in a private licensed 700 MHz wireless system from Arcadian Networks for all their substations, they left some base points available for the co-ops to use. We took advantage of the opportunity to try out a private network.”

In mid-2008, Wright Hennepin targeted several “problem” stations, where the DSL network would bounce off and on and result in intermittent data. “We cannot afford intermittent communication outages in times of peak power usage. We watch our peaks and make load management decisions based on substation data,” said Hovland. “If we can’t follow our load, we can’t make intelligent decisions. We need high reliability communications from substations to headquarters.”

The first substation to go online was Medina. “It successfully brought back all SCADA and metering data,” Hovland said. “And the savings were considerable -- even better than DSL pricing.”

Next came the Trailhaven and Delano substations. “We’ve seen a huge improvement in reliability,” said Hovland. “Coverage had been spotty and some of the 900 MHz systems didn’t have the signal strength, but the Arcadian Networks system has proven reliable over the past year.”

Following the success of the 700 MHz system, the co-op is considering expanding it to eight to 16 of their total 24 substations. “We’ll be looking at them all,” noted Hovland, “with reliability as the guiding issue.”

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