Rural Michigan Co-Op Reaches the Few and Far Between With Hybrid AMI System

Great Lakes Energy supplements PLC with cellular metering to manage interval data from remote industrial sites and substations

Great Lakes Energy’s (GLE) service territory is scattered over 26 rural counties throughout Michigan, nearly stretching the length of the state.  As Michigan’s largest member-owned electric utility and third largest power company overall, it serves 132,000 meters with 14,000 miles of overhead and underground line through 74 substations.

The company originally transitioned from customer read billing to Alcara’s TWACS power line system in 2004 for obtaining more accurate reads and billing resolution of full-time residents, the many vacation rental homes near Lake Michigan and national forests, and commercial customers.  The upgrade also provided a major system update to outage management systems for faster restoration after heavy storms. The system provides a reliable mechanism for reading hourly data at greater than 99 percent of all meters system wide. For larger loads of several industrial customers and substation monitoring, Great Lakes closely monitors the loading at a much lower latency at smaller increments of minutes or less to manage peak demand periods.

For these larger loads, GLE had historically used dial-up lines from the local phone company to remotely monitor C&I meters, but this was a cumbersome and expensive way to keep abreast of peak. Phone lines can often be damaged or tampered with. Modems are vulnerable to lightning and other disruptions that can take them off-line and they’re susceptible to noise from any large industrial equipment nearby. Substations require a Positron isolation rack to protect the telephone facilities and personnel from hazardous voltages.  And if there is a problem reading a dial-up meter, no dial tone, it became a separate matter for members and phone companies to repair.

Great Lakes Energy remote metering sites using a Yagi-type antenna. With a relatively small amount of endpoints spread over a vast area, it made sense to utilize public network infrastructure that was already in place.

By 2010, GLE began investigating alternatives for the phone lines used for their larger C&I customers as well as substation monitoring.  With a relatively small amount of endpoints spread over a vast area, it made sense to utilize network infrastructure that was already in place.  After evaluating several vendors’ technologies, GLE decided to test Aclara’s cellular carrier-based Metrum system at a particularly remote customer site 90 minutes away from the main office.  The hardware and software are compatible with GLE’s existing meters and utilize existing public networks over GSM and GPRS protocols. In this case, a transmitting device and antenna were fit under the meter glass (GLE has since used a variety of antennae based on geography).

Success came quickly. After assigning an IP address to the meter and adjusting a few software settings, GLE immediately received remote data from the meter with no other provisioning, far exceeding expectations of time and complexity.  The utility has since converted nearly half of its dial-up C&I and substation meters with the same level of effectiveness.

“Installation and maintenance costs are way down at the locations served by cellular; a fraction of what they are with dial-up, says GLE’s electrical tech, Dave Hickman.  “The cellular network’s speed can provide readings from six meters in the same time as one reading from a dial-up connection.  Meters can be read at voltages ranging from 120 to 480 V and removing phone lines eliminates the added expense and maintenance of the Positron equipment.”

A representation of a mobile configuration tool for each digital endpoint utilizing the cellular network.

Hickman also notes that time and fuel costs are down considerably as there is no need to visit remote sites as often.  The most striking detail of the cellular technology to him was its simplicity to implement.  “What was most surprising about Metrum was how easy it is to install. As the public network infrastructure is largely in place, there is no need for investing in additional equipment other than internal or external antennae to get a signal from the meter.”

The transition to a hybrid metering system of TWACS/cellular in less than ten years has been effective for Great Lakes Energy in terms of service and cost.  Reliability and functionality have all increased without large investments in network infrastructure.  TWACS for residential and the majority of commercial accounts with the cellular carrier-based system for large industrial loads and substations are proving to be a solid combination that is meeting GLE’s needs in the near term and should accommodate any necessary expansion that may follow.

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