Satellite Communications Technology Enhances Distribution Operations

By Teresa Hansen
Managing Editor

Satellite technology has come a long way since the launch of ORBCOMM’s low-Earth orbit satellite constellation, making it a viable communications option for utilities.

Seldom does one particular communications technology dominate a utility’s infrastructure. Usually a combination of several technologies, such as satellite, microwave, fiber optics, coaxial cable and wireless, are used to satisfy all of a utility’s communications needs. Until recently, satellite technology’s usefulness to utilities had been somewhat limited, mainly being used with global positioning systems for more efficient fleet management and vehicle tracking. However, the recent deployment of low Earth orbit (LEO) satellites by ORBCOMM, a commercial provider of global LEO satellite data communication services, has made satellite technology a cost-effective alternative for utilities’ communications needs. Now utilities have a communications medium that can provide 24-hour coverage anywhere in the world, making it a one-of-a-kind communications technology

Even though satellite technology is not a solution to all communications needs, some utilities are finding that it serves them well in certain network applications, including distribution automation and automatic meter reading (AMR). According to Rick Joyce, sales and marketing director for ViaSat Satellite Networks (formerly Scientific Atlanta) LEO Data Systems Group, a value-added reseller of the ORBCOMM system, satellite technology cannot be marketed as a true alternative for an AMR system. “Satellite technology is an alternative for those hard-to-read areas or areas where other communications technologies are cost prohibitive or unavailable,” he said. “It provides a cost-effective solution for deployment of the last 10 to 15 percent of meters. For example, Carolina Power & Light is using the ORBCOMM system to read about 1,200 meters located in remote areas with no other communications options. But this is not the primary communications medium for its AMR program.”

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Joyce also does not expect to see satellite technology displace traditional distribution automation architecture, but he believes it certainly can serve a purpose in some instances.

Because of the latency associated with the LEO satellites and the data transmission costs, it is important for anyone developing satellite communications technology to have a good understanding of the technology and its limitations. However, with the right programming and configuration, a network that is more cost effective than cellular technology can be developed, Joyce said.

ORBCOMM uses a constellation of LEO satellites-35 satellites are currently in its constellation with an additional launch planned for later this year, which will complete its satellite implementation. Data collected by the satellites is transmitted to gateway Earth stations and network control and management centers to provide message communications. The system is capable of sending and receiving two-way alphanumeric packets, similar to two-way paging or e-mail.

Joyce believes that as other companies deploy their own constellation of LEO satellites, the technology will become even more cost-effective. He expects to see ORBCOMM competitors, with claims that their technology is cheaper, faster and better, enter the market by 2002. Until then however, most utility personnel believe ORBCOMM’s technology is best suited for utility applications.

SRP Benefits from Satellite Technology

One utility that has found satellite technology useful is Arizona-based Salt River Project (SRP). In the mid ’90s SRP was looking for ways to reduce costs and increase revenues in core competencies. Although SRP is a government-owned entity, it is no different than most other utilities when it comes to pressures associated with pleasing regulators and improving efficiencies. In its quest to fulfill these goals, SRP successfully developed a monitoring and communications system that not only improved its own operating efficiencies but also became a new revenue source. In fact, the utility has found the technology so beneficial that it believes it can be sold to other utilities. Thus, SRP recently entered into a partnership with Scottsdale, Ariz.-based Motorola Utility Solutions to further develop and market its system, which it calls SPATIA. With this partnership, Motorola became an ORBCOMM value-added reseller, joining the ranks with ViaSat.

SPATIA’s History

SRP provides irrigation water to agriculture customers, as well as electricity to various customers in a service territory that covers more than 5,000 square miles, and has many remote locations that require monitoring. According to Bruce Hallin, SRP’s Water Group business development and strategic analysis director, the utility must monitor water level and depth, water flow and environmental parameters in various locations throughout the service territory. Sending a person to each monitored site to record the information was the utility’s normal data collection procedure, but it was very expensive. SRP saw remote monitoring as a way to greatly reduce labor expenses and obtain required information at more frequent intervals.

In 1997, with this goal in mind, SRP technicians assembled and developed a multi-functional data logger and communicator that links to virtually any sensor that transmits a digital, pulse or analog (4 to 20 mA) signal. The unit then logs and transmits data collected from a sensor via ORBCOMM’s data communications system. “It is important to note that ORBCOMM’s system was designed for data packet transmission, not voice transmission, as is the case with many LEO systems,” said Hallin. This makes a big difference when you are transmitting data, he added.

Data that is transmitted from the remote sensors to the LEO satellites is then transmitted to ORBCOMM’s Network Control Center (NCC). The NCC is responsible for managing all the information received from the satellites and sending the information to various subscribers, in this case SRP. The information may be transmitted to subscribers via standard communications modes including leased line, dial-up modem, public or private data networks and e-mail networks, including Internet.

In addition to receiving information from the LEO satellites, the NCC can also send real-time and stored commands to the satellites. This feature allowed SRP to include not just monitoring in its system, but control as well.

Additional Uses for SPATIA

SRP explored possible uses for the technology and, as a result, is now using the technology in its electricity business to remotely monitor meters, substation equipment and capacitor banks. The implementation has been especially beneficial for monitoring switch status on some of SRP’s remote groundwater wells. Not only can the utility determine if switches are in the “on” or “off” position, but it also can control the switches through the system.

In June 1998, SRP decided to expand the system beyond its internal use and began offering energy management information such as load profiling and usage data to its commercial and industrial customers. With the SPATIA system, SRP collects the customer’s usage data. This data, which is received at ORBCOMM’s NCC, is then sent to the SPATIA System Data Center at the Motorola facility in Scottsdale, Ariz. where it is sorted into useful information, configured and displayed in accordance with the customer’s requirements. From there it is sent to customers via the Internet.

“The system’s greatest value is its ability to get information to the end-use customer in near real-time,” said Hallin. The information helps customers make informed, prudent decisions about energy usage as well as energy purchases, he added.

Another feature that has been well-received is the alarm feature. This feature allows performance parameters to be programmed into the system at the monitored site. If the parameters are not met, an alarm is sent back to the customer.

Hallin pointed out that even though SRP’s initial Web-enabled solution was developed using LEO satellite technology, SRP also uses other communications technology with SPATIA, such as public switched telephone networks and paging networks (see figure). “The satellite technology added a lot of value for certain applications,” Hallin said. “However, there are applications where we use other available technologies.”

In an attempt to further market the technology, New West Energy, an energy service provider and unregulated SRP subsidiary that sells SRP’s surplus power in California, Nevada and Arizona, is offering energy usage data and load profiling as a value-added service to its energy customers. In addition to buying power from New West Energy, for a monthly fee, customers can obtain usage information that can help them better manage their energy consumption and make better buying decisions.

Although SRP has been pleased with the benefits it has received from the system, and has been fairly successful at marketing the technology to its own customers, it was believed that Motorola’s involvement with the product could provide even more benefits.

“Motorola entered this market because there are some major obstacles with gathering information,” said Rick O’Connell, Motorola Utility Solutions’ system engineering manager. “Motorola is an expert in communications technology and has decided to leverage that expertise by further developing and marketing the SPATIA solution.”

Some of the services being offered include load profiling, benchmarking, energy cost allocation, load curtailment monitoring, fault monitoring, exception reporting, water use, water flow and water quality monitoring. “We are offering solutions to fit our customers’ needs,” O’Connell said. “The LEO technology plays a big role in this; however, solutions often include a combination of wire-line and wireless technologies. Our goal is to provide our customers with appropriate technology at the lowest cost.”

EMEPA’s Applications

Another utility that has gained some efficiencies from the LEO satellite technology, is East Mississippi Electric Power Association (EMEPA), located in Meridian, Miss. According to Pat Williams, an applications engineer at EMEPA, the cooperative became involved with the technology about three years ago when it participated in a National Rural Electric Cooperatives Association (NRECA) project dealing with rural cooperatives and their use of LEO technology.

During the project Williams adapted ViaSat’s Fixed Site Communicator to provide remote terminal unit (RTU) functionality for down-line or distributed equipment such as reclosers and voltage regulators. With the communicator, EMEPA now can monitor and control down line devices and some substation functions through the ORBCOMM system.

According to Williams, because the ORBCOMM system allows for two-way communications and the ViaSat device is programmable-it contains a processor along with code space, which allows the device to be programmed-he was able to make the device perform like a remote terminal unit (RTU) at a reasonable cost.

Substation Solution Development

Like many rural cooperatives, EMEPA still uses high-side fuses rather than three-phase breakers for protection in some of its substations. Although fuse operations are rare, when they do occur, they cause low voltages (single-phasing) to be experienced on the distribution line anytime one or more fuses blow. Without any communications between the substation and the operations center, the EMEPA personnel had no way of knowing when a fuse had blown until customers began calling. Often, by the time cooperative employees were notified of a problem, the co-op’s equipment, as well as its customers’ equipment was damaged.

One solution to this problem would have been for EMEPA to install three-phase protection and relaying, however, according to Williams that would have cost approximately $50,000 per installation. As an alternative, Williams programmed the ViaSat communicator to detect single-phasing, trip the distribution breakers and send an alarm to the EMEPA system operators. “Opening the feeder breaker still causes an outage, but it keeps the low voltage from damaging our equipment and our customers’ equipment,” Williams said.

Williams said the cost of this solution is about $5,000 per implementation, considerably less than the cost of installing three-phase breakers. In addition, not only is the cooperative receiving the protection feature, but it also has the benefits of monitoring and control using traditional digital and analog inputs in these older substations where intelligent devices aren’t used. As with the SPATIA product, data collected by the LEOs is sent to ORBCOMM’s NCC and then on to a network management center owned by ViaSat. EMEPA is using standard Internet e-mail to receive information from and send information to the ViaSat data center.

Response Time

Both Williams and SRP’s Hallin said their systems’ response times vary depending on the LEO satellites’ position during data transmission, but they both reported that the response time is relatively short-usually within two or three minutes. Williams said that during one test, he repetitively polled a field device over several days from a desktop and received the requested information with an average of less than three minutes. So, while the LEO satellite technology is not real-time, it is very close.

Williams pointed out that in addition to being programmable, another advantage to the ViaSat device is that it requires no additional hardware to connect it with intelligent field devices, such as Cooper reclosers or EnergyLine capacitor controls. “The device will plug directly into the RS 232,” he said.

Williams has recently developed other distribution automation applications using the LEO technology and the ViaSat communicator. Williams has a capacitor control system in trials at another rural utility where LEO and modern intelligent capacitor controls were more economically feasible than using a traditional SCADA system and traditional communications. Additionally, a LEO interface was developed for an Australian company, CHK Wireless Technologies Inc., which has an elaborate fault detection product that additionally leverages the LEO by utilizing the GPS synchronized date and time for highly accurate fault reporting.

Williams said the LEO technology is exciting because, with a correctly programmed device, it provides two-way communications from any location at an affordable cost. “You can’t get that kind of performance from a paging system,” he said.

Authors note: More information about Pat Williams’ software development can be obtained at www.globalautomationsolns.com.

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