Utilities across the country are struggling to find a viable replacement technology for the low bandwidth circuits used by system operations to monitor status of their remote terminal units (RTUs) and other distributed intelligent devices. Traditionally, utilities have used a combination of leased lines and wireless radios (licensed and unlicensed) to communicate with these devices. Over time, these solutions have become either inadequate, too expensive, or both. Utilities are now looking for the next generation field area network (“FAN”).
Reaching the limits of current technology
A “last-mile” communication solution, the FAN reaches out from either core backbone or mid-tier back haul locations to end devices in the field. Wireless FANs typically utilize either a point to multi-point (PtMP) or mesh architecture—each with its own benefits and challenges.
Many utilities have used licensed PtMP radio systems to communicate with end devices. These may include both polling information (with exception reporting) as well as command and control data. Historically, these low-bandwidth links were more than adequate to meet needs. But with the emergence of smart grid technologies and IP enabled devices, coupled with utilities’ demand for more information, these technologies are showing their age and no are longer adequate.
Six factors key to finding the “Holy Grail”
Utilities have begun the search for replacement solutions and are discovering that finding “the right” or “the best” solution is tantamount to finding the Holy Grail. Following are six of the most critical factors that a utility must understand and factor into FAN requirements as it prepares to select a vendor and a solution.
Scope. Before honing in on an architecture or spectrum band, decide what the FAN scope includes and excludes. Two of the biggest questions marks are usually centered on NERC-CIP assets and protective relaying. First, given the stringent latency requirements of protective relaying, most utilities choose to exclude this application from the FAN. FAN scope can include NERC-CIP, but more often than not, these sites already have other communication links (such as fiber) in place given their critical nature.
Spectrum. In the United States, the Federal Communications Commission (FCC) has not allocated wide swaths of spectrum for exclusive use by utilities that would enable high-bandwidth applications. The available spectrum is either up for auction, forcing competition with the cellular carriers, or is in frequency bands that are not helpful to emerging utility applications.
Utilities are now looking for spectrum that has good propagation and coverage characteristics, served by high power base stations supporting large channels and preferably licensed. Any frequency band that meets all of those requirements has long been purchased or is already widely in use, so utilities are forced to cobble together bits of frequency here and there.
Geography. The next problem for utilities is service territory. For utilities with a small footprint, this is much easier than for larger utilities. But don’t just consider the size of the service territory, as the FAN may need to operate in densely populated urban areas or sparsely populated rural areas. There may also be the issue of disparate or non-contiguous service territories. A solution that works in one service territory may not work in another.
Terrain. Another consideration is terrain and landscape. Will the FAN be built across the prairies of Kansas or through the Rocky Mountains in Colorado? These factors will be critical in working through the process of selecting an architecture, vendor, and spectrum. A mesh architecture tends to operate better in dense urban deployments than in sparse rural deployments. The frequency range is less important in flatter service territories, whereas lower frequencies have favorable characteristics over higher frequency signals when deploying a FAN in hilly or mountainous areas.
Protocol Support. Most legacy equipment is serial-based and will likely utilize a wide range of protocols including 2179, Harris 5000, or DNP3. The FAN will need to support these devices and protocols. But it also must be IP compatible and support SNMP (preferably version 3) as well as quality of service, MPLS, and traffic segmentation. Some protocols, such as the vintage Micro III protocol, are extremely difficult to convert to work over a modern data network. In these cases, protocol converters or upgrades of vintage equipment may be necessary.
Funding. After selecting the spectrum and completing the architectural design, validating that the solution will support the various protocols in use, and selecting applications the FAN will support, it’s time to secure funding to build the network. These networks are expensive, particularly when factoring in the need for towers and/or spectrum purchase. Additionally, the return on investment (ROI) simply may not exist. Convincing utility executives to invest multiple millions of dollars with a negative ROI is not the easiest of tasks, but ultimately these investments are necessary to "keep the lights on.”
Even after solving for all of these problems, a utility will need to think about the detailed design, deployment, and operation of the FAN. Failing to take into account the above factors can result in a flawed or unsuccessful FAN project.
West Monroe Partners has assisted many utilities with resolving the issues described above, applying a methodology that aids in selection of a FAN solution and technology suite tailored to each utility’s unique requirements. For more information, please contact Tim Valin - firstname.lastname@example.org or Dan Belmont - email@example.com.