By Mohamed A. Ali and Ahmed A. Mohamed
The ownership of future grid communications networks and associated standards and interoperability challenges are setting off significant debate among all stakeholders. At the heart of the ongoing debate is whether future grid communications networks should be based on utility-owned/controlled private networks or using the services of public, commercial mobile networks. Recently, a combination of several cellular technology advances along with compelling techno-economic trends have emerged that will most likely bring the debate to a close and position LTE-A-based Fifth-Generation (5G) mobile wireless technology as the global future grid communication networking standard.
Transitioning from today’s traditional power grid to a truly smart grid of the future, which is enabled by complete automation technology, is the key to efficient wide-scale integration of distributed energy resources (DERs) into mainstream energy generation. Efficient, wide-scale, and cost-effective DER deployment requires enhanced situational awareness so that the system operator knows what devices are installed and where. This will lead to greater reliance on the information and communication technology (ICT). Enormous amounts of data with diverse quality of service requirements will be generated very rapidly, which will necessitate grid data communications networks with increased capacity, reduced latency and orders of magnitude higher reliability than is required today. This was examined in a report by the Pacific Northwest National Laboratory.
The power grid network consists of four functional domains, including bulk generation, transmission, distribution, and consumption, which are typically dispersed in a large geographical area. The supporting communication network infrastructure must cover all of these four segments and is, thus, divided into a number of hierarchical networks, including Home Area Networks (HANs), Neighborhood Area Networks (NANs), Field Area Networks (FANs), and Wide Area Networks (WANs). Typically, different networking technology and interface standards are adopted in different parts of the grid. Utilities have traditionally used multiple non-converged private communication networks that they built as well as public service provider networks. Some utilities have had as many as nine separate communications networks, often owned and managed by different departments within a single utility. These networks, however, are undersized and lack the latency and capacity capabilities required to support advanced distribution automation and meet the challenges of efficiently integrating wide-scale DERs, as reported by the Massachusetts Institute of Technology.
As the grid evolves, numerous multiple vendors’ devices and systems of different kinds and generations, including those of the anticipated wide-scale advanced metering infrastructure (AMI), microgrid, and plug-in electric vehicle (PEV) adoption, will be integrated into the distribution grid. Ensuring end-to-end interoperability among these devices and systems via standardized communications protocols and other interface standards will be critical. The U.S. National Institute of Standards and Technology (NIST) Cyber security Working Group identified 137 interfaces between different grid systems. The key problem has been and still is the lack of an adequate widely accepted, unified global communication technology standard capable of supporting advanced distribution automation in modern distribution grid, including wide-scale integration of DERs.
The ownership of future grid communications networks and associated standards and interoperability challenges are setting off significant debate among all stakeholders. At the heart of the ongoing debate is whether future grid communications networks should be based on utility-owned/controlled private networks or using the services of public, commercial mobile networks. In its National Broadband Plan, the Federal Communications Commission (FCC) makes the following recommendations on the issue of grid data communications network ownership: “The country should pursue three parallel paths. First, existing commercial mobile networks (Long Term Evolution (LTE)/LTE-Advance (LTE-A)) should be hardened to support mission-critical Smart Grid applications. Second, utilities should be able to share the public safety mobile broadband network for mission-critical communications. Third, utilities should be empowered to construct and operate their own mission critical broadband networks.
Recently, a combination of several cellular technology advances along with compelling techno-economic trends have emerged that will most likely bring the debate to a close and position LTE-A-based Fifth-Generation (5G) mobile wireless technology as the global future grid communication networking standard. These include:
- 5G is set to enable the future of the Internet of Things (IoT), the name given to the notion of connecting just about every and anything to the Net, as it will provide the mobile connectivity to the billions of things/devices attached to the IoT;
- Smart grid, however, is just one application among many, including vehicular networking, healthcare, environment and smart cities, etc., that will be supported by the emerging IoT, and, thus, will certainly be supported by 5G as well;
- LTE-A-enabled Heterogeneous networks (HetNets), which comprise a combination of macro-cell base stations and low-cost low-power small cell base stations (BSs) operating over both licensed (e.g., femto and picocells) and unlicensed (e.g., WiFi access points) bands;
- Cellular LTE-A-enabled machine-to machine (M2M) and machine-type communications (MTC); and
- LTE/LTE-A has been already selected by US and EU federal authorities to be the technology for future public safety mobile broadband networks. Thus, the choice of 5G is consistent with FCC recommendations (first two approaches) for future grid communications networks.
We envision a global grid communication network that builds on the emerging 5G cellular network technologies and utilizes LTE-A enabled MTC/M2M communications and HetNet infrastructure as the sole global cellular technology standard seamlessly stretching from HAN to NAN to FAN to WAN. A massive deployment of small cells introduces a new challenge for the backhaul, which must provide connectivity at sufficient capacity and guaranteed quality of service (QoS). The number of small cell sites in certain macrocell coverage can rise up to several hundreds (e.g. large city center) and every one of them needs to have a fast backhaul connection to the mobile core network. To address the backhauling challenge, we propose to utilize a cost-effective fiber-based small cell backhaul infrastructure, which leverages existing fibered and powered facilities associated with a passive optical network (PON)-based fiber-to-the-Node/Home (FTTN/FTTH) residential access network. Due to the sharing of existing valuable fiber assets, a PON–based backhaul architecture, in which the small cells are collocated with existing FTTN remote terminals (optical network units (ONUs)), is much more economical than conventional costly point-to-point (PTP) fiber backhaul designs. Thus, the envisioned hybrid-networking infrastructure offers the reliability of fiber networks and flexibility of public cellular networks.
The 5G-based public, commercial cellular network enables utilities to wirelessly connect to the entire distribution grid assets. Associated with each of these assets, there is one or more low cost stationary LTE-A-enabled M2M module (embedded chip set), or mobile in the case of PEVs, that sends and receives data to and from the macro BSs, small cells, or another M2M module.
LTE-A-based HetNets as well as recent M2M and other developments in the latest LTE-A Releases have the potential to address key challenges such as: providing both comprehensive coverage at the scale of the entire grid or grid operator level as well as sufficient network capacity to accommodate a fast growing and ultimately massive number of LTE-A enabled M2M devices that are widely distributed over the entire grid and the ultra-high aggregate volume of smart-grid data and their mission-critical nature, including wide-scale DERs adoption; device discovery and M2M session setup; signaling storm: the support of the massive simultaneous transmission of low data rate signaling message; detrimental co-channel interference between macrocells, small cells, and M2M devices; and efficient and fair radio resource allocation and QoS guarantee between competing H2H and M2M communications.
Since LTE-A is an all IP-based network, each and every grid asset (appliances, equipment, components, controller, etc.) is equipped with an LTE-A-enabled IP-based M2M module. Thus, communications among the entire multiple vendors grid assets is based on a single IP-based communication protocol. This ensures excellent end-to-end interoperability among the millions of multiple vendors’ communication devices distributed throughout the entire distribution grid. This is significant as the complex multiple vendors’ interoperability standardization problem is simply and eloquently addressed and reduced to a dominant widely accepted single protocol – the Internet Protocol (IP), which is the core protocol of the public Internet. Because IP is already used almost universally, commercially available software and hardware systems are designed to process IP traffic and protect IP-based networks from intrusion, thus making IP the obvious choice for most networking applications including the power grid of the future.
Mohamed Ali has more than 30 years experience in IT and telecommunications research. He is the author and co-author of more than 200 refereed journal papers, invited talks, book chapters, and conference presentations. His research synthesizes and extends results over the full discipline of mobile and wireline networking, from the physical layer of devices and components to the architecture layer of local access, Metro, and global carriers. His most recent work focuses on smart grid technologies and applications including microgrids, plug-in electric vehicle (PEV)-to-grid (V2G) systems, and distributed energy resources (DERs), as well as the strong interdependencies between the ICT and power grid networks. He has an extensive track record in IP/MPLS-based Layer 1/2/3 Enterprise MAN and VPNs, Optical Networking Technology & Architecture, Fifth-Generation (5G) cellular networking architecture and technologies including LTE-A-enabled Heterogeneous networks (HetNets) and machine-to machine (M2M) and machine-type communications (MTC). Dr. Ali has received the NSF Faculty Early Career Development Award. He received his Ph.D. degree in electrical engineering from the City College of the City University of New York in 1989. He joined the faculty of electrical engineering at the City College of New York in 1989 where he is currently a professor.
Ahmed Mohamed is currently an assistant professor at the Department of Electrical Engineering, Grove School of Engineering, City College of New York, City University of New York. He was a post-doctoral research fellow at the Energy Systems Research Laboratory (ESRL), Florida International University. His current research interests include hybrid ac/dc power systems and microgrids, smart grid resilience, and space weather. He received his PhD degree in electrical engineering in 2013 from the Energy Systems Research Laboratory, Florida International University, Miami, FL, USA.