IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS, VOL. 11, NO. 1,FEBRUARY 2015 187 Convergence of Smart Grid ICT Architectures for the Last Mile Michele Albano, Luis Lino Ferreira, and Luís Miguel Pinho, Member, IEEE Abstract—The evolution of the electrical grid into a smart grid, allowing user production, storage, and exchange of energy; remote control of appliances; and, in general, optimizations over how the energy is managed and consumed, is an evolution into a complex information and communication technology (ICT) sys- tem. With the goal of promoting an integrated and interoperable smart grid, a number of organizations all over the world started uncoordinated standardization activities, which caused the emer- gence of a large number of incompatible architectures and stan- dards. There are now new standardization activities that have the goal of organizing existing standards and produce best prac- tices to choose the right approach(es) to be employed in specific smart grid designs. This paper follows the lead of the National Institute of Standards and Technology (NIST) and the European Telecommunications Standards Institute/European Committee for Standardization/European Committee for Electrotechnical Standardization (ETSI/CEN/CENELEC) approaches in trying to provide taxonomy of existing solutions; our contribution reviews and relates current ICT state of the art with the objective of forecasting future trends based on the orientation of current efforts and on relationships between them. The resulting taxon- omy provides guidelines for further studies of the architectures, and highlights how the standards in the last mile of the smart grid are converging to common solutions to improve ICT infrastructure interoperability. Index Terms—Common information model (CIM), energy saving, International Electrotechnical Commission (IEC), protocols, survey. I. I NTRODUCTION T HE ENERGY grid has evolved from a pipeline that brings electricity from the production plant (production domain) to the final user (consumption domain) through the transmis- sion and distribution domains, to a much more complex system. In this novel paradigm, multiple actors of these four domains can interact, produce energy, as well as store it and exchange it with other (peer) actors, in order to enhance the grid’s effi- ciency. The concept of the “smart grid” has emerged, in which Manuscript received January 28, 2014; revised May 15, 2014 and September 17, 2014; accepted November 16, 2014. Date of publication December 08, 2014; date of current version February 02, 2015. This work was supported in part by the National Funds through FCT (Portuguese Foundation for Science and Technology); in part by the European Union (EU) Advanced Research & Technology for EMbedded Intelligence and Systems (ARTEMIS) Joint Undertaking (JU) funding, within the Embedded iNtelligent COntrols for bUildings with Renewable generAtion and storaGE (ENCOURAGE) project, Ref. ARTEMIS/0002/2010; in part by JU under Grant 269354, within Arrowhead project, Ref. ARTEMIS/001/2012; and in part by JU under Grant 332987. Paper no. TII-14-0112. The authors are with the Research Centre in Real-Time and Embedded Computing Systems (CISTER), Instituto Superior de Engenharia do Porto/Instituto Politécnico do Porto (ISEP/IPP), Porto 4200-072, Portugal. Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TII.2014.2379436 the interaction between the involved actors is articulated into an energy plane and a data plane. The new data plane relates to the information that is used to drive the efficient allocation of energy, to different actors as well as to different storage units and energy-consuming appliances. Smart grids are nowadays a very complex interplaying of different systems at different levels. Existing smart grid sys- tems and standards explore a large problem space to attain the same goal of energy efficiency, and they end up featuring many common points and many differences as well. There are numer- ous challenges to address, such as the low-level communication technologies to be employed [1], or the issues arising when integrating distributed energy resources (DERs) [2] or electrical vehicles [3] in the grid. In this paper, the focus is on the interac- tion of final domestic and commercial users with the smart grid information and communication technology (ICT) system, and on involved systems and standards. A common characteristic of smart grids is that the embed- ded devices deployed into the final user’s home (the sensors and actuators that manage energy and data planes) are too lim- ited in computational power to be able to decode a complex protocol; therefore the topology of the smart grid is usually centered around a gateway installed in the users’ houses. The gateway manages a subset of the sensors and actuators deployed in the house using adequate protocols, and it is connected to the internet to interact with services for energy management via a data plane. The in-house topology usually carries the name of home area network (HAN); in the rest of this work, the gate- way installed in the user’s HAN will be called HAN gateway. Another common characteristic of a typical smart grid sys- tem is its size and complexity. In fact, an energy grid usually serves a very large number of users. Together with the fact that each actor is controlled by an independent entity, the emerg- ing complexity is overwhelming for traditional centralized data management paradigms. Differences between smart grid approaches usually regard the employed protocols and the management paradigm for the data. To offer an estimate of the complexity of the ICT sys- tem serving a heterogeneous smart grid, the number of involved protocols can be considered. Potentially, a different protocol can be used for each class of connections in the system, thus between each pair of classes of actors; in this sense, the num- ber of involved protocols in a system with n classes of actors may grow as the number of lines between n points, i.e., ( n 2 ), which grows as fast as n 2 . While standardization processes can decrease the complexity of the data plane, too many stan- dards and architectures have been proposed in the past. In the last few years, novel standardization efforts addressed the 1551-3203 © 2014 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.