Abstract-A communication infrastructure is an essential part to the success of the emerging smart grid. A scalable and pervasive communication infrastructure is crucial in both construction and operation of a smart grid. In this paper, we present the background and motivation of communication infrastructures in smart grid systems. We also summarize major requirements that smart grid communications must meet. From the experience of several industrial trials on smart grid with communication infrastructures, we expect that the traditional carbon fuel based power plants can cooperate with emerging distributed renewable energy such as wind, solar, etc, to reduce the carbon fuel consumption and consequent green house gas such as carbon dioxide emission. The consumers can minimize their expense on energy by adjusting their intelligent home appliance operations to avoid the peak hours and utilize the renewable energy instead. We further explore the challenges for a communication infrastructure as the part of a complex smart grid system. Since a smart grid system might have over millions of consumers and devices, the demand of its reliability and security is extremely critical. Through a communication infrastructure, a smart grid can improve power reliability and quality to eliminate electricity blackout. Security is a challenging issue since the on-going smart grid systems facing increasing vulnerabilities as more and more automation, remote monitoring/controlling and supervision entities are interconnected. Index Terms-Smart grid, communication infrastructure, intelligent network, interconnected power system, monitoring, sensing, cyber security I. BACKGROUND S MART grid is a term referring to the next generation power grid in which the electricity distribution and management is upgraded by incorporating advanced two-way communications and pervasive computing capabilities for improved control, efficiency, reliability and safety. A smart grid delivers electricity between suppliers and consumers using two-way digital technologies. It controls intelligent appliances at consumers' home or building to save energy, reduce cost and increase reliability, efficiency and transparency [1]. A smart grid is expected to be a modernization of the legacy electricity network. It provides monitoring, protecting and optimizing automatically to operation of the interconnected elements. It covers from traditional central generator and/or emerging renewal distributed generator through transmission network and distribution system to industrial consumer and/or home users with their thermostats, electric vehicles, intelligent appliances [2] . A smart grid is characterized by the bidirectional connection of electricity and information flows to create an automated, widely distributed delivery network. It incorporates the legacy electricity grid the benefits of modern communications to deliver real-time information and enable the near-instantaneous balance of supply and demand management [3] . Many technologies to be adopted by smart grid have already been used in other industrial applications, such as sensor networks in manufacturing and wireless networks in telecommunications, and are being adapted for use in new intelligent and interconnected paradigm. In general, smart grid communication technologies can be grouped into five key areas: advanced components, sensing and measurement, improved interfaces and decision support, standards and groups, and integrated communications. Figure 1 illustrates a general architecture for smart grid communication infrastructures, which includes home area networks (HANs), business area networks (BANs), neighborhood area networks (NANs), data centers, and substation automation integration systems [4] . Smart grids distribute electricity between generators (both traditional power generation and distributed generation sources) and end users (industrial, commercial, residential consumers) using bi-directional information flow to control intelligent appliances at consumers' side saving energy consumption and reducing the consequent expense, meanwhile increasing system reliability and operation transparency. With a communication infrastructure, the smart metering/monitoring techniques can provide the realtime energy consumption as a feedback and correspond to the demand to/from utilities. Network operation center can retrieve those customer power usage data and the on-line market pricing from data centers to optimize the electricity generation, distribution according to the energy consumption. In a complex smart grid system, through wide deployment of new smart grid components and the convergence of existing information and control technologies applied in the legacy power grid, it can offer sustainable operations to both utilities and customers [5] . It can also enhance the efficiency of legacy power generation, transmission and distribution systems and penetrate the usage of clean renewable energy by introducing modern communication systems into smart grids.
• Design of smart energy meter for the smart grid, where a smart greed is a next generation power grid having a two-way flow of electricity and information, see REF for more details on smart grids.
A Survey on Smart Grid Communication Infrastructures: Motivations, Requirements and Challenges
IEEE Communications Surveys & Tutorials
IEEE Communications Surveys & Tutorials
Computer Science Engineering