Smart Grid – The New and Improved Power Grid: A Survey Xi Fang, Student Member, IEEE, Satyajayant Misra, Member, IEEE, Guoliang Xue, Fellow, IEEE, and Dejun Yang, Student Member, IEEE Abstract—The Smart Grid, regarded as the next generation power grid, uses two-way flows of electricity and information to create a widely distributed automated energy delivery network. In this article, we survey the literature till 2011 on the enabling technologies for the Smart Grid. We explore three major systems, namely the smart infrastructure system, the smart management system, and the smart protection system. We also propose possible future directions in each system. Specifically, for the smart infrastructure system, we explore the smart energy subsystem, the smart information subsystem, and the smart communication subsystem. For the smart management system, we explore various management objectives, such as improving energy efficiency, profiling demand, maximizing utility, reducing cost, and con- trolling emission. We also explore various management methods to achieve these objectives. For the smart protection system, we explore various failure protection mechanisms which improve the reliability of the Smart Grid, and explore the security and privacy issues in the Smart Grid. Index Terms—Smart grid, power grid, survey, energy, informa- tion, communications, management, protection, security, privacy. I. I NTRODUCTION Traditionally, the term grid is used for an electricity system that may support all or some of the following four operations: electricity generation, electricity transmission, electricity dis- tribution, and electricity control. A smart grid (SG), also called smart electrical/power grid, intelligent grid, intelligrid, futuregrid, intergrid, or intragrid, is an enhancement of the 20th century power grid. The traditional power grids are generally used to carry power from a few central generators to a large number of users or customers. In contrast, the SG uses two-way flows of electricity and information to create an automated and distributed advanced energy delivery network. Table I gives a brief comparison between the existing grid and the SG. By utilizing modern information technologies, the SG is capable of delivering power in more efficient ways and responding to wide ranging conditions and events. Broadly stated, the SG could respond to events that occur anywhere in the grid, such as power generation, transmission, distribution, and consumption, and adopt the corresponding strategies. For instance, once a medium voltage transformer failure event occurs in the distribution grid, the SG may automatically change the power flow and recover the power delivery service. Manuscript received May 27, 2011; revised September 25, 2011; accepted September 30, 2011. Xi Fang, Guoliang Xue, and Dejun Yang are affiliated with Arizona State University, Tempe, AZ 85281. E-mail: {xi.fang, xue, dejun.yang}@asu.edu. Satyajayant Misra is affiliated with New Mexico State University, Las Cruces, NM 88003. Email: misra@cs.nmsu.edu. This research was supported in part by ARO grant W911NF-09-1-0467 and NSF grant 0905603. The information reported here does not reflect the position or the policy of the federal government. TABLE I: A Brief Comparison between the Existing Grid and the Smart Grid [70] Existing Grid Smart Grid Electromechanical Digital One-way communication Two-way communication Centralized generation Distributed generation Few sensors Sensors throughout Manual monitoring Self-monitoring Manual restoration Self-healing Failures and blackouts Adaptive and islanding Limited control Pervasive control Few customer choices Many customer choices Let us consider another example of demand profile shaping. Since lowering peak demand and smoothing demand profile reduces overall plant and capital cost requirements, in the peak period the electric utility can use real-time pricing to convince some users to reduce their power demands, so that the total demand profile full of peaks can be shaped to a nicely smoothed demand profile. More specifically, the SG can be regarded as an electric system that uses information, two-way, cyber-secure commu- nication technologies, and computational intelligence in an integrated fashion across electricity generation, transmission, substations, distribution and consumption to achieve a system that is clean, safe, secure, reliable, resilient, efficient, and sustainable. This description covers the entire spectrum of the energy system from the generation to the end points of consumption of the electricity [80]. The ultimate SG is a vision. It is a loose integration of complementary components, subsystems, functions, and services under the pervasive control of highly intelligent management-and-control systems. Given the vast landscape of the SG research, different researchers may express different visions for the SG due to different focuses and perspectives. In keeping with this format, in this survey, we explore three major systems in SG from a technical perspective: • Smart infrastructure system: The smart infrastructure system is the energy, information, and communication infrastructure underlying of the SG that supports 1) ad- vanced electricity generation, delivery, and consumption; 2) advanced information metering, monitoring, and man- agement; and 3) advanced communication technologies. • Smart management system: The smart management sys- tem is the subsystem in SG that provides advanced management and control services. • Smart protection system: The smart protection system is the subsystem in SG that provides advanced grid reliability analysis, failure protection, and security and privacy protection services. Other surveys on SG were done in [3, 17, 29, 41, 42, 90,