SMART GRID PROPONENTS promise a future with "electricity everywhere." But while making electricity available to a large number of potential customers is a noble goal, it's one that will take more than just power lines. Many of the proposals for Smart Grid solutions not only add the power of microprocessors for energy monitoring and management, but integrate technologies being developed for wireless communications systems as part of a power distribution system that can also communicate between customers and power stations.
The "Smart Grid" has been called by many names, including the Smart Electric Grid, the Smart Power Grid, the Intelligent Grid (or Intelligrid), and the FutureGrid. It is guided by a single concept, however, which is to bring the computing and communications power of this century to a power grid first erected over a century earlier. The Smart Grid will not replace power lines with wireless technology, but augment the existing power-line infrastructure with wireless "extensions" to bring electric power to customers where the cost of stringing power lines might be prohibitive.
Both the power-line and wireless portions of the Smart Grid will benefit from the use of power monitoring sensors, microprocessors, and high-speed communications to allow intelligent monitoring and management of power distribution throughout a system, including automatic-meter-reading (AMR) functionality. Energy for the grid is coming from many sources, including hydroelectric, wind turbines, and solar generators, and a Smart Grid promises increased reliability for the existing 300,000 or so miles of power lines in the United States.
The Smart Grid becomes the "Smart Home" at each residence, as the electricity is intelligently monitored and distributed throughout a residence. Throughout a Smart Grid network, System Control and Data Acquisition (SCADA) is performed by the integration of distributed processing, sensors, and communications throughout the network.
There are numerous wireless options available to Smart Grid designers. To that end, Aviat Networks of Santa Clara, CA offers a free Smart Grid Wireless Technologies Comparison Chart. The two-page document compares technologies such as third-generation (3G) cellular, fourth-generation Long Term Evolution (LTE) cellular, wireless mesh networks (per IEEE 802.11 and 802.16 standards), WiMAX (IEEE 802.16), and point-to-point wireless backhaul links at 5.8, 6, 8, 11, 18, 23, and 60 to 80 GHz bands.
Numerous system-level solutions have been proposed for distributing energy to customers over a wireless network. Trilliant offers a free white paper, "Defining The Smart Grid WAN," which outlines the critical performance requirements for a wireless area network (WAN) that can distribute power and communications.
The paper details the firm's SecureMesh WAN solution. It is a patented synchronous switching wireless network that dynamically aligns highgain directional antennas to create more efficient point-to-point links throughout a network of wireless base stations. Each base station covers 360 deg. by means of of eight 45-deg. antennas.
Spectrum Bridge is involved in one of the early Smart Grid wireless network trials, together with Plumas-Sierra Rural Electric Cooperative (PSREC) and Google. The firm is taking advantage of the interchannel broadcast spectrum or "television white spaces spectrum," to communicate on unused frequencies. Through the wireless network, the PSREC operators can manage the electrical system remotely, request data from power substations, and manage power flow. PSREC employs the "PowerMeter" technology developed by Google to monitor and manage customers' power consumption in real time via the Internet. Details on the trial are available on the Spectrum Bridge website.
In various proposals for Smart Grid networks, opinions differ on which wireless technologies and frequency bands are right for electric power management. Silicon Laboratories, for example, has developed its EZRadio and EZRadioPRO families of low-power radios for under-1-GHz point-to-point and mesh networks. The company also offers microcontroller units (MCUs) which can be combined with the radios, power, and timing integrated circuits (ICs) to form a wireless network for Smart Grid applications (see figure).
The opportunities for electronic components in a Smart Grid network are many. Texas Instruments, for example, offers an application note with an electronic watt-hour meter reference design based on its MSP430FE42x(A)/FE42x2 analog energy- metering devices. The firm also offers embedded processors, power-line modems, and low-power RF transceivers, such as the models CC1102 and CC1020 RFID readers. Another IC supplier, Analog Devices, recently announced their ADF7242 transceiver for Smart Grid applications at 2.4 GHz. It can be used to implement proprietary frequency-shift-keying (FSK) protocols at data rates to 2 Mb/s.