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The final milestone is advanced asset management (AAM). The AAM aims to improve the utilization of transmission and distribution assets and more effectively manage their life cycle. AAM requires smart sensors to provide operational and asset condition information to significantly improve asset management.
NUTS AND VOLTS
Achieving all this presents a host of design opportunities. Smart meters will allow time-based pricing and consumption data exchange, network metering with loss and restoration notification, remote on/off, and load limiting/control for “bad pay” or demand-response purposes. They will also support energy pre-payment, power quality monitoring, and tamper and theft protection. Much of this was evident this past December when Analog Devices introduced its ADE7878 poly-phase multifunction energy metering IC for smart meters.
For demand response, communications with other intelligent devices in the home or business via mesh networks is required. Home area networks (HANs) will constitute consumer portals that link smart meters to controllable electrical loads (smart appliances). The HAN’s attributes can include an in-home display that is responsive to price signals based on consumer-entered preferences. It should have set points that limit utility or local control to within consumer-set limits, and should also allow control of loads without continuing consumer involvement while still allowing consumer override capability.
“Smart buildings” provide a HAN parallel that is more fully implemented today. Industrial and building automation networks employ a similar infrastructure for intelligent control of their electrical loads. Most building automation networks consist of a primary and secondary bus that connects high-level controllers (generally specialized for building automation, but may be generic programmable logic controllers) with lower-level controllers, I/O devices, and a user interface.
Meanwhile, smart meters must communicate back upstream to concentrators. This past December, On Semiconductor introduced its AMIS49587, which provides PHY and MAC layers for data communication at up to 2400 bits/s over power lines using power line carrier (PLC) S-FSK IEC61334 modulation in the Comité Européen de Normalisation Électrotechnique (CENELEC) “A” band (60, 66,72,76, 82, 86 kHz).
The concentrators collect data from groups of meters and transmit that data to a central server via a backhaul channel. They are part of an AMI integrated communications infrastructure employing open, bi-directional, encrypted communications. The infrastructure supports interaction between the utility, the consumer or business portal, and any controllable electrical loads on the HAN or building automation network.
Beyond the concentrators, a meter data-management system analyzes information to be fed to other utility systems. It validates the incoming AMI data to ensure that its output to the other utility processes is complete and accurate, despite communication disruptions or customer premises problems.
Various media can provide all or parts of the backhaul. Some choices include:
- Wireline technologies including power line carrier (PLC), broadband over power lines (BPL), copper UTP, and optical fiber.
- Wireless technologies including multiple address system radio, paging networks, spread spectrum radio, WiFi, ZigBee, OSHAN, TDMA, CDMA, and 3G cellular, WiMAX, and VSAT terminals.
- Other technologies such as hybrid fiber coax (HFC), fiber to the premises (FTTP), and fiber to the home (FTTH).
An integrated communications system comprising combinations of the above media is the most likely future scenario. Urban and remote locations will need different mixes of local and backhaul media.
There are further design opportunities in providing security for the smart grid. The major threats are physical or cyber attack, and the reliability threat of electromagnetic compatibility (EMC) problems. Three recent cyber attacks highlight the possibility of remote destruction of assets, remote hijacking of utility control computers for extortion, and failed penetration tests of utility desktop computers. And the recent shutdown of a nuclear power station caused by a consumer digital camera brings the issue of EMC in utility control settings into sharp focus.