Robust design principles for home smart grid metering
In addition to meeting all these functional requirements, an advanced smart meter design must address several practical concerns. For example, the meter needs a compact form factor in order to maximize the opportunities for placement during field installation. The design should also provide for easy integration with a variety of home and utility networks to maximize the applicability of a meter design to multiple markets.
To be economically feasible, the design needs to utilize components that help keep development and production costs as low as possible by being optimized for metering needs. Yet the design must also be flexible to accommodate evolution in networking and smart grid standards and changing regulatory requirements with little or no modification to the base design or rework of installed units.
These design requirements, in turn, impose requirements on the semiconductor solutions that meter developers will seek out. One of the first requirements on a suitable semiconductor solution is a high level of integration.
This addresses several meter design requirements, including compact form factor resulting from small board size and low design and production cost. The low production cost comes from the minimal BOM needed to implement the design. Having most system elements on the same IC already interconnected and proven to work together helps keep design costs down.
Integration taken too far, however, will compromise another key element of a semiconductor solution: flexibility. The market for advanced smart meters is still highly fragmented in its requirements for utility and HAN interfaces.
Integrating those interfaces completely would narrow a semiconductor solution, and corresponding meter design, to a narrow market. Instead, the solution should include a variety of standard interfaces for attachment of various network-specific components.
In addition to offering a variety of network interface options the semiconductor solution needs to support customization of various functions.
The way in which utilities measure power usage, for instance, is still part of their “secret sauce” in providing services, so the meter design must support customization of metrology. Similarly, the user interface needs to be customizable in order to support a variety of display choices as well as to allow the utility to “brand” the consumer’s experience.
A flexible semiconductor solution can also help “future proof” the basic meter hardware design, as well. A device that is programmable and offers multiple interface choices will make design evolution easier, reducing the effort needed to adapt as industry-wide standards for advanced smart meters emerge. That flexibility also supports the adaptation of meter design to address regional preferences.
An often overlooked requirement on the semiconductor solution is the support a low-power implementation. Meters are typically installed in small, unventilated housings, so the lower the power dissipation the less likely those thermal issues will arise in the field. Further, low power can represent a significant cost savings over the meter’s operating life. Multiplied by millions of installations even a fractional watt less power consumption per meter saves megawatts of power.
Software Support Required
A highly-integrated, flexible, low-power semiconductor is still not a solution to advanced smart meter design needs, however, without adequate software support. That support should include both design tools and reference libraries of readily-adaptable software for most metering tasks.
In addition, the software support should leverage existing standards for communications, networking, security, and the like. This support will greatly simplify the meter design effort, allowing developers to concentrate their energies on their unique requirements and features. Further, by leveraging standards the software will simplify integration of the meter with the smart grid and the HAN.
Such semiconductor solutions for advanced smart meter design have already begun to emerge. One example is the AppliedMicro APM801xx family and the product evolution roadmap behind it. The APM801xx integrates numerous I/O and system interfaces (Figure 2 below).
These include mass storage interfaces for Flash and SATA storage systems; serial communications interfaces such as USB and 1G Ethernet with hardware TCP/IP support; system interfaces such as PCI express, SPI, TDM, and I2C; an LCD controller, and a 10-bit ADC. JTAG and Trace connections are available for debugging and maintenance access and both security and encryption acceleration engines are available options.
Figure 2. The AppliedMicro APM801xx family addresses the many needs of advanced smart meter design by offering high functional integration with multiple connectivity options for easy customization to specific installation requirements. (Click here to see an expanded image)
This combination meets all the functional needs of smart meter applications while offering considerable flexibility in connectivity and operational behavior. The entire package consumes <1W operating at 600 MHz while providing all the processing power and I/O needed to implement a smart meter design with minimal additional hardware.
An example of such a design (Figure 3 below) shows how minimal that addition can be. Along with system DRAM, program EPROM, and a Flash module for non-volatile storage, all the meter design needs is Ethernet and ZigBee PHYs to provide utility and HAN connectivity. This gives the design a footprint of only 3 x 3 inches, including the ZigBee module, thus addressing both BOM cost and size considerations.
Figure 3. A smart meter reference design shows that only a few external components are needed for full operational configuration when using the APM801xx.
The creation of such advanced smart meters is of growing importance. The smart grid is already on its way, with expansion stimulated both by the economics of energy and the dictates of governments.
To achieve its full potential, that grid needs advanced smart meters that can link the energy consumer with the energy provider for the close coordination needed to maximize efficiency and minimize costs.
Design of such meters must meet many demanding system requirements, including low cost, small footprint, low power, and high functionality, while addressing a market that is still emerging with few standards and much diversity.
Now, however, semiconductor solutions that address these concerns have started to emerge. Devices like the AppliedMicro APM801xx family will help make the promise of the smart grid into a reality.
Vamshi Kandalla is senior director for the Consumer and SMB Business Unit for AppliedMicro, where he is responsible for building the multi-media consumer electronics business in embedded processors for home networking in digital entertainment, wired and wireless networking. Prior to joining AppliedMicro, Kandalla held executive level marketing positions at Moschip Semiconductor and SMSC as well as several other companies. He holds both a master’s in marketing and a bachelor’s in engineering.
Loading comments... Write a comment