Smart E-Meter | Smart Meter System Design
Schematic Block Diagram for Smart E-Meter
For AMR (and AMI) to become truly pervasive it needs to provide more than a reduction in meter reading costs. Optimization for Asset tracking, dynamic pricing, tamper notification, outage management, supply automation, load profiling and network diagnostics are critical elements for the success of this infrastructure.
This drives the move from Mechanical Meters towards Static (electronic) meters for all major utilities (Electricity, Water, Gas, Heat).
Currently, meters can be read manually, touch-read (handheld device with a wand or probe), Radio, Bus, Power Line, Modem, or GSM/Satellite. The drivers behind each choice are cost, existing infrastructure, and local regulations. In some regions the usage charge for a radio frequency band is higher than the cost of manual reading, or the local grid may not support communication over the power line (PLC).
In any case, the trend is towards AMR increases the electronics content of the meter itself, and AMI drives a networked infrastructure for all metering. A complete implementation could include power line communication to the electricity meter, and low power wireless communication from the electricity meter to other utility meters. Low power wireless communication to the major loads in the home/business (AC, Heaters, Refrigeration, etc) and would also allow dynamic setting control during power plant peak loading.
Given the need for very low power consumption, microcontrollers like the MSP430 are ideal for any metering application. An advanced electronic meter requires an MCU that offers precise measurements over a wide dynamic range, programmable Flash, non-volatile storage, real-time clock function, flexible display and AMR-enabled communications features. The MSP430 family offers up to up four 16-bit independent sigma-delta converters and programmable gain amplifiers along with specific integrated e-metering modules such as the ESP engine or 32x32 hardware multiplier allowing for easy, high performance metering calculations
Utility Metering
As utilities requirements grow, pushing more and more smart functions like load demand response, Tariff management, communication and others, as metrology firmware may require to be qualified and isolated from the rest of the functions, the application layer for the smart electricity meter may require an additional functional unit to the primary Metrology function commonly called a Main MCU or the Application Processor.
This MCU will typically require large amount of on-chip flash and connectivity. This can be the MSP430 with devices going up to 256kB flash, allowing leveraging development effort made on the Metrology side. Time to market pushing to software re-uses and easy migration, standard cores are very often required. With over 140 members in its family available today, TI's Stellaris Cortex M3 offers the widest selection of
precisely-compatible MCUs in the industry. With many connectivity options, including the unique EMAC PHY+
MAC integrated in one device, many serial port combinations available to accommodate communication options, various flash size offer, TI's Stellaris Cortex M3 enables enabling powerful, cost-effective and simple to program paths for growing application layers for smart electricity meters.
TI’s F28x controller platform provides a cost-effective means to implement PLC technology. Along with advanced DSP cores, the controllers integrate robust peripherals such as analog-to-digital converters (ADCs), timers and pulse-width-modulation (PWM). F28x controllers offer a unique combination of 150 MIPS of 32-bit control-optimized performance, system integration and microcontroller- (MCU) like ease-of-use. This
high level of system integration simplifies design and keeps control systems compact and cost-efficient.
MCU-like instructions and on-chip flash memory enables rapid prototyping. SW flexibility and scalable
performance in the family gives easy migration path from one modulation to another one as communication
standards evolve.
Range, network configuration and power consumption are important factors when selecting a Low Power
Wireless (LPW)solution. Range is affected by output power, sensitivity and selectivity, which in turn impact the
jamming of other signal sources and the ability to distinguish the desired signal from local interferers. Point to
Point, Star or Mesh Network choices not only impact these elements, but also the standards and frequency
ranges chosen. TI’s LPW/Chipcon product family offers the performance and flexibility needed for
Metering AMR and AMI applications.
TI's WiLink™ 6.0 solution, when combined with one of TI's ARM-based microprocessor (MPU) solutions provides a low-power, cost effective means to support broadly deployed wireless network topologies of WLAN (IEEE802.11a/b/g/n) and Bluetooth 2.1+EDR in a single chip. With this solution, Smart Meter customers can connect to a wide range of products such as home wireless routers and residential gateways, enabling the Smart Meter to easily connect to the network.
For the electricity meter, power for the electronics can be derived from the single to 3-phase power lines.
For other utilities, the meter would either need to be attached to a power source or leverage an internal battery. In some regions it may also be possible to use rechargeable batteries and small solar cells to recharge them during the day. In order to do this effectively, high efficiency power and battery management devices are necessary.
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