Ready or not, here comes smart metering

Get ready for a new acronym. Advanced metering infrastructure (AMI) is about to enter the mainstream lexicon of energy efficiency. Electric utilities worldwide are jumping on the bandwagon for AMI, which refers to the vast network of smart electric meters needed to let smart utility grids reconfigure their loads and power sources as conditions dictate.

Power utilities plan to add about 100 million smart meters to buildings, homes, and all manner of appliances. No surprise, then, that AMI has gotten the attention of the electronics industry. Industry heavyweights that include Intel and GE are involved with the AMI concept. Part of the attraction is that chips targeting AMI won't just go into electric meters. They will also get installed in smart sub-stations, plug-in hybrid vehicles, in-home displays, and all manner of renewable energy systems. Nor are AMI chips strictly for metering electricity. They can also meter gas, water and heat.

Despite all of the interest in the AMI, there is a bit of uncertainty about just how successful smart metering will be. Energy experts point out there must be incentives for consumers and businesses to accept a new metering concept. Those incentives are still murky.

Lorie Wigle, general manager of Intel's eco-technology program office, points out another challenge for both utilities and semiconductor IC makers: How to reconcile utility grid equipment life with semiconductor cycles. Such equipment is designed to last 10 to 20 years. This makes it difficult for smart meters to quickly incorporate new generations of semiconductor chips that generally emerge every one two years.

Nevertheless, there's wide agreement that the AMI concept is here to stay. Now the involved parties have begun working out how to take the first baby steps in getting it implemented.

AMI smart metering incorporates the idea of utility meters at every home and office building that collect information about the load demand. The meters would pass such information back to data aggregator nodes on the grid that would have their own smart-metering functions to analyze, among other things, where demand is most concentrated. Aggregators would also predict short-term demand based on historical patterns. Aggregators would, in turn, interact with smart-metering network sensors called phasor-measurement units. PMUs constantly sample the voltage, current, and frequency of power flowing on the grid. Using embedded GPS modules to synchronize their measurements, PMUs and data aggregators will deliver real-time analyses of electric grid conditions.

Simple metering functions don't take much more than an 8-bit processor, but designs are moving to 32-bit systems because of the communication protocols involved in sending demand data back and forth. Also, developers of AMI gear tend to be concerned about building in more accuracy for readings than has been available with the familiar electromechanical meters of today. The international standard has become class 0.5 — for readings of 99.5% accuracy — compared with old electromechanical units giving class 2 or 3 at best.

E-metering designs must also incorporate measures to prevent tampering, as 50% of the energy generated in developing Asian economies is lost to theft. The need is also acute in countries such as China, where many energy users are on a pay-as-you-go billing scheme. Historically, the main safeguard for meter tampering has been mechanical interlocks that shut off power if someone opens the meter. Accelerometers have been built in to detect when meters are jarred or tipped upside down.

But smart metering schemes add more-sophisticated measures. One involves a real-time clock to note the time and date of any tampering. Any time the backup-battery connection for the e-meter electronics gets cut, the system records evidence of the tampering in a way that can't be reset or altered.

Makers of processors for e-metering applications also expect to see the industry transition toward metering functions that can be altered remotely by beamed-in commands, prompting them to devise software that will ease the transition to this operating mode. And, as has become common practice, embedded-systems designers must minimize the power their smart-meter electronics dissipate.

Another concern for smart-metering applications centers on security measures to prevent inappropriate use of real-time data collected for characterizing the grid. So metering MCUs are building security measures into their wireless capabilities and communication protocols.

Inside smart meter chips

One of the more successful manufacturers of smart meter chips is Teridian Semiconductor Corp. It offers the highly integrated 78M6612 single-phase ac power measurement and monitoring (AC-PMON) system-on-chip (SoC) IC for consumers and enterprises. The chip is capable of 0.5% Wh accuracy or better over a 2,000:1 current range.

Teridian says its chips are in use by more than 50 metering manufacturers and are on more than 100 metering platforms. “We have shipped in excess of 30 million units and have the largest market share of SoC metering devices,” claims Kourosh Boutorabi, Teridian vice president and general manager.

Teridian's smart metering circuit, like most others, contains an interface for sensors or transducers to measure input current; signal-conditioning circuitry; a microcontroller unit (MCU), interface circuitry for communications with other devices and the outside world; isolation circuitry; and a power converter. A single IC often referred to as an analog front end handles many of these functions.

A major element of a smart metering circuit is the analog/digital converter. When ADCs are highly integrated with other functions, the combination is often dubbed a “meter on a chip.” Examples include Analog Devices' recently introduced ADE7878/68/58/54 energy metering chips for poly-phase applications. The ADI devices feature 0.1% accuracy over a dynamic range of 1,000:1. Accuracy is 0.2% over a dynamic range of 3,000:1. The ICs also deliver 0.1% accuracy over a 1000:1 dynamic range for RMS current and voltage measurements.

The ADE7878 three-phase IC features seven second-order sigma-delta ADCs, a DSP, three serial interfaces and three flexible pulse outputs. It measures total (fundamental and harmonic) active/reactive energy on each phase and on the overall system. The ADE7868 also includes tamper-detection and low-power-mode circuitry. The chip is meant for per-phase active and reactive power measurements. The ADE7854 is also a three-phase metering IC. Both the AD7858 and the ADE7854 have six second-order sigma-delta ADCs and do not include high- and low-power filtering and digital integrator circuitry present in the first two models.

“These devices are significant in that they can measure total active and reactive energy with accuracy and dynamic range exceeding Class 0.2 specifications for energy meters” says Ronn Kliger, Analog Devices Energy Group director. “They're also the first in the industry to measure both reactive and active energy at 0.1% accuracy. In addition, one device also can measure fundamental-only energies, critical for power quality measurements” he adds.

One company, e2V in the U.K., has been supplying custom ASICs for AMI applications involving measurements, control and RF communications. The ICs are made in the firm's mixed signal business unit in Grenoble, France. These ASICs include 20-bit sigma-delta ADCs, 32-bit microprocessors, and RF blocks. More recently, e2V has begun to evaluate a standard IC chip it calls the EV8452 and is in the process of specifying it for energy management applications.

Cirrus Logic is offering a pair of high-precision industrial power meter ICs targeting AMI structures in India, Japan and other fast-developing markets for residential applications. Its CS5464 contains fourth-order 24-bit sigma-delta ADCs that Cirrus claims improve on the dynamic range of competitive ICs.

The CS5467 is another version aimed at Japan, with two current channels and two voltage channels for simultaneous two-phase measurements. The two chips include system-level calibration, temperature sensing, voltage sag measurement, current fault detection and phase compensation.

Other manufacturers of analog front end ICs for energy metering include austriamicrosystems. Its AS8118 and AS8168 are designed for single-phase instantaneous/average energy metering and include on-chip digital calibration and programming. They feature 0.1% accuracy over a 1,000:1 dynamic range and include sigma-delta ADCs, digital filters, a DSP, and control and power circuitry. The company also offers a pair of SoCs, the AS8218 and AS8228 for single-phase two-current metering.

And Maxim Integrated Products offers the MAX11046, an 8-channel 16-bit simultaneous-sampling ADC aimed at smart metering applications. Its patent-pending architecture provides an ultra-low noise on-chip negative supply voltage for true 16-bit performance from a high-impedance bipolar input using only a single positive external supply. It exceeds the regulatory requirements for Class 2.0 (0.2% of 220 V) mandated by the International Electrotechnical Commission (IEC) 62053 standard as well as the EN 50160 standard.

Freescale Semiconductor offers a broad portfolio of smart metering ICs. These include concentrators, wireless communications ICs, power-line communication devices, single- and three-phase measurement ICs, and anti-tampering devices. The company's MCF51EM128/256 new smart-meter-on-a-chip is based on the 32-bit ColdFire V1 core microcontroller. It includes an embedded LCD controller, 16-bit ADCs, and metrology-specific peripherals optimized for smart meter applications.

Freescale offers a large portfolio of sensing, communications, networking and control functions for smart-grid metering. “Our knowledge of sensing, communications, networking and control technologies allows us to serve smart grid application needs on a wide scale, including electricity, gas, water and heat,” explains Rudan Bettleheim, Freescale's energy sector metering marketing manager.

Texas Instruments (TI) also offers a broad range of mixed-signal microcontrollers based on its widely used MSP430 MCU platform that can handle AMI tasks. More recently, it unveiled 16 new MSP430 metering MCUs that provide 0.1% accuracy measurements, secure energy monitoring, ultra-low-power consumption, and increased memory capacity for load demand responses.

The MSP430 MCU is said to dissipate the least amount of power of any device in the industry, a mere 330 µA (at 3 V and 1 MHz). In the standby mode, current drain is just 0.1 µA. “The metrology section of any AMI chip requires a high level of integration and extremely low power dissipation, an important factor for overseas users. If there is a power outage in, say, Europe or Japan, the smart meter must stay on, powered by a battery. Then the MSP430's ultra-low power dissipation comes into play. Outages may last for a week or more so it is important to maintain the metered information,” explains Emmanuel Sambius, TI's general manger for the smart metering business unit.

Microchip Technology has a broad portfolio of smart metering ICs based on its 8-bit and 16-bit PIC microcontrollers. One of these devices is the MCP3909, an energy monitoring IC with two 16-bit sigma-delta ADCs. It features an SPI interface, an active power pulse output, 0.1% accuracy, a 1000:1 dynamic range, and an on-chip voltage reference with an ultra-low temperature drift of 15 ppm°/C.

Microchip's tweaked nanoWatt XLP extremely-low-power technology, used in its PIC microcontrollers, works well in low-power AMI applications. The company's PIC16, 18, and 24F microcontrollers draw just 100 nA in a power-down mode and feature 800-nA watchdog timers and real-time clocks and calendars. “For AMI applications, power, outages require the use of backup battery power and our nanoWatt technology minimizes energy consumption for longer battery life,” explains Microchip Technology product marketing manager Trent Butcher.

“Some smart meter IC manufacturers with expertise in ADCs integrate their products with smart controllers and add other related circuitry for smart metering. We start with the basic core, the microcontroller, with a choice of either in 8- or 16-bit versions that can be matched to the right front-end and flash-memory functions for smart metering,” explains Microchip's Stephen Cui.

NEC Electronics recently introduced four 8-bit smart meter flash microcontrollers for AMI, optimized for low power dissipation. The all-flash MCUs are based on the company's 78k0R CPU core and operate from 3.3 to 5 V. They feature an integrated LCD driver, 12-bit ADCs and DACs, op amps, and a voltage reference. Standby current of 1.2 µA comes from de-activating the CPU when the LCD is enabled in that mode.NEC technical marketing engineer Bobby Wong emphasizes the importance of MCU hardware and software smarts and their role in energy savings. “Sophisticated algorithms combined with high-performance hardware can have a big impact. For example, in metering applications where several sources of energy are involved (e.g., wind, solar, electricity, etc.), you need to accurately quantify the amount of energy being used for each source,” he says. “A user with both electrical and solar energy must make sure that the solar energy being sold to the utility is in phase with the grid power. You must be able to accurately detect zero crossings and threshold levels.”

Connecting to the grid

Smart metering connections to the utility can employ both wireless and wired communication schemes. That's partly because schemes for communication with the grid have not been standardized. Different parts of the world use various wired and wireless modes to pass information back and forth about loads and demand.

To allow for this uncertainty, makers of smart grid equipment frequently confine communication circuits to a separate module or board which is installed with the metering electronics. The thought is that once standards are settled, communication functions will be more fully integrated into metering chip sets.

ZigBee, WiMax, and ISM-band protocols are trying to gain traction in AMI systems via wireless communications chips. Most IC manufacturers supply power-line carrier (PLC) chips or chip sets for wired communication between a smart meter and a utility substation. One company, Silver Spring Networks, uses the unlicensed 900-MHz frequency spectrum for wireless smart-metering communications.

Modem chips work over communication-enabled existing-infrastructure power lines and are a lower-cost alternative to more expensive wireless chips. They also provide a measure of security when it comes to unauthorized access to meter data. Of course, wireless communication protocols today also provide a high level of data encryption for security.

Broadband PLC modem chips like the Intellon INT6400 chip set, Yitran's IT700 SoC chip, NEC's PLM-1 digital modem IC, On Semiconductor's AMIS 49587, and STMicroelectronics' ST7540/38, 757x, 758x, and 759x SoC transceivers are all AMI candidates. And Maxim Integrated Products has developed a next-generation PLC modem for France's Electricité Réseau Distribution France (EDRF), featuring small-bandwidth low-power operation. The MAX2990 makes use of orthogonal frequency division multiplexing (OFDM) and operates over the frequency range of 10 kHz to 490 kHz.

The French company Watteco makes an SoC PLC modem chip using Watt Pulse Communication (WPC) IP for low-bandwidth and low-power performance. This device transmits bi-directionally at 10 kbits/sec and consumes 10 mW (2 mW in the sleep mode). “The only way that the promise of the smart grid can be fully realized is for the ‘core’ smart plug technology to reach capabilities of a few hundred kilobits per second, consuming several tens of milliwatts of power, in a footprint that's less than a few square centimeters,” explains Watteco marketing VP Didier Boivin.

Watteco is a pioneer in making available the Internet protocol version 6 (IPv6) over the 802.15.4 standard. Also known as 6LoWPAN for low-power personal-area network, the 802.15.4 standard covers the physical layer for the ZigBee wireless protocol.

Also on the IPv6 front comes the first single-chip IPv6 solution for sub-1-GHz smart metering communications. TI's CC430 MCU employs the Nanostack 2.0 software from Sensinode Ltd. in Finland. The TI CC430 is a highly integrated device that contains the MSP430 MCU, the CC1101 RF transceiver SoC IC, as well as intelligent peripherals, all within a 9.1-by-9.1-mm 64-pin quad flat no-lead (QFN) package.

The emergence of hybrid electric vehicles (HEVs) and the desire to charge car batteries from ordinary wall sockets is also a factor in AMI. “There's a need to develop the proper power-line communications technology between an electric utility and the home where the HEV battery is being re-charged,” says TI's Sambius. He also expects to see better communications standards for smart metering. He points out that the IEEE SUN SPOT (802.15.4) physical layer protocol for Zigbee AMI equipment should be finalized by next year. TI also has developed OFDM PLC chips.

Another supporter of ZigBee communications is Freescale Semiconductor with its MC1321x/22x simple media access control ICs. Freescale also supplies a number of PLC modem chips.

WiMax is another nascent AMI wireless communications standard, supported by Motorola, Samsung, Intel and GE. Motorola's wi4 WiMax chips are used in the firm's wireless access point (WAP) 400, 450, 600, 650 and 800 equipment. Samsung and Intel also supply WiMax chips and chip sets. WiMax-based (36.5 GHz) chips are used in GE Mercury radios deployed by the Houston-based utility CenterPoint Energy. These radios also use smart meter software supplied by Grid Net Inc.

“Open standards mean third parties will be able to build various applications and devices in conjunction with these standards, helping to dramatically drive down the cost of WiMax smart metering chips,” says Grid Net founder Ray Bell. WiMax chip sets are currently much more expensive than those for other wireless communications methods. However, Bell expects the price for these chips to fall by an order of magnitude or more in the next year or two.

Bell's optimism about WiMax is fueled by the fact that besides Intel, GE, Motorola, and Samsung, communications companies that include Sprint and Clearwire are building WiMax-based networks. So are cable TV companies and Google.

Using AMI: Do you really need a new hobby?

One of the concepts behind smart metering is that consumers will read their smart energy meters from time to time to manage their energy intakes accordingly. If pondering the readings on a smart meter sounds to you like it could potentially turn into a thankless task, you aren't alone. Some consumer watchdog groups say the idea that consumers will reduce their energy consumption on a minute-by-minute or even hour-by-hour level does not sound practical, unless, of course, utilities provide incentives.

“I just don't know how people are going to get extra time to do these things,” says Mark Toney, executive director of the California-based consumer advocacy group Utility Reform Network.

Still, even if just 20% of the population signs on to the AMI idea, the concept can produce substantial energy savings for both users and utilities. “If every home in the U.S. saved 10% of its energy, that's a substantial cost and energy savings,” claims Michael Terrell, policy counsel for Google's philanthropic arm, Google.org. Google has asked the U.S. Dept. of Energy and the California Public Utilities Commission for guidelines on how to make it easier for consumers to buy smart grid devices and to clarify how third parties can securely access consumer information, as well as other related matters.

Google is partnering with 10 utilities and recently opened its PowerMeter application to anyone whose utilities permit an in-home energy monitor like Energy Inc.'s TED 5000 meter. Working with Google's PowerMeter, it lets users access data by viewing electricity usage, from any Internet-connected devices, including mobile phones. It also provides the customer with energy consumption comparisons by displaying current and historical usage in easy-to-understand charts and graphs.

“People want to save energy and reduce their energy expenses, but they don't want to change their lifestyles much,” explains Mike Ballard, Microchip Technology manager of home application solutions. “This is a long-term challenge that may require utility incentives for the customer, as well as government tax incentives and programs that promote the use of smarter home appliances that reduce energy consumption,” he adds.

That's a lot of smart meters!

In the U.S., 18 million households, representing about 13% of the total, will get smart meters within the next 3 years as part of the U.S. Government's grants to upgrade the nation's electric grid.

Smart meters aren't just a U.S. phenomenon. China is implementing a $596 billion stimulus program for smart grid applications that is expected to make use of 170 million smart grid meters within the next few years. Italy and Sweden have already implemented smart electric-grid meters. France, Spain, Germany and the U.K. are expected to complete AMI roll-outs using smart electric meters within the next 10 years.

Analysts at Pike Research are forecasting a $19.5 billion market for smart meters as they're deployed worldwide by 2015, which works out to a compound annual growth rate (CAGR) of 19%. One reason is that over 45% of the North American and European installed base of traditional meters is up for replacement, breaking the traditional 15-to 20-year meter replacement cycle.

Market research firm ON World says that 100 million new smart meters are planned to be installed worldwide within the next five years. Nearly half of these will have a home-area network (HAN) gateway for in-home energy management and program services. ON World says some $21 billion will be spent on the smart metering infrastructure over this time span.

ABI Research is equally bullish on the smart meter market. It is predicting that 212 million smart meters will ship worldwide by 2014, with the market taking off in the next two years. One reason is that the EU recently enacted a “Third Energy Package” which aims to make every European electricity meter smart by 2022. There are also tantalizing hints of a massive 300 million electricity meter upgrade over the next five or so years in China.

Any way these figures get sliced, they point to mushrooming sales of smart meter chips. According to TI microcontroller products director of ultra-low power systems Mark Buccini, if all the 500 million electric meters worldwide were to be replaced by smart meters over the next 10 years, the semiconductor IC industry would realize sales of $7.5 billion. TI believes that only 6% of electricity meters worldwide are presently automated.