Smart meters are well-established, but companies are still finding ways to improve communications and smart energy management.
The two-way communications and data systems of smart meters benefit consumers, as they are able to measure energy consumption and so reduce usage to save on bills. The monitoring and measuring functions can also alert users and utility companies when behavior changes to signal maintenance checks. Outside of the home environment, smart meters ensure that manufacturing equipment and motors run efficiently and with minimal downtime. For utility companies, the cost of meter reading is reduced, with reports also noting a decrease in collections and disconnections following smart meters’ debut. Earlier detection of meter tampering and theft strengthens security, compared with older, mechanical meters, and improved transformer load management and capacitor bank switching aid efficiency and reliability.
Initial fears of exposure to Radio Frequency (RF) have proved groundless. Smart meters have lower RF than other sources found in a typical home. Around the world, however, the operating frequencies vary. IEEE 802.15.4g stipulates a frequency range of 750 to 960MHz. In the European Union (EU) the Wireless M-Bus standard has an operating frequency of 169MHz (for systems in N mode), 433MHz (for systems operating in F mode) and 868MHz, for systems operating in S, C and T modes. Japan’s ARIB STD-T108 operates at 920MHz, and China has adopted Q-GDW347.3, operating at 470 to 510MHz.
Another fear, that smart meter accuracy is weaker than mechanical meter accuracy, has been allayed, overcoming consumer reticence to adopt the smart meter systems.
Recognizing the variations around the world, Lapis Semiconductor, part of the ROHM Group, introduced a sub-GHz, wireless communication Large Scale Integration (LSI) device, designed for low power consumption over long distances, for example in smart meters. It allows system developers to configure wireless networks, which are compatible with smart meters worldwide and with agricultural, alarm, and security systems.
The Lapis ML7345 device (Figure 1) covers 160MHz to 960MHz to support the ARIB STD-T108 and IEEE 802.15.4g. It is also compliant with the latest, 2013, version of the Wireless M-bus standard, where improvements to packet handling support extended packet specifications. As well as simplifying networking, a reduction in the number of relays improves system reliability. To conserve energy consumption there is a reduced sleep current during standard operating mode, the majority of communication time, points out the company. The average current is decreased by 48 percent, in 10 second intervals, compared with conventional products, claims the company. Energy management is further enhanced with a high-speed radio wave check function that performs receiver start-up in a short period of time to conserve power. This minimizes the total time for receiver strength detection and decreases current during sleep mode to 0.9µA, or 58 percent less than currently available models, says the company.
The LSI’s high output of 100mW is optimized for the Chinese market. The programmable receiver bandwidth settings support the specifications for electricity, gas, water and thermal meters, and for crime and disaster prevention systems.
A transmission power variation of less than ±1dB across the operating temperature range adds stability. The company claims that this increases stability by a factor of three compared to conventional products and simplifies network configuration, as changing environmental conditions do not require the use of multi-hop operation smart meters.
An evaluation kit with onboard LSI is available, with reference design data (circuit diagram, peripheral parts list, PCB pattern recommendation), multiple test scenarios and sample programs, a user manual and tools.
SoC for Multiple Power Sources
Appealing to a wide, near-universal marketplace is clearly a theme for smart meter semiconductor companies. STMicroelectronics has achieved certification at 500kHz for its STCOMET smart meter Systems on Chips (SoCs). The company’s multicore SoC incorporates a PowerLine Communication (PLC) modem, which complies with smart meter industry standards, to simplify design.
The recent certification to the latest G3-PLC protocol for narrow band, low frequency, powerline communications, and PowerRline Intelligent Metering Evolution, or PRIME, v1.4-profile 2 specifications, are described as vital to wide-scale adoption by the company. The PRIME v4.1 powerline communication architecture covers frequency bands up to 500kHz, such as U.S. Federal Communications Commission (FCC) bands. The SoC is certified according to existing G3-PLC and PRIME v1.4 approvals covering European electrotechnical standardization, CENELEC-A, meeting major, worldwide standards.
To meet the needs of various territories, there are four devices in the family. There is the STCOMET05 and STCOMET10 with either 512-kbyte or 1-Mbyte of program Flash, an application-processing sub-system, dedicated security engine with privacy and anti-hacking protection, metering front end, and the PLC module. The simplified versions of each can be used with the developer’s own, proprietary metering front end with the on-chip application processor, security engine, and PLC module.
An ecosystem, including certified protocol stacks, reference designs, prototyping hardware, and tools such as metrology-management software and drivers, supports the development of single-phase or three-phase smart meters based on the ICs.
Software for Energy Measurement
The value of smart meters stems not just from power management, but also from the meters’ usefulness for power consumption monitoring. Software can record energy usage, and the data can be analyzed to meet a building’s requirements or to set parameters for efficient use.
A recent introduction is WAGO’s Energy Data Management system (Figure 3), which combines hardware and software to record and manage energy data. Based on the PFC200 Series Application Controller and the WAGO-I/O-SYSTEM 750 fieldbus-independent, I/O systems, the modular systems can record energy-specific values. For example, the values could be electrical currents or voltages, gas, heat, water, compressed air or temperature. Software is pre-loaded on the modules. Inputs for recording can be adjusted using parameters, with settings that can be input during operation via a mouse click. The Graphic User Interface (GUI) can be accessed via HyperText Transfer Protocol Secure (HTTPS) communication and a standard browser.
Data can be forwarded to a higher-level energy management software via Modbus Transmission Control Protocol/Internet Protocol (TCP/IP) communication protocol or as a comma-separated values (CSV) file, which stores tabular data. Recorded data can be saved on a Secure Digital (SD) card.
Using the integrated visualization tool makes generating different energy use evaluations possible— a means to create consumption curves that are synchronized to a power supplier. Alternatively, a second-by-second display can show which areas consume peak loads. Monitoring energy in relation to specific process adaptations, another activity the visualization tool enables, can determine how much energy would be saved by using variable speed motors or new lamps, for example, in industrial settings or domestic/office buildings.
Smart energy can provide many benefits for the end user and for the utility supplier. Some of the recent developments highlighted here show how these benefits can be integrated more simply and efficiently for a managed, reliable smart energy network around the world.
Caroline Hayes has been a journalist covering the electronics sector for more than 20 years. She has worked on several European titles, reporting on a variety of industries, including communications, broadcast and automotive.