In recent years, driven by green and energy-saving awareness, smart grids, with smart meters at their core, have become a key area of development for many countries, including the US, Europe, Japan, and China. For example, the European Commission mandated that all electricity meters in EU member states be replaced with smart meters by 2022. The US also plans to install smart meters in every household. China also proposed the concept of building a robust smart grid in May 2009, with a planned investment of up to 4 trillion yuan. After the current pilot phase and full-scale construction starting in 2011, the plan aims to basically realize the concept by 2020. Driven by this, power grid technology is facing a significant revolution, not just a simple technological evolution.
In smart grids, smart meters play a crucial role, enabling interaction between users and the power system. On one hand, they help power companies accurately understand users' electricity consumption patterns, setting differentiated electricity prices for peak and off-peak periods. On the other hand, users can also adjust their electricity plans to optimize their electricity costs. From a functional perspective, in addition to power supply and metering modules, smart meters involve data storage, requiring secure and reliable memory. Furthermore, two-way real-time communication is a key feature of smart grids, making the communication module critical and necessitating the selection of suitable communication methods and optimal solutions.
In reality, a smart grid is a vast system involving multiple layers such as power, communications, and applications, as well as different network types like Local Area Networks (LANs) and Wide Area Networks (WANs). LANs connect different types of smart meters within homes or buildings to a data concentrator. For this segment of the network connection, the requirements for communication speed are typically not high; the primary consideration is cost reduction. Common communication methods include wireless radio frequency networks, or wired power line carrier (PLC) or power line broadband (BPL). The specific communication method adopted depends on factors such as the actual conditions of each country's power grid, and the practices of countries that have implemented pilot programs can also provide valuable insights.
For example, Electricity de France ( EDF), a major player in the European energy market, launched Linky, currently the world's largest smart meter project, in mid-2009, planning to deploy 35 million smart meters in France by 2017. This project chose PLC technology for communication between the smart meters and the data concentrator, and then used General Packet Radio Service (GPRS) technology to transmit the data to the company's data center. Given that China's smart grid is still in the pilot stage, EDF's choice offers valuable lessons for China and other countries.
Selection of PLC modulation technology
While PLC technology offers a low-cost option, power lines were not originally designed for communication, thus presenting challenges when applying PLC communication. In particular, designers need to pay close attention to signal attenuation and noise issues, which in turn necessitates sophisticated transceiver technology.
To suppress signal attenuation caused by noise, reduce the bit error rate, and improve frequency efficiency, it is necessary to utilize suitable signal modulation techniques. In fact, power companies use a variety of modulation methods when deploying smart meter reading systems, but there are three main ones: Orthogonal Frequency Division Multiplexing (OFDM), Phase Shift Keying (PSK), and Spread Spectrum Frequency Shift Keying (S-FSK).
OFDM theoretically offers high bandwidth, but in practice, it suffers significant bandwidth loss under noisy conditions in low-voltage networks. Furthermore, OFDM is costly to implement and consumes considerable power during operation. PSK modulation is inexpensive but not particularly reliable, its performance is affected by phase noise, and it cannot adequately cover long distances. In comparison, while S-FSK has a lower data rate than OFDM, it is better suited for smart meter applications. This modulation technique achieves reliable communication at a lower cost and consumes less power. Therefore, for current smart grid PLC applications, S-FSK modulation, with its lower complexity, greater commercial potential, and reliable field application track record, is undoubtedly the more suitable choice.
In fact, the physical layer reference specification in the Linky project of the French ERDF is IEC61334-5-1/EN50065, which specifies the modulation technology as S-FSK, the communication frequency as the mark frequency ( Fm) of 63.3kHz and the space frequency ( Fs) of 74kHz, the transmission rate as 2.4Kbps , and physical synchronization with the 50Hz electrical network frequency.
Application advantages of semiconductor PLC modems
Semiconductors have a long history of developing PLC modems. The earlier AMIS-30585, with a speed of 1.2kb , was initially developed to comply with the IEC 61334 standard (SFSK specification) and has undergone eight years of field application testing. The newly released AMIS-49587 is a highly integrated, standards-compliant, low-power PLC solution supporting four different modes required for PLC field deployment: NO_CONFIG, MASTER (concentrator), SLAVE (meter), and SPY (raw data for testers), making it ideal for smart meters, smart streetlights, and smart sockets. Compared to the AMIS-30585, the AMIS-49587 supports a higher half-duplex adjustable communication rate of 2.4kb , meeting new market requirements such as the ERDF specification. It has already been adopted by French original equipment manufacturers (OEMs) and several leading meter customers in China. Both devices are pin-to-pin compatible, providing greater design convenience for customers.
The AMIS-49587 complies with the IEC 61334-5-1 standard, offering customers numerous application advantages. For example, this device, based on the ARM7TDMI processor core, integrates both a physical interface transceiver (PHY) and a media access controller (MAC) layer, combining analog modem front-end and digital post-processing functions in a single-chip solution. Most competing solutions require complex embedded software to perform the same functions as the AMIS-49587. Using the AMIS-49587 modem simplifies design, enabling designers to develop complete interoperable PLC solutions in less than a quarter, while also reducing development and application costs. In fact, an AMIS-49587-based modem solution uses only two ICs (the other being an NCS56502APLC line driver), plus 16 resistors, 17 capacitors, two diodes, one crystal, and one pulse transformer, for a total of only 39 components, providing a low bill of materials (BOM) cost.
Furthermore, the AMIS-49587 employs S-FSK modulation technology, combined with a high-resolution filtering algorithm and an automatic reliability/repeater function, to provide highly reliable data communication over long-distance power lines. Communication errors are lower than other optional and existing solutions. This device synchronizes with the AC mains signal via an onboard low-jitter phase-locked loop (PLL). The inclusion of a 16-bit resolution analog front-end gives the device excellent noise immunity and extremely high receiver sensitivity.
The AMIS-49587 also excels in ease of use. Its built-in protocol processing eliminates the need for designers to concern themselves with PHY and MAC protocol transmission details, saving up to 50% in software development costs, thus accelerating time-to-market and reducing overall cost. This device connects directly to the user's host microcontroller (MCU) via a serial interface.
The AMIS-49587 is compatible with both single-phase and multi-phase meters, meeting diverse customer needs. Furthermore, its power consumption is lower than digital signal processor (DSP)-based solutions, making it ideal for PLC communication applications from smart meters to concentrators. To help designers accelerate development, ON Semiconductor also offers the AMIS49587EVK evaluation kit for user convenience. This kit includes two PLC modems for configuring communication between the client and server; it also includes an open-source graphical user interface for configuring end-to-end communication.
Semiconductors provide complete solutions for smart meter applications
Compared to ordinary electricity meters, smart meters are undoubtedly more complex systems. ON Semiconductor provides complete solutions for smart meter applications, including PLC modems and line drivers for communication applications, as well as solutions for key functions such as power management, measurement, and storage. For example, in power management modules, ON Semiconductor's NCP1014 and NCP1015 AC-DC converters, LM2596, NCP3063, and CS51411 DC-DC converters, MC78L05, MC7805, CAT6217, and CAT6219 low-dropout (LDO) regulators, and NTMFS4823 medium- and high-voltage FETs can be used. Furthermore, smart meter applications can also utilize ON Semiconductor's EEPROM and SDRM memory series, as well as ESD/TVS, SIM card interfaces, logic, USB protection, monitoring, I/O expansion, clock, and temperature sensors.
In the burgeoning field of smart grid applications, smart meters play a crucial role. Designers need to select suitable communication methods for the communication between smart meters and data concentrators, and PLCs have become the preferred choice for leading companies and early-stage pilot projects, serving as a significant model and reference. Designers need to choose modem solutions for PLC communication. ON Semiconductor's modem products for PLCs comply with standards and customer specifications, offering numerous application advantages such as simplified design, reduced costs, lower power consumption, reliable communication, and faster time-to-market. ON Semiconductor also provides complete solutions for smart meter applications, including key functions such as power/power management and protection, communication, measurement, and storage, facilitating customer selection and helping them reduce procurement costs and accelerate time-to-market.
