Why Power Line Communication Smart Grid Technology Has An Eye on SoCs

Read the nutrition label on Smart Grid Brain Food and the first ingredient just might be SoC, as utilities strive for precision metering without compromising flexible and programmable processing.

The traditional power utility’s electrical network moves vast amounts of energy from power stations to a large number of customers. In essence, this old power plant consists of centralized control, the mechanism for one-way flows of power, and passive networks.

This classic view of the power grid is passing into history. The energy network today has more lines, circuit breakers, and transformers, as well as electronics, information, and communication protocols. The smart meter provides the way to get information regarding load usage into the communications channel. From there, the information is sent back to the power utilities’ generation and control centers.

One of the main drivers pushing this development is the goal to reduce greenhouse gas emissions by 20% over the next 5 years compared to 1990 levels.

Smart grids are the future of electronics and communications. But what will ensure the successful adoption of smart grids worldwide? Two things are vital: standardization and data protection.

This trend is confirmed by the statements of the European Commission Recommendation on preparations for the rollout of smart metering systems (2012/148/EU), which we have summarized as follows:

Because Smart Grids enable consumer empowerment, usage of renewable and more efficient energy, reduction of greenhouse gas emissions, job creation, and technological development, member states must monitor progress and establish guidelines for performance and implementation as well as efficiency analyses. And since data protection is of the utmost concern to everyone involved, the states need to ensure a consistent approach to security as well as to inform and raise awareness of the risks and benefits of smart metering technology. This goal is best achieved by massive rollouts or large-scale pilot projects, which will set the foundation for best practices. These projects would provide a set of recommended requirements that would give all players a tested and proven approach to apply within the Member States.

The Statements of the European Commission bring us back to the importance of two aspects of smart-grid technology:

  • The need for commonly agreed standards for the communication network of the smart grid and
  • The importance of realizing smart grids and smart metering systems while ensuring the fundamental right to the protection of the consumers’ data.

How will these goals be achieved?
Companies that produce integrated, silicon-based, System on Chips (SoCs) are focusing on the development of products that will allow electric utility providers to read and manage customers’ meters remotely. They will require that IC producers in the smart metering integrated application segment work to satisfy those two key points for the success of smart grid technology.

Indeed, the trend for smart grid systems management in the industry is to integrate a complete smart-meter System-on-Chip (SoC) that combines precision metering with flexible and programmable processing. In addition, there should be some connectivity subsystems to safely and effectively transmit and receive all needed smart grid monitoring and control data. By exploiting power cables as communication medium, Power Line Communication (PLC) is today probably the most suitable and adopted connectivity technology for Smart Metering and Smart Grid systems. . Finally, provisions should be in place for advanced security methods for the transfer of data. With careful engineering design, it should be possible to integrate all of this functionality in a single SoC and transmit data from the meter to a data collection unit (DCU) by means of a PLC link.

An SoC for the smart grid would be optimal—a device that integrates a programmable PLC modem with a high-performance application core as well as metrology functions (see Figure 1).

Figure 1: The optimal architecture of an SoC for smart metering is composed of a primary digital core for application management, a secondary digital core for connectivity management, analog and power dedicated metering and PLC subsystems to properly sense and couple the signals to the power lines

Only a few companies have a portfolio of integrated products for each part of a smart grid system. These few market players in the smart grid sector must focus on supporting customers with all the relevant parts required to build the smart grid.

In particular, the effectiveness of the design and the implementation of the smart-meter portion of the smart grid is a key ingredient of the performance of the overall smart-grid system. This consideration highlights the importance of an effective smart-metering process that matches the standardization of communication protocols to deliver data, in a real time mode, through the smart network of energy, and the security of the data itself. Semiconductor manufacturers will need to play together towards an international unification: Communication and Safety Standards utilized for the smart meter SoC transparently to the maximum extent possible in their national and regional standards, to achieve a PLC for smart metering that can be inserted in a wealth of possible smart grid applications.

The goal of these smart meter systems is real-time control and adaptability of the grid, integration of decentralized generation from renewable energy sources, and support for multiple communication standards. These standards have to be secured by physical routers and by software firewalls such as, for example, the encryption of the communication. The information about energy flow in the smart grid cells has to be reliable and secure to avoid the waste of energy and to guarantee an end-to-end optimized management of the energy.

As we’ve said, the standards have to be universally utilized to ensure the success of the Smart Meter integrated solution, and the protection of the data must be certified in order to ensure an optimized management of the energy flow into the smart grid. That’s why any smart metering solution will have to support some universally diffused communication standards such as, in case of PLC connectivity, METERS AND MORE, PRIME G3-PLC, and IEEE 1901.2. These protocols allow remote reconfiguration, which will guarantee secure and effective end-to-end communication. Moreover, the metrology sub-system should support the international metering standards for power measurement that ensures that the sub-system will meet with accuracy requirements.

Meeting accuracy requirements and supporting various communications standards will add value in the direction of developing a well-secured and universally compatible smart metering system. The adoption of this solution for the smart meters SoC guarantees a high precision and reliable metering process because it supports high accuracy measurement standards like the EN 50470-1, EN 50470-3, IEC 62053-21, IEC 62053-22 and IEC 62053-23 class1, class0.5 and class0.2 standards.

Let’s see how the effectiveness of a smart meter SoC can enhance the overall reliability of the smart grid system.

Multicore Sub-Systems
Running a meter application and a metrology algorithm is the main feature of the primary digital core. This should be achieved even with the help of hardwired digital processing for turnkey and effective power calculations, according to standardized algorithms. A secondary digital core is needed as a PLC signal-processing engine. This runs mainly the real-time PLC functions to guarantee real-time control of the communication data without affecting primary core performances, while ensuring separation from critical communication tasks and application firmware. Each of the two cores has a dedicated memory.

The PLC engine is also directly connected with a high performing PLC front end and Line Driver to ensure effective signal coupling to the line and safe and fast signal control. The metrology subsystem would be composed of high accuracy voltage and current sensors that input data are then filtered and processed by the primary core before being coded and transmitted into the line to the DCU by the secondary core.

The communication of the data has to be secured by mean of a cryptographic engine. This guarantees that a failure in the security of the data transmission would not affect the overall system end-to-end security.

An example of such a highly integrated Smart Meter SoC is the novel STCOMET platform from STMicroelectronics.

It includes a fully programmable PLC signal-processing engine for multi-protocol management and an ARM 32-bit Cortex-M4F sub-system with programmable SRAM and flash memory (Figure 2) for application management.

Figure 2: The block diagram of STCOMET smart-meter SoC.

The embedded metering front-end is realized by means of three-channel 24 bit sigma-delta converters supporting class 0.2 accuracy meters and beyond, with 4 kHz bandwidth. Moreover, a state of the art AES 128/192/256-bit security engine is integrated to enable secure data communication, as well as privacy, integrity and authentication features. The integrated PLC engine has a very high receiving sensitivity and supports transmitted signal levels up to 28 V peak-to-peak covering an extended bandwidth of up to 500 kHz to exploit all allowed bands worldwide (CENELEC, FCC, ARIB,…) while ensuring the highest link budged.

To increase the flexibility, the Smart Meter SoC is powered with a wide set of universally utilized communication interfaces: USART, SPI, I2C, CAN.

Smart-grid technology holds tremendous promises of development in the next few years, and multi-function integration, connectivity standardization and end-to-end security in a system like this are critically important.

Many electronics manufacturers are working on the answers to all of these needs with some outstanding products that constitute their smart grid and smart meter portfolios but only very few semiconductor manufacturers with the portfolios and technical expertise to meet their needs.

Ale Moscatelli graduated in applied physics at the University of Milan (Italy) in 1997, and began his career in STMicroelectronics R&D Technology department, developing advanced mixed signal silicon processes. After being responsible for multi-power radio frequency technologies for mobile applications, he moved to Industrial and Power Conversion Division where today he is in charge of Smart Grid products marketing. In his current position, he also contributes to several Industrial Alliances and Standardization Committees.

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