Highly integrated SoCs are helping designers to design energy meters with ease and less engineering efforts. What are the various design considerations and challenges for energy metering? And how can you select a SoC for designing energy meters?
Andy Wang, Senior Business Manager, Energy Solutions Business Group, Maxim Integrated talks to Pankaj Vashisht from EFY.
Q. To start with, what is one thing about smart meter hardware that everyone should know about?
A. Traditionally speaking, all electronic meters are just simple solid-state meters. It is now that communications are being integrated, which has led to their evolution into smart energy meters. In India, I think solid-state meters predominantly drive the market. There are simple solid-state meters available for single/poly phase lines, with the communication functionality being incorporated as the latest trend. It is this communication functionality that makes the meter ‘smart’.
Q. What are the key driving elements of the smart meter design in India?
A. A major driver of smart meter functionality is improving the local anti tampering capabilities. This is especially important in developing markets like India, where electricity theft accounts for a large percentage of overall power usage. The ability of solid-state electricity meters to detect and prevent tampering can significantly improve control and cost recovery for utility companies.
Also, the promise of improving service to customers represents an important goal of smart metering, especially over the long term. By enabling customers to better manage their own energy usage through incentive-based programs—such as direct load control, interruptibility rate agreements, and demand bidding or buyback, smart metering can help utilities manage overall energy consumption patterns and cope with peak-demand challenges.
Q. What are the biggest considerations and challenges in designing these smart meters?
A. The deployment of smart meters is far from a “one-size-fits-all” undertaking. Manufacturers must account for the varying regulatory requirements of each region, as well as the different functionalities and services required for different markets.
For meter manufacturers servicing global utility markets, the combination of different driving forces or elements present significant opportunities and challenges. Utility companies have to consider the implications of future smart metering applications when making today’s deployment decisions. Therefore, meter manufacturers need to be flexible, offering both low-cost metering solutions and high-end smart meter alternatives.
Also, the biggest challenge in designing any energy meter is to make sure the metrology is stable and repeatable in terms of accuracy. When it comes to designing energy meters, the accuracy of the integrated smart devices, is also very important, because it decides the reliability of the system.
Q. What are the benefits provided by highly integrated SOCs in designing energy meters?
A. These highly integrated SOCs with high-powered processors help the designers to design energy meters with ease, reducing the engineering effort. SoC solutions can be adapted across the entire spectrum of functionality requirements. Using these SOCs, one doesn’t need to spend much on engineering resources. This is because the engineer does not have to start the design from scratch. They lower BOM costs by eliminating the need for discrete components, and provide rich feature sets for smart metering and simpler upgrade paths with minimum hardware and operational costs. Moreover, all the high integration reduces cost and improves user experience.
Their key strength is the family effect and scalability. Engineers can design with one product and easily migrate to different products in the family depending on their needs. It allows them to just move to different product and leverage the designs they did in the past.
Q. What are the features that ensure the stability and repeatability in terms of accuracy in energy meters?
A. The basic features like the dynamic range of the ADC, sample rate of the ADC and the processing power of the microcontrollers account for the accuracy in energy metering. For instance, there are SOC solutions integrating multiple 24‐bit ADCs for as many as 7‐channel data collection and high ±0.1% measurement accuracy over a wide 5000:1 dynamic range. For this kind of higher measurement accuracy, these integrated solutions include powerful processor combined with multiplier for metering application codes. Also, the metrology compute engine (CE) ensures high-accuracy processing of all collected data. It is dedicated to computing the metering parameters from voltage and current samples.
Q. What new features do these SOCs bring to energy metering?
A. There is a whole portfolio, and these features depend upon the segment that you are talking about. If you look at the whole family from low-end market to high-end market, when you go to the higher end, you will get more memory, which in turn allows the engineer to incorporate DLMS/COSEM stacks (communication protocols for smart meter) in there allowing you to communicate with the modems. Also, in some regions it is required to encrypt/decrypt the data and for that these SOCs incorporate hardware accelerators for encryption and decryption.
For example, the lower ZON family is basically a silicon that does everything and one need to have an external modem for ZON but the high end product family called ZEUS basically has ZON plus all the communication components integrated.
Q. Any key parameters on which a metering SOC should be selected to design energy-metering requirement?
A. Selecting the correct SOC according to your need is the key today. Accuracy, memory size, processing power, and amount of peripherals integrated are the key parameters to consider when selecting any metering SOC solution. An engineer should make sure it features field programmability, and enable ease of integration with local devices such as thermostats, as well as support a variety of sensor inputs with minimum hardware to help them design better solutions.
Q. What are the tools and guidelines available to help designing with these types of SOCs?
A. From hardware perspective there are reference designs, layout and hardware guidelines available for any engineer. All they have to do is leverage the technology with these SOCs and modify it and just make sure the power supplied is stable and sensing circuitry is clean. From the software perspective, we provide very modulated source code so they can take it from there and easily modify it depending upon their end customer’s requirements. Because we provide highly integrated SOC solutions, our goal is really to make their life easier.
Q. How do you see the future of energy metering?
A. Looking into the future, I feel it is about more upgrades in the metrology along with the metering firmware. The products that most vendors vision, are the products with increased integration of communications and security features. There are some regions that are talking about security as a feature, private/public keys trying to make meters as much secure as possible to prevent hacking into the meters.