Low Power Consumption Delta-Sigma A/D Embedded MCU and Development Kits for Smart Metering

Solutions: 19 of 20

Solutions for Smart Grid-related Devices Part 1: Electricity Metering Taking a New Step Forward in Energy Saving

Global "energy saving" efforts aim to improve the future of all humanity and are driving the development of many different technologies. Increasingly, R&D efforts are being focused on elements of smart-grid infrastructures such as smart meters. In this two-part series, EDGE discusses Renesas' solutions for creating smart meters. The updated information presented will help electronic design engineers create designs for practical and affordable products that meet the requirements of huge market opportunities.

Expanding the smart grid concept to optimize electricity production and use

Smart electrical grids are the key to ensuring stable supplies of electricity to homes, businesses and industry as eco-friendly generating stations come on line. Massive amounts of power are becoming available from facilities that harness energy from the sun and wind, for example. Smart grids are needed to manage the distribution process so that it accommodates the best mix of sources.

Another important ecologically friendly trend is obtaining greater overall power savings in utility systems by extending the concept of the smart grid. Methods are being developed that enable and encourage end users to consume less electricity, especially during peak levels of demand.

The concept envisioned to enable the latter trend is a pervasive smart-power grid, one that originates at smart meters. In real time, those meters measure instantaneous power consumption and usage trends thereof. They communicate the resulting digitized data to remotely located utility company control systems and on-site Home Energy Management System (HEMS) and Building Energy Management System (BEMS) products.

In particular, this Part-1 story covers the basics of smart meters, describes their markets and applications, and highlights tools for developing power-measuring capabilities. The Part-2 story will describe solutions for implementing the communication capabilities that are also essential features of these energy-saving devices.

A smart meter is equipped with two different communication functions—communication with supplier (route A, NAN*1) and communication with consumer (route B, HAN*2) (see Figure 1). Having had no connection with communications traditionally, a meter is now increasingly expected to play a major role in bringing energy-saving to the next level by sending and receiving information from suppliers and consumers.

*1 NAN:Neighbour Area Network

*2 HAN:Home Area Network

Figure 1. Electric smart meter-based HEMS

Figure 1. Electric smart meter-based HEMS

Smart meters are indispensable for proactively optimizing power usage. They can make significant contributions to improving the efficiency of power production and retail distribution, while simultaneously facilitating reductions in end-user consumption.

Their performance in real-world applications is a well-proven reality because for many years smart meters have been deployed in Japan, North America, Europe and other places, reliably measuring and tracking electricity usage from moment to moment. The major successes achieved in large-scale smart-meter deployments have created worldwide demand for mass production quantities. Vibrant, fast-growing markets now exist worldwide for these robust, highly effective devices.

Quantifying the growth of the smart meter market

The proliferation of smart meter deployments has been impressive. In Japan, for instance, ten major domestic utility companies began to deploy smart meters following the revision of the Energy Saving Act in April 2014. Industry pioneer Tokyo Electric Power is scheduled to have finished replacing all of its conventional meters with smart ones by 2020, and the rest of the Japanese electrical utility industry will do so by 2025.

In the United States, over 50 million smart electricity meters have already been installed in over 40% of households (see Figure 2). More are being deployed every month.

Figure 2. Smart meters deployed in the United States

Figure 2. Smart meters deployed in the United States


In Europe (the EU), energy-conservation regulations have encouraged rapid smart-meter deployments, with remarkable success (see Figure 3). The European Parliament issued a mandate for smart metering (Directive 2009/72/EC) in 2009. This directive calls on member countries to develop regulations that support smart metering. As of 2014, all of Sweden's electricity consumers now have smart meters, while Italy has installed them for 95% of its consumers.

Figure 3. Smart meter deployment targets in EU countries

Figure 3. Smart meter deployment targets in EU countries

Source:Status Review of Regulatory Aspects of Smart Metering: Including an assessment of roll-out as of 1 January 2013 (Council of European Energy Regulators ASBL)

The trend toward replacing conventional meters with smart ones is occurring not only in industrialized nations. Interest in adopting smart meter technology is growing in emerging nations around the globe, as well.

Accelerated deployments of smart meters are being driven by a rising acknowledgement of the need for and benefits of smart grid infrastructures. To capitalize on this market opportunity, many Renesas customers are seeking ways to speed up the development of new smart meters. In response, our application experts have produced some valuable support tools. They will be described later in this story.

Incorporating communication capabilities into meters brings multiple benefits

A smart meter basically performs two tasks: measuring and tracking the electricity being consumed, as previously discussed, and exchanging information with both the utility firm and the user (routes A and B, respectively, in Figure 1). The measurement functions are essential, of course. But it's the communication capability that lets smart meters play increasingly important roles in raising energy-saving efforts to the next level.

Smart meters improve the speed and efficiency with which a utility collects consumption information. No longer does a meter reader have to visit sites to collect data. Instead, up-to-date data is transmitted on a very frequent schedule to a control facility for rapid analysis. The personnel there can even remotely start or cut off the energy supply without making a service call. Also, they can get service alarms when problems arise.

The biggest advantage of smart meters doesn't lie in remote control, however. In households and buildings, they are key components of the HEMS/BEMS equipment that makes electricity usage visible minute by minute. Previously, consumers could only learn how much electricity they were using by looking at the monthly summaries in billing statements. They couldn't obtain the greater detailed data needed for finding ways to save power.

Smart meters remove this limitation, making it possible to know electricity usage in real time through communication link B shown in Figure 1. The displayed data allows them to determine if a gap exists between their energy consumption target and the actual amount being used. If it does, they can take steps to better manage their HVAC system, appliances and other line-powered devices.

Consider, for example, a situation where a person turns on a major household appliance: an electric clothes dryer. The energy-management system would use information obtained from a smart meter to check the energy usage situation. If the electricity being consumed is already near the contracted capacity, the HEMS equipment alerts the user that power might be shut down if it exceeds the limit. Or an automated power manager might be able to keep power usage below the maximum by decreasing the consumption of other devices in the home.

The electricity usage monitoring capabilities of smart meters could also be incorporated into individual home appliances to enable more detailed power management. This would allow optimized adjustments of power consumption to be made during peak hours, for instance.

When electric power industries are deregulated, consumers are allowed to choose suppliers offering the lowest rates, depending on their power consumption. Smart meters promote energy-saving actions in entire households and buildings, whereas conventionally energy optimizations were only possible for individual devices and pieces of equipment.

Additionally, as mentioned previously, there is growing confidence that in the future an entirely smart power grid will originate at smart meters. The electronic meters devices are indispensable for minimizing the energy supplied to dwellings and buildings. The enhanced measurement and control capabilities enabled when smart meters are installed at all points of consumption significantly boost the efficiency of electrical generation and distribution systems.

Metering—a keystone of smart grid devices. Renesas' solutions for smart grid devices
—Electricity metering—

1. Ultra-low-power consumption

Although the communication function is the major feature of smart meters, the primary task is to accurately measure how much electrical power is being used on an ongoing basis. To help system engineers create new designs in less time, Renesas offers kit solutions designed to achieve the most efficient development of such metering functions.

Our metering function kits are built around the RL78/I1B microcontroller (MCU) designed for high-accuracy metering and is applicable to various kinds of development. The RL78/I1B ensures thorough low power consumption and minimizes power consumed by meters and other devices.

In smart-metering products, it's essential that the exact time at which each power measurement is made be recorded. Accurate timekeeping is mandatory for producing meaningful consumption data for utility companies and their customers. Thus, the electronics in smart meters must include a Real-Time Clock (RTC) function, with battery backup to ensure continuous operation. Traditionally, designs have used both a low-power MCU and a low-power precision clock chip because older built-in RTCs consume too much power. That is no longer the case, however.

The Renesas RL78/I1B MCU is a single-chip solution that integrates a newly developed, ultra-low-power RTC. This timekeeping function reduces the complexity and cost of a smart meter's electronics, while also allowing smaller-size circuit boards that facilitate miniaturization.

The RL78/I1B's very stable on-chip oscillator is capable of adjusting the RTC's frequency to within ±0.05% of optimal. No external high-speed oscillator is required to achieve highly accurate timekeeping for meter data. Moreover, the MCU's built-in RTC is highly resistant to surges caused by lightning, EMI, etc., ensuring stable performance even in severe outdoor environments.

The ultra-low-power consumption of the RL78/I1B chip also saves cost and aids miniaturization because it allows the use of smaller backup batteries. An integrated automatic power switch significantly simplifies power backup-related circuitry.

Application: Go to the electricity meter (single-phase) page


2. Readily available development kits

There are two types of RL78/I1B-based electricity metering development kits—Analog Characteristic Assessment Kit and Single-phase Meter Reference.

The Analog Characteristic Assessment Kit shown in Figure 4 is basically a test and evaluation tool. It lets system engineers verify the interface between various electrical-current sensors and an RL78/I1B MCU, as well as analyze the operation of the advanced analog signal-handling capabilities built into the MCU. Development teams can immediately begin applying their electricity metering know-how in an RL78/I1B-based circuit design. They can readily perform tests to determine how well the MCU works with familiar types of sensors (see Figure 4).

Figure 4. Analog Characteristic Assessment Kit

Figure 4. Analog Characteristic Assessment Kit

The Single-phase Meter Reference Platform is a fully developed circuit board incorporating all the basic functions needed for electronic power metering (see Figure 5). It provides a solid starting point from which system engineers can build the electricity metering section of a smart meter that meets the requirements of IEC62053, an international standard for electronic products that independently measure power usage. This reference design achieves the mandated 0.5% metering accuracy and lets design teams develop IEC 62053-compliant smart meters in a surprisingly short time.

Both the assessment kit and the reference design come with the power-measuring firmware and sensor-read value calibration firmware that Renesas application engineers have developed based on a wealth of experience in this field. These support tools also include GUI software for displaying status and performance information on an LCD screen. Simple operations for sending commands and parameter data to these products help ease test routines.

Figure 5. Single-phase Meter Reference Platform

Figure 5. Single-phase Meter Reference Platform

This Part-1 in a series on Renesas' smart grid-related device development solutions has provided updates on the market trends of smart grids and smart meters. It also introduced solutions for smart grid-related products. Part-2 will explain key technical issues related to the communications functions required for smart-grid products and will discuss the solutions Renesas has developed for addressing them. Keep an eye out for it.