PLC technology drives smart energy command and control


By Didier Boivin

Smart home energy command and control is one of three pillars required for creating a modern smart grid capable of streamlining power delivery and dramatically improving energy efficiency. Utilities around the world have settled on PLC technology as one of the two primary candidates for deploying home energy management systems that, along with advanced metering infrastructure (AMI) and new energy distribution systems, will help maximise the world’s use of variable energy sources, establish automation and monitoring capabilities, and leverage real-time transmission to drive energy conservation.

Utilities and equipment suppliers apply the term smart grid to a variety of future networking technologies that can be used to solve the issues related to delivering smart energy. In a nutshell, the smart grid covers all aspects of the modernisation of electrical distribution grids. Such modernised grids (electricity networks being only one example) are being promoted by many governments to address energy independence or global warming issues (such as those targeted in the US economic stimulus package).

According to the United States Department of Energy (DOE) Modern Grid Initiative report, a smart grid must:

  • Be able to heal itself
  • Motivate consumers to actively participate in operations of the grid
  • Resist attack
  • Provide higher quality power that will save money wasted from outages
  • Accommodate all generation and storage options
  • Enable electricity markets to flourish
  • Run more efficiently.

To accomplish these objectives, three technologies are required: AMI, home energy command and control, and efficient energy distribution.


Figure 1 – The two primary AMI
technologies are PLC and
IEEE802.15.4. Proprietary standards
are also being considered

First, AMI meters must be developed that meet energy efficiency goals by enabling utilities to charge variable rates that reflect the large cost differences between peak and offpeak periods. Smart meters enable more than just reading. By leveraging available information at the meter (such as real-time power consumption and billing, energy control during peak hours, quality of service, etc.), all meters are becoming “smart” meters. To support smart metering features, they must have two-way communication capabilities.

Second, the smart grid requires that home energy control and command (or demand and response) capabilities be deployed within the house or building, etc. In the case of the residential market, home energy command and control also requires an interface to in-house network capability, such as a home area network (HAN). Consumer education about energy conservation (including steps such as reducing air conditioning, managing the heater, adapting refrigerator usage, etc.) will greatly help in facilitating interactions between customers and utilities that will lead to improved energy management.

Finally, smart energy distribution is the third factor required for a next-generation smart grid, and is widely regarded as the most complicated development vector. How will we tie everything together? How will we enable “real time” management of energy assets and improve delivery efficiency, reduce shortages, minimise construction of new power plants while still managing peak demand, and reduce environmental impacts?

The internet has been a great example of how global standardisation contributed to exponential growth in market acceptance. In contrast, the smart grid industry has been scrambling to agree on a set of standards over the past decade. This is certainly one of the factors that has slowed adoption by utilities.

While the standards picture still remains confusing, utilities around the world have recently settled on two primary technologies for future deployment of AMI solutions (Figure 1). One is power line communication (PLC) technology, for which standard bodies are looking at modifications to support the specific needs of the smart grid. The other is IEEE802.15.4. The choice of AMI technology tends to vary based on geography. There are several reasons for this, including demographics and the topology of energy networks around the world. As an example, China is focusing closely on PLC technology, while other parts of the world, like the United States, are using wireless technology (including ZigBee, IEEE802.15.4, and many proprietary wireless standards spanning a frequency range from 440 MHz to 2.4 GHz) and, on a very limited basis, some wireline technology.

Recent progress by some U.S. utilities and manufacturers in driving future standard adoption is resulting in many initiatives to define the different communications layers. The HomePlug Alliance is working on creating a new physical layer called “Green PHY” (HP-GP).

In addition to these foundational standards, a true smart grid network also must address the need to interact with other standards from other industries. This includes heating and air conditioning, commercial buildings, home appliances and automation, etc.


Figure 2 – IPv6 is the likely standard
for a higher layer protocol that
will enable the smart grid to meet
interoperability requirements

Different standards bodies have explored many technical considerations when it comes to the deployment of future smart grid technology. New standards at different layers of the communications protocol stack will be required in order to insure proper communication between various technologies used by smart meters, in-house smart energy products (including gateway solutions), and general distribution solutions deployed by utilities.

At the lower level of the communications protocol stack, most utilities that have already deployed smart meters are pushing for some level of backward compatibility with the most recently deployed legacy solutions, but only for technologies such as IE802.15.4 (including ZigBee) and PLC. Because PLC technology is used for applications such as IPTV to deliver video content within the house, there is also a need for co-existence of various products using similar technologies.

Even though there is still much standards development work that must be completed before we can achieve global adoption, Internet Protocol (IPv6) is already considered as the future standard for a higher-layer protocol (Figure 2). The recent draft of the smart grid interoperability requirements that were released by the NIST for US deployment include the use of the IPv6 protocol. This protocol is expected to be considered in other parts of the world as well.

As mentioned earlier, two communication technologies are preferred by utilities in the US – HomePlug and ZigBee. Other parts of the world are still considering possible alternatives, such as the frequency shift keying (FSK) modulation scheme in the Comité Européen de Normalisation Electrotechnique (CENELEC) frequency band. Achieving integration of all these technologies into an IPv6 network can be accomplished through the use of IEEE802.15.4 as a media access control (MAC) and physical layer (PHY), and by the use of IETF-6LowPAN as an adaptation layer to send and receive IPv6 packets.

Unfortunately, even if ZigBee products use IEEE 802.15.4 as MAC and PHY layers, the routing capabilities differ from the ones in the IETF 6LowPAN specification. Another issue in terms of backward compatibility is the type of headers used by IETF-6LowPAN and ZigBee, which cannot be decoded from one network to another. These incompatibilities between the IETF 6LowPAN and ZigBee networks make it impossible to provide any compatibility over the air between these two solutions. As of today, ZigBee devices cannot support any IP frames in a simple way. Options are being discussed such as “encapsulation” capabilities, or the use of gateway solutions between existing smart energy standard (SE V1.0) and upcoming (SE V2.0) devices, but none of these are very attractive when it comes to cost, ease of deployment and other important factors.


Table 1 – Capabilities required of home energy technology

Smart grids will expand the infrastructure for transporting electricity and therefore will present a more physically challenging infrastructure to protect. To meet this challenge, the smart grid will leverage today’s internet technologies to ensure that a fully protected infrastructure will be a matter of national security prior to deployment.

Smart grid risk management involves three crucial steps. First there is a need to thoroughly assess threats. After this has been accomplished, there will need to be disciplined procedures for detecting vulnerabilities. Finally, systems will be required for accurately gauging the actual risks, and identifying appropriate and highly reliable countermeasures. This will involve a combination of both federal and private programmes. The chair of the Federal Energy Regulatory Commission (FERC), Jon Wellinghoff, has called for standards to “ensure the reliability and security, both physical and cyber, of the electric system.” The fact that many intrusions have been detected by US intelligence agencies – and not by the companies in charge of the energy infrastructure – indicates that federal programmes to protect computer networks must expand across both the public and private level. For the smart grid to be successfully deployed, physical security and cyber security must succeed together, or both will fail.

Mass market deployment will happen only after all major energy appliances in the home can be interfaced to smart meters or other “smart energy” gateway equipment within the house. This will enable consumers to efficiently control energy consumption within their homes. To do this, “smartplug” devices need to be installed to securely control and command all those energy appliances.

Monthly energy savings need to counterbalance the short term costs of deploying smartplugs within the consumer’s homes and embedded in appliances and various powered consumer products.

To achieve that goal, the enabling technology must deliver specific capabilities, summarised in Table 1.

Once the aforementioned are in place, the industry will be able to drive smart energy product deployment and integrate smartplug capabilities into all of a home’s appliances, down to the lamps and other powered products and devices. This, in turn, will drive consumer interest in, and access to, smart energy management. Market drivers such as convenience (remote control of equipment, in-home network support, etc.) and security will converge and spur mass-market deployment in ways that would be impossible for each factor, alone.

Many forces are driving smart grid development, including the need for energy efficiency to meet rising demand, growing consumer awareness of environmental issues, and government initiatives aimed at pressuring utility companies to deliver smart energy solutions. The technology to implement a smart grid network starts at the meter, and now, with key standards in place and silicon ready for design-in, the smart grid is entering the next phase of rapid development and deployment.