Energy management home gateway and interoperability standards Timothy Schoechle International Center for Standards Research [email protected]

Keywords: interoperability, conformance, Ethernet, Wi-Fi, SNMP 1.

I NT R ODUC T I ON

1.1

The “smart grid” and the energy economy

The smart grid may indeed be the key to a new energy economy—and a new national and global energy economy may offer the key to addressing significant global problems: national security, oil addiction, war, the economy and jobs, climate change and global warming, pollution, transportation architecture and economy, and international trade and commerce. This paper deals with the role of home (and small building) electronic systems and premises equipment in the evolution of the smart grid. It is there, at the end-point or delivery-point of the grid, where the actual use—as well as potentially also generation and storage—of electricity occurs. 1.1.1

Renewable and sustainable sources

Oil costs, coal pollution, and the successful development and mass deployment of wind and solar technologies in various parts of the world have raised public interest in moving more generation to renewable and sustainable sources. Consumers have shown that they support renewable energy sources—and would pay extra for them. As small-scale solar photovoltaic (PV) panels and small wind turbines—“micro-generation”—become more economical, consumers and communities are increasingly expecting to include them in their local energy mix. However, there are significant limitations. Wind and solar are unpredictable and hard to store. This has posed a dilemma for consumers and utilities in integrating these sources to any significant extent. New technical approaches such as demand response (DR), new electricity pricing protocols i, premises energy management systems, and smart appliances offer a partial solution to the incorporation of renewable energy.

1.2.2

Defining the smart grid

One generic functional definition of the smart grid describes it as “an intelligent, auto-balancing [supply and demand], self-monitoring power grid that accepts any source of fuel (coal, sun, wind) and transforms it into a consumer’s end use (heat, light, warm water) with minimal human intervention.” ii This definition provides a good starting point. But where does this intelligence reside and how can the auto-balancing and self-monitoring be done? Part of that answer will lie in the home. This is the subject of this paper. Wind and solar energy are inherently distributed in time and space. Although centralized utility-scale wind or solar plants are an obvious approach, distributed generation offers a promising future path because these sources and their technologies are inherently scalable, modular, massproducible, and economical—and additionally, they can provide security through independence and redundancy. This approach is becoming known as the microgrid iii— where energy is largely produced, stored, used, and traded locally in a community among “smart” users—smart homes, smart appliances, smart thermostats, smart plug-in cars, etc. Ultimately, from the local perspective, the larger power grid beyond becomes a back-up rather than the main source of energy. From the utility perspective, their customers become their major generating source, back-up storage, and their means of load-shaping and supply-demand balancing. 1.2.3

Home and small building systems

The technological and commercial environment in homes and buildings is diverse and complex. The suppliers, sources, and standards are many, encompassing such industries and markets as consumer electronics, home appliances (“white” goods), heating and cooling equipment, lighting, homebuilding, mortgage lending—and now, automobiles and solar PV. As new energy-saving systems and equipment attempt to enter this market, these diverse products increasingly need to work together as a coherent system—and work with the electric supply. The challenges

of a diversity of communication standards and their lack of interoperability present formidable barriers.

and accommodate specific application areas of importance to emerging smart grid services.

This paper describes certain promising approaches to these interoperability and home system integration challenges that have been adopted or are presently being undertaken as information technology standardization projects. These standards have been included in the NIST smart grid roadmap.

One such application area includes energy management application processes that will support the on-premises generation, storage, and use of electricity, as well as facilitating demand response and coordination with utilities and with other grid users in a microgrid configuration (e.g., real-time pricing protocols). Model of an energy management system for HES (ISO/IEC 15067-3) that is intended to show how energy-related premise devices and applications can be managed.

1.2.4

Scope

The standards specifically of interest here concern the communication architecture needed to support the smart grid concept in the home-to-grid or building-to-grid interface domain. This discussion examines certain key HES technical standards that support interoperability. It deals primarily with the Technical and some Informational interoperability categories including syntactic and semantic network interoperability. Although the paper is primarily targeted at a technical audience, it also covers related business, regulatory and policy issues. 2. H OM E E L E C T R ONI C SY ST E M (H E S) ST A NDA R DS The Home Electronic System (HES) is a broad set of information technology standards relevant to consumer residential and small building environments being developed by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC) Joint Technical Committee 1 (JTC1) for Information Technology. HES includes standards for specific home network communication protocols as well as those related to systems or applications (e.g., safety, security, system management, building automation, taxonomy, terminology, etc.). Although several specific communication protocols used in home and building systems have been standardized under HES (e.g., LonWorks, KNX, Echonet, UPnP, IGRS, etc.), it is unrealistic to expect that any protocol will dominate in such a diverse and rapidly advancing technical marketplace. As a result, HES has focused on a means of making these protocols and systems interoperable with each other without modification. This means include standards for 1) achieving product interoperability, 2) building gateways, and 3) energy management. Technical standards for Interoperability Guidelines (ISO/IEC 18012) and for a Gateway (ISO/IEC 15045) implementing such guidelines for communication among and between diverse of home networks and external networks have been initially established and are included in the NIST interoperability roadmap. Work is currently proceeding on additional parts of these standards to identify

3. I NT E R OPE R A B I L I T Y ST A NDA R D— I SO/I E C 18012 The widespread development of many national and regional home automation specifications, some standard and some proprietary, necessitates a mechanism for interoperability. Interoperability ensures that products from multiple manufacturers (potentially implemented using different automation systems) can interwork. It is desirable that devices needing to interwork do so seamlessly to provide users with a variety of integrated applications without modification of their underlying protocols. ISO/IEC 18012-1 Home electronic system–Guidelines for product interoperability–Part 1: Introduction provides an introduction to the basic approach and to system issues such as safety, management, and operation. Part 2: Taxonomy and lexicon provides a descriptive mechanism at the application level, so that there is a common way of describing applications in any underlying system, and an unambiguous mapping to key implementation items (e.g., data type primitives) to allow for transparent interoperability. Application-level interoperability cannot be achieved without being able to describe applications. The term “product interoperability” should be considered synonymous with application-level interoperability, since products are developed to implement applications - the value of products derives from their applications. Work on this International Standard began with an in-depth review of the following existing client systems, to understand the various application, interaction, and implementation models in use: CEBus, LonTalk, KNX, EHS, UPnP, and EchoNet. From that analysis, key similarities were identified between the various approaches and implementations. Those similarities are primarily in the high-level application functions that are being implemented, with differences appearing in the details of how the functions are represented. In short, there is a great deal of semantic similarity between various automation system application functions, but significant differences at the syntactic level.

The approach taken is to create a Common Interoperability Framework (CIF) that comprises a descriptive system for any home network on three levels: Protocol level – the exchange of messages Syntactic level – the structure of the messages Semantic level – the meaning contained in the messages This approach is depicted in Figure 1. The CIF defines a specific generic interworking function (GWIF) for each client network which then can be used to produces a common expression for each message unit using an Abstract Intermediate Language (AIL)—a sort of lingua franca of home networks. This common expression is conveyed across a common real time “event bus” to second client GWIF that carries out the reverse process, rendering an equivalent native expression in the second client network. HES Abstract Intermediate Language (AIL)

Simple gateway – interconnecting one-to-one networks, and is non-expandable Multi-network gateway – interconnecting more than two networks Distributed gateway – interconnecting multiple gateway units ISO/IEC 15045-2 essentially describes a way to implement ISO/IEC 18012-2. It defines a common event bus or “gateway-link” that interconnects the individual networkspecific modules, and the necessary service requirements. In the case of the simple gateway, the standard need not apply unless future expandability is anticipated. This modular architecture is depicted in Figure 2, showing a generic multi-network gateway. In theory, any number of gateway-link modules may be plugged into the common gateway-link bus to form an infinitely expandable gateway system. For purposes of illustration, both wide area networks (WAN) and home area networks (HAN) are shown, but they are effectively the same. Domain of HES-gateway

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As new networks are introduced, it is necessary to create a corresponding GWIF. This GWIF may take the form of a translation table that might be made available in a universally accessible metadata registry for those wishing to configure gateways. This approach avoids the pitfalls of depending on proprietary one-to-one gateway/translators that may or may not render a translation approved by the original network manufacturer. This approach also lends itself to a modular and infinitely expandable method of implementation that is “future proof” and network agnostic. Such an implementation is the purpose of the Gateway standard, ISO/IEC 15045. 4.

G A T E W A Y ST A NDA R D —I SO/I E C 15045

ISO/IEC 15045-1 Home electronic system–Guidelines for product interoperability–Part 1: A residential gateway model for HES provides an introduction to the basic architecture of the residential gateway and to its functional requirements, safety requirements, and privacy and security requirements. Part 2: Modularity and protocol provides a specific modular architecture for alternative gateway implementations:

home area networks

Figure 2 — Modular gateway architecture Each module carries its network-specific GWIF and enough processing power to meet its own service requirements. The gateway-link bus utilizes a form of Ethernet capable of meeting the overall service requirements of the gateway as a whole, depending on its application. The modules need not be contained in the same box or location. Figure 3 depicts both a centralized and a distributed gateway (or system of gateways).

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Part 2 – Lighting model for HES Part 3 – Model of an energy management system for HES Part 4 – Model of a security system for HES

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Figure 3 — Centralized and distributed gateway architectures In summary, this standard shows how to build a gateway out of modular building blocks. Other than network-specific interface modules, another building block or class of modules may be incorporated, known as the service module. Such modules do not have a network connection, but do have access to the gateway-link and thus to all the interface modules and their networks. This capability is depicted in figure 4. Service modules could be designed for application specific functions and could be of any level of complexity. On obvious service module application is energy management. Domain of HES Gateway GL (HES-link) Bus Domain of HESgateway WAN a Interf ace Modu le

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Figure 4 — Service module The following describes the energy management model standard which could offer a guide for the design of any number of specific energy management service modules. 5. E NE R G Y M A NA G E M E NT M ODE L ST A NDA R D—I SO/IEC 15067-3 ISO/IEC 15067 Home electronic system (HES)–application model currently consists of four parts. All parts were previously published as Technical Reports. These models have been developed to foster interoperability among products from competing or complementary manufacturers. Product interoperability is essential when using home control standards, such as HES. Part 1 – Application services and protocol

Part 3: Model of an energy management system for HES, is presently being upgraded from a Technical Report to a International Standard at the request of the IEC Standards Management Board, Study Group on Energy Efficiency. Energy management is becoming an essential part of the worldwide development of smart grids. Part 3: Model of an energy management system for HES defines a standard for a generic energy management system and describes the communications services needed. A high-level model for an energy management system using HES is presented. It provides an architecture and set of functions for energy management systems in homes and small buildings. This energy management model envisions a control element or agent, known as an Energy Management Agent (EMA). This agent could reside in one or more service modules in the gateway architecture, or alternatively, it could reside as an application/appliance on one or more of the HANs in the home. In any case the EMA could embody such functions as communicating externally with utilities or other service providers to manage demand response, remote meter reading, or correspond with real-time pricing or bidding systems. Internally, EMA could manage electrical loads, communicate with smart appliances or displays, etc. Following is a list of possible functions or devices that are contemplated as components of the Model: • • • • • • • • •

smart home appliances, smart thermostats and other sensors, solar PV equipment, and associated inverters, micro-turbines and other generating devices, smart battery charging and discharging devices (including plug-in hybrid vehicles), power conditioning equipment (e.g., wave shaping, phase synchronization, power factor compensation, etc.), metering and power quality logging devices, demand response protocols, and real-time pricing protocols and premises equipment responses.

Demand response is one key element in the concept of the smart grid which integrates subsystems for generation, transmission and distribution, and customer services to improve the reliability and efficiency of electricity systems. The smart grid also extends these subsystems to accommodate distributed energy resources and demand response. A goal of the smart grid is to enable all these subsystems to interoperate using information technology.

Therefore, this standard is an important contribution to the smart grid. 6.

C ONC L USI ON

As the market develops for energy management products, consumer electronics companies, appliance manufacturers, and other residential suppliers may offer products that combine load management using demand response with energy conservation. Energy conservation may offer consumer methods for reducing energy consumption overall, in addition to reducing consumption at times of peak demand. These methods include products and systems for electrical generation, storage, and management. Such products and systems are located on premises and can communicate with other on-premises products and systems in order to interoperate as a larger system. Standards for these products are anticipated to expand this energy management model in future updates. Examples are included in Annex A. The HES standards for Interoperability and for the Gateway provide important enabling technologies that are market neutral and form a platform for an ever expanding inventory of energy management options. Most importantly, these standards provide a pathway for the incorporation of renewable and sustainable energy sources into the electric power grid system and consumer’s homes. They also offer a new set of options to the electric utility industry and its suppliers to gain control of their fuel costs, pollution problems, and to provide their customers with expanded and beneficial services. A.

APPENDIX

Potential EMA functions for HES and how they could contribute to smart grid demand response: A.1

Demand response – hours

Demand response (hours)—This is conventional DR and it is the simplest to understand. This operates over a time scale of hours. High-speed communication capability is not needed here. The EMA could provide switching control of several circuits for smart demand control for appliances like refrigerators, air conditioners, etc. The more intelligent approach is an EMA that never actually turns any thing off or on, but just changes the settings of the thermostats, pressures, and other parameters that have immediate large impacts on energy use. This form of DR can keep the grid from having to start up auxiliary (i.e., marginal generating) capacity and more expensive power plants at hours of peak use. A.2

Demand response – seconds

Automatic Surge Assist (seconds)—Almost no one seems to be talking about this one although it could ultimately save as much money as demand response. Every power plant has some maximum capability. If the loads ever exceed this limit, then the frequency and voltage drops. When such changes occur the current drawn by inductive motors increases dramatically making the voltage drop even more. Since about 40% of the loads on the grid are inductive motors, this effect is enough to collapse the grid, which is exactly what happens with most power failures. To guard against this, the grid must always operate significantly below this "red line" to avoid collapse. Inductive motors are real machines with inertia so this process takes several seconds to a minute to unfold. The general move to higher efficiency generally increases the percentage of loads that are inductive motors as heating elements are replaced with heat pumps, and replacing incandescent lights with CFL dramatically reduces the lighting part of the load. The EMA could provide this automatic surge assist from the energy stored in batteries of UPS systems and vehicle-based storage systems. This entire surge assist event normally is over within a minute or so and the ultimate stored energy drain on the batteries is negligible and will have no effect on the life of the battery. Because the EMA detects and performs this operation locally, there is no need for communication at all, let alone high speed communication. Responding to surges is the most expensive problem for the grid utilities to address since they do not have time to fire up extra generators when this happens. Their only solution is extra capacity with the main power plants that are in use every day. The cumulative effect of this could be as much as two times the supply, which relates directly to capital expenditures and dwarfs most of the smart grid features that are in the spotlight right now. A.3

Demand response – milliseconds

Automatic Power Factor Compensation (milliseconds)— Again, this is left out of most smart grid plans, but this is a very real issue. CFL and LED lights have a power factor of about .5 and computers often have a power factor of between .7 and .8. The time scale for power factor is milliseconds rather than seconds. This directly translates to not only the real usable power available from the power plant but also the real usable power from all of the power lines and transformers in the distribution system. Even if the utility compensated for the power factor at the power plant or at major power distribution centres, it would not provide any help on the distribution lines and local transformers. The EMA could incorporate this feature into UPS systems and home and office renewable energy

distributed generation systems at a scale that could totally compensate for all problem power factor devices locally. This is clearly out of the realm of effective high-speed communications and needs to be handled locally by an automatic means. This not only saves the grid companies money and infrastructure cost, but it improves the waveshape of the AC power delivered by the grid. A.4

Demand response – minutes

Local Distributed Renewable Energy Generation with Communication (minutes)—This not only puts the renewable energy generation on free local real estate, but it is generally consumed locally so there is nothing lost to transmission. The ultimate energy security aspect of local renewable energy generation is endless while the EMA at each node could continue to operate if needed. Real time communications and control with the grid allows for renewable energy to be significant, overcoming the present 1% (or less) maximum barrier to implementing solar and residential-scale wind power. Aside from the raw value of the energy produced, it is hard to put a price on the value of energy security, but there are some examples from recent weather disasters. Even in the absence of major catastrophes, the cost of power interruptions is enormous and escalating. BIBLIOGRAPHY ISO/IEC TR 14762 Guidelines for Functional Safety ISO/IEC 14543 HES Architecture ISO/IEC 29341 UPnP Device Architecture ISO/IEC 15045-1 Home Electronic Systems (HES) gateway -- Part 1: A Residential Gateway model for HES Biography Timothy Schoechle, Ph.D. has been engaged in the field of computer and communication engineering, including their standardization, for over 30 years, and has been involved in communication policy for over a decade. As an entrepreneur, he was an early pioneer in key technologies including microprocessors, UPC bar codes, RFID tags, VoIP, PLC (power-line carrier), CEBus networking, broadband access, and residential gateways. He has written and lectured on such topics as electronic privacy, network architectures, Internet telephony, higher education, distance learning, technical standards, patents, innovation, and intellectual property. Dr. Schoechle is a speaker and author of technical engineering and public policy papers at numerous international conferences and forums. He advises corporations, law firms, and governments on standards policy and on related intellectual property issues. He has

served in many capacities in various standards bodies, including chair and secretary, and he presently serves on the editorial board of the JITSR, an international scholarly journal on standardization research, and as an organizer of SIIT, a biennial academic international conference on the same topic. Since 1990, he has served as the Secretary of ISO/IEC JTC1 SC25 WG1, the international standards committee for Home Electronic System, where he also serves as a technical expert representing the United States, and as an editor of international standards documents. He also serves as Secretary of JTC1 SC32 (Data Management and Interchange). In 2006, he was appointed to a special standards oversight committee on Intelligent Transportation Systems associated with the National Academy of Science. He holds a B.S. in Administrative Science from Pepperdine University, and an M.S. in Telecommunications (engineering) and Ph.D. in Communication Policy from the University of Colorado. His 2009 book, “Standardization and Digital Enclosure: The Privatization of Standards, Knowledge and Policy in the Age of Global Information Technology” focuses on the development of the international standardization system and on its current issues and dynamics. i

e.g., grid feed-in tariffs, solar PV net metering, time-of-use pricing, and real-time pricing. ii Xcel Energy website iii Anya Kamenetz, “Why the Microgrid Could Be the Answer to Our Energy Crisis, Fast Company.com, July 1, 2009 < http://www.fastcompany.com/magazine/137/beyond-thegrid.html>. Galvin