Electric utility companies are struggling to provide cost-effective and clean energy alternatives to a market where demand is exceeding capacity. The need to curtail demand during periods of peak load is a matter of prime importance. Solving the issue on the supply side by adding new capacity is one option; however, the expense and the bureaucratic hurdles required to build new facilities makes this solution less than ideal; demand side solutions are preferable but can be challenging to implement. This article explains some of the tools and standards that can be used to achieve demand side control.
Governmental regulations to reduce greenhouse CO2 emissions and the reliance on off-shore energy for electrical generation require the introduction of new technologies into the electrical grid. These new technologies must make the smart grid ‘smarter’ by providing utility companies with a type of demand response capability that not only informs the market of peak demand and price variations, but also offers the means to control demand during these periods. Consumers need to know when demand is exceeding capacity and when rates are high, so informed decisions can be made.
Utility companies must have tools to reduce demand when capacity is exceeded. Working with electric utility companies, industrial and commercial customers have already begun to integrate smart energy features into their systems. With the early success of these systems, a smart grid for residential customers is quickly becoming a reality (Figure 1 ).
Figure 1: The key difference for the grid of the future will be to transition from blind delivery to a closed loop with commands, requests, and status traveling in both directions.
Is there a good supply side solution? For the last three decades the growth in peak demand has exceeded the growth in electric utility companies’ transmission capability by more than 25 percent. Estimates vary; however, the U.S. Department of Energy (U.S. DOE) reports suggest a $1.5 trillion investment will be required over the next 20 years to pay for infrastructure alone to support the growing demand. Today, a large portion of a consumer’s electric bill goes towards grid upkeep.
Any future grid investment will be passed directly to the consumer, and that will be on top of the expected rate increases of 50 percent over the next few years. The prospects don’t look good for a cost effective supply side solution. A smarter grid is required.
Allowing customers to take control
Reducing demand by as little as 5 percent during peak periods can save between $50 and $100 billion annually according to the U.S. DOE. One approach to managing demand during peak periods is to deploy a standards-based framework that allows electric utilities to communicate directly to customers. Open Automated Demand Response (OpenADR) is one standard that is being embraced (Figure 2 ). OpenADR messages provide demand response information to inform customers of pending price changes due to excess demand.
Figure 2: A two stage approach, with the producer maintaining control to the meter, and an open system architecture integrating customer devices provides full end-to-end functionality.
Because OpenADR can be used with existing protocols and control systems, it has been quickly embraced by industrial and commercial customers, many of which have sophisticated communication protocols in place that are capable of controlling individual devices. The Building and Automation Control Network (BACnet) is one example of an industrial network protocol.
Designed to control applications such as heating, air-conditioning, lighting control, fire detection, and access control, BACnet provides building automation to exchange information over existing IP networks in an effort to maximize energy efficiency. The combination of OpenADR messages from the utility company and a BACnet-capable network to automatically execute the appropriate response has been proven to lower electric demands during peak periods for industrial and commercial customers. In order to expand the benefit of standards like OpenADR to residential customers, a protocol must be introduced to the home that can manage appliances, lighting, and environmental conditions without the need for complex device configuration. Further, it must work over existing home networks.
The Smart Energy Profile (SEP) specification
The Smart EnergyProfile 2.0 (SEP 2.0) specification is designed to enable a wide varietyof devices that generate, distribute, and consume energy to communicatewith each other over IP networks. Unlike higher level protocols, suchas OpenADR, SEP 2.0 includes specifications on network insertion andmanagement that relieves the user from having to perform any networkadministrative functions. This makes SEP 2.0 ideally suited for thefinal step of energy management to the consumer device.
Theintent of SEP 2.0 is to configure all devices as peers, and anyclient/server relationships are built upon the SEP 2.0 foundation. Thisenables devices to enter and exit a network in an unplanned fashionwithout causing operational interruption to any of the other devices inthe network. To accomplish this, SEP 2.0 uses zero-configurationnetworking, such as mDNS and DNS-SD. This is ideally suited for devicesin the residence where networking expertise may not be available.
Othersmart energy standards, such as BACnet, don’t approach the issue ofnetwork connection and administration. Such specifications targetcommercial, industrial, and other professional environments where theimplementation of the underlying communication path is assumed to beimplemented by technically knowledgeable individuals. Thesespecifications are also more tightly focused on power utility operationor building automation outside of the residence, whereas SEP 2.0 is afar more general protocol intended to work in all environments,especially residential.
The emergence of an OpenADR/SEP 2.0 combination
Ahybrid OpenADR/SEP 2.0 solution is evolving where utilities areunilaterally implementing OpenADR to solve their immediate powermanagement requirements. This allows them to bring an intelligent gridonline quickly without waiting for a far more gradual acceptance ofresidential protocols. This also brings a truly ‘smart meter’ closer tothe periphery of the home residence.
With the implementation ofSEP 2.0, residential devices/appliances are able to communicate witheach other, thus minimizing simultaneous in-rush of power demand fromcompeting devices. In addition to staggering device/appliance start-updemands, home appliances with high thermal capacity, such as waterheaters, clothes dryers, and stove and oven heating elements, can switchoff temporarily to reduce current draw when a heating or cooling systemis starting its compressor. Such pauses will not be noticed by the userof the interrupted appliance.
Further, once OpenADR and SEP 2.0become even more integrated, load leveling will be managed acrossresidences to even out current loads through local distributiontransformers, which will help balance the instantaneous loads acrosspolyphase transport lines.
Requirements for SEP enabled devices.It’s imperative that SEP-enabled devices include software to supportsuch activities as fast booting and power management capabilities,including the ability to easily switch to back-up battery in case of apower outage. Embedded systems within these types of smart devices oftencontain limited memory resources, meaning the software that powers themmust have a small yet highly optimized footprint.
The importance of a real-time OS
Areal-time operating system (RTOS) is the preferred operating system forSEP 2.0 devices because of its deterministic behavior and its abilityto support the sophisticated functionality required by the SEP 2.0specifications (Figure 3 ). An RTOS can provide for all themust-have capabilities within a smart device such as instant ON and stayON; real-time responsiveness; a wide range of peripheral support;TCP/IP networking; graphics support for the UI; and network security.
Figure3: Mentor Graphics Nucleus is a good example of an RTOS that meets allthe smart grid and SEP 2.0 specifications with a variety of integratedpower management services and process model capabilities.
Theabilities offered by SEP 2.0 coupled with OpenADR offer a fine grain ofcontrol for the residential user who wants to take a more proactiverole in control of power use in the home. This hybrid approach will nodoubt provide the necessary transition that allows for the gradualincrease of power consumption efficiency, while addressing the loomingpower shortage and at the same time allowing home owners to maintaintheir current standard of living.
Andrew Caples is a Product Marketing Manager for the Embedded Software Division (ESD) of Mentor Graphics .He has over 20 years of experience in start-ups and fortune 500 hightech companies and has served in a variety of roles ranging fromtechnical marketing to sales management. He has a B.S. in Electrical andComputer Engineering from California Polytechnic University. Hiscurrent responsibilities include product management for the Nucleus RealTime Operating System.
Rich Rejmaniak is a Technical Marketing Engineer for the Embedded Software Division (ESD) of Mentor Graphics . Hehas been an engineer for over 30 years, with the last 20 years spent asa Field Applications Engineer for various semiconductor and softwarecompanies. Rich specializes in the hardware/software boundary issues inembedded systems.