Electronic Design

EPRI's Smart Grid Report Offers Best Hope Ahead

In June, the Electric Power Research Institute (EPRI) released its “Report to NIST on the Smart Grid Interoperability Standards Roadmap.” This document signals the replacement of vague promises about the Smart Grid with pointers toward concrete specs that engineers will be able to use to design new products.

The 291-page report comprises a general overview, a summary of efforts to define the Smart Grid, and a conceptual model for thinking about the Smart Grid and its implementation. Issues of significance to designers include cyber security, wide-area situational awareness (WASA), market communications, and distributed generation (DG) and energy storage.

More importantly, the document defines specific application areas that will require product development, including an automated metering infrastructure (AMI), new communications hardware and software for demand response (DR) across multiple levels of energy producers and aggregators, and hardware and software for load-leveling consumer products, not least of which will be plug-in electric vehicles (PEVs).

The EPRI report to NIST begins by defining the Smart Grid. It’s still a little elevated in tone, but it does help mark the scope of what the people in the power industry are trying to accomplish.

“The term ‘Smart Grid’ refers to a modernization of the electricity delivery system so it monitors, protects and automatically optimizes the operation of its interconnected elements—from the central and distributed generator through the high-voltage network and distribution system, to industrial users and building automation systems, to energy storage installations and to end-use consumers and their thermostats, electric vehicles, appliances and other household devices,” the report says.

“The Smart Grid will be characterized by a twoway flow of electricity and information to create an automated, widely distributed energy delivery network. It incorporates into the grid the benefits of distributed computing and communications to deliver real-time information and enable the near-instantaneous balance of supply and demand at the device level,” it continues.

If only half of that comes true, it could still result in a lot of new engineering design jobs—which somebody, probably everybody, is going to have to pay to fund. Given the potential cost, what’s the value proposition?

Industry insiders have said that a great deal of the value comes down to flattening the daily electricpower demand curve. That’s seen as a more realistic alternative to building new power plants and transmission lines, which are expensive in themselves and even more expensive if not impossible to build, considering the difficulties in obtaining licenses. Alternatively, if you think green, you may consider the Smart Grid a stealth energy-conservation plan with grand ambitions. Not convinced of that? Consider some assertions from the report:

“A Department of Energy study found that the idle capacity of today’s electric power grid could supply 70% of the energy needs of today’s cars and light trucks without adding to generation or transmission capacity—if the vehicles charged during off-peak times.”

Also: “In the United States, electric-power generation accounts for about 40% of human-caused emissions of carbon dioxide... If the current power grid were just 5% more efficient, the resultant energy savings would be equivalent to permanently eliminating the fuel consumption and greenhouse gas emissions from 53 million cars.”

The automotive angle is significant if expectations for electric cars are anywhere near correct.

“PEV will add significantly to the load that the power system will have to serve, and if no regulation, coordination, and/or incentives are included, then PEV could significantly increase the cost of peak power. \\[However,\\] PEV, although still adding to the load, will help balance on- and off-peak loads through shifting when they are charged and also eventually by providing storage and discharging capacity,” the report says.

That’s more likely to happen than some might think. In October, Ford announced that it had already distributed a fleet of test plug-in hybrids to a number of electric utilities to alpha-test a built-in interface for controlling time-of-day charging. This generation of test vehicles does not include the wireless network for two-way communication with electric meters, but that function is on the drawing board.

Off-peak car-battery charging will be a big part of load leveling in general. Some plans for PEVs include using some excess vehicle battery capacity as a reservoir of energy that can be tapped during peak demand periods—think “If I’m not going to use it, I can sell it back.”

Many consumers already have time-ofday billing. That includes me, as my home solar installation includes a smarter meter than the old spinning disk, though there is still no communication upstream or down. Communication capability can be added, with wireless mesh for appliance-to-meter, narrow-bandwidth, 5-kHz frequency-shift keying (FSK) for the first upstream stage.

In-home and powerline communications upstream to a concentrator/fiber node would constitute the first and second stages of a multi-layer system for buying and selling electric power. This system involves continuous interactions among home and industrial consumers, middle men, utilities (many of whom are getting out of the business of generating power), and public and private power generators, across a scale from the Tennessee Valley Authority to my own rooftop solar panels.

A good deal of the load-leveling of the Smart Grid comes down to an extension of the kinds of deals that utilities have extended to industrial consumers for decades. Businesses agree to be subject to rolling brownouts and blackouts at times of high demand (hot summer afternoons) in return for lower rates per kilowatt hour.

The Smart Grid would allow a sort of auction in which rates would change minute by minute based on present capacity and the cost of operations. Those rates would be regularly fed over the grid to all users, whose electrical equipment would use complex algorithms to decide whether or not to turn on.

The EPRI report is important because the bulk of it contains more fine-grain detail and information engineers can use to begin to conceptualize future products. This is included in the Smart Grid Conceptual Model, a set of diagrams and descriptions that facilitate discussions of the characteristics, uses, behavior, interfaces, requirements, and standards of the Smart Grid (see the figure).

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