Power engineering continues to grow and offer potential for innovation (see “Watch These Three Power Conversion Trends”). Yet the Smart Grid provides the widest range of opportunities for electronic designers across a range of hardware and software sub-disciplines (Fig. 1). To understand where the opportunities lie, though, it helps to get past some misconceptions about the Smart Grid.
It isn’t about replacing old electric meters with new ones that say you’re using more electricity when you haven’t changed anything else in your house (see “PG&E’s SmartMeter Rollout Off to Rough Start” in the San Jose Mercury News, www.mercurynews.com/ci_13774449?) or about the power company remotely turning off your refrigerator, as I’ve heard some people complain. It’s about engineering a realistic, albeit complex, alternative to simply building new physical plants, a superficially direct approach that never attracted the necessary investment or public support.
WHY A SMART GRID?
On November 9, 1965, at about quarter past 5 in the afternoon, I was shooting hoops with a bunch of my fellow grad students, using a rusty basket on a utility pole in Troy, N.Y. A wild blocked shot brushed a power wire and all the lights went out. Every one of us, all EEs, forgot everything we knew about electricity and thought, “Uh-oh. What have we done?”
Of course, it wasn’t us. A safety relay at a generating station in Queenston, Ontario, had been set too low. A chain of quirky events propagated through the grid and some 25 million people across 80,000 square miles of the U.S. and Canada lost their electricity for as long as 12 hours.
Ever since the 1965 East Coast blackout (and with every subsequent blackout), we have been hearing that the North American electrical grid is antiquated and brittle and that it needs to be upgraded. Why don’t we just do that? A 2003 report by the U.S. Department of Energy, “GRID 2030 A National Vision for Electricity’s Second 100 Years,” provides some background (Fig. 2).
“It is becoming increasingly difficult to site new conventional overhead transmission lines, particularly in urban and suburban areas experiencing the greatest load growth. Resolving this siting dilemma, by a) deploying power electronic solutions that allow more power flow through existing transmission assets and b) developing low impact grid solutions that are respectful of land use concerns, is crucial to meeting the nation’s electricity needs,” the report says.
“The ‘technology readiness’ of critical electric systems needs to be accelerated, particularly for high-temperature superconducting cables and transformers, lower-cost electricity storage devices, standardized architectures and techniques for distributed intelligence and ‘smart’ power systems, and cleaner power generation systems, including nuclear, clean coal, renewable, and distributed energy devices such as combined heat and power,” it continues.
According to the report, there are more than 3100 electric utilities and nearly 2100 non-utility power producers, including both independent power companies and customer-owned distributed energy facilities. Not counting homeowners with grid-tied solar systems on their roofs, that adds up to 4200 separate entities selling and distributing electricity over what’s called the bulk power system.
The bulk power system consists of three independent networks: Eastern Interconnection, Western Interconnection, and the Texas Interconnection. These networks incorporate international connections with Canada and Mexico.
All told, U.S. commercial and public-utility power plants number around 10,000. Although there are “distributed energy” plants that use “waste” heat, in general, the average thermal efficiency of electrical generating plants is around 33%. Most of the existing capacity is 30 or more years old.
Who owns the power plants? Interestingly, there has been a recent shift in ownership, from regulated utilities to competitive suppliers. The share of installed capacity provided by competitive suppliers has increased from about 10% in 1997 to about 35% today. Recent data suggests this trend is slowing, but there is a clear trend toward for-profit electrical generation using equipment that used to be owned by public utilities.
In parallel with this trend, a competitive bulk power market has been growing. The report says that the number of transactions is increasing substantially, noting that “transactions on the Tennessee Valley Authority’s transmission system numbered less than 20,000 in 1996. They exceed 250,000 \\[in 2003\\], a volume the system was not originally designed to handle.”
Meanwhile, “annual investment in new transmission facilities has declined over the last 25 years. The result is grid congestion.” To deal with those bottlenecks, transmission operators may curtail transactions for economic reasons, throttling the supply of cheaper electricity to users, sometimes for economic reasons, or to maintain reliability. Such actions “grew from about 300 in 1998 to over 1000 in 2000.”
High demand implies potential profits, so why not build more plants? GRID 2030 notes that the impediments include “opposition and litigation against the construction of new facilities, uncertainty about cost recovery for investors, confusion over whose responsibility it is to build, and jurisdiction and government agency overlap for siting and permitting. Competing land uses, especially in urban areas, leads to opposition and litigation against new construction facilities.”
A HELPING HAND FOR ADAM SMITH
In his “Theory of Moral Sentiments,” Adam Smith referred to the “invisible hand” to describe the apparent benefits to society of people behaving in their own interests. The impediments described above suggest the situation isn’t so simple.
What should designers do, then? One has to read to page 7 of the body of the report to find the way the Smart Grid is intended to guide the invisible hand.
It’s based on the observation that, in the aggregate, more power is available than we need for the present. We just can’t have it all when we want it. Managing the daily demand profile would be a pretty good ameliorative step. And, surprise, the government and the power industry would both prefer to guide the invisible hand, rather than operate by fiat.
“The ability to monitor and influence each customer’s usage, in real time, could enable distribution operators to better match supply with demand, thus boosting asset utilization, improving service quality, and lowering costs. More complete integration of distributed energy and demand-side management resources into the distribution system could enable customers to implement their own tailored solutions,” GRID 2030 explains.
“The national average load factor (the degree to which physical facilities are being utilized) is about 55%. This means that electric system assets, on average, are used about half the time. As a result, steps taken by customers to reduce their consumption of electricity during peak periods can measurably improve overall electric system efficiency and economics,” it continues.
There is more to the Smart Grid than allowing users to deal with a dynamically changing rate structure, controlled by a more privatized generation and distribution network, but that’s a big part of it. Other aspects involve improved, lower-loss materials for electrical transmission, the ability to rapidly isolate single-point failures, rather than allowing them to propagate, the facilitation of more micro sites, and hardening the system against physical and cyber terrorist and criminal attacks.
However, the strongest driver is simply the need to get some breathing room by stretching present capacity through voluntary load-leveling, driven by an economic carrot-and-stick approach to business and private users of electricity.
The report originally referred to local mini- and micro-grids, some powered by photovoltaics, wind, or tides (see “Commercial Solar Power And The Smart Grid”). Yet it can be construed as a vision for the whole smart grid. For example, “Power from distributed energy facilities flows to and from customers and into the regional network, depending on supply and demand conditions,” GRID 2030 says.
“Real-time monitoring and information exchange enables markets to process transactions instantaneously and on a national basis,” it continues. And, “Customers have the ability to tailor electricity supplies to suit their individual needs for power, including costs, environmental impacts, and levels of reliability and power quality. Sensors and control systems link appliances and equipment from inside buildings and factories to the electricity distribution system.”