As with so many terms bandied about in
mass media, "Smart Grid" is a cutesy umbrella term that allows
politicians, analysts, and newscasters to vaguely refer to a
collection of technologies that neither they nor their audiences
fully comprehend, with advantages that are easily stated, and of
uncertain measurability.
While that sounds pretty negative, let
me point out that nothing in the above paragraph says anything
against the technologies themselves, or their value, but merely pans
vague marketspeak terms in general, and the folks who rely on them
for ... anything.
Smart grids are part of a general
technology trend toward incorporating embedded microcontrollers and
data-communication capabilities into all sorts of previously existing
devices. For those unfamiliar with them, a "microcontroller"
is an integrated circuit that includes a microprocessor and
peripheral circuits that allow the microprocessor to sense conditions
and events in the external world (data acquisition) and put out
signals to drive actuators in the external world (control).
Perhaps the first "smart" devices
were automobile engines, which came under microprocessor control
during the late 1970s, long before the term "smart xxx" became current. Such
engine control modules (ECMs) sensed such variables as outside air
temperature and throttle position, and used that information to
control such parameters as fuel/air ratio and spark timing. Later,
ECMs gained the ability to communicate with additional embedded
microcontrollers managing such functions as anti-lock braking systems
(ABS) and alarm systems. Modern automobiles now contain dozens of
networked microcontrollers operating nearly all functions.
Today, most significant appliances
operate under guidance of microcontrollers. Microwave ovens,
dishwashers, clothes dryers, televisions, and home thermostats are
familiar examples. The extent to which manufacturing operations rely
on "smart" technology is even more profound.
Electricity generation and distribution
networks, however, are far behind other industries in incorporating
smart technology. That is the impetus behind all of the noise and
fury about "Smart Grids" in the media.
To be fair, there are significant
barriers to incorporating smart technology into electric-power
infrastructure. Most significantly, it is imperative to keep the
system operating reliably while applying new technology to it.
Second, the cost of upgrading existing equipment that was never
intended to be part of a computer-integrated system is, shall we say,
large. There are many additional issues to be considered when making
the move to smart utility grids.
The motivation to incorporate computer
control and networking technology into the electric power system is
not just to make it more "modern." The concept avoids Scheiber's
Rule (Just because you can doesn't mean you should.) by solving a
number of present and future problems arising from electric-utility
development trends.
The first issue is the fact that the
present distribution grid developed from early systems where a single
generating plant distributed power to an isolated netword of loads.
That placed the responsibility for maintaining voltage, frequency,
and phase of the provided electricity squarely on one generating
facility. Such installations are amenable to simple closed-loop
control.
Later, but still quite some time ago,
outputs from multiple generating plants were combined to supply power
to the user network. That created the issue of coordinating the
output levels and phases of the sources. At least, the sources on a
given network were controlled by a common authority capable of
centrally guiding the generators via more complex closed-loop
control.
Problems became serious when
power-distribution networks were interconnected to allow power sharing between sources
operated by separate authorities. This makes simple reactive
closed-loop control problematic. When you have multiple agents
independently providing control inputs in response to observed
conditions, the system becomes chaotic. This is not a slam on the
engineers who designed and operated the system. It's a fact of life
dictated by mathematics. Voltage variations, unpredictable frequency
and phase shifts, and seemingly random catastrophic failures ensue.
Happily, all the folks on the supply
side of the system were highly intelligent professionals who realized
that the only solution was to co-operate their power-generation
controls. We'll call it meta-control, where individual operators
don't blindly react to every movement of the controlled system,
which is what drives the system into chaotic behavior. Instead, when
they observe a departure from nominal status, they first communicate
among themselves, and devise a coordinated response that brings the
entire system back toward nominal.
You can do that when there are
relatively few operators. As the number of operators grows, the time
needed to communicate and devise a coordinated strategy becomes
longer, while the frequency and severity of divergences become more
severe.
In the past, the economics of
power-generation have favored large generating stations because they
can be made more efficient. Costs for fossil fuels and nuclear power
scale more slowly than generating plants' output. Emerging energy
sources, such as photoelectric and wind power, have been billed as
"free energy sources," although they are nothing of the kind, so
power-plant efficiency figures less in the installation decision.
Thus, we expect to see many more smaller plants. With more small
plants, the number of sources that need to be coordinated will rise
dramatically, and system-control cost and difficulty will increase.
The assumption is that increased
deployment of smart-grid technology will make it possible to maintain
system control in the face of increased chaos. High-speed data
sharing is to improve coordination while expanded computer automation
improves the speed and quality of meta-control decision making.
According to Wikipedia,
support for smart grids
became federal policy with passage of the Energy Independence and
Security Act of 2007. The law, Title13, set out $100 million per
fiscal year in funding for fiscal years 2008-2012, established a
matching program for states, utilities and consumers to build smart
grid capabilities, and created a Grid Modernization Commission to
assess the benefits of demand response, and recommend protocol
standards.
The Act directs the National Institute
of Standards and Technology (NIST) to coordinate the development of
smart grid standards, which the Federal Energy Regulatory Commission
(FERC) would then promulgate through official rulemakings. Smart
grids received further support with the passage of the American
Recovery and Reinvestment Act of 2009, which set aside $11 billion
for the creation of a smart grid.
Progress has been swift, as it needs to
be. Federal Energy Regulatory Commission (FERC) issued a proposed
policy statement and action plan on 19 March 2009 for standards
governing the development of a smart grid. However, FERC noted that
the electric industry started moving ahead with smart grid
technologies prior to these government initiatives. The Commission is
proposing to establish some general principles that the smart grid
standards should follow.
We have known for some years that the
trend was toward more numerous smaller power plants. The handwriting
has been on the wall since the introduction of a feed-in tariff (FIT)
system in 1978. A
feed-in tariff is an incentive structure to encourage the adoption of
renewable energy through government legislation. The regional or
national electricity utilities are obligated to buy renewable
electricity (electricity generated from renewable sources, such as
solar photovoltaics, wind power, biomass, hydropower and geothermal
power) at above-market rates set by the government. The higher price
helps overcome the cost disadvantages of renewable energy sources.
The rate may differ among various forms of power generation.
FIT means that any Tom, Dick, and
Harriett with access to enough cash can set up a generating station,
then sell the power to utilities, which are obliged to buy it. This
model works well for facilities, such as hospitals and certain
manufacturing operations, that need to maintain back-up power
generation plants in the event of power failure. Most of the time
these generators stand idle. FIT allows their owners to defray some
of their cost by running them during peak periods, when demand may
exceed fixed-power plant capacity and electricity costs (and FIT
repayments) are largest.
The unintended consequence, of course,
was a more chaotic electricity environment. Specifically, since a
hallmark of chaotic systems is scale invariance, departures from
nominal expanded to higher spectral frequencies with smaller
amplitude signals (amplitude varies inversely with frequency. While
these departures are smaller, their higher frequency translates into
the need for faster response. Utilities began experimenting with
smart-grid technology in hope of reigning in chaos over a much larger
bandwidth.
ADDITIONAL RESOURCES:
U.S. Department of Energy Smart Grid
IBM Smart Grid
American Superconductor Smart Grid:
It's More than you Think