A Smarter Power Grid (also written in 2001)

Les Schaffer schaffer at optonline.net
Sat Aug 16 22:08:18 MDT 2003


A Smarter Power Grid

New "power electronics" that swap voltage from line to line may be the
best--and cheapest--fix for our aging electric grid.

By Peter Fairley
July/August 2001

[snip]

The novel Siemens switch that holds these electric-power processors
stands four meters high, and its silicon valves juggle electrons at
power levels that would blow your cell phone or PC to bits. But just
as silicon chips in your cell phone process electromagnetic signals to
transmit information, Siemens's brawny electrical-power processor can
filter and manipulate the alternating current flowing through the
Marcy station. The immediate goal is to stabilize central New York's
stressed electric grid, making it safe to transmit more energy through
the lines. Then next summer, with a few more patch cables and a hefty
new fuse added to the system, the power switch should be ready for an
even more sophisticated trick: nimbly swapping electricity between
high-power transmission cables--a feat never before attempted.

If it succeeds, the electricity swap will be like a coronary bypass
for a critical artery in the increasingly sclerotic national power
grid. In many ways, the energy "crisis" that is gripping California
and threatening the rest of North America is as much about getting
electricity to flow where you need it--when you need it--as it is about
a lack of energy. The problem is that the existing network of
high-power transmission lines, the interconnected web of electricity
that keeps the continent charged (power grids in northern Mexico and
in Canada are closely intertwined with those in the United States),
was built in the middle of the last century and was never meant to
handle the complexity and congestion of today's ever growing energy
demands and changing markets.

In light of this situation, the North American Electric Reliability
Council, the industry's voluntary watchdog group, is telling just
about anyone who will listen that the system is at risk. "The question
is not whether, but when, the next major failure of the grid will
occur," wrote the group's general counsel David Cook in a recent
entreaty to the U.S. Department of Energy in Washington, DC.


White Elephant

The U.S. power grid has been called the largest machine ever built by
man. In fact it's really three loosely interconnected grids: one in
Texas, and two more splitting the bulk of the country roughly along
the Continental divide (see "The Electricity Lifeline," below). These
systems are far from orderly; each grid is composed of a tangle of
transmission lines operated by a hodgepodge of owners, from sprawling
federal power authorities to regulated utilities to market-savvy
conglomerates. An equally variable set of state, regional and federal
regulators governs aspects of this mosaic, deciding how much power can
enter the grids and flow over each set of lines.

[snip]

Despite its structural and regulatory complexity, though, the power
grid operates on a startlingly simple basis: electricity flows from
where it's produced to its destination through the path of least
resistance. That worked fine in the days when monolithic electrical
monopolies strategically sited their power plants on the grid, with
the path of least resistance leading straight to their own customers
and no one else's. But those days are long gone. Deregulation of the
electrical industry in the 1990s opened the grid to anyone and
everyone who had electricity to sell. Dozens of brokers building new
power plants and old utility giants with a fresh entrepreneurial bent
now want to supply whoever offers the highest price for their power,
wherever he or she may be. And that's where the physics of the
existing grid comes up dangerously short.

The changing nature of the electrical industry dictates complex
crisscrossing flows of electricity and the need to send more and more
power over long distances. "We're trying to use [the electric grid]
for a lot of longer-distance power transfers, and it's just stretching
to the limit," warns Thomas Overbye, a power systems expert at the
University of Illinois at Urbana-Champaign. Indeed, there already have
been signs of troubles. In the blistering summer of 1996, the western
U.S. electric grid snapped twice as swollen lines feeding
hydroelectric power from the Pacific Northwest to California
overloaded and shorted out. The result? Blackouts in 11 western
states, Alberta, British Columbia, and Baja California. To avoid a
repeat of that crisis, grid operators in California must restrict
flows to the state, a fact that is greatly exacerbating its ongoing
power crunch.

If today's situation sounds to you like a recipe for even worse power
meltdowns, get your candles ready--because while hundreds of planned
new power plants around the country will increase the amount of
available electricity, utilities are investing next to nothing in
additional transmission lines to get the juice to where it's
needed. It used to be that the big utilities owned and maintained
their share of the grid. But deregulation has orphaned the
transmission business, uncoupling the lines that deliver electricity
from revenue-producing power plants. And owning transmission lines is
a business few want any part of. If you think building new power
plants is unpopular, try running high-power transmission lines through
someone's backyard. (Do electromagnetic radiation and contentious
town-hall meetings come to mind?) Just 13,500 kilometers of
high-voltage transmission additions are planned throughout North
America over the next decade--a 4.2 percent increase--of which only a
fraction are likely to get built. Meanwhile, the U.S. Department of
Energy estimates that generating capacity in the United States alone
will grow more than 20 percent over that period.

[snip]

Power Chips

[snip]

While the electric grid was originally interconnected to increase
reliability and reduce cost, that's turned out to be a mixed
blessing. Interconnection means the most expensive generators can be
kept off if others--even several hundred or several thousand
kilometers away--can fill the need more cost-effectively. The bad news
is that the grid can also transmit disturbances, making the whole
system harder to control. Fluctuations can work their way around the
grid like the wave among fans at a football stadium. And just as the
wave works better at a crowded arena, an electric disturbance becomes
more pronounced at higher power levels and with increased power
transfers. "Unfortunately, by the nature of the physics involved, the
higher the power flows the more dynamically unstable you become," says
Karl Stahlkopf, vice president of power delivery at the Electric Power
Research Institute.

[snip]

Power Play

Impressive, maybe, but these systems are still more or less
Band-Aids. The installation at Marcy represents the first attempt at
major surgery for the grid. The diseased arteries are the two
345,000-volt transmission lines that run south from Marcy to New York
City: one skirts Albany and then chases the Hudson; the other
traverses the Catskill Mountains to the west before it heads for
Manhattan. With a push of a button, a series of breakers at Marcy will
reconfigure the station's circuits to pump electricity from one line
to the other as needed (see "The Electronics Solution at Marcy,"
below)."We will have the ability to actually alter the flow of
energy--take it off of one line, put it on another line, particularly
if that line is starting to get into an overload condition," says
Gerald LaRose, who runs the Power Authority's mission control center
at Marcy.

LaRose is particularly eager to relieve the line connecting Marcy to
New York City via Albany. The operators know it as Marcy-South, and it
is easily the state's most congested high-power transmission line,
stuffed to capacity 25 percent of the time and skating within 100
megawatts of overload for much of the rest. The line is obsessively
monitored, and each time it approaches critical, the New York
Independent System Operator, the agency that manages the state's grid,
must cease adding power to it--indeed, to all of the highly connected
circuits running throughout central New York. Even those lines with
spare capacity must be squelched, since some fraction of any
additional power could reach the stressed Marcy-South line and push it
over the edge.

On a hot day when power demand is peaking, squelching electricity
flowing from upstate could spell trouble in New York City. At best,
the city must fire up expensive and polluting gas- or oil-fired power
plants to make up for the constrained flow of hydropower from
Quebec. At worst, neighborhoods could be plunged into darkness. While
this worst-case scenario has yet to happen, experts agree that New
York City is becoming ever more vulnerable.

Then there is the matter of getting cheap electricity to Long Island,
one of the country's fastest growing areas. There, too, power
electronics could change everything. The problem is that New York City
literally stands between Long Island and cheap power. Squeezing more
electricity past this massive bottleneck is nearly impossible. The
transmission lines running into New York City are simply too full to
carry additional power onward to Long Island. So while Connecticut
residents just 40 kilometers away across the Long Island Sound gorge
on vast amounts of cheap juice flowing down from Canada's
hydroelectric plants, the eccentricities of the existing grid mean
electrically isolated Long Islanders must fend for themselves, relying
on local generators to supply a hefty 93 percent of peak power
demand. This is one reason that Long Island endures some of the
highest electricity rates in the country.

[ssnip]

Anarchy Rules

[snip]

The grand vision, of course, is to electronically tame the nation's
vast power network. Unlike isolated devices that regulate a few lines
each, integrated network controls could synchronously tweak all of a
system's electronics to optimize flow over the entire grid. Stahlkopf
of the Electric Power Research Institute estimates that integrated
control could boost the overall transmission capacity of existing
infrastructure by 30 to 40 percent. Stahlkopf figures this leap
forward is at least 10 years off, but he says utilities are already
beginning to take an important step--wide-area telemetry providing
operators with a real-time picture of how much power is flowing over
their lines and from where.

However, with anarchy gripping today's power grid, integrated
controls--even in a decade from now--seem like a bit of a pipe
dream. Rapid deregulation has swept away the old rules without
offering coherent alternatives for who should run the network and how
they will get paid for it--making it an especially tough time to market
advances offered by power electronics.

New systems like those at Marcy are even more politically charged
because they can spontaneously reconfigure the grid, potentially
increasing the strategic value of some power plants and idling
others. LaRose says the Marcy project has few enemies because it can
only shift a few hundred megawatts in a system that handles over
30,000 megawatts daily. But he says a larger project could find itself
facing formid-able opposition. To implement these new technologies,
you've "got to walk very gingerly through that minefield," says
LaRose.

[snip]

So why roll the dice on expensive equipment? The engineering answer is
that for the foreseeable future, anyway, power electronics is the best
hope for stabilizing the electric grid. The more pragmatic answer is
that the New York Power Authority, a state-owned corporation, is
directly accountable to politicians who fear the wrath of voters if
the rolling blackouts darkening California's economy roll across the
Empire State. Unfortunately, it may take a few more dark days and cold
nights without electricity before the rest of the grid's numerous
interested parties begin to see the light.

http://www.technologyreview.com/articles/fairley0701.asp?p=0





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