ＥＥＥ会議（北米大停電：　「停電はいつでも起こるものだ！?」）........................................2003.8.26


「今後も停電は常にいつでも起こるだろう、山火事や自動車事故が常にいつでも起こ
るようなものだ」"We'll always have blackouts. It's like we'll always have
forest fires and automobile accidents."　- DR. ROBERT H. LASSETER, a
professor of electrical and computer engineering at the University of
Wisconsin.

これは、米国の著名な電気コンピューター工学専門の大学教授の言です。素人の小生
などには一寸ショッキングな発言ですが、「電気」というものの特性を考えると、あ
ながち不思議でもないのかもしれません。況や電力自由化の進み過ぎた感のある米国
においておや。

今回の事件を「他山の石」として、日本においてもこの際、もっと一般市民教育を行
う必要があるような気がします。エジソンの時代から１２０年足らず。エネルギー・
原子力教育も急務ですが、その前に電気教育も、ですね。小生も過日、東電の「電気
史料館」（川崎市）
へ見学に行ってきましたが、送配電の仕組みの複雑さを再認識しました（どれだけ理
解できたかは分りませんが）。

というわけで、以下のNew York Times記事(8/25)は、小生には極めて啓蒙的でした
が、皆様はどうお感じになりますか？　コメントをお聞かせください。（少々長文で
すが、端折らないで全文をお目にかけます。）
--KK

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Technology and Brain Power Used to Tame an Aging Grid
By KENNETH CHANG


The day-to-day operation of the nation's power grid is, in many respects, a
great marvel ・a second-by-second balancing act of the tremendously volatile
thing known as electricity, a sometimes wicked creature with a mind of its
own that can cause great damage in a hurry.

The grid, much misunderstood, is not a programmable network like the phone
system or the Internet. Electricity cannot be sent from here to there in
nice packages.

Rather, the grid is like a giant invisible reservoir where the amount of
power being put in at any moment must match the amount being consumed.

"It's the ultimate perishable," said Dr. Paul M. Grant, a science fellow at
the Electric Power Research Institute in Palo Alto, Calif.

That the power grid has suffered only a handful of major collapses in nearly
half a century is, to many, a good record. And despite much criticism in the
last 11 days that the grid is antiquated, the system's transmission towers,
power lines and transformers are not rusting hulks on the verge of collapse.

However, the damage that is done when a swath of the United States goes dark
・in public confidence and economic losses as well as huge inconvenience ・
has kept engineers working on technology to make the grid more reliable.
Indeed, experts are proposing billions of dollars of new equipment to
relieve congestion at bottlenecked electrical junctions on the grid and
improve the system's ability to limit the damage when something does go
wrong ・concerns that will only increase with rising power demands.

The new technology includes totally electronic switches able to divert
electrical flows protectively at moments of crisis. It also includes
superconducting cables that carry greater quantities of electricity, which
will allow utilities to add transmission capacity without building unsightly
transmission towers.

Some of the ideas and inventions are in place to one degree or another in
certain parts of the country. Others will soon be tested in pilot projects.

The new technology is needed in part to respond to the consequences of
deregulation. Power producers now sell electricity to distant utilities,
putting far more strains on the grid.

"Many of us call it the largest machine that man has ever made, and it
serves its purpose admirably well," Dr. Grant said.

But, he added, "it's confused now because the power flows can come from any
direction and go anywhere, and that was not the situation it was originally
designed for."

With the investigation of the Aug. 14 blackout continuing, no one is yet
sure of its precise cause or how much the proposed upgrades or improvements
would have helped, if at all. A 100 percent reliable grid is impossible,
experts say.

"We'll always have blackouts," said Dr. Robert H. Lasseter, a professor of
electrical and computer engineering at the University of Wisconsin. "It's
like we'll always have forest fires and automobile accidents."

Even when a better technology exists, economics and policy considerations
have sometimes limited widespread use. Investment in the grid has dropped
sharply in recent years.

For instance, for three decades, silicon electronic switches have been
available as replacements for some of the mechanical circuit breakers at
power substations across the country. Electronic switches act more quickly.
But a more important advantage is that, unlike mechanical switches, they can
manage electrical flow more subtly.

Mechanical switches can only be open or closed, but the electronic switches
can act more like water valves, letting some of the current through. That
would allow grid operators to narrow the river of electric current quickly
on an overburdened power line without shutting it down entirely.

The electronic switches, each about the size and shape of a hockey puck, can
be wired together to perform fancier electric transformations that could
vary how much power the substation injects into the grid.

"You can put in some control on the line," said John Schwartzenberg,
engineering manager of Silicon Power Corporation of Exton, Pa., a company
that manufactures the electronic switches.

The switches have been tested but not widely deployed because of cost. The
price to upgrade a substation is $1 million or more, although upgrades would
be necessary only at key points of the grid.

"It's not a minimum investment by any stretch of the imagination," said Jack
M. Ladden, chief operating officer of Silicon Power.

By coincidence, on the day of the blackout, Intermagnetics General
Corporation of Latham, N.Y., announced a $12 million program to develop a
new type of electronic device to protect power grids from damaging surges in
current. The federal Department of Energy is providing half of the
financing, and the Electric Power Research Institute is also participating.

When a power station suffers a short circuit, electric currents can jump
from a couple of thousand amperes to 60,000 amperes or more. When a circuit
breaker opens to interrupt the short circuit, current can arc across the
gap, probably destroying the circuit breaker, and often escalating the
problem.

The new device, called a fault current limiter, is intended to act as a
brake on the current, allowing the circuit breaker to operate safely and
limiting damage to the station, and thus perhaps also restricting the spread
of problems in a city or region.

Intermagnetics plans to install a prototype at a power substation in three
years.

The company is also involved in a $26 million project that will, it hopes,
help address the fundamental question of how to safely accommodate greater
demands for power ・a 1,150-foot-long cable made of superconductors to be
added to the power grid in Albany. Superconductors can carry three to five
times as much power as the copper and aluminum cables in the country's
transmission lines.

Utilities hope to use superconducting cables to increase the transmission
capacity in congested portions of the grid without building additional
towers.

Superconductor cables will be buried underground and can be laid in the same
corridors that existing transmission towers use.

Construction of the Albany project will begin next spring with completion by
fall 2005. Two other superconducting cable projects are also in the planning
stages, one for Long Island, the other in Columbus, Ohio.

American Superconductor Corporation of Westborough, Mass., is leading a
project that will install a half-mile-long superconducting cable capable of
carrying 600 million watts from a Long Island substation in East Garden
City, N.Y. Completion is also expected in 2005.

With greater capacity, superconducting cables could allow utilities to build
in more buffers to handle unexpected failures, experts say. But, Dr.
Lasseter pointed out, a higher-capacity cable would also cause bigger
ripples if it failed.

Already, one superconducting cable pilot project ・in Detroit ・was stymied
by cracks in the outer protective sheath around the cable that allowed
coolant to leak out. (The superconductors require temperatures of around
minus-320 degrees Fahrenheit to work.)

Another way to improve the reliability of the grid, many in the industry
believe, would be to make the grid simpler, dividing it back into smaller
regional pieces that are only loosely connected.

That way, even if a regional grid suffered a total blackout, the blackout
would be less likely to cascade to neighboring grids.

Texas's power grid, for example, is already largely isolated from the rest
of the country's. Electrical problems elsewhere would have difficulty
cascading into Texas, and problems in the state would not affect the rest of
the country.

"The complexity is nearly impossible to study and predict ahead of time,"
Dr. Lasseter said of the current grid that connects one region of the
country to another. "Ultimately, you've got to reduce the complexity."

Some experts argue that the grid could be made less vulnerable by making a
fundamental change in the high-capacity connections between regional grids.
At present, the electricity pumped along most of these lines is, like most
of the rest of the grid, in a form known as alternating current.

Pumping the electricity through these great connections in direct current
instead, the experts say, would help prevent the spread of certain types of
problems, like sudden swings in the frequency of the alternating current.

It was, after all, frequency fluctuations that caused many power plants to
pull themselves offline on Aug. 14.

In a news conference Friday, Pat Wood III, head of the Federal Energy
Regulatory Commission, said direct current connections would provide
"interconnectivity through a much more controllable, manageable device" and
"ought to be part of the technology mix."

Power problems for any particular part of the country would be further
reduced if the equivalent of a large rechargeable battery could be
developed.

The concept has been in operation for 12 years at a site in Alabama where
electricity is stored as compressed air. Electrical pumps push air into an
underground cavern at pressures up to 1,078 pounds per square inch, or more
than 70 times ordinary atmospheric pressure.

The air is later released and heated to pass through a turbine generator,
turning the stored energy back into electricity.

Electricity can be similarly stored by pumping water into reservoirs, but
these strategies are not practical in most places. Hydrogen fuel cells might
prove useful for power storage in the future, but that will have to wait.

"It's still pretty roll-your-eyes-back type of stuff," Dr. Grant said. "It's
something that needs to be looked at."