POWER December 2010 - 14

500-kV Sunrise power grid expansion in southern California-
would enable a more rapid deployment of renewable energy.
A timeline for the project's construction and an anticipated operation
date have not been specified yet. However, Claus Rubenius,
inventor and founder of the formerly Danish company, recently told
Greentech Media that the 1,000-MW worth of NaS batteries would be
bought from Japanese battery manufacturer NGK, which, he pointed
out, was the world's only volume producer of NaS cells. Rubenius
went so far as to say that the deal made with NGK would take up that
company's entire production capacity for nearly the next decade.
How the U.S. Grid's Unpredictability
Increases Its Security
Experts have decried congressional and academic reliance on
a mathematical model for understanding complex systems that
suggests an attack on a small part of the U.S. power grid could
disrupt the entire power system network.
" Some modelers have gotten so fascinated with these abstract
networks that they've ignored the physics of how things actually
work-like electricity infrastructure, " said Paul Hines, University
of Vermont assistant professor at the College of Engineering and
Mathematical Sciences. " And this can lead you grossly astray. "
Hines pointed specifically at a model described in a scientific
study in the journal Safety Science (Dec. 2009); the paper was
cited by a military analyst at a congressional hearing this March
when he warned of how an attack on an unimportant part of the
U.S. power grid might, like dominoes, bring the whole grid down.
A similar paper was published in the journal Nature the following
month that presented a model of how a cascade of failing interconnected
networks led to a countrywide blackout in Italy in 2003.
According to Hines, the so-called topographical model in the
Safety Science paper came to the " highly counter-intuitive conclusion "
that the smallest, lowest-flow parts of the electrical
system-a minor substation in a neighborhood, for example-
were likely to be the most effective spots for a targeted attack to
bring down the U.S. grid.
A study published by Hines and Penn State's Seth Blumsack
in the journal Chaos this September found just the opposite.
Drawing on real-world data from the eastern U.S. power grid and
accounting for the two most important laws of physics governing
the flow of electricity, they show that " the most vulnerable
locations are the ones that have most flow through them, " such
as highly connected transformers and major power-generating
stations. " If the government takes these topological models seriously, "
Hines said, " and changes their investment strategy to
put walls around the substations that have the least amount of
flow-it would be a massive waste of resources. "
As Hines explained, many topological models are basically
graphs of connected links and nodes that represent the flows and
paths within a system. When a node changes or fails, its nearest
connected neighbor will often change or fail next. " This abstraction
has provided profound insights into many complex systems,
like river networks, supply chains, and highway traffic. But electricity
is strange and the US electric grid even stranger. "
Hines pointed to the August 2003 blackout, which started in Ohio
and then spread to New York City. Cleveland went down, and soon
Toronto was affected. " The blackout was able to jump over long distances "
because, " when a transmission line fails-instantly, at nearly
the speed of light, everything changes. Everything that is connected
will change just a little bit, but in ways that are hard to predict. "
This is compounded by the fact that the U.S. electric grid is more an
" intractable patchwork of history than a rational design, " he said.
14
Using real-world data from a 2005 North American Electric
Reliability Corp. test case, Hines and Blumsack compared how
vulnerable parts of the grid appeared in the differing models. The
topological measures-so-called " characteristic path lengths "
and " connectivity loss " between nodes-came up with dramatically
different and less-accurate results than a model that calculated
blackout size driven by the two rules that most influence
actual electric transmissions: Ohm's and Kirchhoff's laws.
The study, funded by the National Science Foundation, shows
that the electric grid " is probably more secure than many people
realize-because it is so unpredictable. "
" Our system is quite robust to small things failing-which is
very good, " Hines said. " Even hurricanes have trouble taking out
power systems. Hurricanes do cause power system failures, but
they don't often take out the whole system. "
" It takes an incredible amount of information, " he concluded,
" to really figure out how to make the grid fail. "
POWER Digest
Iberdrola Renovables Starts Up National Wind Turbine Control
Center. Iberdrola Renovables, a company that owns 41 operating
wind farms (3,900 MW in nameplate capacity) in the U.S.,
on Sept. 26 began operating its National Control Center (NCC), a
facility based in Portland, Ore., that has operational control over
some 800,000 inputs from 2,500 wind turbines across the nation.
Based on the company's CORE control center in Toledo, Ohio, NCC
monitors and controls all the company's wind farms and substations
in the U.S. all year round and in real time. Essentially,
the center obtains information from control and data systems at
wind farms as well as the main operating variables from substations.
Analysts then diagnose problems, including breakdowns.
The company said the facility would help optimize operational
management and cost efficiency at its wind farms in the U.S.
B&W to Provide Steam Generators for TVA's Bellefonte
Reactor. Babcock & Wilcox Co. (B&W) subsidiary Babcock &
Wilcox Canada Ltd. won a contract from the U.S. government-
owned Tennessee Valley Authority (TVA) to design and manufacture
two steam generators for the Bellefonte Unit 1 nuclear
reactor, as part of a plan to complete that project. The steam
generators are scheduled to be delivered to the Bellefonte site in
2015, pending a decision by the TVA board to complete construction
of the unit, the Ontario-based company said on Oct. 14.
B&W supplied the original 1,210-MW reactors to the plant when
construction began in 1974, before being halted in 1988 when
the plant was 90% complete. Unit 1 is now considered about 55%
complete due to the transfer or sale of many components and the
need to replace others.
Cavico Completes Construction of 180-MW Vietnamese
Hydro Unit. Vietnamese infrastructure development company Cavico
Corp. on Oct. 14 said its subsidiary Cavico Hydropower had
completed all construction activities at the 180-MW Dong Nai 3
Hydropower Plant, adding that it had started the handover process
to project owner Electricity of Vietnam. Cavico began building
the plant, located on the Dong Nair River in Dac Nong province, in
2007. Work comprised excavation and construction of a 655-meterlong
(and 8-meter-wide) headrace tunnel and a 73-meter-long incline
tunnel. The plant has a twin unit, Dong Nai 4.
SSE Gets Green Light to Build 60-MW Pumped Storage Facility.
Scottish and Southern's generation business, SSE Generation,
garnered the Scottish government's consent to develop a 60-MW
pumped storage plant at its existing Sloy hydroelectric power station
in Loch Lomond, Scotland. Sloy, commissioned in 1950, is the largest
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