IEEE Spectrum November, 2008 - 45

moving too slowly to translate Libya's
recent oil and gas windfalls into improve--
ments in the average person's quality of
life, saying that the nation was "para--
lyzed by bureaucracy and corruption."
Unfortunately, his proposed solution-
to privatize the ministries by the end
of this year and redistribute oil wealth
directly to the citizenry-threw govern--
ment planning into disarray.
The ferment is evident in Faraj al--
Ammari's office at the electric--power
ministry, the General Electric Company
of Libya, where the phone seems to ring
constantly. "For the past two years, I've
been working from, maybe, 8:30 until
12 at night," laments the mild--mannered
engineer. Ammari is preparing his min--
istry for privatization while simultane--
ously overseeing a massive expansion of
the Libyan power system. Peak demand
has been increasing by about 7 percent
a year, but that rate could soon double
because of the electricity needed to run
the massive pumps of Libya's ambitious
Great Man--Made River, a megaproject of
wells and aqueducts designed to transport
water from deep aquifers in the Sahara
Desert to coastal population centers.
To meet this challenge, Ammari's
ministry commissioned a national cen--
ter to control the country's transmission
grid; the ministry claims to have more
than 5000 km of 400--kV lines, 25 new
400--kV substations, and 6000 MW of
natural gas-fired generation under con--
tract or construction. When that work is
finished, power transfer across the grid's
weakest link-a key east--west connector
that failed during the April blackout-will
jump from a few hundred to 2000 MW.
"We will be the strongest network south of
the Mediterranean," boasts Ammari.

A -

k ey - t e st of North Africa's
upgraded power infrastructure
will come in early 2009, when Libya
is scheduled to try once again to connect
with Tunisia. A first attempt in 2005 was
cut short after just 7 minutes, when slight
mismatches in North Africa's ac frequency,
compensated for by the might of the UCTE,
caused larger--than--expected power flows
in and out of the UCTE that overtaxed
the North African lines. This time around
those lines are beefier, and they are now
regulated by smarter control systems.
If everything works as planned, the
trial will run for four days, at which point
engineers will shut down the linkage to
study how well it functioned. Barring
any surprises, they will reconnect and
www.spectrum.ieee.org

go on. And if they fail again? Then they
will have to turn to high--voltage direct
current (HVDC) interconnections, which
is how the eastern, western, and Texas
grids are linked together in the United
States, for example. HVDC transmis--
sion systems move power by converting
ac into dc at one end of the line and then
converting this dc back to ac on the other
side. Two ac grids tied together in this
way do not need to be synchronized and
can even run at different frequencies.
The downside of HVDC is that it

requires solid--state converters, which
cost hundreds of millions of dollars. The
upside, besides immunity to instabilities,
is increased power transfer. Electricity
travels over ac networks following the
path of least resistance, so managers of
ac grids must leave a large margin of
safety on their lines to accommodate
unexpected shifts. In contrast, HVDC's
power electronics precisely control the
electricity flow, so HVDC connections
can operate closer to the physical limit
that their cables can bear.

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Table of Contents for the Digital Edition of IEEE Spectrum November, 2008