POWER September 2010 - 8

China Completes UltraHigh-Voltage
Transmission
Superhighway
The State Grid Corp. of China (SGCC) in
July put into operation the world's first
ultra-high-voltage direct current (UHVDC)
superhighway when it commissioned the
Xiangjiaba-Shanghai link. The ±800 kV
project, completed in 30 months-a year
ahead of schedule-has the capacity to
transmit up to 7,200 MW from the Xiangjiaba
hydropower plant in southwest China
to Shanghai, the country's leading industrial
and commercial center, about 2,000
kilometers (km) away.
The project's primary technology provider,
ABB, also reported that transmission losses
on the new $440 million line are under
7%-considerably lower than on the existing
500 kV system (Figure 1). This means
that the single overhead line link sets a new
benchmark in terms of voltage levels and
transmission capacity, ABB said, superseding
the 600-kV Itaipú transmission line in Brazil,
which the company also delivered.
The project is the among the first of
many to come online as part of China's
ambitious plan to boost trans-regional
power supply capacity. Defining anything
over 800 kV as " ultra-high voltage, " the
country has pledged 300 billion yuan
($44 billion) to build as many as eight
long-distance high-voltage lines by 2015
and as many as 15 by 2020. The new
lines allow for the transmission of more
power with significantly reduced losses
from areas rich in resources to regions of
heavy power consumption. Nearly 80% of
China's hydropower resources are in the
1. Somewhere along the line. China,
which in 2008 had already completed one
1,000-kV UHV AC circuit, in July put into operation
the 2,000-km, 800-kV Xiangjiaba-Shanghai
link. Two other 800-kV DC circuits are under
construction. The Longquan high-voltage direct
current converter station shown here is similar
to those used at these massive hydropower
transmission projects in China. Courtesy: ABB
southwest, and two-thirds of its coal is in
three northern provinces. Demand centers,
meanwhile, are in coastal regions.
Before the Xiangjiaba-Shanghai link,
the SGCC put into operation a 600-km
1,000-kV UHV AC circuit in late 2008.
Meanwhile, work continues at two other
800-kV DC projects. The China Southern
Power Grid in June said it put into operation
the second pole of a 1,500-km
UHVDC line that would bring hydropower
from Yunnan province to Guangdong province
(and its megacities Guangzhou and
Shenzhen)-effectively doubling transmission
capacity to 5,000 MW.
Siemens Energy put into operation in
December 2009 the first pole for that project,
which operated at a nominal power of
2,500 MW. " At a transmission capacity of
5,000 MW, losses are as low as around 2%
per 1,000 km, plus less than 1.5% losses
for both converter stations at the sending
and receiving end of the transmission
line, " the company said.
Xcel Energy Fires
Up Solar/Coal Hybrid
Demonstration
At the end of June, Xcel Energy fired up
a demonstration project that integrates a
4-MW parabolic trough solar technology
with an existing 44-MW coal-fired power
plant. Designed to increase the plant's
efficiency, decrease its use of coal, and
test the viability of solar power thermal
technology, the project at the company's
Cameo Generating Station near Grand
Junction, Colo., is being billed as the first
of its kind in the U.S. (See " Fossil Fuels
+ Solar Energy = The Future of Electricity
Generation " in POWER's April 2009 issue
for an in-depth look at hybrid solar/coal
systems.)
Designed by Spain's Abengoa Solar, the
concentrating solar power system consists
of eight rows of 500-foot-long parabolic
troughs covering 6.4 acres. Essentially,
these solar collectors-specially curved
" ultra pure glass mirrors " -concentrate
2. The best of superterrestial and subterrestial power. Xcel Energy's Colorado
Integrated Solar Project near Grand Junction, Colo., uses parabolic trough technology at its coalfired
Cameo Generating Station to increase the plant's efficiency and decrease the use of coal.
Mineral oil used in the solar collectors is heated to about 575F and then used to preheat boiler
feedwater from 360F to 407F, thereby reducing the amount of coal consumed to produce the
same amount of power in the steam turbine. Courtesy: Xcel Energy
Boiler
Silo
Continuous
emissions
monitoring
Turbine Generator
Coal Air
Low
NOx
Mill
Air emissions
burners
Cooling
Spray pond
Stack
Baghouse
Fly
Ash
Bottom
Ash
Condenser
Hot
Heat
exchanger
Ash management
Solar
collectors
Canal
Cold
8
www.powermag.com
POWER | September 2010

http://www.powermag.com

POWER September 2010

Table of Contents for the Digital Edition of POWER September 2010