abundant energy sources are often characterised
by low power consumption due to an underdeveloped economy and small population. For
example, more than 80% of Russia’s power
generation resources are distributed in the east
(Siberia has abundant hydropower and coal
resources), but load centres are located in the
west. Historically, China’s load centres are in the
central and eastern regions, but its energy sources
are mainly in the west and north. For instance,
coal, wind and solar power and other new energy
sources are largely in west and north China, and
hydropower resources in south-west China.
Such misalignment is determined by geography, but shaped and intensified by social and
economic development. In countries like China
and Russia, large-scale, long-distance and efficient power transmission is needed to connect
energy resources with load centres.
(2) Characteristics
Long-distance power transmission technologies
are mainly divided into: extra-high voltage and
ultra-high voltage (EHV/UHV) AC, EHV/UHV
DC, flexible AC/DC power transmission,
multi-terminal direct current (MTDC) power
transmission, and new technologies like fractional frequency transmission, superconducting
transmission, half-wavelength transmission, etc.
10–220 kV AC transmission is the most
common technology in large power systems. AC
transmission at low voltage over hundreds of
kilometres results in substantial electrical losses.
One solution is to increase the voltage level to
EHV. Another is to convert AC to DC for
long-distance transmission (DC has lower power
losses). EHV generally refers to 330–765 kV AC
and ±500 to ±660 kV DC transmission
technologies.
UHV means a voltage level of at least
1,000 kV for AC transmission and ±800 kV or
more for DC transmission. UHV transmission
systems can carry more power at a higher voltage
over longer distances and with lower losses than
EHV.
6.4.2 Current Trends in Global
Long-Distance Power
Transmission
(1) Application analysis
First, technological progress.
Several major economies have developed technologies and equipment critical to long-distance
power transmission since the 1960s. The former
Soviet Union, Japan, the USA and Italy initiated
UHV power transmission.
The former Soviet Union was one of the earliest countries to investigate UHV transmission,
and the only country (except China) to have
UHV AC transmission projects in operation up to
now. The former Soviet Union started to construct
the Siberia-Kazakhstan-Ural 1,150 kV UHV AC
transmission project in 1980 to transmit electricity
from Siberia to load centres in the European part
of the country. The project started to operate at its
intended rated voltage in 1985 but was later
reduced to 500 kV due to technical difficulties.
Research and experiments in UHV technology have been carried out in the USA but have
not been deployed. In 1974, American Electric
Power and General Electric conducted audible
noise, radio jamming and other tests at the UHV
test station at Pittsfield, Massachusetts. A 1,000–
1,500 kV three-phase test line was constructed
by the Electrical Power Research Institute in
1974. It provided experience in electromagnetic
operating environments, tower installation and
transformer design.
Japan started to construct 1,000 kV transmission and substation projects in 1988. By 1999 it had
built two 1,000 kV power transmission lines with a
Special Report 3: A Study of China’s Technology Revolution
355
by low power consumption due to an underdeveloped economy and small population. For
example, more than 80% of Russia’s power
generation resources are distributed in the east
(Siberia has abundant hydropower and coal
resources), but load centres are located in the
west. Historically, China’s load centres are in the
central and eastern regions, but its energy sources
are mainly in the west and north. For instance,
coal, wind and solar power and other new energy
sources are largely in west and north China, and
hydropower resources in south-west China.
Such misalignment is determined by geography, but shaped and intensified by social and
economic development. In countries like China
and Russia, large-scale, long-distance and efficient power transmission is needed to connect
energy resources with load centres.
(2) Characteristics
Long-distance power transmission technologies
are mainly divided into: extra-high voltage and
ultra-high voltage (EHV/UHV) AC, EHV/UHV
DC, flexible AC/DC power transmission,
multi-terminal direct current (MTDC) power
transmission, and new technologies like fractional frequency transmission, superconducting
transmission, half-wavelength transmission, etc.
10–220 kV AC transmission is the most
common technology in large power systems. AC
transmission at low voltage over hundreds of
kilometres results in substantial electrical losses.
One solution is to increase the voltage level to
EHV. Another is to convert AC to DC for
long-distance transmission (DC has lower power
losses). EHV generally refers to 330–765 kV AC
and ±500 to ±660 kV DC transmission
technologies.
UHV means a voltage level of at least
1,000 kV for AC transmission and ±800 kV or
more for DC transmission. UHV transmission
systems can carry more power at a higher voltage
over longer distances and with lower losses than
EHV.
6.4.2 Current Trends in Global
Long-Distance Power
Transmission
(1) Application analysis
First, technological progress.
Several major economies have developed technologies and equipment critical to long-distance
power transmission since the 1960s. The former
Soviet Union, Japan, the USA and Italy initiated
UHV power transmission.
The former Soviet Union was one of the earliest countries to investigate UHV transmission,
and the only country (except China) to have
UHV AC transmission projects in operation up to
now. The former Soviet Union started to construct
the Siberia-Kazakhstan-Ural 1,150 kV UHV AC
transmission project in 1980 to transmit electricity
from Siberia to load centres in the European part
of the country. The project started to operate at its
intended rated voltage in 1985 but was later
reduced to 500 kV due to technical difficulties.
Research and experiments in UHV technology have been carried out in the USA but have
not been deployed. In 1974, American Electric
Power and General Electric conducted audible
noise, radio jamming and other tests at the UHV
test station at Pittsfield, Massachusetts. A 1,000–
1,500 kV three-phase test line was constructed
by the Electrical Power Research Institute in
1974. It provided experience in electromagnetic
operating environments, tower installation and
transformer design.
Japan started to construct 1,000 kV transmission and substation projects in 1988. By 1999 it had
built two 1,000 kV power transmission lines with a
Special Report 3: A Study of China’s Technology Revolution
355