tonnes, 50,000 tonnes and 56,000 tonnes per
year, significantly improving the air quality in
China’s second biggest city.
66
(4) Main problems
Generally, China’s UHV technology is
world-class in terms of technology and capacity.
However, there are still some issues to be
resolved.
First, UHV increases the complexity of the
power system and puts it at greater risk. Effective
precautions need to be taken to ensure system
security. AC-DC interconnections and increasing
volumes of new energy change the system profoundly. Once interconnected, regional grids are
interdependent and impact each other mutually.
This increases overall complexity, risk and
uncertainty. If a commutation failure occurs on a
±800 kV DC line, it generates an 8,000 MW
power surge, which is 3–4 times that of AC. If a
DC commutation failure occurs, requiring multiple restarts, an instantaneous 21,000 MW
power surge and 8,000 MW repeat surges will be
generated, which could cause an outage.
67
Higher transmission voltage levels and larger
amounts of new energy increase the risk to grid
security.
Second, there is still a quality gap between
locally manufactured UHV equipment and
advanced international technologies. Some key
components still need to be imported. Supply
channels for drawings, materials, user manuals,
software, and some other spare parts are simplex.
This increases the cost and complexity of operating and maintaining UHV projects.
6.4.4 The Role of Long-Distance Power
Transmission in China’s
Energy Revolution
(1) Role
Long-distance power transmission provides
strategic support for the development of clean
energy in China. It is an important tool to shape a
national market and optimise resource allocation,
and an integral part of the modern power system.
First, long-distance power transmission
enables electricity to be transferred in bulk across
the country. As China’s energy sources and load
centres are in different regions, trans-regional
electricity flows with multiple sending and
receiving ends is the future. The capacity, distance and types of electricity flow will only
increase. As a result, China needs to speed up
development of long-distance power transmission and plan in a centralised manner the links
between sending and receiving regions.
Second, the development of long-distance
power transmission delivers comprehensive
benefits, including regional interconnections,
inter-basin hydropower transfer, trans-regional
allocation, peak shaving, the complementary and
coordinated use of hydropower and thermal
power, and less need for backup capacity.
Trans-regional allocation reduces the need for
receiving regions in east and central China to
build coal-fired power plants. New power
demand is supplied mainly with local nuclear
power and with electricity from other regions.
Peak shaving is used to optimise the power mix
and better integrate clean renewable energy.
Third, long-distance power transmission can
help connect and consume clean energy. As
clean energy is intermittent and far from load
centres, grid connection is faced with two challenges: (i) clean energy poses more demanding
requirements than conventional power on the
grid’s peak shaving capacity; and (ii) the ability
of clean energy-abundant areas to use all the
energy locally is limited. China can make the
most of its national peak-shaving resources and
new energy capacity only when grid connection
and consumption of clean energy in large areas is
66
http://www.xinhuanet.com/, Calculation of Economic
and Environmental Benefits of UHV Technology from the
Perspective of Anhui-East China UHV Power Transmission Project, http://news.xinhuanet.com/2016-11/01/c_
1119830177.htm.
67
Tang Yong, speaker at the 5th China Power Development and Technology Innovation Forum, April 27, 2017,
http://shupeidian.bjx.com.cn/news/20170428/822880.
shtml.
364
S. Zifeng and N. Dickens
year, significantly improving the air quality in
China’s second biggest city.
66
(4) Main problems
Generally, China’s UHV technology is
world-class in terms of technology and capacity.
However, there are still some issues to be
resolved.
First, UHV increases the complexity of the
power system and puts it at greater risk. Effective
precautions need to be taken to ensure system
security. AC-DC interconnections and increasing
volumes of new energy change the system profoundly. Once interconnected, regional grids are
interdependent and impact each other mutually.
This increases overall complexity, risk and
uncertainty. If a commutation failure occurs on a
±800 kV DC line, it generates an 8,000 MW
power surge, which is 3–4 times that of AC. If a
DC commutation failure occurs, requiring multiple restarts, an instantaneous 21,000 MW
power surge and 8,000 MW repeat surges will be
generated, which could cause an outage.
67
Higher transmission voltage levels and larger
amounts of new energy increase the risk to grid
security.
Second, there is still a quality gap between
locally manufactured UHV equipment and
advanced international technologies. Some key
components still need to be imported. Supply
channels for drawings, materials, user manuals,
software, and some other spare parts are simplex.
This increases the cost and complexity of operating and maintaining UHV projects.
6.4.4 The Role of Long-Distance Power
Transmission in China’s
Energy Revolution
(1) Role
Long-distance power transmission provides
strategic support for the development of clean
energy in China. It is an important tool to shape a
national market and optimise resource allocation,
and an integral part of the modern power system.
First, long-distance power transmission
enables electricity to be transferred in bulk across
the country. As China’s energy sources and load
centres are in different regions, trans-regional
electricity flows with multiple sending and
receiving ends is the future. The capacity, distance and types of electricity flow will only
increase. As a result, China needs to speed up
development of long-distance power transmission and plan in a centralised manner the links
between sending and receiving regions.
Second, the development of long-distance
power transmission delivers comprehensive
benefits, including regional interconnections,
inter-basin hydropower transfer, trans-regional
allocation, peak shaving, the complementary and
coordinated use of hydropower and thermal
power, and less need for backup capacity.
Trans-regional allocation reduces the need for
receiving regions in east and central China to
build coal-fired power plants. New power
demand is supplied mainly with local nuclear
power and with electricity from other regions.
Peak shaving is used to optimise the power mix
and better integrate clean renewable energy.
Third, long-distance power transmission can
help connect and consume clean energy. As
clean energy is intermittent and far from load
centres, grid connection is faced with two challenges: (i) clean energy poses more demanding
requirements than conventional power on the
grid’s peak shaving capacity; and (ii) the ability
of clean energy-abundant areas to use all the
energy locally is limited. China can make the
most of its national peak-shaving resources and
new energy capacity only when grid connection
and consumption of clean energy in large areas is
66
http://www.xinhuanet.com/, Calculation of Economic
and Environmental Benefits of UHV Technology from the
Perspective of Anhui-East China UHV Power Transmission Project, http://news.xinhuanet.com/2016-11/01/c_
1119830177.htm.
67
Tang Yong, speaker at the 5th China Power Development and Technology Innovation Forum, April 27, 2017,
http://shupeidian.bjx.com.cn/news/20170428/822880.
shtml.
364
S. Zifeng and N. Dickens