4 The Transition of China’s Power System
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large-scale construction of new DC grids and the maintenance and renovation of
existing ones. To accommodate large capacity, a gradual migration is required from
IGBT module packaging and compression IGBT to compression IGCT in order to
provide high reliability. From the material standpoint, it’s important to introduce
gallium arsenide and silicon carbide as new wide band gap semiconductor materials
to enable larger capacity of single semiconductor switch components. The concurrent
localization efforts have brought about tremendous cost reduction. And the development of high-voltage and large-capacity equipment will greatly contribute to new
breakthrough in the performance of power electronic equipment. It is projected that by
2050, key research findings from new semiconductor materials will be commercialized for massive production, with 100% localization and a big boost in the capacity
and performance of equipment.
Major breakthroughs have been made in power electronics related equipment
of flexible DC grids, with substantial improvement in performance of such equipment as modular multilevel converters, DC circuit breakers and DC transformers,
which have seen increasing local production. To illustrate, the performance of DC
circuit breakers in Zhoushan’s 5-terminal flexible DC network launched in 2016
has achieved 200 kV/15 kA/2.64 ms. Not only that, the performance of breakers
in Zhangbei 5-terminal flexible DC network set to operate in 2020 has hit a new
high of 500 kV/26 kA/2.64 ms, and its multi-level power electronic converter has
also broken a new world record of 500 kV/3000 MW. With further upgrade in the
capacity of converters, circuit breakers and other equipment, construction of flexible
DC networks with larger capacity and in a wider range could be made possible by
2050.
Core power electronic devices in DC transmission (such as high-voltage highcapacity IGBT, IGCT, IETO, etc.) are expected to be fully localized in the future,
and new semiconductor devices with large capacity, low cost and high reliability
will be developed. Flexible DC core equipment such as modular multilevel converter
(MMC), DC circuit breaker and DC transformer will be fully commercialized. As
an increasingly more economically attractive option than traditional high-voltage
DC transmission, flexible DC transmission is likely to be adopted as the mainstream
technology for long-distance high-capacity transmission and grid interconnection.
Flexible transmission and distribution technologies will produce dramatic impact on
grid structure, which will be distinctly featured by the hybrid of AC/DC and multidirectional transmission. The share of distributed power supply and energy storage
will be significantly increased, and energy self-sufficiency of regional grids will be
improved, with a notable downsizing of backup capacity.
4.3.3 DC Distribution Network
The rapid development and wide application of new energy, information technology
and power electronics technology has prompted rising demand for the amount, quality
and reliability of power, which has in turn created challenges to the existing AC
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large-scale construction of new DC grids and the maintenance and renovation of
existing ones. To accommodate large capacity, a gradual migration is required from
IGBT module packaging and compression IGBT to compression IGCT in order to
provide high reliability. From the material standpoint, it’s important to introduce
gallium arsenide and silicon carbide as new wide band gap semiconductor materials
to enable larger capacity of single semiconductor switch components. The concurrent
localization efforts have brought about tremendous cost reduction. And the development of high-voltage and large-capacity equipment will greatly contribute to new
breakthrough in the performance of power electronic equipment. It is projected that by
2050, key research findings from new semiconductor materials will be commercialized for massive production, with 100% localization and a big boost in the capacity
and performance of equipment.
Major breakthroughs have been made in power electronics related equipment
of flexible DC grids, with substantial improvement in performance of such equipment as modular multilevel converters, DC circuit breakers and DC transformers,
which have seen increasing local production. To illustrate, the performance of DC
circuit breakers in Zhoushan’s 5-terminal flexible DC network launched in 2016
has achieved 200 kV/15 kA/2.64 ms. Not only that, the performance of breakers
in Zhangbei 5-terminal flexible DC network set to operate in 2020 has hit a new
high of 500 kV/26 kA/2.64 ms, and its multi-level power electronic converter has
also broken a new world record of 500 kV/3000 MW. With further upgrade in the
capacity of converters, circuit breakers and other equipment, construction of flexible
DC networks with larger capacity and in a wider range could be made possible by
2050.
Core power electronic devices in DC transmission (such as high-voltage highcapacity IGBT, IGCT, IETO, etc.) are expected to be fully localized in the future,
and new semiconductor devices with large capacity, low cost and high reliability
will be developed. Flexible DC core equipment such as modular multilevel converter
(MMC), DC circuit breaker and DC transformer will be fully commercialized. As
an increasingly more economically attractive option than traditional high-voltage
DC transmission, flexible DC transmission is likely to be adopted as the mainstream
technology for long-distance high-capacity transmission and grid interconnection.
Flexible transmission and distribution technologies will produce dramatic impact on
grid structure, which will be distinctly featured by the hybrid of AC/DC and multidirectional transmission. The share of distributed power supply and energy storage
will be significantly increased, and energy self-sufficiency of regional grids will be
improved, with a notable downsizing of backup capacity.
4.3.3 DC Distribution Network
The rapid development and wide application of new energy, information technology
and power electronics technology has prompted rising demand for the amount, quality
and reliability of power, which has in turn created challenges to the existing AC