IEEE Power & Energy Magazine - July/August 2016 - 77

exist. a sufficient short current capacity is essential for the
stable operation of the hVdc, and there should be enough
dynamic reactive power to help the ac system recover
from a fault. Lacking dynamic reactive power reserve is
one of the main reasons for voltage stability problems in
multi-infeed hVdc.
as a new generation of dc transmission technology,
a VSC-based hVdc is more controllable and flexible.
in VSC-hVdc, a converter can independently regulate
the active and reactive power of the ac side and is able
to commutate without the support of ac voltage. in the
future power grid, VSC-hVdc will be widely applied in
long-distance power transmission or back-to-back networking to handle the low voltage after ac failures and
provide dynamic reactive power support for a nearby
grid to reduce the operation risk of complex large-scale
power systems.
To lower manufacturing costs, it is reasonable that in highcapacity hVdc transmission systems only inverter stations
will be constructed as VSC-hVdc or reform conventional
hVdc inverter stations into VSC-hVdc. There will be a breakthrough at VSC-hVdc when the characteristics of power electronic devices improve and a new topology of converters is
invented. Furthermore, VSC-hVdc is more suitable for multiinfeed hVdc and will contribute to a more robust and controllable power grid.
one VSC-hVdc (!350 kV, 1,000 Mw) has been applied
in Yunnan and CSG back-to-back networking and is scheduled to be put into operation in 2016. CSG is researching
VSC-hVdc based separation operation of the Guangdong
multi-infeed power grid to further enhance the controllability of power grid under risks.

Guaranteed Network for Natural Disasters
Considering the balance between safety and economy, we
have developed a guaranteed network frame of CSG during large-scale ice/typhoon disasters, which is defined as the
main frame consisting of lines of great significance to the
grid safety and the power-supply capability.
The defining principles are as follows:
✔ ensure the normal operation of lines and power plants
of great significance to grid safety and stability
✔ ensure the integrity of the 500-kV main network
frame as far as practical
✔ ensure the safe power supply for urban areas, county
towns, and important customers
✔ ensure the islanded system balance and safety after
disconnection.
Based on these principles, the significant lines and substations will be constructed using stricter anti-typhoon, antiice, and anti-earthquake standards, configuring dc deicer
equipment and cables to form the guaranteed network frame.
Control systems of some generators will be reconfigured to
be adaptable in islanded operation.

ieee power & energy magazine

ice coating monitoring systems, lightning locating systems, bush fires alerting systems, and hydrograph monitoring systems are built to give early warning. Special procedures are also developed to guide dispatching and operation
in emergencies.

Conclusions
Being one of the most unique hVac/hVdc hybrid transmission power grids, the CSG has special operational challenges when compared to other large-scale interconnected
power grids. in this article, we have presented major operation challenges threatening the CSG grid, such as bulkpower shift to an ac system after hVdc bipolar, simultaneous commutation failure, dc current flowing through the
earth, and natural disasters, which is also common for
hVdc/hVac hybrid systems. Based on our experience with
these challenges, the power system planning applied in the
CSG to deal with these challenges was presented, with
main idea of planning to separate the huge synchronous
grid into two or three subsystems and connect them by
using hVdc or VSC-hVdc. The practical experiences and
our future improvements could benefit the system operation of other power grids in other parts of the world.

For Further Reading
F. F. wu and S. Fu, "China's future in electric energy,"
IEEE Power Energy Mag., vol. 7, no. 4, pp. 32-38, July
2005.
X. Chen, "Problems to be emphatically researched in
power planning of China southern power grid," Guangdong
Electric Power, vol. 18, no. 6, pp. 1-4, 2005.
J. Zhao and Y. Xue, "design of blackout defense framework for China Southern power grid," Southern Power Syst.
Technol., vol. 2, no. 1, pp. 1-13, 2008.
w. Juanjuan, F. Chuang, C. Yiping, r. hong, X. Shukai,
Y. Tao, and L. Licheng, "research and application of dc
de-icing technology in China Southern power grid," IEEE
Trans. Power Deliv., vol. 27, no. 3, pp. 1234-1242, 2012.
h. rao, d. Zhang, and X. Zhao, "Practice and analyses of
uhVdc power transmission," High Volt. Eng., vol. 41, no. 8,
pp. 2481-2488, 2015.

Biographies
Hongyang Zhou is with the CSG Control Centre, Guangzhou, Guangdong, China.
Yinsheng Su is with the CSG Control Centre, Guangzhou, Guangdong, China.
Yiping Chen is with the CSG Control Centre, Guangzhou, Guangdong, China.
Qian Ma is with the CSG Control Centre, Guangzhou,
Guangdong, China.
Weike Mo is with the South China university of
Technology, Guangzhou, Guangdong, China.
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