IEEE Electrification Magazine - December 2015 - 59

substations under the edge effect are expected to
exceed 400 A, making the substations nodes at high
risk. This is a problem in need of close attention.
xx
As is suggested by the GIC analysis of future largescale power grids, disaster prevention and GIC mitigation for large-scale grids are critical to grid construction and operation, and the grids are also crucial for
social development in the future. However, since the
scale of power grids will be extremely large in the
future, there is still no good way to effectively protect
them from geomagnetic storms. Installation of devices
for GIC mitigation, compensation, or separation in substations at high GIC risk by aforementioned calculation
will cause the risk to be transferred to other nodes.
Large-scale installations not only require enormous
cost but will also introduce new liabilities to the grid,
reducing its stability. Note that the essential threats
from GIC that cause transformer malfunction and
power grid insecurity are temperature rise, harmonics,
and reactive power loss; an economical and effective
method to alleviate the problem is to focus on developing, designing, and manufacturing transformers based
on nonpermeable supporting members. But knowledge of the GIC derivative effect on single-phase, fourpillar and single-phase, five-pillar 1,000-kV UHV transformers is still inadequate so far. The influence of factors such as core size, material, load current, and
GIC-caused leakage inductance will have to be investigated. Additionally, further research on models for
transformer temperature rise, harmonics, and reactive
power loss effect is required. On the other hand,
because a large margin of error may exist in theoretical
calculation, international cooperation on scientific
experiments would be a feasible way to investigate the
GIC derivative effect on 1,000-kV UHV transformers.
xx
If we can make precise forecasts of the arrival time of
solar wind and accurately predict the magnitude of the
corresponding geomagnetic storms, then it will be possible to avoid major blackouts by controlling the loads of
power plants, substations, and transmission lines that
are at high risk. With GIC data monitored in the power
grid and oil pipes, our research team made a basic comparative analysis on the relationship between GIC patterns and heliographic and interplanetary parameters
of coronal mass ejection (Liu, 2013). The result suggests
that GIC is influenced by multiple parameters of heliographic and interplanetary solar wind, among which
the velocity toward earth is a key factor that determines
the GIC level. As technologies for solar activity observation develop, progress and achievements have been
made by solar and space physics research on solar
activities and interplanetary and near-Earth space
events. If these achievements are incorporated into GIC
research, it will be possible to precisely forecast GICs in
the power grid. Therefore, it is suggested that international organizations such as the IEEE Power & Energy

Society pay attention to and lead research on the influence of power grid GIC and its forecast.

For Further reading
C.-M. Liu, "Geomagnetically induced currents in the highvoltage power grid in China," IEEE Power Deliv., vol. 24, no. 4,
pp. 2368-2374, 2009.
C.-M. Liu, L.-G. Liu, R. Pirjola, and Z.-Z. Wang, "Calculation
of geomagnetically induced currents in mid- to low-latitude
power grids based on the plane wave method: A preliminary
case study," Space Weather, vol. 7, no. 4, p. S04005, 2009.
C.-M. Liu, "Influence and hazard of disastrous space weather on power grid in China," Eng. Sci., vol. 4, pp. 83-87, 2011.
L.-G. Liu, "Calculation analysis of geomagnetically induced
currents with different network topologies," in Proc. IEEE
Power and Energy Society General Meeting, 2013, pp. 1-4.
R. Horton, "A test case for the calculation of geomagneriically induced currents," IEEE Power Deliv., vol. 27, no. 4,
pp. 2368-2373, 2012.
S.-X. Guo, "Impact of EHV power system on geomagnetically induced currents in UHV power system," IEEE Power
Deliv., vol. 30, no. 5, pp. 2163- 2170, 2015.
B. Zhang, "Research on the GIC effect on mega power
transformers," Ph.D. dissertation, North China Electric Power
Univ., School of Electrical and Electronic Engineering, 2010.
L.-G. Liu, "Solar storm heliographic parameters and conditions driving the GIC in grid," Trans. China Electrotech. Soc.,
vol. 28, no. S2, pp. 360-366, 2013.

biographies
Lian-Guang Liu (liulianguang@ncepu.edu.cn) received his
M.S. degree in electrical engineering from North China
Electric Power University (NCEPU), Beijing, China, in 1994.
He is a senior member of the Chinese Society for Electrical
Engineering. He is also a commissioner of the Chinese
Space Weather Committee and National Space Weather
Monitoring and Pre-Warning Technology Standard Committee. He is currently a professor and a doctoral supervisor
at the School of Electrical and Electronic Engineering,
NCEPU. His research interests include the safe operation
and hazard prevention of power systems and power quality.
Kai Wei (innocentevil@163.com) received his B.S. degree
in electrical engineering and automation from North
China Electric Power University (NCEPU), Beijing, China, in
2013. He is currently pursing his M.S. degree in electrical
engineering at NCEPU. His research interests include control
and analysis in power system operation, modeling geomagnetically induced currents in the power grid, and power system risk assessment.
Xiao-Ning Ge (825044755@qq.com) is a Ph.D. candidate
in electrical engineering at North China Electric Power
University, Beijing, China. Her research interests include
power system monitoring and mitigation, modeling geomagnetically induced currents in the power grid, and
assessing the effect on power systems.

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