IEEE Electrification Magazine - December 2015 - 35

DVP actively shares its academic findings and best
practices with the power industry at national and
international forums and councils, and continues
an interactive partnership with research institutes,
manufacturers, and industry peers.

HE SUN, THE ONLY STAR IN OUR SOLAR SYSTEM, IS AN ESSENTIAL ENERGY SOURCE
for all human activities as well as the entire Earth biosphere. Galileo discovered the existence of sunspots in 1610, and 200 years later, Schwabe proved that our home star's
activities follow a cycle of 11 years. Using high-tech devices, scientists and engineers
have gained a clearer vision of solar activities and are now better able to discern the
sun's behavior. Known solar activities include a combination of sunspots, solar flares, and coronal mass
ejections. Solar activity occurs in peaks, with roughly equal intervals between them. The sun interacts
significantly with Earth's magnetosphere. Extraordinary solar activities (or solar storms) can severely
interfere with Earth's magnetospheric and ionospheric electrical current system, causing rapidly changing Earth surface potential (ESP). The destructive consequences become more evident with the everincreasing propagation of electrical and electronic equipment. The first recorded example of the negative effects of solar activity on human society was an unprecedented solar storm that raged from
28 August through 2 September 1859 (cycle 10), in which telegraph systems all over Europe and North
America failed.
Large, interconnected electric power-transmission networks are among the greatest inventions of
mankind. Yet the grid is vulnerable to abnormal solar activities. One of the earliest recorded power-system failures attributed to solar activities occurred in the northern United States and Canada on 24 March
1940. Philadelphia Electric Company experienced strong reactive power swings and voltage surges. Transformers at several utilities tripped out of service during the storm. The most destructive storm in powersystem history occurred on 13 March 1989. On that morning, at 2:44 a.m. eastern standard time (7:44 a.m.
UTC), a massive K9 storm, resulting from a coronal mass ejection four days before, struck North America,
causing the Hydro Quebec power grids in Canada to collapse within 2 min (Figure 1). The blackout tripped
offline 21,500 MW of generation, and system restoration took more than 9 h. A major social and economic loss occurred. The March 1989 event brought power-system geomagnetic disturbances (GMDs) into the
spotlight. Since then, surviving severe solar storms and mitigating their impacts have become high-priority research topics for the entire power industry.
The physical manifestation of the magnetic-field fluctuation acting on Earth's surface material is
the ESP gradient at a very low frequency (0.1-0.001 Hz, or quasi-dc), a function of the magnetic-field
rate of change and Earth conductivity. Under a severe K8 or K9 storm and low Earth conductivity condition, the ESP gradient could reach the order of 6 V/km or greater. This quasi-dc potential would find a
way to flow into the power-system network wherever a pathway is presented-normally at the
grounded neutral of wye-connected transformers or reactive power compensators. This dc geomagnetically induced current (GIC), in general, is proportional to the length of the transmission lines and ESP
gradient and can be extremely harmful to system operations and power equipment.
Looking back, there are three major factors that have exacerbated the power grid's vulnerability
to GIC. The first is the exposed nature of the electric transmission infrastructure with neutral
grounding to keep the system safe. The same practice has been used for over a century. In other
words, GIC is not preventable in a power system without changing the current grid grounding

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Table of Contents for the Digital Edition of IEEE Electrification Magazine - December 2015

IEEE Electrification Magazine - December 2015 - Cover1
IEEE Electrification Magazine - December 2015 - Cover2
IEEE Electrification Magazine - December 2015 - 1
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IEEE Electrification Magazine - December 2015 - Cover3
IEEE Electrification Magazine - December 2015 - Cover4
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http://www.nxtbook.com/nxtbooks/pes/electrification_september2019
http://www.nxtbook.com/nxtbooks/pes/electrification_june2019
http://www.nxtbook.com/nxtbooks/pes/electrification_march2019
http://www.nxtbook.com/nxtbooks/pes/electrification_december2018
http://www.nxtbook.com/nxtbooks/pes/electrification_september2018
http://www.nxtbook.com/nxtbooks/pes/electrification_june2018
http://www.nxtbook.com/nxtbooks/pes/electrification_december2017
http://www.nxtbook.com/nxtbooks/pes/electrification_september2017
http://www.nxtbook.com/nxtbooks/pes/electrification_march2018
http://www.nxtbook.com/nxtbooks/pes/electrification_june2017
http://www.nxtbook.com/nxtbooks/pes/electrification_march2017
http://www.nxtbook.com/nxtbooks/pes/electrification_june2016
http://www.nxtbook.com/nxtbooks/pes/electrification_december2016
http://www.nxtbook.com/nxtbooks/pes/electrification_september2016
http://www.nxtbook.com/nxtbooks/pes/electrification_december2015
http://www.nxtbook.com/nxtbooks/pes/electrification_march2016
http://www.nxtbook.com/nxtbooks/pes/electrification_march2015
http://www.nxtbook.com/nxtbooks/pes/electrification_june2015
http://www.nxtbook.com/nxtbooks/pes/electrification_september2015
http://www.nxtbook.com/nxtbooks/pes/electrification_march2014
http://www.nxtbook.com/nxtbooks/pes/electrification_june2014
http://www.nxtbook.com/nxtbooks/pes/electrification_september2014
http://www.nxtbook.com/nxtbooks/pes/electrification_december2014
http://www.nxtbook.com/nxtbooks/pes/electrification_december2013
http://www.nxtbook.com/nxtbooks/pes/electrification_september2013
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