IEEE Electrification Magazine - December 2015 - 23

During Geomagnetic Disturbances, AEP-being the owner and
operator of the bulk-power system-would be required to
develop GMD operating procedures and conduct initial and
ongoing assessments on potential impacts of benchmark
GMD events on bulk-power system equipment, especially
extra-high-voltage (EHV) transformers, and the bulk-power
system as a whole. Based on these assessments, it is also
required to prepare a plan (if necessary) to mitigate any GMD
impacts. This article describes AEP's comprehensive
approach and efforts on GMD monitoring, modeling, and
mitigation to ensure reliable performance of its critical transmission network and assets.

Historical Gmd Impact Observations

dc (A)

AEP's transmission network portfolio includes more than
2,100 mi of 765-kV EHV transmission lines, 8,300 mi of
345-kV EHV lines, 18,000 mi of 138-kV lines, and tens of
thousands of miles below 138 kV. AEP's PJM EHV grid is
located above the 35th parallel, and some EHV grid areas
are on or near resistive igneous rock. The relatively high
latitude, along with the long, interconnected, low-resistance EHV lines across high-resistive areas, make the AEP
EHV grid theoretically susceptible to GMD impacts; however, with more than 40 years of operation at 765 kV and
more than 60 years of operation at 345 kV, AEP has

experienced no history of transformer failure or damage
due to GMD. Due to the concerns of the blackout and
other adverse experiences of Hydro Quebec and other utilities during earlier GMDs, AEP installed temporary monitoring systems on the neutrals of some vulnerable EHV
transformers to detect geomagnetically induced current
(GIC) and to assess its vulnerability in two past solar
cycles. From 1989 to 1994, GIC currents were monitored at
four locations during the peak of Solar Cycle 22. For the
13 March 1989 K-9 solar storm, less than 10 A of GICs was
recorded. Other observations, such as high audible noise
at one generator step-up unit, high harmonics, and voltage fluctuations were reported during the major storm.
No other special system behavior or visible equipment
damage was observed at the monitored sites. Also, regular
dissolved-gas analyses were performed, showing no evidence of transformer damage from the GMD events. For
the peak of Solar Cycle 23, from 1999 to 2002, GIC monitors were installed at three locations, with the highest GIC
observed at 87 A at the Jefferson 765-kV transformers on
15 July 2000 during a K-9 GMD event, while typical readings were much lower. Figure 1 shows the GIC measurements at three 765-kV substations (Jefferson, Kammer,
and Jackson's Ferry) during the K-9 GMD event. Again, no
failures, gassing, or lasting impacts were attributed to the

19:00 19:15 19:30 19:45 20:00 20:15 20:30 20:45 21:00 21:15 21:30 21:45 22:00 22:15 22:30 22:45 23:00
100
80
60
40
20
0
-20
-40
-60
-80
(a)
19:00 19:15 19:30 19:45 20:00 20:15 20:30 20:45 21:00 21:15 21:30 21:45 22:00 22:15 22:30 22:45 23:00
60

dc (A)

40
20
0
-20
-40
(b)
19:00 19:15 19:30 19:45 20:00 20:15 20:30 20:45 21:00 21:15 21:30 21:45 22:00 22:15 22:30 22:45 23:00
40
dc (A)

20
0
-20
-40
(c)
Figure 1. GIC currents observed during a Kp = 9 GMD event on 15 July 2000 (Universal time of day-Columbus, Ohio time is 4 h behind):
(a) J-Station T1 neutral dc current, (b) K-Station T200 neutral dc current, and (c) JF-Station T1 neutral dc current.

IEEE Elec trific ation Magazine / d ec em be r 2 0 1 5

23



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

IEEE Electrification Magazine - December 2015 - Cover1
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http://www.nxtbook.com/nxtbooks/pes/electrification_september2015
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http://www.nxtbook.com/nxtbooks/pes/electrification_september2014
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