IEEE Electrification Magazine - December 2015 - 33

The design review requirements are extensive and include a
detailed review of the GIC design. On the other hand, some of
the old transformers with lead structures or flux shields most
susceptible to stray flux heating have been identified and
modified through the years.
Furthermore, AEP has specified fiberoptic probes to measure hot-spot temperatures inside dozens of EHV transformers ordered from several vendors.
For instance, one such specification
includes total of 12 fiber probes, with two
each at the hottest spot of each winding
(series, common, and tertiary) and core,
and one each at the hottest spot of the
low-voltage tap lead, tie-plate, top yoke
clamp, and bottom yoke clamp. These
measured temperatures will be correlated with other GMD measurements or
can be used to validate the transformer
thermal assessment calculations.

xx
enhancing new EHV transformer specifications by

quantifying GIC current withstand capacity.
With the GMD monitoring system and the GMD
operating procedure in place, together with enhanced EHV
transformer GIC specifications, no
foreseeable GMD scenarios would
result in widespread transformer
failures at AEP. AEP will continue
collaborating with the industry to share
knowledge and mitigate the risks of
potential GMD impacts.

AEP will continue
collaborating with
the industry to share
knowledge and
mitigate the risks of
potential GMD
impacts.

Enhanced Spare Transformer Program
By standardizing transformer ratings for each voltage level,
AEP is able to greatly simplify transformer spare requirements
and further enhance interchangeability for its transformer
fleet. AEP also maintains an ample supply of spare transformers, and it would take nearly simultaneous failure on the order
of 20% of the EHV transformer population to cause significant
risk to the system. At the same time, the AEP asset renewal
program frees up more EHV transformers, with the best of the
retired transformers retained as emergency spares.

conclusions
For the past several years, AEP has been taking a comprehensive approach in monitoring, modeling, and mitigating
potential GMD impacts, specifically
xx
installing permanent GIC/harmonics monitors to
detect and evaluate GMD impacts at multiple locations
xx
developing/refining the operating procedure and visualization tools to assist operators to take appropriate
actions based on GMD monitoring data consisting of
NOAA GMD alerts, GIC levels, harmonics, transformer
reactive power losses, transformer temperature rises, etc.
xx
collaborating with the NERC, the EPRI, power system
software vendors, and others to develop GIC simulation
models and conducting independent GMD study of AEP
transmission grid to identify areas of greatest potential
vulnerability for transformer impacts
xx
working with transformer vendors to evaluate the GIC
impacts on selected in-service and new EHV transformers
xx
developing a GMD data reporting and notification tool
to automatically generate GMD event reports and to
facilitate postevent correlation analysis, GIC model
validation, and transformer health evaluation

Acknowledgments

We gratefully acknowledge the AEP
GIC Team (Zhenhua Wang, Mike Spurlock, Frank Fowler, Yiyan Xue, etc.) for
their valuable contributions on AEP
GIC system simulations and the GMD
monitoring system installations and
the ABB Team (Ramsis Girgis and
Kiran Vedante) for their consultation on performing transformer GIC thermal assessment.

For Further reading
"Effects of geomagnetic disturbances on the Bulk Power System," NERC 2012 Special Reliability Assessment Interim Rep.,
Feb. 2012.
Transmission System Planned Performance during Geomagnetic Disturbances, NERC Reliability Standards, TPL-007-1,
Dec. 17, 2014.
NERC GMD Standard Draft Team, "Benchmark geomagnetic
disturbance event description," White Paper, Dec. 2014.
NERC GMD Standard Draft Team, "Transformer thermal
impact assessment," Dec. 2014.
NERC GMD Task Force, "Application guide for computing
geomagnetically-induced current in the Bulk Power System,"
Dec. 2013.
R. Girgis and K. Vedante, "Effect of GIC on power transformers and power systems," presented at the IEEE T&D Conf.,
Orlando, FL, May 2012.

biographies
Qun Qiu (qqiu@aep.com) is with American Electric
Power. He is a member of North American Electric Reliability Corporation (NERC) Geomagnetic Disturbance
(GMD) Standard Draft Team and NERC GMD Task Force
and the chair of the IEEE Power System Relaying Committee Working Group K17-GMD Impacts on Protection Systems.
Jeffery A. Fleeman (jafleeman@aep.com) is the director
of advanced transmission studies and technologies at
American Electric Power.
David R. Ball (drball@aep.com) is the director of transmission protection and control engineering at American
Electric Power.

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

33



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
IEEE Electrification Magazine - December 2015 - 2
IEEE Electrification Magazine - December 2015 - 3
IEEE Electrification Magazine - December 2015 - 4
IEEE Electrification Magazine - December 2015 - 5
IEEE Electrification Magazine - December 2015 - 6
IEEE Electrification Magazine - December 2015 - 7
IEEE Electrification Magazine - December 2015 - 8
IEEE Electrification Magazine - December 2015 - 9
IEEE Electrification Magazine - December 2015 - 10
IEEE Electrification Magazine - December 2015 - 11
IEEE Electrification Magazine - December 2015 - 12
IEEE Electrification Magazine - December 2015 - 13
IEEE Electrification Magazine - December 2015 - 14
IEEE Electrification Magazine - December 2015 - 15
IEEE Electrification Magazine - December 2015 - 16
IEEE Electrification Magazine - December 2015 - 17
IEEE Electrification Magazine - December 2015 - 18
IEEE Electrification Magazine - December 2015 - 19
IEEE Electrification Magazine - December 2015 - 20
IEEE Electrification Magazine - December 2015 - 21
IEEE Electrification Magazine - December 2015 - 22
IEEE Electrification Magazine - December 2015 - 23
IEEE Electrification Magazine - December 2015 - 24
IEEE Electrification Magazine - December 2015 - 25
IEEE Electrification Magazine - December 2015 - 26
IEEE Electrification Magazine - December 2015 - 27
IEEE Electrification Magazine - December 2015 - 28
IEEE Electrification Magazine - December 2015 - 29
IEEE Electrification Magazine - December 2015 - 30
IEEE Electrification Magazine - December 2015 - 31
IEEE Electrification Magazine - December 2015 - 32
IEEE Electrification Magazine - December 2015 - 33
IEEE Electrification Magazine - December 2015 - 34
IEEE Electrification Magazine - December 2015 - 35
IEEE Electrification Magazine - December 2015 - 36
IEEE Electrification Magazine - December 2015 - 37
IEEE Electrification Magazine - December 2015 - 38
IEEE Electrification Magazine - December 2015 - 39
IEEE Electrification Magazine - December 2015 - 40
IEEE Electrification Magazine - December 2015 - 41
IEEE Electrification Magazine - December 2015 - 42
IEEE Electrification Magazine - December 2015 - 43
IEEE Electrification Magazine - December 2015 - 44
IEEE Electrification Magazine - December 2015 - 45
IEEE Electrification Magazine - December 2015 - 46
IEEE Electrification Magazine - December 2015 - 47
IEEE Electrification Magazine - December 2015 - 48
IEEE Electrification Magazine - December 2015 - 49
IEEE Electrification Magazine - December 2015 - 50
IEEE Electrification Magazine - December 2015 - 51
IEEE Electrification Magazine - December 2015 - 52
IEEE Electrification Magazine - December 2015 - 53
IEEE Electrification Magazine - December 2015 - 54
IEEE Electrification Magazine - December 2015 - 55
IEEE Electrification Magazine - December 2015 - 56
IEEE Electrification Magazine - December 2015 - 57
IEEE Electrification Magazine - December 2015 - 58
IEEE Electrification Magazine - December 2015 - 59
IEEE Electrification Magazine - December 2015 - 60
IEEE Electrification Magazine - December 2015 - 61
IEEE Electrification Magazine - December 2015 - 62
IEEE Electrification Magazine - December 2015 - 63
IEEE Electrification Magazine - December 2015 - 64
IEEE Electrification Magazine - December 2015 - Cover3
IEEE Electrification Magazine - December 2015 - Cover4
http://www.nxtbook.com/nxtbooks/pes/electrification_december2019
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
http://www.nxtbookMEDIA.com