IEEE Electrification Magazine - December 2015 - 30

Table 1. The number of transformers with negative impact due to blocking.
Transformer
(E-GIC > 15 A)
with NBD

E-GIC Elevated

N-GIC Elevated

Mvar Loss Elevated

Average Transformer Elevated % Average Transformer Elevated %
Number
Number

Average Transformer Elevated %
Number

Top 20%

119

47.2

122

48.3

93

36.9

Top 33%

119

47.1

119

47.1

98

38.6

Top 66%

120

47.3

106

41.9

105

41.4

Top 100%

121

48.0

99

39.1

109

42.9

Temporary safety
grounds can
be placed on the
transformer
grounding structure
for GIC installation
without taking the
transformer out
of service.

NERC GMD benchmark event. A list
of transformers with a maximum
E-GIC greater than 15 A per phase,
referred to as 15-A E-GIC List, is
identified when the system total
E-GIC is at its maximum, then the
NBD is applied to the top top
20-100% of the identified transformers on the 15-A E-GIC list.
As shown in Table 1, when NBDs
are applied to the top 20% of transformers experiencing the highest
E-GIC (~14 transformers, which is
referred to as the top 20% blocking
thereafter) in the vulnerable transformer list, the E-GIC in 119 transformers increases, and the N-GICs in
122 transformers are elevated, which accounts for 47% and
48%, respectively, of the total 253 transformers in the GIC
system model.

Figure 9(a) and (b) shows the
percentages of system E-GIC and
N-GIC, respectively, for various
percentage blockings compared to
those in the no-blocking base case for
the rotating benchmark geoelectric
field. With 100% blocking, the average
E-GIC reduction is less than 20%, while
the N-GIC reduction achieves a little
more than 40%.
The blocking performance for
reactive power loss reduction is
illustrated in Figure 10. For the
storm directions when the system
total Mvar loss is at its minimum
(i.e., about 60° and 240°), the NBDs
achieve the lowest percentage
Mvar loss reduction. For example, there is almost no
effect at all on reducing the system Mvar loss in the 20%
blocking case.

With Blocking
120

100

100

80

80

N-GIC (%)

E-GIC (%)

With Blocking
120

60
40

20% Blocking
33% Blocking
66% Blocking
100% Blocking

20
0

0

50

100

150

120

250

300

60
40

20% Blocking
33% Blocking
66% Blocking
100% Blocking

20
350

0

0

50

100

150

120

Storm Direction (°)

Storm Direction (°)

(a)

(b)

Figure 9. The percentages of total (a) E-GIC and (b) N-GIC against storm direction for various blocking scenarios.

30

I E E E E l e c t r i f i cati o n M agaz ine / december 2015

250

300

350



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