# IEEE Power & Energy Magazine - May/June 2018 - 47

```may/june 2018

scenarios. the red line in the middle connects the median
(normalized) values of the nine years within each group.
taking the first three-year training period (2008-2010) for
example, each of the corresponding nine dots represents the
predicted saiDi values if those three years were experiencing
the same weather as one of the nine-year period (2008-2016).
the red dot in the middle is the median value that can be used
to indicate the daily operations during this three-year period
normalized based on nine years of weather history. overall, the
slopes from the dashed lines range from −0.1 to −1 min/year. in
other words, given the same weather from any year of the nineyear period, the weather-related saiDi of this utility shows a
decreasing trend from 2008 to 2016. the normalized curve
has a slope of −0.7 min/year, indicating weather-normalized
improvement of the weather-related saiDi at this lDc.
have utility operations been improving over the last nine
years? at this stage, we have answered the question for the
weather-related outages, which assemble the largest share of the
total saiDi for the small lDc in this case study. since weather

Calibration Results of
Daily SAIDI (in Minutes) Prediction Model
25
20
15
10
5

2008 2009 2010 2011 2012 2013 2014 2015 2016
Actual (Slope = -0.8 min/year)
Predicted (Slope = -0.4 min/year)

figure 3. The calibration results of the model that predicts
the weather-related daily SAIDI.

A Probabilistic View of
Weather-Related SAIDI (in Minutes)
25
20
15
10

-2
01
6

20
14

-2
01
5

20
13

-2
01
4

20
12

-2
01
3

20
11

-2
01
2

-2
01
1

20
10

20
09

-2
01
0

5

20
08

variables: temperature, dew-point temperature, heat index,
feels-like temperature (the combination of the heat index
and the wind-chill factor), wind chill, wind-chill energy, wet
bulb temperature, relative humidity, wind speed, speed gust,
and precipitation. to match them up with the daily saiDi
data, we convert the original records of the first ten weather
variables to daily values by taking the maximum, mean, and
minimum of the hourly values. for precipitation, we sum up
the hourly records by day to obtain the daily precipitation.
in addition, we include four dummy variables to describe the
weather events of the day, such as fog, rain, snow, and thunderstorm. in total, we use 37 candidate-independent variables to build a model that predicts the dependent-variable,
weather-related daily saiDi.
We use the regression procedure of the sas stat package to conduct the model selection process. after trying several different options, such as forward selection, backward
elimination, stepwise, maximum R 2 improvement, adjusted
R 2 selection, and mallows' C p selection, we select the following 11 variables: maximum dew-point temperature, minimum dew-point temperature, daily precipitation, average
relative humidity, average speed gust, minimum speed gust,
thunderstorm, maximum wind chill, average wind chill, average wind speed, and minimum wind speed.
calibrating this model using the 3,268 days of historical
data, we obtain predicted values of the weather-related daily
saiDi for the lDc. figure 3 shows the annual aggregates
of the actual and predicted saiDi values. Both saiDi
curves show a decreasing trend, with the slope of −0.8 and
−0.4 min/year for the actual and predictive saiDi, respectively. as mentioned earlier, the slope of the actual saiDi
curve indicates the trend of customer experience regarding
interruptions rather than the improvement of daily operations.
alternatively, one could assume that the lDc has engaged in
relatively consistent daily operational practices over the nineyear period. under this assumption, the decreasing slope
indicates that the weather, rather than improved operational
practices, has contributed to the trend of increased reliability
over the nine-year period.
however, maintaining constant daily operational practices
over a long period (i.e., nine years) is quite a strong assumption. Whether the utility has improved its daily operations is
the question we have been trying to answer. to further investigate this issue, we conduct a simulation to offer a probabilistic view of the weather-related saiDi. We first shrink the
training period to three years. We then fit the same 11-variable
model using the three-year training data and predict the daily
saiDi values of the nine-year period. By repeating this training window on a rolling basis, we can obtain seven groups
of predicted saiDi profiles, where each group includes nine
years of predicted daily saiDi values representing three years
of operational practice under nine different years of weather
scenarios from 2008 to 2016. figure 4 shows the annual
aggregates of the predicted saiDi values that are caused by
weather. the nine dashed lines represent the nine weather

figure 4. A probabilistic view of the weather-related SAIDI
over a nine-year period.
ieee power & energy magazine

47

```

# Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - May/June 2018

Contents
IEEE Power & Energy Magazine - May/June 2018 - Cover1
IEEE Power & Energy Magazine - May/June 2018 - Cover2
IEEE Power & Energy Magazine - May/June 2018 - Contents
IEEE Power & Energy Magazine - May/June 2018 - 2
IEEE Power & Energy Magazine - May/June 2018 - 3
IEEE Power & Energy Magazine - May/June 2018 - 4
IEEE Power & Energy Magazine - May/June 2018 - 5
IEEE Power & Energy Magazine - May/June 2018 - 6
IEEE Power & Energy Magazine - May/June 2018 - 7
IEEE Power & Energy Magazine - May/June 2018 - 8
IEEE Power & Energy Magazine - May/June 2018 - 9
IEEE Power & Energy Magazine - May/June 2018 - 10
IEEE Power & Energy Magazine - May/June 2018 - 11
IEEE Power & Energy Magazine - May/June 2018 - 12
IEEE Power & Energy Magazine - May/June 2018 - 13
IEEE Power & Energy Magazine - May/June 2018 - 14
IEEE Power & Energy Magazine - May/June 2018 - 15
IEEE Power & Energy Magazine - May/June 2018 - 16
IEEE Power & Energy Magazine - May/June 2018 - 17
IEEE Power & Energy Magazine - May/June 2018 - 18
IEEE Power & Energy Magazine - May/June 2018 - 19
IEEE Power & Energy Magazine - May/June 2018 - 20
IEEE Power & Energy Magazine - May/June 2018 - 21
IEEE Power & Energy Magazine - May/June 2018 - 22
IEEE Power & Energy Magazine - May/June 2018 - 23
IEEE Power & Energy Magazine - May/June 2018 - 24
IEEE Power & Energy Magazine - May/June 2018 - 25
IEEE Power & Energy Magazine - May/June 2018 - 26
IEEE Power & Energy Magazine - May/June 2018 - 27
IEEE Power & Energy Magazine - May/June 2018 - 28
IEEE Power & Energy Magazine - May/June 2018 - 29
IEEE Power & Energy Magazine - May/June 2018 - 30
IEEE Power & Energy Magazine - May/June 2018 - 31
IEEE Power & Energy Magazine - May/June 2018 - 32
IEEE Power & Energy Magazine - May/June 2018 - 33
IEEE Power & Energy Magazine - May/June 2018 - 34
IEEE Power & Energy Magazine - May/June 2018 - 35
IEEE Power & Energy Magazine - May/June 2018 - 36
IEEE Power & Energy Magazine - May/June 2018 - 37
IEEE Power & Energy Magazine - May/June 2018 - 38
IEEE Power & Energy Magazine - May/June 2018 - 39
IEEE Power & Energy Magazine - May/June 2018 - 40
IEEE Power & Energy Magazine - May/June 2018 - 41
IEEE Power & Energy Magazine - May/June 2018 - 42
IEEE Power & Energy Magazine - May/June 2018 - 43
IEEE Power & Energy Magazine - May/June 2018 - 44
IEEE Power & Energy Magazine - May/June 2018 - 45
IEEE Power & Energy Magazine - May/June 2018 - 46
IEEE Power & Energy Magazine - May/June 2018 - 47
IEEE Power & Energy Magazine - May/June 2018 - 48
IEEE Power & Energy Magazine - May/June 2018 - 49
IEEE Power & Energy Magazine - May/June 2018 - 50
IEEE Power & Energy Magazine - May/June 2018 - 51
IEEE Power & Energy Magazine - May/June 2018 - 52
IEEE Power & Energy Magazine - May/June 2018 - 53
IEEE Power & Energy Magazine - May/June 2018 - 54
IEEE Power & Energy Magazine - May/June 2018 - 55
IEEE Power & Energy Magazine - May/June 2018 - 56
IEEE Power & Energy Magazine - May/June 2018 - 57
IEEE Power & Energy Magazine - May/June 2018 - 58
IEEE Power & Energy Magazine - May/June 2018 - 59
IEEE Power & Energy Magazine - May/June 2018 - 60
IEEE Power & Energy Magazine - May/June 2018 - 61
IEEE Power & Energy Magazine - May/June 2018 - 62
IEEE Power & Energy Magazine - May/June 2018 - 63
IEEE Power & Energy Magazine - May/June 2018 - 64
IEEE Power & Energy Magazine - May/June 2018 - 65
IEEE Power & Energy Magazine - May/June 2018 - 66
IEEE Power & Energy Magazine - May/June 2018 - 67
IEEE Power & Energy Magazine - May/June 2018 - 68
IEEE Power & Energy Magazine - May/June 2018 - 69
IEEE Power & Energy Magazine - May/June 2018 - 70
IEEE Power & Energy Magazine - May/June 2018 - 71
IEEE Power & Energy Magazine - May/June 2018 - 72
IEEE Power & Energy Magazine - May/June 2018 - 73
IEEE Power & Energy Magazine - May/June 2018 - 74
IEEE Power & Energy Magazine - May/June 2018 - 75
IEEE Power & Energy Magazine - May/June 2018 - 76
IEEE Power & Energy Magazine - May/June 2018 - 77
IEEE Power & Energy Magazine - May/June 2018 - 78
IEEE Power & Energy Magazine - May/June 2018 - 79
IEEE Power & Energy Magazine - May/June 2018 - 80
IEEE Power & Energy Magazine - May/June 2018 - 81
IEEE Power & Energy Magazine - May/June 2018 - 82
IEEE Power & Energy Magazine - May/June 2018 - 83
IEEE Power & Energy Magazine - May/June 2018 - 84
IEEE Power & Energy Magazine - May/June 2018 - 85
IEEE Power & Energy Magazine - May/June 2018 - 86
IEEE Power & Energy Magazine - May/June 2018 - 87
IEEE Power & Energy Magazine - May/June 2018 - 88
IEEE Power & Energy Magazine - May/June 2018 - 89
IEEE Power & Energy Magazine - May/June 2018 - 90
IEEE Power & Energy Magazine - May/June 2018 - 91
IEEE Power & Energy Magazine - May/June 2018 - 92
IEEE Power & Energy Magazine - May/June 2018 - 93
IEEE Power & Energy Magazine - May/June 2018 - 94
IEEE Power & Energy Magazine - May/June 2018 - 95
IEEE Power & Energy Magazine - May/June 2018 - 96
IEEE Power & Energy Magazine - May/June 2018 - 97
IEEE Power & Energy Magazine - May/June 2018 - 98
IEEE Power & Energy Magazine - May/June 2018 - 99
IEEE Power & Energy Magazine - May/June 2018 - 100
IEEE Power & Energy Magazine - May/June 2018 - 101
IEEE Power & Energy Magazine - May/June 2018 - 102
IEEE Power & Energy Magazine - May/June 2018 - 103
IEEE Power & Energy Magazine - May/June 2018 - 104
IEEE Power & Energy Magazine - May/June 2018 - 105
IEEE Power & Energy Magazine - May/June 2018 - 106
IEEE Power & Energy Magazine - May/June 2018 - 107
IEEE Power & Energy Magazine - May/June 2018 - 108
IEEE Power & Energy Magazine - May/June 2018 - Cover3
IEEE Power & Energy Magazine - May/June 2018 - Cover4
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091020
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070820
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050620
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030420
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010220
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111219
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091019
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070819
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050619
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030419
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010219
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111218
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091018
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070818
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050618
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030418
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010218
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111217
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091017
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070817
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050617
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030417
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010217
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111216
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091016
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070816
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050616
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030416
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010216
https://www.nxtbook.com/nxtbooks/ieee/powerenergy_010216
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111215
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091015
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070815
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050615
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030415
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010215
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111214
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091014
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070814
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050614
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030414
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010214
https://www.nxtbookmedia.com