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A Comparable Method for Benchmarking the Reliability Performance of Electric Utilities
Dan Kowalewski630-437-2905
IEEE PES 2002 Summer Meeting
Chicago, Illinois
Palmer House Hilton – Private Dining Room 9
Monday, July 22, 2002 – 2:00 to 5:00 PM
2
Overview
Criteria and Desired Elements Analysis
– Approach– Alternatives Considered– Proposed Application Rules– Calculation Specifics– Analysis Results
Conclusions
3
Event Criteria
Create Event Exclusion Criteria
– Facilitates Consistent Exclusions
– Allows “Fair” Benchmarking
– Provides Information to Understand Performance Trends
– Repeatability of Results
4
Desired Elements
Has Clear Rules for Application and Exclusion Removes Subjectivity Scales to Various Sized Utilities Removes Outlying Events Removes Major Weather Variability Allows Trends to Appear Balances Operational Concerns
– Frequency– Duration
Allows for Consistent Results Ease of Calculation
5
Analysis: Approach
Compare Proposed Methods to Understand– Consistency and Understandability– Differences of Exclusions– Impacts on Different Sized Companies– Variability of Results
A Great Deal of Confusion Initially
– Methodology and Calculation Approach was Not Clear 3 Years vs 5 Years of Historic Data Log vs Non-Log Data Basis Unclear: SAIDI, SAIFI, Customer Minutes
– Had to Apply Data to Understand
Traded Methodology and Results– Ensures Consistent Application– Expanded Understanding with Broader Data Set
6
Analysis: Alternatives Considered
Traditional 10% IEEE Definition– ComEd Region– ComEd– PECO
Bootstrap– 3 Year Historic
– 5 Year Historic
2.5 or 3 Beta (SAIDI per Day)– 3 Year Historic– 5 Year Historic
6 Beta (SAIDI per Day)
Other Analysis
– SAIDI per Calendar Day Start Time of Interruption Customer Interruption Minutes Experienced per Day Rolling 24 Hour Window
7
Alternative Comparison
Scala
bilit
yR
emov
es O
utlie
rs
Rem
oves
Wea
ther
Var
iabi
lity
Allo
ws
Tren
ding
Bal
ance
s D
urat
ion
Bal
ance
s Fr
eque
ncy
Cle
ar R
ules
for E
xclu
sion
Ease
of C
alcu
latio
n
Rem
oves
Sub
ject
ivity
10% Sys/Region x x x
Boot Strap x x x x x
2.5 or 3 Beta x x x x ! x x x x x
6 Beta x x x
8
ComEd Major Event Days
METHOD 1998 1999 2000 2001
Exelon Energy 11 8 10 16
10% Regional 3 0 2 0
10% System 2 0 0 0
Bootstrap 7 2 3 0
3 Beta (SAIDI / Day) 10 3 5 0
3 Beta (SAIDI / Day) 10 2 6 0
3 Beta (SAIDI / Day) 17 4 11 06 Beta (SAIDI / Day) 0 0 0 0
Hypothetical Application of 1998 - 2001 Threshold Values
*
* * *
* Based On Outage Start Date* * Customer Interruption Minutes by Calendar Day
* *
* * * Based on 24 hour rolling customer outages
9
ComEd Major Event Days
METHODExelon Energy10% Regional10% System
Beta (SAIDI / Day) 2.5 3 2.5 3 2.5 3 2.5 3Major Event Days 15 10 6 3 7 5 6 0
6 Beta (SAIDI / Day) 0 0 0 0
2000 200111 8 10 16
1998 1999
Hypothetical Application of 1998 - 2001 Threshold Values
3 02 0
2 00 0
*
* Based On Outage Start Date
10
3 Beta SAIDI Day -Threshold Calculation
IEEE data (all outages > 5minutes) Five years of most recent historic SAIDI per day data Take the log of SAIDI per day values Calculate the mean Calculate the population standard deviation Calculate the mean plus 3 times the standard deviation Convert back to SAIDI per day values by taking the exponential
of the calculated mean plus 3 times the standard deviation number
Results in a Threshold Exclusion value– Threshold value is applied to the year following the five-year data
analysis period– All days with SAIDI greater than or equal to the calculated
Threshold value are considered Major Event Days
11
8.13
9.25
7.27
8.308.51
7.07
7.50
8.46
5.25
8.88
5.00
5.50
6.00
6.50
7.00
7.50
8.00
8.50
9.00
9.50
10.00
1995 1996 1997 1998 1999 2000 2001 2002
YEAR
SA
IDI(
MIN
) P
ER
DA
Y PECO
COMED
Thresholds of Daily SAIDI (3 Year Rolling)
12
Thresholds of Daily SAIDI (5 Year Rolling)
7.53
8.45
7.77
7.06
7.70
6.07
8.087.78
7.97
8.58
5.93
5.00
5.50
6.00
6.50
7.00
7.50
8.00
8.50
9.00
9.50
10.00
1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
YEAR
SA
IDI(
MIN
) P
ER
DA
Y
PECO
COMED (4 yr average)
13
Variability of Thresholds
ComEd & PECO2.5 and 3 Beta versus Bootstrap Daily SAIDI Thresholds
0
5
10
15
20
25
30
35
40
45
50
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003
SA
IDI(
MIN
) P
ER
DA
Y
ComEd Bootstrap 1 - 4 yrs
ComEd 3 Beta 1 - 4 yrs
PECO 3 Beta 5 yrs
PECO Bootstrap 5 yrs
ComEd 2.5 Beta 1 - 4yrs
PECO 2.5 Beta 5 yrs
14
SAIDI/Day Thresholds5 yrs of Data
0
2
4
6
8
10
12
14
16
18
20
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003
SA
IDI(M
IN) P
ER D
AY
SAIDI/Day Thresholds3 yrs of Data
0
2
4
6
8
10
12
14
16
18
20
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003
SA
IDI(
MIN
) P
ER
DA
Y
Bootstrap Thresholds can be highly volatile, especially with few years of data (the saturation effect).
PECO - Variability of Thresholds
3 Beta
Bootstrap
Bootstrap
3 Beta
15
ComEd Daily SAIDI (1998 - 2001)
ComEd Daily SAIDI (1998-2001)
07/31/99
07/30/9907/19/98
06/18/98 04/08/0003/10/98
05/28/9806/26/98
09/07/98
08/24/98
11/10/98
03/09/98
09/11/00
05/18/0008/06/00
05/08/00
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
110.0
120.0
130.0
140.0
150.0
160.0
170.0
180.0
190.0
200.0
Date
SAID
I
Non-Storm Days
Storm Days
2.5 BETA = 4.3 (34 days)
3 BETA = 7.70 (18 days)
10% IEEE (System) 2 days
10% IEEE (Region) 5 days
16
ComEd Daily SAIDI (1998 - 2001)
ComEd Daily SAIDI (1998-2001)
07/31/99
07/30/99
07/21/9908/25/9807/19/9806/18/98 09/11/0004/08/00
05/08/0005/28/98
06/26/9809/07/9803/10/98
08/06/00
05/18/00
08/24/98
11/10/98
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
Date
SA
IDI
Non-Storm Days
Storm Days
(RESCALED)
2.5 BETA = 4.30 (34 days)
3 BETA = 7.70 (18 days)
10% IEEE (System) 2 days
10% IEEE (Region) 5 days
17
ComEd Daily SAIDI (1998 - 2001)
ComEd Daily SAIDI (1998-2001)
06/06/99
11/11/98
10/25/0108/09/01
07/23/01
07/22/01
06/12/01
04/07/0110/08/00
05/09/00
05/17/99
06/11/99
06/28/98
07/20/98
06/25/98
05/29/98
04/08/00
07/21/99
08/25/98
07/19/98
06/18/98
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
Date
SA
IDI
Non-Storm Days
Storm Days
(RESCALED)
2.5 BETA = 4.30 (34 days)
10% IEEE (System) 2 days
10% IEEE (Region) 5 days
3 BETA = 7.70 (18 days)
18
Conclusions
Recommend 3 Beta SAIDI per Day
Achieves Objectives– Consistent
– Facilitates Fair Benchmarking
– Provides Information to Understand Performance
Trends
– Repeatability of Results
Proven with REAL Data
