AC Circuit Outage rates, Durations and Availability by Voltage Class Availability Data... · 2014-08-14 · Outage Rates, Durations and Element Availability: AC circuit Automatic

Outage Rates, Durations and Element g ,Availability: AC circuit Automatic and Non-Automatic Outages by Voltage ClassAutomatic Outages by Voltage Class

Statistical Analysis Based on 2010-2013 TADS dataSvetlana Ekisheva Senior StatisticianSvetlana Ekisheva, Senior Statistician August 7, 2014

2010-2013 TADS: AC Circuit Counts and Miles by Voltage Class

9%

2%

AC circuits by Voltage Class (TADS 2010‐2013)

66%

24%

AC circuit miles by Voltage Class (TADS 2010‐2013)

51%

15%5%

29%

RELIABILITY | ACCOUNTABILITY2

200‐299 kV 300‐399 kV 400‐599 kV 600‐799 KV

Average Annual Automatic Outage Rateper Line: Testing Homogeneity

1.20

Annual Outage Rate per Line by Voltage ClassAutomatic vs. Sustained Outages (2010‐2013)

0.50

0.77 0.76

0.99

0.60

0 420.51

0.580.60

0.80

1.00

1.20

0.300.42

0.35

0.00

0.20

0.40

200 299 kV 300 399 kV 400 599 kV 600 799 KV All AC i i

All pair-wise annual outage rate differences between

200‐299 kV 300‐399 kV 400‐599 kV 600‐799 KV All AC circuits

Automatic Outages Sustained

All pair wise annual outage rate differences between voltage classes are statistically significant except• 300-399 kV and 400-599 kV (All Automatic outages)• 400-599 kV and 600-799 kV (Automatic Sustained)


400 599 kV and 600 799 kV (Automatic Sustained)

Average Annual Automatic Outage Rate per 100 Miles by Voltage Class (2010-2013)

Annual Outage Rate per 100 Miles by Voltage ClassA t ti S t i d (2010 2013)

2.23 2.202.06

2 00

2.50

Automatic vs. Sustained (2010‐2013)

1.48

1.161.31

1.201.00

1.201.50

2.00

0.68

0.50

1.00

0.00200‐299 kV 300‐399 kV 400‐599 kV 600‐799 KV All AC circuits

Automatic Outages Sustained


g

Average Annual Outage Ratesper Line by Voltage Class (2010-2013)

2 7

TADS AC Circuits: Annual Outage Rates per Line (2010‐2013)

0.6

2 9

1.8

12.0

2.1

13.0

2.7

600 799 KV

All AC circuits

0 8

1.0

1.7

2.9

2.53.2

400‐599 kV

600‐799 KV

0.8

0.8

1.51.7

2.5

300‐399 kV

0.51.92.0

2.5

0 00 2 00 4 00 6 00 8 00 10 00 12 00 14 00

200‐299 kV


0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00

All Outages Non‐Automatic Planned Operational Automatic Sustained

Average Annual Outage Ratesper 100 Miles by Voltage Class (2010-2013)

TADS AC Circuits: Annual Outage Rates per 100 Miles (2010‐2013)

2.16.2

14.1

7.4

15.2

9.5

All AC circuits

1 5

1.2

3.3

3.4

4.8

14.1

6.3

400‐599 kV

600‐799 KV

2.2

1.5

4.34.8

7.0

300‐399 kV

2.28.5

9.011.3

0 0 2 0 4 0 6 0 8 0 10 0 12 0 14 0 16 0

200‐299 kV


0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0

All Outages Non‐Automatic Planned Operational Automatic Sustained

Average Outage Duration by Voltage Class (2010-2013)

Average Outage Duration (in Hours) b V lt Cl (2010 2013)

87 8796 101

109

100

120

by Voltage Class (2010‐2013)

87 87

39

6471 74

68

50 4860

80

30 3339

15

0

20

40


Automatic Sustained Planned Operational


Average Annual Non-Operational Time per Lineby Voltage Class (2010-2013)

Average Annual Non‐Operational Time per Line (in Days) by Voltage Class (2010 2013)

16.416.0

18.0

(in Days) by Voltage Class (2010‐2013)

7 5

10.5

10.0

12.0

14.0

5.8

7.56.8

4.0

6.0

8.0

0.0

2.0



Mean Time of Continuous Operationby Voltage Class (2010-2013)

Mean Time of Continuous Operation (Days) for an AC Circuit by Voltage Class (TADS 2010‐2013)

142 144

110

131

120

140

160

60

80

100

27

0

20

40

60

All MTOCOs by voltage class are statistically distinct except for 200-299 kV and 300 399 kV lines



299 kV and 300-399 kV lines

Mean Time of Continuous OperationExcluding Non-Automatic Outages

Mean Time of Continuous Operation excluding Non‐Automatic Outages for an AC circuit

698

587700

800

by Voltage Class (in Days)

453 456387

587

400

500

600

0

100

200

300

All MTOCOs between voltage classes are statistically distinct except for 300 399 kV and 400 599 kV lines



for 300-399 kV and 400-599 kV lines

AC Circuit Unavailabilityby Voltage Class (2010-2013)

AC Circuit Unavailability by Outage Type by Voltage Class (2010‐2013)

0.6%

3 5%

4.0%

4.5%

5.0%

0 2%0.4%

1.6%

0.2%

0.5%

0 2%2.0%

2.5%

3.0%

3.5%

1.4% 1.6% 1.9%2.4%

1.5%

0.1%0.2% 0.2%0.1%

0.2%

0 0%

0.5%

1.0%

1.5%

0.0%200‐299 kV 300‐399 kV 400‐599 kV 600‐799 KV All AC circuits

AC circuit Unavailability due to Sustained outages

AC circuit Unavailability due to Operational outages


y p g

AC circuit Unavailability due to Planned outages

AC Circuit Availabilityby Voltage Class (2010-2013)

Transmission AC Circuit Availability by Voltage Class (TADS 2010 2013)

98.4%

97.9%98.1%98.5%

99.0%

by Voltage Class (TADS 2010‐2013)

97.1%

96 5%

97.0%

97.5%

98.0%

95.5%

95.0%

95.5%

96.0%

96.5%

94.0%

94.5%

95.0%



AC Circuit Unavailability by Year

AC Circuit Unavailability by Year( )

2.50%

(TADS 2010‐2013)

0.15%0.20%

0.24%0.15%0.17%

0.21%0.12%

0.13%1.50%

2.00%

1.35% 1.53% 1.67% 1.52%0.50%

1.00%

0.00%2010 2011 2012 2013

Planned outages Operational outages Automatic sustained outages


Planned outages Operational outages Automatic sustained outages

200-299kV Lines: Unavailability by Month








AC Circuits: Unavailability by Month


AC Circuits: Availability by Month


AC Circuit vs. TransformerAvailability by Year

TADS Element Availability by Year

98.3%

98.1%98.0%

98.2%

98 0%98.2%98.4%98.6%

97.6%

97 1%97.2%

97.6%

97.4%97.6%97.8%98.0%

97.1%

96.6%96.8%97.0%97.2%

96.4%2010 2011 2012 2013

AC circuit Availability Transformer Availability


Outage Rates: Summary 1

• From 2010 to 2013, TADS contains records of 79,887 AC circuit outagesAC circuit outages 17,428 (22% of the total) are automatic outages; 10,174 (13% of the total) are sustained outages

52,632 (66% of the total) are planned outages and 9,827 (12% of the total) are operational outages

h l li i• The average annual outage rate per line is 2.7.

•By voltage class, the annual outage rate increases with lt l ith th ll t t t f 2 5voltage class, with the smallest outage rate of 2.5

outages per a 200‐299 kV line and the biggest outage rate of 13 0 outages per a 600‐799 kV line


rate of 13.0 outages per a 600 799 kV line

Outage Rates: Summary 2

•Unlike other voltage classes, the operational outage rate for a 600‐799 kV line is 3 times greater than therate for a 600 799 kV line is 3 times greater than the planned outage rate

•About 89% of all operational outages in the 600‐799 kVAbout 89% of all operational outages in the 600 799 kV Voltage class have the operational cause code System Voltage Limit Mitigation


Outage Durations: Summary

• From 2010 to 2013, combined AC circuit outage duration was 543.5 element‐years: 45.8 element‐years (8% of the total duration) was the total duration of automatic sustained outages

443.6 element‐years (82% of the total) was due to planned outages and 54.1 element‐years (10% of the total) due to operational outages

• The average sustained outage duration over all voltage classes was 39 hours the planned outage duration was 74 hours andwas 39 hours, the planned outage duration was 74 hours, and the operational outage duration 48 hours. There were significant differences in durations by outage types among the l lvoltage classes.

• The annual non‐operational time per line was the largest for 600‐799 kV lines (about 16 days) and the shortest for the 200‐


600 799 kV lines (about 16 days) and the shortest for the 200299 lines (6 days), with the overall average of 7 days a year

AC Circuit Availability: Summary

• Mean Time of Continuous Operation per line was on average 131 days y Longest MTOCOs were for a 200‐299 kV line (142 days) and 300‐399 kV line (144 days) which are statistically equal

The smallest MTOCO (27 days) was for a 600‐799 kV lineThe smallest MTOCO (27 days) was for a 600 799 kV line

• For the last 4 years, overall AC circuit availability remained close to 98% (the lowest of 97.97% was in 2012)

• AC circuit unavailability was on average 1.9% with the largest unavailability of 4.5% for the 600‐799 kV voltage class

• 82% of overall AC circuit unavailability is due to planned• 82% of overall AC circuit unavailability is due to planned outages.




2010-2013 TADS Data

AC circuit Outages (2010‐2013) 200‐299 kV 300‐399 kV 400‐599 kV 600‐799 KV All AC circuitsNumber of lines 19144.0 7040.1 2511.4 451.0 29146.5Total miles 430873.4 247430.1 128345.9 38443.1 845092.5A li l th ( il ) 22 5 35 1 51 1 85 2 29 0Average line length (miles) 22.5 35.1 51.1 85.2 29.0Number of Automatic Outages 9630 5446 1905 447 17428

Sustained 5654 2976 1283 261 10174Momentary 3976 2470 622 186 7254

Total Automatic Outage Duration (Years) 19.1 11.3 12.7 2.6 45.8Average Sustained Outage Duration (Hours) 29.7 33.4 86.8 86.9 39.4Average Sustained Outage Duration (Hours) 29.7 33.4 86.8 86.9 39.4Annual Automatic Outage Rate per line 0.50 0.77 0.76 0.99 0.60

Sustained 0.30 0.42 0.51 0.58 0.35Number of Non‐Automatic Outages 38917 11978 6154 5410 62459

Planned 36533 10573 4202 1324 52632Operational 2384 1405 1952 4086 9827

Total Non‐Automatic Outage Duration (Years) 287.0 133.6 59.5 17.7 497.7Planned 268.4 116.1 48.3 10.7 443.6

Operational 18.6 17.4 11.2 7.0 54.1Average Non‐Automatic Outage Duration (Hours) 64.6 97.7 84.7 28.7 69.8

Planned 64.4 96.2 100.8 70.8 73.8O ti l 68 2 108 6 50 1 15 0 48 3Operational 68.2 108.6 50.1 15.0 48.3

Annual Non‐Automatic Outage Rate per line 2.03 1.70 2.45 12.00 2.14Planned 1.91 1.50 1.67 2.94 1.81

Operational 0.12 0.20 0.78 9.06 0.34


2010-2013 TADS Data (continued)

AC circuit Outages (2010‐2013) 200‐299 kV 300‐399 kV 400‐599 kV 600‐799 KV All AC circuitsAC circuit Outages (2010‐2013) 200‐299 kV 300‐399 kV 400‐599 kV 600‐799 KV All AC circuitsTotal Number of Outages 48547 17424 8059 5857 79887Total Outage Duration (Years) 306.1 144.9 72.2 20.3 543.5Average Outage Duration (Hours) 55.2 72.8 78.5 30.3 59.6Average Annual Non‐Operational Time per Line (Days) 5.8 7.5 10.5 16.4 6.8Annual Total Outage Rate per line 2.54 2.47 3.21 12.99 2.74g pAC circuit Unavailability due to Sustained outages 0.1% 0.2% 0.5% 0.6% 0.2%AC circuit Unavailability due to Planned outages 1.4% 1.6% 1.9% 2.4% 1.5%AC circuit Unavailability due to Operational outages 0.1% 0.2% 0.4% 1.6% 0.2%Transmission AC Circuit Availability 98.4% 97.9% 97.1% 95.5% 98.1%Mean Time between Operations per Line (Days) 141.6 144.4 110.5 26.8 130.7

Annual Automatic Outage Rate per 100 miles 2.2 2.2 1.5 1.2 2.1Sustained 1.3 1.2 1.0 0.7 1.2

Annual Non‐Automatic Outage Rate per 100 miles 9.0 4.8 4.8 14.1 7.4Planned 8.5 4.3 3.3 3.4 6.2

Operational 0.6 0.6 1.5 10.6 1.2l l ilAnnual Total Outage Rate per 100 miles 11.3 7.0 6.3 15.2 9.5


2010-2013 TADS Data (continued)

TADS AC circuit Unavailability 2010 2011 2012 2013AC circuit Availability 98.3% 98.1% 98.0% 98.2%Transformer Availability 97.6% 97.1% 97.2% 97.6%Automatic sustained outages 0.17% 0.21% 0.12% 0.13%

Operational outages 0.15% 0.20% 0.24% 0.15%p gPlanned outages 1.35% 1.53% 1.67% 1.52%

Non‐Automatic Outages 1.50% 1.73% 1.91% 1.67%

All Outages 1.67% 1.94% 2.03% 1.80%Number of AC circuits 6975.1 7149.7 7475.1 7546.6Total hours 61101876 62631372 65661278.4 66108216Total automatic sustained outage duration (Hours) 104700.4 132150.7 79682.8 84501.9Total non‐automatic outage duration (Hours) 916359.6 1084927.1 1254195.4 1103157.6Total Operational outage duration (Hours) 91232.2 126072.6 157794.4 99188.4Total Planned outage duration (Hours) 825127.4 958854.6 1096401.0 1003969.2Total outage duration (Hours) 1021059.98 1217077.8 1333878.1 1187659.5


Statistical Methodology

• For comparison of the expected outage rates (year‐over‐year and for different voltage classes) the testing the homogeneityand for different voltage classes), the testing the homogeneity of Poisson frequencies was used

• The tests are valid under assumption of the Poisson distribution of the occurrences of outages

• For comparison of the mean times of continuous operations (MTOCO) the ratio tests for two exponential means were used(MTOCO), the ratio tests for two exponential means were used

• The tests are valid under assumption of the Poisson distribution of the occurrences of outages; and Time of Continuous Operation has the exponential distribution

• The null hypotheses on the equality of the expected outage rates and the equality of the mean times were tested at the


rates and the equality of the mean times were tested at the significance level of 0.05

Element Reliability Function

•


Reliability Calculation (Example)

•

i (d ) ( )t time (days) R(t)10 0.9320 0.8730 0 8130 0.81100 0.49365 0.08500 0 03


500 0.03

References

• P.G. Hoel. Testing the homogeneity of Poisson Frequencies. Annals of Mathematical Statistics (1945) pp 362‐368Annals of Mathematical Statistics (1945), pp. 362 368.

• L. Bain and M. Englehardt. Statistical Analysis of Reliability and Life‐Testing Models: Theory and Methods, Second Edition. CRC Press (1991)


Documents

AC Circuit Outage rates, Durations and Availability by Voltage Class Availability Data... · 2014-08-14 · Outage Rates, Durations and Element Availability: AC circuit Automatic