© 2006

Cost Effectiveness of Cost Effectiveness of Distribution AutomationDistribution Automation

Charlie WilliamsCharlie WilliamsS&C Electric CompanyS&C Electric Company

© 2006© 2006

© 2006

Reliability Improvement OptionsReliability Improvement OptionsTwo General CategoriesTwo General Categories

•• Fault PreventionFault Prevention•• Fault MitigationFault Mitigation

© 2006

Fault PreventionFault Prevention

•• Lightning protectionLightning protection•• Tree TrimmingTree Trimming•• Animal ProtectionAnimal Protection•• OthersOthers•• Can be targeted in an Can be targeted in an

integrated optimized blend integrated optimized blend of programs of programs

RELI INITIATIVES RAW CMI

-

5,000,000

10,000,000

15,000,000

20,000,000

25,000,000

30,000,000

0 100 200 300 400 500 600 700 800 900

# FeedersC

umul

ativ

e C

MI

© 2006

Fault MitigationFault Mitigation

•• Fuse Save Overcurrent ProtectionFuse Save Overcurrent Protection–– Prevents temporary branch line faults from Prevents temporary branch line faults from

becoming sustained interruptionsbecoming sustained interruptions•• Feeder Design SchemesFeeder Design Schemes

–– Main Line ReclosersMain Line Reclosers–– SwitchesSwitches–– Distributed Automation (DA) or SCADADistributed Automation (DA) or SCADA–– Switching and Restoration StrategiesSwitching and Restoration Strategies

© 2006

Why Automation or SCADA?Why Automation or SCADA?

••Improved Improved ReliabilityReliability

•• But how much improvement?But how much improvement?•• At what Cost?At what Cost?

© 2006

Predictive ReliabilityPredictive Reliability

•• Evaluates the system performance based on system Evaluates the system performance based on system design configuration and historical operating data or design configuration and historical operating data or assumptionsassumptions

N.O.

1 2 3A B C

4

Substation

1 2 3A B C

Substation

© 2006

TermsTerms

•• SBD = Solid Blade Disconnect SwitchSBD = Solid Blade Disconnect Switch•• SCADA = Remote controlled switch SCADA = Remote controlled switch –– requires requires

human input to change statehuman input to change state•• DA = Distributed Automation system with local on DA = Distributed Automation system with local on

site intelligence and communication (Intelliteam II)site intelligence and communication (Intelliteam II)

© 2006

Input ParametersInput Parameters

•• Frate = annual permanent fault rate ( Faults/mile / yr)Frate = annual permanent fault rate ( Faults/mile / yr)•• Length = total miles of main line feeder exposureLength = total miles of main line feeder exposure•• Customers = total customers served (includes Customers = total customers served (includes

customers on fused taps)customers on fused taps)•• MTTS = Mean time to switch ( varies by switch type)MTTS = Mean time to switch ( varies by switch type)•• MTTR = Mean time to repair and restore faulted MTTR = Mean time to repair and restore faulted

segmentsegment•• Segment = section of line between switching devicesSegment = section of line between switching devices

© 2006

© 2006

Reliability MeasuresReliability Measures

•• IEEE 1366 IEEE 1366 –– Standard for Reliability ReportingStandard for Reliability Reporting•• SAIDI = CMI/CSAIDI = CMI/C•• SAIFI = CI/CSAIFI = CI/C•• CAIDI = CMI/CICAIDI = CMI/CI•• CMI = Customer minutes of interruptionCMI = Customer minutes of interruption•• Outage = interruption > = 5 minutesOutage = interruption > = 5 minutes•• Momentary = interruption < 5 minutesMomentary = interruption < 5 minutes

–– Measured by MAIFI = Mi*Ci / CMeasured by MAIFI = Mi*Ci / C

© 2006

Feeder Design SchemeFeeder Design Scheme

N.O.

1 2 3

A B C

4

Substation

Segments

Switches

Tie Point

Switches can be many types:

SBD – RCL - SCADA - DA

© 2006

Feeder Design SchemesFeeder Design Schemes

•• SBD RadialSBD Radial•• RCL RadialRCL Radial•• SBD LoopSBD Loop•• RCL LoopRCL Loop•• SCADA RCL LOOPSCADA RCL LOOP•• SCADA SBD LOOPSCADA SBD LOOP•• Distributed Automation Loop (DA Loop)Distributed Automation Loop (DA Loop)

© 2006

Feeder Design Schemes Feeder Design Schemes –– Loop SBDLoop SBD

•• All Switches are SBDAll Switches are SBD•• Require local manual operationRequire local manual operation•• Non Fault interruptNon Fault interrupt•• Provide for manual segmentation after faultProvide for manual segmentation after fault•• May or may not have alternate feeder tie(s)May or may not have alternate feeder tie(s)•• All segments experience initial outageAll segments experience initial outage•• Faulted segment outage duration = MTTRFaulted segment outage duration = MTTR•• Other segment outage durations = MTTSOther segment outage durations = MTTS

© 2006

Feeder Design Schemes Feeder Design Schemes –– Loop RCLLoop RCL

•• Provide Switching capabilities Provide Switching capabilities –– fault and load fault and load interrupt ratedinterrupt rated

•• Faulted Segment and downstream segments see initial Faulted Segment and downstream segments see initial outageoutage

•• Faulted segment outage duration = MTTRFaulted segment outage duration = MTTR•• Downstream outage segment duration = MTTSDownstream outage segment duration = MTTS•• Upstream segments see no outageUpstream segments see no outage•• Provide automatic isolation for downline faultsProvide automatic isolation for downline faults•• Requires local manual operation to restore serviceRequires local manual operation to restore service

© 2006

Feeder Design Schemes Feeder Design Schemes –– SCADA RCLSCADA RCL•• Provide Switching and fault isolation capabilitiesProvide Switching and fault isolation capabilities

–– Fault interrupt rated with overcurrent protection Fault interrupt rated with overcurrent protection –– only downstream customers experience outageonly downstream customers experience outage

•• Provide remote fault indication and switching controlProvide remote fault indication and switching control•• Requires dispatcher operation to restore serviceRequires dispatcher operation to restore service•• Faulted segment duration = MTTRFaulted segment duration = MTTR•• Other segment durations = MTTSOther segment durations = MTTS

N.O.

1 2 3A B C

4

Substation

1 2 3A B C

Substation

© 2006

Feeder Design Schemes Feeder Design Schemes –– SCADA SBDSCADA SBD•• Provide Switching capabilitiesProvide Switching capabilities

–– Usually fault close but only load interrupt rated Usually fault close but only load interrupt rated –– All customers experience initial outageAll customers experience initial outage

•• Provide remote fault indication and switching controlProvide remote fault indication and switching control•• Requires dispatcher operation to restore serviceRequires dispatcher operation to restore service•• Faulted segment duration = MTTRFaulted segment duration = MTTR•• Other segment durations = MTTSOther segment durations = MTTS

N.O.

1 2 3A B C

4

Substation

1 2 3A B C

Substation

© 2006

Feeder Design Schemes Feeder Design Schemes –– Loop DALoop DA•• Uses Distributed Intelligence and CommunicationUses Distributed Intelligence and Communication•• Provides automatic faulted segment isolationProvides automatic faulted segment isolation•• Provides automatic restoration to loads via feeder ties Provides automatic restoration to loads via feeder ties

(<5 min) = No “outage” per IEEE 1366(<5 min) = No “outage” per IEEE 1366•• Only the faulted segment experiences an outageOnly the faulted segment experiences an outage•• Can automatically check for and prevent overloadsCan automatically check for and prevent overloads

N.O.

1 2 3A B C

4

Substation

1 2 3A B C

Substation

© 2006

Predicted Reliability AssumptionsPredicted Reliability Assumptions

•• Uniform Fault Rates = FrateUniform Fault Rates = Frate•• Uniform Customer distribution (Customers/mile)Uniform Customer distribution (Customers/mile)•• Adequate capacity for transfer of loadAdequate capacity for transfer of load•• All segments are linear All segments are linear –– only one alternate tieonly one alternate tie

© 2006

Segmentation AdvantagesSegmentation Advantages•• Breaks Feeder into smaller piecesBreaks Feeder into smaller pieces

–– Less customers interrupted per segmentLess customers interrupted per segment–– Less miles = lower fault exposure = fewer outages Less miles = lower fault exposure = fewer outages

to a particular segmentto a particular segment•• Measure of Segmentation = Customers*MilesMeasure of Segmentation = Customers*Miles

N.O.

1 2 3A B C

4

Substation

1 2 3A B C

Substation

© 2006

Segmentation AdvantagesSegmentation Advantages Impact of Increased Segmentation on Reliability

0

-6.3%-8.3% -9.4% -10.0% -10.4% -10.7% -10.9%

0

-12.5%-16.7%

-18.8% -20.0% -20.8% -21.4% -21.9%

-

-25.0%

-33.3%-37.5%

-40.0% -41.7% -42.9% -43.8%

-

-31.3%

-41.7%

-46.9%-50.0%

-52.1% -53.6% -54.7%

-

-43.8%

-58.3%

-65.6%-70.0%

-72.9%-75.0% -76.6%

-

-50.0%

-66.7%

-75.0%

-80.0%-83.3%

-85.7%-87.5%

-37.5%

-50.0%

-56.3%-60.0%

-62.5% -64.3% -65.6%

-100%

-90%

-80%

-70%

-60%

-50%

-40%

-30%

-20%

-10%

0%1 2 3 4 5 6 7 8

# Segments

% C

MI R

educ

tion

SBD RadialSBD LoopRCL RadialLoop RCLLoop SCADA RCLLoop AUTO DASCADA LOOP SBD

Base Case = 1 Segment - No Switches or Breakers

© 2006

Radial Systems Radial Systems –– Segmentation BenefitsSegmentation BenefitsNo Alternate Feeder TiesNo Alternate Feeder Ties

Segmentation Impacts Radial Systems

0%

-17%

-22%

-25%-27%

-28% -29% -29%

0%

-25%

-33%

-38%

-40%-42%

-43%-44%

-50%

-45%

-40%

-35%

-30%

-25%

-20%

-15%

-10%

-5%

0%1 2 3 4 5 6 7 8

% C

MI I

mpr

ovem

ent

SBD RadialRCL Radial

Base Case = 1 segment

# Segments

© 2006

NonNon--Uniform Segmentation DriversUniform Segmentation Drivers

•• Non Non –– Uniform Fault ratesUniform Fault rates–– Isolate the bad segments!Isolate the bad segments!

•• Sensitive or Critical CustomersSensitive or Critical Customers•• GeographyGeography

–– Major taps or significant splitsMajor taps or significant splits•• LoadingLoading

–– Concentrated or large loadsConcentrated or large loads

© 2006

Impact of TImpact of T--SectionsSections•• No impact on predicted reliability calculationsNo impact on predicted reliability calculations•• Impacts economics Impacts economics

–– 2 or 3 switches added for segment instead of 12 or 3 switches added for segment instead of 1•• May be required to meet feeder capacity limitsMay be required to meet feeder capacity limits

This scheme is not linear. It uses T sections with multiple feeder ties. This increases the number of switches and cost – no change in predicted reliability for Single Contingency

© 2006

Economics of Reliability Economics of Reliability –– cost assumptionscost assumptionsSystem Cost Assumptions

$28,000

$30,000

$25,000

$18,000

$-

$5,000

$10,000

$15,000

$20,000

$25,000

$30,000

$35,000

SCADA RCL DA Switch cost Manual RCL $ SCADA SBD $

Switc

h &

Con

trol C

ost

© 2006

Economics of ReliabilityEconomics of Reliability

•• Typical overall optimized Typical overall optimized reliability improvement program reliability improvement program cost ranges cost ranges –– all programsall programs–– $0.67 per CMI$0.67 per CMI

•• “low hanging fruit”“low hanging fruit”–– $1.67 per CMI$1.67 per CMI

•• “at end of program”“at end of program”•• Looped DA Costs are typically Looped DA Costs are typically

$0.33 $0.33 -- $0.76 per CMI $0.76 per CMI --depending on segmentation leveldepending on segmentation level

•• Other variables will impact these Other variables will impact these costs (MTTS, MTTR, Frate, Cust, costs (MTTS, MTTR, Frate, Cust, Miles, ETC)Miles, ETC)

RELI INITIATIVES RAW CMI

-

5,000,000

10,000,000

15,000,000

20,000,000

25,000,000

30,000,000

0 100 200 300 400 500 600 700 800 900

# FeedersC

umul

ativ

e C

MI

© 2006

Regulatory Penalties for Poor ReliabilityRegulatory Penalties for Poor Reliability

•• Penalties = ???Penalties = ???–– $1million per SAIDI over limit$1million per SAIDI over limit

© 2006

Parameter SensitivityParameter Sensitivity

•• CMI or SAIDI are sensitive to Frate, Cust, Miles, CMI or SAIDI are sensitive to Frate, Cust, Miles, MTTR, MTTS, # SegmentsMTTR, MTTS, # Segments

•• % CMI or %SAIDI Changes % CMI or %SAIDI Changes AreAre NOTNOT sensitive to sensitive to Frate, Cust, Miles but Frate, Cust, Miles but AreAre sensitive to MTTS and sensitive to MTTS and MTTRMTTR

© 2006

Example SystemExample System

N.O.

1 2 3A B C

4

Substation

1 2 3A B C

Substation

0AUTO Switch Time30SCADA Switch Time90Manual Switch Time

2000Cust10FDR Miles0.2Fault rate120MTTR

© 2006

N.O.

1 2 3A B C

5

Substation

6D E

Substation

4

7

Loop System Reliability

2,500 83455667904

5,000 13590971051202

5 MILE Feeder

5,000 10560831281954

10,000 1501201351652102

10 Mile Feeder

SEG Cust * MilesSCADA

SBDLoop Auto

DASCADA

RCLRCL LOOPSBD LOOP# SEGMENTS

© 2006

System SAIDI ResultsSystem SAIDI Results

8330561091351882148

8634601111371892147

9040651151401902156

9648721201441922165

10560831281501952184

120801001401602002203

1501201351651802102252

2402402402402402402401

SCADA SBDLoop

AUTO DALoop SCADALoop RCL

RCL Radial

SBD Loop

SBD Radial

SAIDI# Segments

© 2006

Reliability Improvement IssuesReliability Improvement Issues

•• Regulatory Requirements or PenaltiesRegulatory Requirements or Penalties•• Budget Constraints or LimitationsBudget Constraints or Limitations•• Customer Service requirementsCustomer Service requirements•• OthersOthers

© 2006

System % CMI Comparisons System % CMI Comparisons 2 segment vs. 4 segment2 segment vs. 4 segment

Reliability vs Protection Scheme Change

-21%

-35%-36%

-58%

-43%

-69%

-29%

-46%

-80%

-70%

-60%

-50%

-40%

-30%

-20%

-10%

0%2 Segments 4 Segments

% S

AID

I or C

MI C

hang

e

RCL LOOPSCADA RCLLOOP DASCADA SBD

Base Case = SBD Loop

© 2006

Reliability Improvements with DA

$0.33

$0.38

$0.44

$0.52

$0.60

$0.68

$0.76

120

80

60

48

40

3430

$-

$0.10

$0.20

$0.30

$0.40

$0.50

$0.60

$0.70

$0.80

2 3 4 5 6 7 8

# Segments

$/CM

I Sav

ed

-

20

40

60

80

100

120

140

Feed

er S

AID

I

$/CMI SavedFeeder SAIDI

Assumptions:2000 Customers10 Mile Feeder2 outages/year

© 2006

Reliability Improvement Costs & BenefitsReliability Improvement Costs & BenefitsWhat are your Drivers?What are your Drivers?

2,500 60 $ 0.95 $ 200,000 (210,000)-64%8

2,857 69 $ 0.85 $ 175,000 (205,714)-60%7

3,333 80 $ 0.75 $ 150,000 (200,000)-56%6

4,000 96 $ 0.65 $ 125,000 (192,000)-50%5

5,000 120 $ 0.56 $ 100,000 (180,000)-43%4

6,667 160 $ 0.47 $ 75,000 (160,000)-33%3

10,000 240 $ 0.42 $ 50,000 (120,000)-20%2

for Segmentation FDR SAIDI$/CMI DA Switch Cost CMI Changes % CMI Reduction# Segments

Avg Cust Miles DA Economics

Base Case = SBD Loop with existing segmentation = # Segments

© 2006

Economics of ReliabilityEconomics of Reliability CMI Reduction Costs by Changing Protection Scheme

@ Stated Segmentation Level

$-

$0.74

$0.83

$0.99

$1.16

$1.33

$1.51

$1.69

$-

$0.50$0.56

$0.66

$0.78

$0.90

$1.02

$1.14

$-

$0.44$0.50

$0.59

$0.69

$0.80

$0.91

$1.02

0.400.45

0.53

0.63

0.72

0.82

0.91

$-

$0.20

$0.40

$0.60

$0.80

$1.00

$1.20

$1.40

$1.60

$1.80

1 2 3 4 5 6 7 8

# Segments

$/C

MI I

mpr

ovem

ent

Loop RCLLoop SCADA RCLLoop AUTO DASCADA LOOP SBD

Base Case = SBD Loop

© 2006

CMI Impact of Different Protection SchemesCMI Impact of Different Protection Schemes% CMI Improvement by Changing Protection Schemes

@ Stated Segmentation levelsBase Case = SBD Loop

0%

-21%

-30%

-35%-38%

-39% -41% -42%

0%

-36%

-50%

-58%

-63%-66%

-68%-70%

0%

-43%

-60%

-69%

-75%-79%

-82%-84%

0%

-29%

-40%

-46%-50%

-53%-55% -56%

-90%

-80%

-70%

-60%

-50%

-40%

-30%

-20%

-10%

0%1 2 3 4 5 6 7 8

# Segments

% C

MI C

hang

e

Loop Manual RCLLoop SCADA RCLLoop AUTO DASCADA LOOP SBD

Base Case = SBD LoopMTTR = 120 minMTTS = 90 minSCADA MTTS = 30

© 2006

Incremental Reliability Improvement CostDistributed Intelligent Automation

0.00

0.50

1.00

1.50

2.00

2.50

1 2 3 4 5 6 7 8

# Segments

$/C

MI R

educ

tion

0.3

0.6

1.2

Annual Outages/mile

MTTR = 120 minDA Switch = $30,000MTTS Manual = 90 minDA Switch Time = < 1 min

Feeder = 1500 Cust3.5 Miles Main FeederFrate = 0.3 > 1 outage/yrFrate = 0.6 > 2 outage/yrFrate = 1.2 > 4 outage/yr

Average Overhead Outage Rate/Mile per EEI OH/UG Study

© 2006

Feeder Design SchemesTotal Cost vs. CMI Reduction

-

50,000

100,000

150,000

200,000

250,000

$- $50,000 $100,000 $150,000 $200,000 $250,000 $300,000

Cost

CM

I Red

uctio

n Loop RCLLoop SCADA RCLLoop AUTO DASCADA LOOP SBD

MTTR = 120 minDA Switch = $30,000MTTS Manual = 90 minDA Switch Time = < 1 minSCADA SwitchTime = 30 minFeeder = 1500 Cust3.5 Miles Main Feeder1500 CustomersFrate = 0.6 faults/mile/yrBase Case = SBD Loop

© 2006

Intelligent DA BenefitsIntelligent DA Benefits

•• Intelligent DA provides 2X the reliability Intelligent DA provides 2X the reliability improvement of reclosers when compared to an SBD improvement of reclosers when compared to an SBD SystemSystem

•• Doubling Segmentation with DA provides 50% Doubling Segmentation with DA provides 50% Improvement in ReliabilityImprovement in Reliability

•• Doubling Segmentation with Reclosers provides 36% Doubling Segmentation with Reclosers provides 36% Improvement in ReliabilityImprovement in Reliability

Segmentation level for reclosers may be limited by coordination issues

© 2006

$/CMI vs Segmentation Level

$-

$0.20

$0.40

$0.60

$0.80

$1.00

$1.20

$1.40

$1.60

$1.80

- 500 1,000 1,500 2,000 2,500 3,000

CUST * MILES

$/C

MI

Loop RCL $- Loop SCADA RCL $- Loop AUTO DA $- SCADA LOOP SBD