for Underground Power

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Novel Decision Support System
for Underground Power
Network Asset Management

Asawin

Rajakrom

CAMT, CMU

August 29, 2009

Problem and Justification

69/115 kV Customer

230/500 kV

Grid Station

Substation

Power Plant

12/24 kV Customer

12/24 kV

220/380 V Customer

69/115 kV

220/380 V

Problem and Justification


Failure of distribution feeder directly impacts end users’
wellbeing


Concerns on safety, health, environment and aesthetics
are increasingly high


Network equipment is reaching its designed service age


Overhead feeder facilities are vulnerable to external
environment


Investment on feeder rehabilitation is extremely high


Better decision making of utility asset management can
be obtained through a sort of DSS that can incorporate
all impacted factors: technical, economical, societal, and
environmental aspects.

Research Questions


How shall the power distribution domain knowledge
be modeled?


How can the risks of distribution network failure be
efficiently assessed?


How can the costs involving network failure and
preventive action be quantified?


How can the social and environmental consideration
be included in investment decision?

Key Assumptions


Conversion of overhead distribution line into underground
feeder is of the prime concern.


Risk assessment is solely based on the performance of
network components, not considering any other aspects such
as network configuration, or operating process (e.g. switching
philosophy).


Snap shot comparison, investment cost of network
reinforcement at the time of network failure is of interest and
compared with the cost of failure.


Available data are of sufficient quality to enable assessment
modules to predict corresponding outputs/outcomes.


DSS tries to replicate the decision making of human experts
so that the utility expert’s judgment are assumed sufficient to
validate the models.

Publications

1.
“Improvement of Underground Cable Installation
Performance by Knowledge Management”, the 16th
Conference of the Electric Power Supply Industry, Mumbai,
India, 2006.

2.
“Asset Categorization for Enhanced Asset Management
Using Object Oriented Approach”, the 16th Conference of the
Electric Power Supply Industry, Mumbai, India, 2006.

3.
“Enhance Decision Making on Underground Power System
Implementation Using MCDA”, the 16th Conference of the
Electric Power Supply Industry, Mumbai, India, 2006.

4.
“Underground Power Line Risk Assessment Using Heuristic
Approach”, the 1st Software, Knowledge, Information
Management and Applications, Chiang Mai, Thailand, 2006.

Publications

5.
“Fuzzy Risk Assessment for Distribution System Asset
Management”, Presented at the Conference of Asian Energy
Week 2007, Bangkok, Thailand, 2007.

6.
“Fuzzy
Multicriteria

Approach for Power Distribution
System Risk Analysis” , Presented at Energy21C: The 10th
International Transmission and Distribution Conference &
Exhibition, Sydney, Australia, 2007.

7.
“Determination of Power Distribution Network Risk Using
Fuzzy Markov”, the 2nd Software, Knowledge, Information
Management and Applications, Kathmandu, Nepal, 2008.

8.
“Asset Modeling To Support Cost
-
Risk Evaluation In
Distribution System Asset Management”, the 17th
Conference of the Electric Power Supply Industry, Macau
SAR, China, 2008.

Methodologies and Tools


Asset categorization


CommonKADS

Categorization and Assessment
template


Ontology 101


UML


CIM/RDF/XML


Risk assessment:


Fuzzy
logic


Markov chain


MS Excel



Methodologies and Tools


Cost
evaluation:


Interrupted energy rate (IER)


Work breakdown structure (WBS)


Multicriteria

Decision Analysis:


Analytic Hierarchy Process (AHP
)


Tools:


Protégé 2000


MATLAB


MS Excel



DSS Framework

Markov
Chain

Distress
indicators

FIS

Present Asset
Condition

Future Asset
Condition

Deterioration
Rate

Initial Asset
Condition

Operational
Environment

FIS

FIS

Present/Future
Failure Likelihood

Expected Repair Time

Connected Load

IER

x

-

Customer

x

Price Cap

Repair Cost

Utility

Outage Cost

+

Upgrade

Replacement

Conversion

v

Resolution Cost

MCDA

(AHP)

Investment Option

x

Financial
Index

Public
Interest

Technical
Matter

Asset Categorization

Risk Module

Decision Module

Cost Module

+

Age

Asset Categorization

Asset

name

description

commissioningDate

Component

materialCode

materialDetail

AssetContainer

ImplementationCost

name

description

commissioningDate

ConditionGrade

name

grade

inspectionDate

relativeImportanceDegree

Feeder

ampacity

ratedVoltage

predictedFailurePotential

expectedFailureDuration

PointComponent

Location

name

coordinateX

coordinateY

Failure

failureDescription

failureDate

failureTime

failureDuration

OutageCost

costOfOutage

InvestmentCriteria

degree

description

Customer

customerID

customerType

IER

kW

priceCap

Stressor

degree

description

has

has

locateAt

supply

has

operateIn

has

has

is

is

is

is

compose

compose

Asset

name

description

commissioningDat
e

Component

materialCode

materialDetail

AssetContainer

Feeder

ampacity

ratedVoltage

predictedFailurePotential

expectedFailureDuration

ComponentGroup

OverheadLine

UndergroundLin
e

PoleAssembly


CableComponent

ConductorAssemb
ly

CableContainer

LightningProtectio
n

UndergroundSwitche
s

CircuitSwitches

LinearCompone
nt

length

Conductor

OHConductor

UGCable

DuctBank

PointCompone
nt

Pole

Manhole

UGCable

Splice

Splice

Duct

Manhole

Rack

Pole

Guy

Crossarm

Fittings

Arrester

Groundwire

Switches

Recloser

FuseCutout

Splice

Insulator

Conductor

RMU

ATS

UnitSubstation

Simulation

Simulated Feeder

3 MW Industry

T1: 4,000 kVA

T4: 2,500 kVA

T6: 4,000 kVA

T2: 3,000 kVA

T3: 2,000 kVA

2 MW Commercial

T5: 2,500 kVA

Substation 24kV bus

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

LS3

T1

T2

T3

T4

T5

T6

Substation

Simulation

Feeder Condition Grade:

0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0
10
20
30
40
50
Serviced Year
Condition Grade
Simulation

Failure Rate Contributed by Feeder Condition:

0%
10%
20%
30%
40%
50%
60%
0
5
10
15
20
25
30
35
40
Serviced Year
Failure Rate
Simulation

Financial Analysis of Alternative Options:

-
1.00
2.00
3.00
4.00
5.00
6.00
7.00
0
10
20
30
40
50
OutageByDeterioration(Benefit)
OutageByTree(Benefit)
Bare(Cost)
ASC(Cost)
UG(Cost)
Simulation

Investment Decision Hierarchy:

Select the Most Suitable Feeder Rehabilitation

Technical

Financial


Social

Reliability

Bare OH

ASC OH

UG

Construction

Maintenance

Aesthetics

Safety

Bare OH

ASC OH

UG

Bare OH

ASC OH

UG

Bare OH

ASC OH

UG

Bare OH

ASC OH

UG

Bare OH

ASC OH

UG

Simulation

Ranking of Investment Options:

Criteria

Significant
Weight

Bare OH

ASC OH

UG

Reliability

0.0901

0.0548

0.3583

0.5869

Construction

0.0110

0.4545

0.4545

0.0909

Maintenance

0.0274

0.4545

0.4545

0.0909

Finance

0.5949

0.4899

0.4507

0.0594

Safety

0.2075

0.0698

0.1659

0.7644

Aesthetics

0.0692

0.0909

0.0909

0.8182

Overall marks (%)

33.46

35.85

30.69

Feeder Condition Grade:

0
0.2
0.4
0.6
0.8
1
1.2
0
10
20
30
40
50
Year
Condition Grade
Case Studies: Feeder Rehabilitation in
Industrial Estate

Feeder Failure Rate:

1.49
1.50
1.51
1.52
1.53
1.54
1.55
1.56
1.57
1.58
0
5
10
15
20
25
30
35
40
Year
Failure Rate (times/year)
Case Studies: Feeder Rehabilitation in
Industrial Estate

Financial Analysis of Alternative Options:

-
2.00
4.00
6.00
8.00
10.00
12.00
14.00
0
5
10
15
20
25
30
35
40
Year
Million Baht
Outage
ASC OH
UG
Case Studies: Feeder Rehabilitation in
Industrial Estate

Investment Decision Hierarchy:

Select the Most Suitable Feeder Rehabilitation

Technical

Financial


Social

Reliability

ASC OH

UG

Construction

Maintenance

Aesthetics

Safety

ASC OH

UG

ASC OH

UG

ASC OH

UG

ASC OH

UG

ASC OH

UG

Case Studies: Feeder Rehabilitation in
Industrial Estate

Case Studies: Feeder Rehabilitation in
Industrial Estate

Ranking of Investment Options:

Criteria

Significant
Weight

ASC OH

UG

Reliability

0.4580

0.1429

0.8571

Construction

0.0557

0.8333

0.1677

Maintenance

0.1392

0.8333

0.1677

Finance

0.2510

0.9000

0.1000

Safety

0.0720

0.1429

0.8571

Aesthetics

0.0420

0.1000

0.9000

Overall marks (%)

46.65

53.35

Case Studies: Undergrounding Feeders in
World Heritage Site

Particular Requirement:

Criteria

Subcriteria

Description

Technical

Reliability

Well
protection and well performance of network equipment

Installation

Simplicity of construction and installation of duct, cable,
switchgear and transformer including less adverse effect to
public sector

Maintenance

Convenience of underground network maintenance
(inspection, repair, replacement) and operation

Extension

Network expansion (new substation connected) and new
customer connection can be achieved with ease

Conversion process

Simplicity of conversion step from existing overhead to
underground) as well as including less adverse effect to
customers and public in vicinity.

Aesthetic

The network shall be in harmony with the cityscape and
existing construction

Safety

Safety to employees and public community

Cost

Cost of implementation; this cost will eventually be borne by
every stakeholder

Case Studies: Undergrounding Feeders in
World Heritage Site

Investment Decision Hierarchy:

Select the Most Suitable Underground System

Technical

Cost


Aesthetics

Reliability

DR
-
CS

DR
-
US

DB
-
CS

Installation

Maintenance

DB
-
US

Extension

Conversion

DR
-
CS

DR
-
US

DB
-
CS

DB
-
US

DR
-
CS

DR
-
US

DB
-
CS

DB
-
US

DR
-
CS

DR
-
US

DB
-
CS

DB
-
US

DR
-
CS

DR
-
US

DB
-
CS

DB
-
US

DR
-
CS

DR
-
US

DB
-
CS

DB
-
US

DR
-
CS

DR
-
US

DB
-
CS

DB
-
US

Case Studies: Undergrounding Feeders in
World Heritage Site

Ranking of Investment Options:

Criteria

Significan
t Weight

DR
-
CS

DR
-
US

DB
-
CS

DB
-
US

Reliability

.1183

.0477

.1080

.2588

.5854

Construction &
installation

.0453

.0732

.1969

.1969

.5330

Maintenance

.0534

.0569

.1219

.5579

.2633

Extension

.0159

.3750

.1250

.3750

.1250

Conversion procedure

.0275

.1250

.1250

.3750

.3750

Aesthetics

.6333

.3750

.1250

.3750

.1250

Cost

.1062

.5579

.2633

.1219

.0569

Overall marks (%)

31.81

14.08

33.61

20.50

Conclusion and Future Work


Asset model of expressivity, interchangeability,
extensibility, reusability and
integratability


Human expert emulation of risk assessment


Balancing of risk, cost and performance of asset
through MCDM mechanism


Proposed approaches can be extended to cover other
area such as:


Rehabilitation of transmission lines or substations


Risk assessment of underground cable system

Thank you

Asset Categorization


Purpose:
To determine risks, costs and socials
factors associated with the implementation of power
distribution network.


Domain:
Encompass medium voltage distribution
feeder including network components, network
operation, and operational environment


Scope:
Limited to information that aids determining
risks, costs and socials factors involved with
distribution feeder.


Asset Categorization

Informal description:


Distribution feeder is used to carry electric current through
electrical wire.


Distribution feeder runs along public road.


Overhead feeder is an electrical wire laying or hanging on
insulator which in turn supported supporting structure.


Failure occurs when feeder fails to perform an intended
function such as carrying electric current, withstanding
presence voltage, threatening the living standard.


Power utility does not gain revenue due to unavailability of
energy sale when feeder fails.


Burying distribution network improve city aesthetics.


etc.

Asset Categorization

Classes and Attributes:


Pole is a distribution network component


Material cost of pole is 8,104.00 baht.



Labor cost of pole installation is 8,376.80 baht.


Condition grade of pole inspected on March 20, 2009 is 1.8.


Feeder comprises of overhead cable and underground cable.


Feeder PI417 supplies Imperial Hotel.


etc.

Asset Categorization

Classes and Attributes:

Feeder



AssetContainer

name



Asset


name



Component

code


commissioningDate


unitPrice



Conductor



Insulator



Pole



is

is

is

is

is

contains

Risk Assessment

Condition Grade of Distribution Assets:

Grade

Description

Verbal Grade

1

No noticeable deterioration. Some aging may
be visible

good

2

Some

deterioration

is

evident,

but

the

function

of

component

is

not

significantly

affected
.

Adequate

3

Moderate deterioration. Ability to function is
adequate.

Fair

4

Serious deterioration. Ability to function is
significantly affected.

Poor

5

Severe deterioration. General failure or a
complete failure of component

Failed

Risk Assessment

Feeder Component Categories and Contributing Weight:

Category

i

Weight
(
W
i
)

Component

i,j

Weight
(
W
i,j
)

Pole

structure

1

5

Pole

1,1

4

Crossarm

1,2

3

Guy

1,3

3

Fittings

1,4

3

Conductor

assembly

2

5

Conductor

2,1

5

Insulator

2,2

5

Splice

2,3

3

Lightning

protection

3

2

Overhead

ground

wire

3,3

3

Lightning

arrester

3,2

5

Circuit

protection

4

8

Fuse

cutouts

4,1

3

Switch

4,2

5

Recloser

4,3

3

Risk Assessment

Category and Overall Condition Grade:





H
j

= [W
1j


W
ij


W
Nij
]*[C
1j

C
ij

C
Nii
]




C
ij

is condition grade fuzzy set of each distress indicator



W
ij

is scalar normalized weight given to each distress indicator


H
j

is condition grade fuzzy set of category




C = [W
1


W
i

… W
M
]*[H
1

H
j
… H
M
]



H
j

is condition grade fuzzy set of
cateogory


W
j

is scalar normalized weight given to each category

C

is overall condition grade fuzzy set

Risk Assessment

Fuzzy Rules for Deterioration Model:

Deterioration Rate

(
D’
)

Condition Grade (
C
)

Age (
A
)

good

adequate

fair

poor

failed

new

average

fast

fast

very fast

very fast

young

average

average

fast

fast

very fast

Meddle
-
aged

slow

average

aver
age

fast

fast

Old

very slow

slow

slow

aver
age

fast

Very old

very slow

very slow

slow

average

aver
age

Risk Assessment

Time Based Condition Grade Evaluation Using Markov
Transition Model:

























1
0
0
0
0
1
0
0
0
0
1
0
0
0
0
1
0
0
0
0
1
)
,...,
(
)
,...,
(
5
,
4
5
,
4
4
,
3
4
,
3
3
,
2
3
,
2
2
,
1
2
,
1
1
1
5
1
5
1
t
t
t
t
t
t
t
t
C
t
C
t
C
t
C
t
D
D
D
D
D
D
D
D




Risk Assessment

Fuzzy Inference System:

Inference

Fuzzification

Defuzzification

Knowledge

Base

Expert Knowledge

Field Data

Subjectiv
e

Objective

Inputs

Output


Degree of feeder overload


Degree of feeder overvoltage


Degree of exposure to
mechanical harmfulness


Asset condition



Failure likelihood

Risk Assessment

Stage Wise Fuzzy Reasoning Process:

RB1:

Load current

Ambient temp.

Ventilation

Thermal
violation
degree

RB2:

Lght
. exposure

Lght

protectn
.

Pollution

Voltage
violation
degree

RB3:

Tree

Accident

Animal

Mecha
.
contact
degree

RB4:

Thermal

Voltage

Mechanical

Stressor
degree

RB5:

Stressor

Condition
grd
.

Failure
possibility

Risk Assessment

Fuzzy inference rules to deduce feeder failure
possibility:

Feeder failure
possibility

Stressor degree

very low

low

Medium

High

very high

Condition
grade

good


very low

Low

Medium

High

very high

adequate

very low

Low

Medium

high

very high

fair

very low

Low

Medium

high

very high

poor

very low

Low

Medium

high

very high

failed

very high

very high

very high

very high

very high

Cost Evaluation

Sectoral

Customer Damage Cost (
Sectoral

IER)

0
100
200
300
400
500
600
700
800
900
0
2
4
6
8
10
Interruption duration (hours)
Damage cost (Baht)
Residential
Small general service
Medium general service
Large general service
Specific business
Government
Cost Evaluation

Average and Composite Damage Cost (IER)

Duration

2 s

1 m

30 m

1 hr.

2 hr.

4 hr.

8 hr.

MEA

3.033

1.944

19.020

65.996

136.717

245.184

458.956

PEA

8.533

13.131

37.661

62.794

105.610

208.010

374.720

All customers

6.452

8.905

30.587

63.881

117.097

221.618

405.735

IER (Bath/kWh)

MEA

53.799

PEA

60.165

60.348

Cost Evaluation

Price Cap

Customer

Type

Size

(kW)

Rate

Price Cap

On peak

Off peak

On peak

Off peak

Residential

3.6246

1.1914

1.5289

0.1011

Small business

< 30

3.6246

1.1914

1.5289

0.1011

Medium business

30


99

2.6950

1.1914

0.5993


0.1011

Large business

> 999

2.6950

1.1914

0.5993

0.1011

Cost Evaluation

Work Breakdown Structure (WBS)


WBS

Task name:

Pole installation

Scope:

installing 12 m concrete pole on ordinary ground

Material:

Code

Description

Quantity

5625
-
668
-
12100

Concrete pole 12m

1

5620
-
643
-
00100

Cement

10

5610
-
641
-
00100

Rough sand

0.5

Manpower:

Position

Number

Worker

2

Technician

1

Crane Operator

1

Machine:

Machine & Tool

Number

Mobile crane

1

Duration:
2 hrs.

Responsible person:
Somsak

Cost Evaluation

Typical Cost Figure for 1 Circuit
-
km UG Feeder:

Components

Qty

Unit

Cost

Duct

1000

m

1,500,000.00

Manhole

4

set

200,000.00

Cable support

4

set

54,644.80

Underground cable

3,000

m

4,026,750.00

Splice

9

set

45,602.64

Terminator

3

set

30,588.00

Total cost

6,457,585.44

Cost Evaluation

Concept of Loss of Fixed Asset by Prevention
Replacement

Analytical Hierarchy Process (AHP)

Hierarchical Structure Decision Model:

Goal

Criterion1

Criterion2


Criterion3

Subcriterion11

Alternative1

Alternative2

Alternative3

Alternative4

Subcriterion12

Alternative1

Alternative2

Alternative3

Alternative4

Alternative1

Alternative2

Alternative3

Alternative4

Alternative1

Alternative2

Alternative3

Alternative4

Analytical Hierarchy Process (AHP)

Numerical Rating and Verbal Preference:

Numerical
Scale

Verbal Importance

Explanation

1

Equal

importance

Two activities contribute equally to
the object

3

Moderate

importance

Slightly

favors

one

over

another

5

Essential or strong
importance

Strongly

favors

one

over

another

7

Demonstrated

importance

Dominance of the demonstrated in
practice

9

Extreme

importance

Evidence favoring one over another
of highest possible order of
affirmation

2,4,6,8

Intermediate

values

When compromise is needed

Analytical Hierarchy Process (AHP)

Comparison Matrix:

Criteria

Alternative 1

Alternative 2

Alternative 3

…..

Alternative
n

Alternative 1

1

a
12

a
13

a
1n

Alternative 2

a
21

1

a
23



a
2n

Alternative 3

a
31

a
31

1



a
3n

…..







1



Alternative
n

a
n1

a
n2

a
n3



1

i
,
j

= 1,….,
n

a
ij

= 1,….,9

a
ji

= 1/

a
ij



Analytical Hierarchy Process (AHP)

Consistency Check:


1.
Determine the principal Eigen value:
l
max


2.
Compute the consistency index (
CI
)







3.
Compute the consistency ration (
CR
)



1
max



n
n
CI
l
RI
CI
CR

Simulation

Results Analysis and Discussion:


Data modeling


Data availability and sufficiency


Accuracy:


Inclusion of impacted factors


Expert knowledge


Applicability


Results Analysis and Discussion:


Failure rate of assessed feeder estimated from DSS of 1.5 times/year
lower than actual events of 7.


Result obtained looks alright when compared to other feeders operating in
neighboring area.


Difference possibly due to:


Different deterioration behavior of components


Some components may deteriorate faster than 2
d
0
under certain stressor


Fuzzification

and fuzzy rules


design, workmanship, switching, overheat/overvoltage effect or particular
features inherent to assessed feeder.


Undergrounding system cannot compete with overhead counterpart if only
financial aspects are considered.


Cost figured already provided for each option.


Case Studies: Feeder Rehabilitation in
Industrial Estate

Case Studies: Undergrounding Feeders in
World Heritage Site

Results Analysis and Discussion:


Aesthetic and world heritage site harmony are prime
important for decision making.


Information on feeder configuration and design are
offered by asset model.


Cost figured already provided for each option.


If there exist more criteria/requirements to examine,
they can be added into the decision hierarchy
without any difficulty