Barcelona, May 13, 2003 ASSET MANAGEMENT Development of new approaches Gerd Balzer

Barcelona, May 13, 2003

ASSET MANAGEMENTDevelopment of new approaches

Gerd BalzerDarmstadt University of Technology

TU Darmstadt Institute of Electrical Power Systems

Overview

- Introduction

- Age profile of equipment

- Consequence of the ageing process

- Maintenance strategies

- Reliability-Centered Maintenance (RCM)

- Example: Assessment of substations

- Renovation strategy with Fuzzy-Logic

- Proposal for a Risk-Assessment

- Conclusion



Component level

System level

Corporate level

1:Maintenance and diagnostic evaluationscenario search and evaluation ofeffectiveness & usability

2:Economical evaluation of scenarios,creation of maintenance strategies,calculation of non-availability of energy

3:Risk management,selection of optimal scenario,and optimal strategy

Technicalinformation(on assets)

Economical information(on assets)Technical information(on grid)

Economical information(on business)Sociological information

Decision

Asset Management decision process (Cigre WG 23/39)

Age distribution for m.v. equipment(VDEW-statistic, Germany)


0.00E+00

2.50E+05

5.00E+05

7.50E+05

1.00E+06

1.25E+06

1.50E+06

1.75E+06

2.00E+06

19

58

19

60

19

62

19

64

19

66

19

68

19

70

19

72

19

74

19

76

19

78

19

80

19

82

19

84

19

86

19

88

19

90

19

92

19

94

19

96

19

98

TR VT CBLD CT Bay

Year of installation

Po

pu

lati

on

Age distribution for substations (AIS)(Cigre Brochure no. 176)

0100020003000400050006000700080009000

10000

0-5 10 15 20 25 30 35 40 45 50 55 60 65Age in 1998 (Years)

Po

pu

lati

on

Gas CB Oil CB Air CB Bay Assets Transformers Indoor GIS E/mech Prot

Range of Asset Life Estimates


Installations and replacement distribution(substation equipment, Cigre Brochure no. 176)

Installation Replacement


Consequence of ageing

Falling reliability of the system is a majorconsequence of the ageing process:

- decision to delay asset replacement- an attempt to recover by increasing asset

replacement at a later stage

Lower availability and further fault outages


The spiral of decline

Delayedreplacement leads

to

move inservicefaults

leadsto

longerrepair outages

leadsto

loweravailability

leadsto

leadsto

leadsto

cancelledplanned

work

even morefaults

Attempt torecover

leadsto

leadsto

leadsto

loss ofsupply

by

morereplacement

loweravailability

whilststill in a

period ofhigh unreliability

more doublecircuit events

CONTINUALLYFALLING

AVAILABILITY ANDRELIABILITY


In general the Reliability Centered Maintenance (RCM) strategy for substation can be used in two different ways:

- substation approach: Which equipment/components influence the function of the

complete substation (Failure Mode Effect Analysis, FMEA)

- system approach: Which substations influence the availability and the performance of the system (reliability calculation and assessment of the non-delivered energy, risk management)

The report deals with the system approach


The system approach solves the main task of an utility, due to the financial constraints and to receive a ranking of substations concerning the yearly budget:

which substation has to be maintained first, second, and so on.


Different types of maintenance strategies

Condition-based

Reliability-centered

Time-based Corrective


Corrective or Reactive Maintenance

- repair or replacement after a fault

- no influence on the time of failure

- availability of the substation depends on the reliability of the single equipment

- lowest maintenance costs without consideration of further expense


Time-Based or Scheduled Maintenance

- predefined inspections (time period)

- replacement after a fixed life time

- high availability

- no use of the equipment up to the end ofthe life time

- most expensive maintenance strategy


Condition-Based or Predictive Maintenance

- inspection or replacement due to thecondition

- all identical equipment are treated in the

same manner


Reliability-Centered Maintenance

- inspection or replacement due to the technical condition

- importance of the equipment for thenetwork

- optimal maintenance strategy


Maintenance Strategies

CMCorrective

Maintenance

yesno?

Maintenance activitiesfor specific

types of equipment

?no yes

diagnostic

CBMConditionBased

Maintenance

TBMTimeBased

Maintenance

yesno?

RCMReliabilityCentered

Maintenance

importance


Procedure for maintenance planning (equipment)

Index ccondition of equipment

Index iimportance of equipment

Maintenancestrategy

Index ooverall indexof equipment


Procedure for maintenance planning (substation)

Index iimportance of

substation

Index iimportance of

substation

Index ooverall indexof substation

Index ccondition

of substation

Circuit-breaker

DisconnectorBay Building

Protection & Control


Interpretation of the assessment resultc condition of the equipmenti importance of the equipment


Condition based maintenancec condition of the equipmenti importance of the equipment


Replacement

maintenance work

inspections

Corrective, time-based or reliability centered maintenancec condition of the equipment i importance of the equipment


inspections maintenance work

replacement

Combination of different strategiesc condition of the equipmenti importance of the equipment


Assessment of 40 secondary substations


21 6/10 kV

19 30 kV

(four tower stations)

Equipment of the substations


- bay/type of construction

- disconnector

- load disconnector

- transformer

- building/tower

condition criteria for theassessment of bays

- age; type

- experiences; spare parts

- safety aspects

- partial discharge

- pollution; humidity



Impact of equipment evaluationg the condition assessment in percentage

0

10

20

30

40

50

60

70

HE

IS-

10

1

NE

NN

-3

22

PO

HL

-3

01

GL

AS

-8

01

HO

HA

-3

04

bays disconnector transformer buildingC

on

dit

ion

/%

Importance criteria for the assessment of secondary substations

- kind of substation

- maximum active power

- customer

- redundancy of the substation

- hazard rate


0

20

40

60

80

100

0 10 20 30 40 50 60 70 80 90 100

c

i

EHSN-307SHAF-299

POHL-301

HOHA-601


importance

con

dit

ion

Final result of the assessment

replacementA

BC

d

dA

dB

dC service


Basic principle of a decision-taking process using fuzzy logic

Rules

Fuzzification DefuzzificationKnowledgeprocessing

Input valuesOutput values


Implementation of a maintenance strategy for substations


Secondary substation

condition 3: load/disconnector condition 1: bay

Conditon 3 Conditon 1

resu

lt


Time after commissioning resp.

service

Propability of outage of equipment Non delivered

energy

Result of reliability calculation

Equipment model

Outage costs

Interruption costs- repair- interuption of supply - penalty and so on

Risk-Management

Szenario:- no action- service- renovation

“sociological effects”

Risk Assessment

Maintenance costs- service- renovation


Equipment model

time after commissioning/last servive

haz

ard

rat

e

T2T1 T3 T4

2

1

4

I IIIII


time after commissioning/last service

pro

ba

bil

ity

of

ou

tag

es

Probability of outages of the considered equipment

0.0

0.2

0.4

0.6

0.8

1.0

0 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

T T +t

Tdt)t(f

tT

Tdt)t(f


Probability of outages of the considered equipment

Pro

bab

ilit

y o

f o

uta

ges

time after commissioning/last service

Q

Qb

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0 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

Result of the assessment (substation):

- comparison of different substations

- determination, which equipment influences mainly the condition of the substation

- what is the optimal order of substation to be maintained or replaced

Decision: replacement of the equipment or newinvestment of the complete substation


Advantage of a computer aided assessment:

- fixing of compulsory criteria

- determination of the ranking due to replacementor ranking

- documentation of the decision


Barcelona, May 13, 2003 ASSET MANAGEMENT Development of new approaches Gerd Balzer

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