Comparative case studies for value-based distribution system reliability planning

Electric Power Systems Research 68 (2004) 229–237

Comparative case studies for value-based distributionsystem reliability planning

Teng-Fa Tsao, Hong-Chan Chang∗

Department of Electrical Engineering, National Taiwan University of Science and Technology,43, Keelung Road, Sec. 4, Taipei, Taiwan, ROC

Received 5 April 2003; received in revised form 12 June 2003; accepted 12 June 2003

Abstract

This paper will develop a set of reliability worth evaluation models to evaluate the load point reliability worth indices for five differentdistribution types. The distribution substations, primary distribution systems, and the interaction between them contribute to the load pointreliability worth indices. The reliability worth of the distribution systems are evaluated in terms of customer interruption costs, by using thesector customer damage function (SCDF). The most suitable system design is based on comparisons of the total system costs of the candidatesunder consideration. Four case studies are thoroughly examined in this paper. Also, the impact on customer interruption costs associated withcustomer type, substation configuration, and feeder configuration are investigated.© 2003 Elsevier B.V. All rights reserved.

Keywords:Reliability worth evaluation models; Reliability worth indices; Distribution substations; Primary distribution systems; Customer interruption costs;Sector customer damage function

1. Introduction

After deregulation of electric utilities, the customers’willingness to pay for a higher level of reliability has beenincreased due to their own particular electricity demand andthe competitive mechanism of liberalization[1–3]. It followsthat the traditional configurations of distribution systemswill change likely. Consequently, it is necessary to inves-tigate reliability enhancement technologies of distributionsystems and the benefits received from reliability upgrades.The ultimate goal is to reduce the impact caused by failure ofdistribution systems so that electric utilities can provide con-tinuous and high quality electric service to their customers ata reasonable rate. In general, the more is invested in the cap-ital equipment of a utility, the higher the service reliabilitycustomers will receive. However, customers must pay higherprices to receive a higher reliability of electrical energysupply. The type and extent of planning for a distributionsystem must carefully balance the costs of anticipated inter-

∗ Corresponding author.E-mail address:[email protected] (H.-C. Chang).

ruptions to customers against the capital costs of the systeminvolved.

There have been many studies associated with value-basedreliability assessment for distribution system planning pub-lished in the past decade[1–7]. Most of the research dealtwith radial topology[1–5]. Furthermore, the distributionsystem reliability worth assessment was confined to theprimary distribution system[2–5], and the distribution sub-station was excluded. To date, the research on reliabilityworth for non-radial distribution system has been studiedseldom. However, it is necessary to select the proper topol-ogy for a distribution system satisfying the requirementsof both reliability and cost efficiency for a particular typeof load area or customers. Hence, quantitative reliabilitycost/worth assessment is of considerable importance forvarious topologies of distribution system. The reliabilityworth of each distribution system topology is evaluated interms of customer interruption costs, which can be relatedto reliability indices and customer types[8,9].

A set of reliability worth evaluation models for calculat-ing the load point reliability worth indices of five typicaldistribution types are developed in this paper. The con-cerned five types of distribution system, are basic radial,

0378-7796/$ – see front matter © 2003 Elsevier B.V. All rights reserved.doi:10.1016/j.epsr.2003.06.003

230 T.-F. Tsao, H.-C. Chang / Electric Power Systems Research 68 (2004) 229–237

link arrangement, open loop, closed loop, and primary net-work system, respectively. The developed reliability worthevaluation models can reflect the effects of distributionsubstations, primary distribution systems, and the interac-tion between them. In this paper, the composite distributionsystem reliability worth evaluation model will be appliedto assess the reliability worth for the five distribution typesin combination with five configurations of distributionsubstation. The corresponding customer interruption costscontributed to by all the load point isolated events, areestimated. Four case studies will be presented to illustratethe value-based reliability planning for different systemconfigurations. The results obtained show that the proposedapproach can provide information for value-based decisionmaking in distribution systems reliability planning.

2. Concept of value-based reliability planning

The value of electric service to the customer is called thereliability worth. It is the benefit received by customers as-sociated with better reliability. It is a difficult task to evalu-ate the reliability worth directly; hence, the reliability worthis usually represented indirectly by customer interruptioncosts. The reliability cost is the capital cost of the utility in-vested to improve reliability for customers serviced. In thisstudy, the utility costs of reliability consist of annual invest-ment capital costs and equipment maintenance costs. Themethod for value-based reliability planning is to evaluatethe reliability costs associated with different system config-urations and the corresponding reliability worth. Using theconcept of value-based distribution system reliability plan-ning, the requirement of both lower cost and achieving anacceptable level of service reliability should be satisfied.

The total cost of reliability is the summation of utility costand customer interruption cost. By comparing the total costsof various candidate plans, one can achieve the most suitableconfiguration for balancing utility cost and customer inter-ruption cost. Interruption cost data compiled from customersurveys can be used to develop a sector customer damagefunction (SCDF). The SCDF is a function of customer classand outage duration, which can be used to estimate mone-tary loss incurred by customers due to power failure.Table 1

Table 1The sector customer damage function (US$/kW)

Sector type Outage duration (min)

1 20 60 240 480

Larger user 1.005 1.508 2.225 3.968 8.240Small industrial 1.625 3.868 9.085 25.16 55.81Commercial 0.381 2.969 8.552 31.32 83.01Agricultural 0.060 0.343 0.649 2.064 4.120Residential 0.001 0.093 0.482 4.914 15.69Government and institutions 0.044 0.369 1.492 6.558 26.04Office and buildings 4.778 9.878 21.06 68.83 119.2

shows the SCDF in US dollars per kiloWatt for seven sec-tors of customers[3]. The sector types used are large user,small industrial, commercial, agricultural, residential, gov-ernment and institutions, and office and building.Table 1gives the interruption costs for five discrete outage dura-tions. Using interpolation or extrapolation techniques, wecan obtain the interruption cost per kiloWatt for any outageduration.

3. Composite reliability worth evaluation model

In order to assess the reliability worth of the five types ofdistribution system, quantitative reliability worth evaluationmodels were developed in this paper. Contingency enumer-ation is used to evaluate the reliability worth in this study.This can be done in the following steps:

Step 1: Identify the failed component that constitutes aload point outage event.

Step 2: Determine the corresponding SCDF according tosector type and interruption duration.

Step 3: Evaluate the load point expected interruption cost(ECOST) contributed to by the failed component.

Step 4: Repeat the above steps until all failed componentsthat isolate the load point are considered.

The reliability worth models consider the impact of dis-tribution substations, primary distribution systems and theinteraction between them. First, it evaluates the load pointreliability worth index contributed to by distribution sub-station. Second, the reliability worth indices contributed toby the primary distribution systems are developed basedon their topologies. Third, the reliability worth index con-tributed to by the interaction between distribution substationand primary distribution system is evaluated. Finally, com-bining the three contributions develops the composite loadpoint reliability worth evaluation models. The load point andsystem reliability worth indices are given by the followingequation:

ECOSTi = ECOSTsub,i + ECOSTprimary,i

+ ECOSTcb,i + ECOSTstuck,i (1)

ECOSTsys =NP∑i=1

ECOSTi (2)

3.1. The impact of distribution substation on the loadpoint reliability worth index

The distribution substation is the source of the primaryfeeder system, and the failure of a substation may result inpower interruption at all load points. The reliability of sub-stations must be high, however, it is necessary to perform re-liability cost/worth assessment to achieve a reasonable levelof reliability.

T.-F. Tsao, H.-C. Chang / Electric Power Systems Research 68 (2004) 229–237 231

This paper uses minimal cut-set technique to identify allthe load point outage events of a distribution substationbased on the criterion of continuity of service. The minimalcut-sets of substation components are divided into severalgroups according to their failure modes[10–14]. The failuremodes considered in this study include the first order totalfailure (include both passive failure and active failure), thefirst order active failure, the first order active failure withstuck condition of circuit breakers, and the second orderoverlapping failure event involving two substation compo-nents. Overlapping failure events include total failure or ac-tive failure overlapping the total failure or maintenance out-age of another component[10]. Malfunctions of normallyopen circuit breakers[10] are also considered in this study.The expected customer interruption cost of load pointi con-tributed to by distribution substation is evaluated using thefollowing equations:

ECOSTsub,i =NE∑j=1

LiλjCi(rj) (3)

3.2. The impact of primary distribution system on the loadpoint reliability worth index

According to the primary feeder configuration of the pri-mary distribution system, the reliability worth index of loadpoint i contributed to by this portion can be expressed asfollows:

ECOSTprimary,i =

Li

[λ

pcbCi(rcb) + λtiCi(rti) + λliCi(rli)

+∑mi

m=1λmCi(rm) + ∑Fm,i

m=mi+1λmCi(ts)]

for basic radial

Li

[λtiCi(rti) + λliCi(rli) + ∑Fm,i

m=1λmCi(ts)]

for primary network and closed-loop

Li

[λ

pcbCi(ts) + λtiCi(rti) + λliCi(rli) + ∑Fm,i

m=1λmCi(ts)]

for link arrangement and open loop

(4)

The inequationm ≤ mi denotes themth main section lo-cated upstream of load pointi, andmi + 1 ≤ m ≤ Fm,i isdownstream of load pointi.

3.3. Interaction between distribution substation andprimary distribution system

The interaction between distribution substation and pri-mary distribution system can be examined from two aspectsof feeder circuit breakers.

3.3.1. Primary protectionIf a short circuit active failure occurs on a feeder circuit

breaker, all the feeder breakers that are connected at thesame low voltage bus must trip. The low voltage bus thenloses continuity of supply, and the load points supplied bythe bus suffer an outage event except for the load pointson the primary network. As for the primary network, onlythe breakers located at the two ends of a primary feedercan interrupt the load points supplied by the feeder. The

reliability worth indices of load pointsi contributed to bythe factor can be formulated as follows:

ECOSTcb,i

=

2LiλacbCi(ts) for primary network type

LiλacbCi[rcb

+(Ncb − 1)ts] for basic radial

LiNcbλacbCi(ts) for the other three types

(5)

3.3.2. Backup protectionWhen a feeder breaker fails to clear the fault on its as-

sociated main section, the backup protection of the feederbreakers connected at the same low voltage bus need to op-erate. This action may result in power interruption of loadpoints supplied by the de-energizing bus for every type ex-cept the primary network. The reliability worth indices ofload pointi contributed to by the factor can be formulatedas follows:

ECOSTstuck,i

={

0 for primary network

Li

∑Nm

m=1,m/∈fiPcλmCi(ts) for the other four types

(6)

m /∈ fi denotes that the main feeder that serves load pointi is excluded. The reliability worth index of load pointi

contributed to byfi has been considered in the primary dis-tribution system.

4. Case studies and discussions

The concept of value-based reliability planning will beapplied to assess the economic impact of considering differ-ent distribution types and substation arrangements. The fivetypes of distribution system shown inFig. 1 and the fiveconfigurations of distribution substation shown inFig. 2areused to illustrate the approach developed in the paper. Thecapacity of each substation transformer for the link arrange-ment and primary network is 8 MVA, whereas the capacityof each substation transformer for the remaining types is16 MVA. It assumes that the alternate supply will require2 km of tie lines. The lateral section is equipped with afuse-cut and a distribution transformer except for the smallindustrial customer. The relevant reliability parameters andload point data for the distribution system are given in[15].


N/O

N/O

LP8 LP1LP2LP3LP4

LP10LP11LP12

(a)

(b) (c)

(d)

LP7

LP6

LP5

LP4

LP3

LP2

LP1

LP8

LP9

LP16

LP18

LP19

LP20

LP21

LP17

LP22

LP15

LP14

LP13

LP12

LP11

LP10

(e)

LP5

LP6

LP7LP9

LP13

LP14

LP15

LP20

LP21

LP22

LP16 LP17 LP18 LP19

N/C N/C

LP1

LP2

LP3

LP4

LP5

LP6

LP7

LP8

LP9

LP10

LP11

LP12

LP13

LP14

LP15

LP16

LP18

LP19

LP20

LP21

LP17

LP22

Low voltage bus

Low voltage bus

Low voltage bus

N/O N/O

LP1

LP2

LP3

LP4

LP5

LP6

LP7

LP8

LP9

LP10

LP11

LP12

LP13

LP14

LP15

LP16

LP18

LP19

LP20

LP21

LP17

LP22

Low voltage bus

LP1

LP2

LP3

LP4

LP5

LP6

LP7

LP8

LP9

LP16

LP18

LP19

LP20

LP21

LP10

LP11

LP12

LP13

LP14

LP15

LP17

LP22

Low voltage bus

Fig. 1. Five types of distribution system. (a) Basic radial system; (b) open loop; (c) closed loop system; (d) link arrangement system; (e) primary networksystem.

It is assumed that the disconnect switches, the lateral fusesand the alternate supply shown inFig. 1 are 100% reliablein all the case studies. The stuck probability for a circuitbreaker is 0.05. A failed distribution transformer is replacedrather than repaired. For simplicity, the outage componentsof the substation shown inFig. 2only consider subtransmis-sion lines, circuit breakers, bus bars, and transformers.

The SCDF given inTable 1are the basic data used inthis paper for the evaluation of reliability worth at specificload points. The capital and maintenance costs data associ-ated with the distribution equipment used in this paper aretaken from[16]. We assume that the annual maintenance

costs are 2% of annual investment costs, the operating lifeof the equipment will be 20 years, and the annual interestrate will be 3%. According to the costs data, the estimatedannual utility cost to build the five types of distribution sys-tem in combination with five configurations of distributionsubstations are given inTable 2.

4.1. Case study 1—reliability cost/worth assessment fordifferent distribution types and substation configurations

In this case study, all the feeders and laterals of theprimary system are overhead lines. The customer classes


L 2

Low voltage bus(d)

L 1 L 2

Low voltage bus

T1 T2

(e)

B1 B2

B3 B4

L 1

B1 B2 B3 B4

B5 B6 B7

T1

B8

T2

L 1 L 2

Low voltage bus

T1 T2

(a)

B1 B2

B3 B4

L 1 L 2

Low voltage bus

T1 T2

(b)

B1 B2

B3

B4 B5

Low voltage bus

L 1 L 2

T1 T2

(c)

B1 B2

B3 B4

B5 B6

Fig. 2. Five different configurations of distribution substation. (a) Singlebus; (b) sectionalized single bus; (c) breaker-and-a-half; (d) double busdouble breaker; (e) ring bus.

of the five types of distribution system shown inFig. 1consist of small industrial, commercial, residential, andgovernment/institutional customers. In order to determinethe most suitable distribution type and configuration ofdistribution, the reliability cost/worth assessment is per-formed by calculating the costs associated with differentsystem configurations and evaluating the correspondingreliability worth indices. The customer interruption costsand total costs for five types of distribution system con-sidering five configurations of distribution substation arepresented graphically inFigs. 3 and 4. Several interest-ing observations from the study can be summarized asfollows:

(1) The primary network has the lowest customer interrup-tion costs, next is the link arrangement, and as expected

Table 2The annual utility cost for the five types of distribution system in combination with five configurations of distribution substations (kUS$ per year)(overhead line)

Substation configuration Distribution type

Basic radial Open loop Closed loop Link arrangement Primary network

Single bus 122.74 129.87 149.97 149.97 214.90Sectionalized single bus 128.20 135.33 160.90 160.90 236.76Breaker-and-a-half 132.95 140.08 170.41 170.41 255.78Double bus double breaker 142.46 149.59 189.42 189.42 293.80Ring bus 124.87 132.00 154.25 154.25 223.46

Fig. 3. Comparison of customer interruption costs, ECOST. (1) Radial;(2) open loop; (3) closed loop; (4) link arrangement; (5) primary network.(a) Single bus; (b) sectionalized single bus; (c) breaker-and-a-half; (d)double bus double breaker; (e) ring bus.

Fig. 4. Comparison of total costs (TCOST) for case study 1. (1) Radial;(2) open loop; (3) closed loop; (4) link arrangement; (5) primary network.(a) single bus; (b) sectionalized single bus; (c) breaker-and-a-half; (d)double bus double breaker; (e) ring bus.

basic radial produces the highest customer interruptioncosts because of its simple configuration and lowest cap-ital investment.

(2) The most cost-effective type of distribution system is anopen loop system supplied by a single bus substationbased on the minimum total costs.

(3) The customer interruption costs associated with openloop are very close to those of the closed loop, however,the capital investment for the latter is higher.

(4) Higher utility capital and maintenance costs associatedwith the link arrangement and the primary network sys-tem cause the annual total cost to be higher despite lowercustomer interruption costs.


(5) The customer interruption costs are dominantly af-fected by primary distribution system more than distri-bution substations. Hence, a more complex substationconfiguration is not a suitable selection for economicreasons.

(6) The customer interruption costs of the primary networkare not affected by substation configurations. Hence,the simpler the substation configuration for the primarynetwork, the higher the cost effectiveness.

(7) The customer interruption costs contributed to by thefive substation configurations have the same trend forthe five distribution types. Breaker-and-a-half and dou-ble bus double breaker are the most reliable configura-tion, however, they are not suitable configurations dueto their higher utility costs. In contrast, the utility costsassociated with a single bus or ring bus configurationresult in lower total costs despite much higher customerinterruption costs.

4.2. Case study 2—the economic impact of consideringdifferent customer classes

In this case study, office building customers, instead ofall residential and government/institutional customers. Now,the test systems shown inFig. 1 consist of small indus-trial, commercial, and office building customers. The distri-bution system planning in this case needs higher reliabilitythan case study 1 because the office building needs premiumpower service. The total costs for five types of distributionsystem considering five configurations of distribution sub-station are presented graphically inFig. 5. The open loopsystem remains the most cost-effective distribution type.The difference between case studies 1 and 2 is described asfollows:

(1) The ring bus is the most cost-effective substation con-figuration for serving basic radial, open loop, closedclop, and link arrangement. The single bus remains themost cost-effective substation configuration for servingthe primary network that needs more distribution sub-stations.

(2) The breaker-and-a-half configuration is more cost effec-tive than the single bus for the distribution type servedby a single substation.

(3) The link arrangement system causes lower total costthan basic radial.

Table 3The annual customer interruption costs (kUS$ per year)

Line type Number of switch Basic radial Open loop Closed loop Link arrangement Primary network

Overhead line 1 47.61 35.63 35.54 33.76 31.222 47.61 28.42 28.33 26.55 24.01

Underground cable 1 232.82 142.02 141.93 140.61 138.062 232.82 86.98 86.88 85.56 83.01

Fig. 5. Comparison of total costs (TCOST) for case study 2. (1) Radial;(2) open loop; (3) closed loop; (4) link arrangement; (5) primary network.(a) Single bus; (b) sectionalized single bus; (c) breaker-and-a-half; (d)double bus double breaker; (e) ring bus.

4.3. Case study 3—the economic impactof disconnect switches

A main feeder can be divided into several sections by dis-connect switches. Disconnect switches can isolate the failedcomponent while the rest of the system is supplied normally.The more sectionalizing switches, the higher the system re-liability. However, the additional switches perhaps cause ahigher total cost despite a lower customer interruption cost.In this case, the reliability cost/worth assessment of consid-ering two disconnect switches at the two ends of each mainsection to only one disconnect switch at the beginning ofeach section is performed. The five types of distribution sys-tem given inFig. 1are again selected to investigate the effectof disconnect switches. Herein, the single bus substation isconsidered according to the result of case study 1.

The annual customer interruption costs are given inTable 3. The annual utility cost to install the additionalswitches was estimated at US$ 4955. Comparing the cus-tomer interruption costs given inTable 3 for the case ofone switch and two switches, the project for locating twodisconnect switches at the two ends of each main section isjustified whether overhead line or underground cable. Theresult ofTable 3shows that the additional disconnect switchin each feeder section can lower customer interruption costsfor all the distribution types except basic radial. The reasonis that basic radial has no ability of load transfer, and theother four types have the ability. It can also be seen fromTable 3that the cost effectiveness of the additional switchin an underground cable system is significantly better thanin overhead line systems.


Tr#1

Substation #1

N/C N/C

LP1

LP2

LP3

LP4

LP5

LP6

LP7

LP8

LP9

LP10

LP11

LP12

LP13

LP14

LP15

LP16

LP18

LP19

LP20

LP21

LP17

LP22N/C N/C

LP1

LP2

LP3

LP4

LP5

LP6

LP7

LP8

LP9

LP10

LP11

LP12

LP13

LP14

LP15

LP16

LP18

LP19

LP20

LP21

LP17

LP22

Substation #1

Tr#1 Tr#2

N/C N/C

LP1

LP2

LP3

LP4

LP5

LP6

LP7

LP8

LP9

LP10

LP11

LP12

LP13

LP14

LP15

LP16

LP18

LP19

LP20

LP21

LP17

LP22

(c)

(b )(a)

Substation #1

Tr#1

Substation #2

Tr#2

Fig. 6. Three types of closed loop system. (a) Type I; (b) Type II; (c) Type III.

4.4. Case study 4—investigation on the electric source forthe closed loop system

The three types of closed loop system shown inFig. 6were designed to simulate three possible interconnectionschemes of two primary feeders for load transfer. The twoprimary feeders are from the same main transformer (TypeI), different main transformer in a substation (Type II),and from different substation (Type III), respectively. Thecapacity of each substation transformer for the Type I is

Table 4The annual costs for the three types of closed loop system (overhead line)

Closed loop type Customer interruption cost Total cost

Type I 49.8 167.8Type II 33.6 166.1Type III 32.8 160.6

32 MVA, whereas the capacity of each substation trans-former for the Type II and Type III is 16 MVA.Table 4is the result of reliability cost/worth assessment for thethree types. It can be seen that Type III can satisfy therequirement of both higher reliability level and lowercost.

5. Conclusion

This paper has developed a set of composite load pointreliability worth evaluation models that include the impactof distribution substations, primary systems, and the inter-action between them for five typical structures. The relia-bility worth evaluation models have been used to performvalued-based reliability planning for selecting the most suit-able distribution type and substation configuration based onthe minimum total cost. The results of case studies show


that the degree order of the reliability worth level for thefive types of distribution system is primary network, linkarrangement, closed loop, open loop, and basic radial type,in turn. However, the reliability worth level is variable ac-cording to the complexity of each type. For example, if cir-cuit breakers are used instead of disconnect switches forthe various disconnect points of each primary main feederof a closed loop system, the reliability worth level maybe superior to the primary network system. The reliabilityworth evaluation model developed in this paper can quanti-tatively provide a basis of comparison for decision-makingon selecting the appropriate type of system for particu-lar kinds of customers. This approach of value-based dis-tribution system reliability planning can help a utility toplan, and design distribution utilities in a most cost-effectivemanner.

Acknowledgements

The authors acknowledge the financial support of the Na-tional Science Council of Republic of China under ContractNSC 91-2213-E-011-096.

Appendix A. List of symbols

Ci(rj) the interruption cost (US$/kW) of loadpoint i due to outage eventj with anoutage durationrj

ECOSTcb,i the reliability worth index of load pointicontributed to by active failure of feedercircuit breakers

ECOSTi the reliability worth index of load pointiECOSTprimary,i the reliability worth index of load pointi

contributed to by primary distributionsystem

ECOSTstuck,i the reliability worth index of load pointicontributed to by active failures of mainfeeder sections in combination with anassociated stuck circuit breaker

ECOSTsub,i the reliability worth index of load pointicontributed to by distribution substation

ECOSTsys the system total reliability worth indexFm,i the number of main sections of a

primary feeder which services loadpoint i

Li the average load power connectedat load pointi

Ncb the number of feeder circuit breakersconnected at the same low voltage bus

NE the number of outage events that isolatethe load pointi

Nm the total number of main feedersections connected at the samelow voltage bus

Pc the probability of a circuit breakerfailing to open when calledupon to open

rcb the repair time for a feeder circuitbreaker

rj the average outage duration of substationequipmentj that causes substation tolose continuity of supply

r li the repair time for the lateral thatservices load pointi

rm the repair time for a main feedersection

rti the repair time for the distributiontransformer that services load pointi

ts the time required to perform therequired isolation, switching, andload transfer actions

Greek lettersλa

cb the active failure rate of a feedercircuit breaker

λpcb the passive failure rate of a circuit

breakerλj the average failure rate of

substation equipmentj that causessubstation to lose continuity of supply

λm the failure rate of themth main sectionof a primary feeder

λli the failure rate of a lateral thatservices load pointi

λti the failure rate of a distributiontransformer that services load pointi

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Biographies

Teng-Fa Tsaowas born on September 20, 1965, in Chang-Hua, Taiwan. He received his BSEE and MSEE degreesfrom the National Taiwan University of Science and Tech-nology (NTUST) in 1990 and 1992, respectively. He hasbeen with the Nan Kai College since 1992, where he is aninstructor of the EE Department. He is currently a PhD stud-ent in the Electrical Engineering Department of the NTUST.His research interests include the application of artificialintelligence to power systems operation and planning.

Hong-Chan Changwas born in Taipei, Taiwan on 5 March1959. He received his BS, MS, and PhD degrees all in elec-trical engineering from National Cheng Kung University in1981, 1983, 1987, respectively. In August 1987, he joinedNational Taiwan University of Science and Technology as afaculty member. He is presently a professor. His major areasof research include power system stability, reliability, andapplication of artificial intelligence to power systems.

Documents

Comparative case studies for value-based distribution system reliability planning