An Algorithm on Optimal Placement Decision of Automatic Switches for 6 Sections/3 Links Configuration in DAS

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1 328 Joural of Electrical Egieerig & Techology Vol. 6, No. 3, pp. 328~333, 2011 DOI: /JEET A Algorithm o Optimal Placemet Decisio of Automatic Switches for 6 Sectios/3 Liks Cofiguratio i DAS Il-Hyug Lim, We-Hao Zhag*, HamsyahTrirohadi**, Myeo-Sog Choi***, Seug Jae Lee*** ad Bok-Nam Ha Abstract A Distributio Automatio System (DAS) is operated by moitorig ad cotrol of the field statesusig Feeder Remote Termial Uits (FRTUs) istalled together withautomatic switches.a optimal placemet of automatic switchesca ehace efficiecyof the operatio ad restoratio, ad improve the power supply reliability ofa DAS.This paper proposes a algorithm to decide the optimal placemet of automatic switches ia DAS.The proposed algorithm was developed oa DAS witha six sectios ad three liks cofiguratio. The proposed algorithm was provided iaeight-feeder power distributio system. Keywords: Distributio automatio system, Automatic switch, FRTU, Power distributio system 1. Itroductio A Distributio Automatio System (DAS) operatesremotelyby moitorig ad cotrol of power distributio system through Feeder Remote Termial Uits (FRTUs). FRTU measuressystem iformatio from the field adreports them to a DAS server. The DAS ca cotrol ad chagethe power distributio system cofiguratio for optimal operatio through the FRTUs istalled together with automatic switches [1]. The placemet of automatic switches with FRTUs (A/S) is the most importat elemet i icreasig the operatio efficiecy of a DAS. Whe fault occurs o the power distributio lie of a DAS, a restoratiomakesa miimized blackout areadepeds o cotrols of the A/S switches. The miimized blackout area meas power is supplied to the customers to except customers of fault sectio; hece, the placemet of the A/S switches should be cosidered a vital factor i the operatio of a DAS. To date, automatic switches i a DAShave beeeither istalled whe a DASis iitiallycostructed or addedlater. Although a distributio of the automatic switches i a DASis required to be costructed with six sectios ad three liks cofiguratio, the automatic switches have bee istalled a positio to be required by operatio ad as a Correspodig author: Departmet of Electricalad Computer Egieerig, The Uiversity of Wester Otario, Caada. (sojoo2ja@gmail.com) * Departmet of Electrical Egieerig, Togji Uiversity, Chia (xiwe.re@gmail.com) ** PT.PLN (Persero)Natioal Electricity Compay, Idoesia (hamsyah_t@hotmail.com) *** Departmet of Electrical Egieerig, Myogji Uiversity, Korea.(mschoi@mju.ac.kr, sjlee@mju.ac.kr) Departmet of Trasmissio ad Distributio Research, KEPRI, Korea.(bha@kepri.re.kr) Received: November 26, 2009; Accepted: March 7, 2011 result, six sectios ad three liks cofiguratio were t kept i the field. To icrease the operatio efficiecy of a DAS,may papers have bee published for decidig the optimal placemet of automatic switches. Several studies have sought to address this problem from various aspects. Referece [1] studied the placemet of power facilities from a geographical perspective. I [2-6], the placemets of switches were located usig the itelligece algorithms. The switch locatio,which takes the operatig reliability ito accout, was itroduced i [7 9]. Moreover, methods cosiderig various ecoomic viewswere explored i [10]. The mostefficiet fuctio of a DAS is restoratio through remote moitorig ad cotrol. However, previous researches have studied placemets of automatic switches from iitial system plaig, butdid ot cosider restoratio efficiecy. I this paper, a algorithm is proposed to decide the optimal placemet of automatic switches cosiderig the outage load equalizatio forthe restoratio of the DAS. The proposed algorithm is applied tothe six sectios ad three liks system cofiguratio. Sectio 2 explais the relatioship betwee the placemets of automatic switches ad restoratio uder the cofiguratio of six sectios ad three liks. Sectio 3 illustrates the optimal placemet of automatic switches algorithm through three steps. I Sectio 4, the effectiveess of the proposed algorithm is prove by case studies. 2. Relatio of the placemet of automatic switches ad restoratio i DAS I a distributio feeder, asectio is defied by a group of lie segmets betwee adjacet switches or circuit breakers.

2 Il-Hyug Lim, We-Hao Zhag, HamsyahTrirohadi, Myeo-Sog Choi, Seug Jae Lee ad Bok-Nam Ha 329 Each sectio has maycustomers ad a sectio loadis decided fromthe summatio of a cotract load or the maximum load of customers withi a sectio[10]. A lik is defied as the coectio with a automatic tie switch thatis opeed ormally ad closed for restoratio. I the curret study, a voltage level is 22.9 kv, a ormal permit capacity(c ) is 10 MVA, ad a emergecy capacity(c e ) is 14 MVA o a power distributio lie. The optimal umber of liks to differet feeders ca be obtaied as follows: L ( C C ) e C (1) where L : umber of liks C : ormal capacity C e : emergecy capacity. Eq. (1) idicates a umber of ecessary liks cosiderig a margi for restoratio. If feeders are beig operated with full loads (10MW) ad a fault occurs at a feeder, the faulted feeder may eed 10 MW loads for restoratio i the worst case. The, a umber of ecessary liks will be 3 because a result by Eq. (1) is 2.5. Fig. 2. Structures of four, five, ad six sectios with three liks Structures with differet sectios are show i Fig. 2. As see from the load distributio i each sectio, we ca ifer that more sectio switches careduce outage load capacity, but the cost of facilities ad maagemet will icrease correspodigly. Thus, i this paper, a algorithm o optimal placemet decisio of automatic switches wasdevelopedby cosiderig a structure of six sectios ad three liks o the power distributio lie i DAS followig KEPCO s techical report [11]. 3. A algorithm for optimal placemet of automatic switches Fig. 1. Three liks o a power distributio lie From(1), the optimal umber of liks ca be ascertaied as three, ad the feedereeds to be divided itoat least four sectios. Thus, each lik coects a sectio to the other feeder, except for the first sectio which oly coects to the source, as show i Fig. 1. Accordig to a effect by umber of sectio switches, three liks based o each case of four sectios, five sectios, ad six sectios are show i Fig. 2. I a four sectios case, the sectio load is 2.5 MVA o a stadard that the maximum load o a power distributio lie is 10 MVA at a ormal state. I a five sectios case, the sectio load is 2 MVA, ad i a sixsectios case, the sectio load is 1.6 MVA. I all of the four, five, ad six sectios cases, a DAS ca secure the restoratio capacity from other feeders i ay fault locatio. Thus, the outage load is 2.5 MVA whe a fault occurs i a structure of four sectios. A structure with six sectios is better tha that with four sectios from the stadpoit of restoratio because DAS ca reduce a outage load whe a fault occurs. The optimal placemet of the automatic switches algorithm is composed of three steps.the first step is to fid the ormal ope switches i the radial distributio lies. The ext step is to choosea automatic tie switch amog the ormal ope switches. Fially, the automatic switches to divide sectios aredecidedby sectio load equalizatio, a positio of lik lie, ad the cofiguratio of the six sectios. 3.1 Tie Switch Allocatio To determiethe optimal placemet of automatic switches, the first step is torearrage the distributio system with eight feeders (Fig. 3) as radial structure. The optimal placemet of the tie switch should eable all feeders to have evely distributedloads, which also esure the largest margicosiderig restoratiouder the sixsectios adthreeliks cofiguratio. Fig. 4 shows a method to fid the locatio of the tie switch usig the followig steps:

3 330 A Algorithm o Optimal Placemet Decisio of Automatic Switches for 6 Sectios/3 Liks Cofiguratio i DAS 3.2 Decisio of Three Liks The tie switches selected through the procedure i 3.1 are maual tie switches, amog which the automatic switches are selected to decide the three liks. Whe a fault occurs i the system, the three liks amog the feeders are supposed to provide reserved capacity to the faulty feeder. If the liks are ot properly decided, there would be failure of fault restoratio. Fig. 3. Eight feeders o the power distributio system Fig. 4. A method to fidthe maual tie switch betwee feeders (1) Assume each feeder has a virtual tie switch at the begiig of the feeder; (2) Move the assumed tie switch alog the feeder with evely distributed loads; (3) If there are multi-braches alog the feeder durig the switch movemet, add a umber of virtual tie switches correspodig to the brach umber; (4) Decide the poit where the tie switches meet oe aother as the ormal ope poit. If locatio of the tie switches with the above method is decided, the loads of all feeders would ot always be evely distributed so the tie switch should move from the feeder with larger loads to a feeder with smaller loads. To esureevely distributed loads, we ca calculate the miimum sum of the squares of all the feeders. For example, if there are two feeders with loads as 3 ad 5 respectively, the sum of the squares would be 9+25=34. If these two loads become evely distributed, which meas that each feeder has a load as 4, the sum of the squareswould be 16+16=32. Accordig to this rule, we ca obtai the optimal locatio of the tie switch. Fig. 5. A process for fidig the lik with the automatic tie switch lie I the curret study, the proposed method which decides the three liks locatio divides a power distributio lie as show i Fig. 5. Assumig that the ormal ope poit is decided, the feeder is divided ito sixsectios with evely distributed loads. The, all sectios are grouped ito threegroups as show i Fig. 5. Three groups should be made byevely distributio of the loads i all the feeders ad a possible that a fault ca be i all the feeders. So there would be oly oe lik i each group. Accordig to the six sectiosthree liks cofiguratio, the three liks ca be coectedto sectios giveby the rules below: Rule 1. Sectio 2, sectio 4, sectio 6 Rule 2. Sectio 3, sectio 4, sectio 6 Rule 3. Sectio 3, sectio 5, sectio 6 The tie switches which satisfythe above rules will be selected as the automatic tie switch. Cosequetly, the restoratio ca be successfully processed o matter where the fault occurs. 3.3 Decisio of Sectio Automatic Switch Placemet The distributio system would operate efficietlyif all feeders are well cofigured. However, there arevariouscases that do ot satisfy the preseted rules i the field. Fig. 6. Decisio of the automatic tie switch by movig sectio A/S (Case I)

4 Il-Hyug Lim, We-Hao Zhag, HamsyahTrirohadi, Myeo-Sog Choi, Seug Jae Lee ad Bok-Nam Ha 331 Fig. 6 shows a case where there is o liki Sectio 2. I this case, if there is a fault occurrig i Sectio 1, with reserved capacity, Sectios 4 ad 6 caot coduct the restoratio successfully.thus, S1 moves to the source side ad the lik is coected to Sectio 2 to satisfy Rule 1. Fig. 7. Decisio of the automatic tie switch by movig sectio A/S (Case II) I Fig. 7, all sectios do ot satisfy ay rule except the last sectio. Similarly, we eed to move the switches i order to eable all the sectios to satisfy the rules of the lik coectio ad the requiremet of the load distributio. I Fig. 8, there are two successful results based o the method to fid the three liks, ad the optimal cofiguratio should guaratee that the loads are evely distributed. Fig. 9. Distributed parameters of two cofiguratios 4. Case Study I order to test the validity of the proposed algorithm, the model system show i Fig. 10 is adopted for the case study. (a) Success 1 (b) Success 2 Fig. 8. Two results by the proposed algorithm The distributed parameter to judge the load distributio is calculated by Fig. 10. Iitial cofiguratio of the model system The proposed algorithm is coducted through three steps.the distributed loads of all sectios, which are show i Fig. 11, fially achieved the optimized six sectios adthree likscofiguratio. i= 1 δ = ( x ) 2 i x (3) where x : Average sectio load of a power distributio lie : Total sectio δ : Distributed load factor x : Load at sectio i i The two results show i Fig. 9 correspod to the load distributio of the two systems i Fig. 8. Evidetly, Success 2 has a smaller distributed parameter which meas that the loads are better dispatched i all the sectios. Fig. 11. Load dispersio after optimal placemet of the automatic switches

332 A Algorithm o Optimal Placemet Decisio of Automatic Switches for 6 Sectios/3 Liks Cofiguratio i DAS I Table 1, the total load of each feeder is give ad the load dispersio is calculated with the

5 332 A Algorithm o Optimal Placemet Decisio of Automatic Switches for 6 Sectios/3 Liks Cofiguratio i DAS I Table 1, the total load of each feeder is give ad the load dispersio is calculated with the loadig level Table 1. Load dispersio fial results Feeder umber Total load Load dispersio Through the case study, this paper proves the effectiveess of the algorithm i establishig the optimal placemet of automatic switches i the six sectios adthree likscofiguratio. 5. Coclusio The optimal placemet of the automatic switches plays a importat role i the restoratio of the DAS. To date, the system cofiguratio differs with the variatio of the operatig coditio so that most of them do otcomply with the criterio of the six-sectio three-lik cofiguratio. I this paper, a algorithm is proposed for the optimal placemet of automatic switches to meet the requiremet of the six-sectio three-lik cofiguratio. The proposed optimal A/S placemet algorithm is composed of three steps: The first step is to fid the ormal ope poit of the switches to make the distributio system a radial system. Secod, decide the lik as the positio of the automatic tie switch. Fially,distribute the load evely to esure its restoratio capacity. The proposed algorithm is applied to a system with eight feeders to test its effectiveess; it is also loaded to the Itelliget Distributio Maagemet System of KEPCO ad will be applied i the field soo. Politehica Uiversity of Bucharest. [2] M.-R. Haghifam, "Optimal Allocatio of Tie Poits Distributio Systems Usig a Geetic Algorithm," Euro. Tras.Elect.Power [3] C.-S. Che, C.-H. Li, H.-J. Chuag, M.-Y. Huag, ad C.-W. Hug, "Optimal Placemet of Lie Switches for Distributio Automatio Systems Usig Immue Algorithm," IEEE Tras. Power Delivery, vol. 21, o. 3, pp , August [4] D. B. Kulkari, G. R. Udupi, ANN-Based SVC Switchig at DistributioLevel for Miimal-Ijected Harmoics, IEEE Tras.o Power Delivery, vol. 25, o. 4, pp ,Jul [5] Ahmed E. B. Abu-Elaie, M. M. A. Salama, A Wavelet-ANN Techique for Locatig SwitchedCapacitors i Distributio Systems, IEEE Tras.o Power Delivery, vol. 24, o. 1, pp ,Ja [6] C. Che, C. Li, H. Chuag, C. Li, M. Huag, C. Huag, Optimal Placemet of Lie Switches for DistributioAutomatio Systems Usig Immue Algorithm, IEEE Tras.o PowerSystems, vol. 21, o. 3, pp , Aug [7] Willis H., Power distributio plaig referece book, New York, Marcel Dekker, pp 29-30, [8] TuraGoe, "Electric Power Distributio System Egieerig," McGraw-Hill Iteratioal Editio, pp [9] H. Khai, M.Moallem, S. Sadri, M.Dolatshahi, A New Method for Olie Determiatio ofthe Locatio of Switched Capacitor Baks idistributio Systems, IEEE Tras.o Power Delivery, vol. 26, o. 1, pp , Ja [10] A. Moradi, ad M. Fotuhi-Firuzabad, "A Reliability cost/worth approach to determie optimum switchig placemet i distributio systems," IEEE/Power Eg. Soc. Trasmissio ad Distributio Cof. Exhibit: Asia ad Pacific, Dalia, Chia, [11] KEPCO, A study o the cofiguratio ad the operatio stadard for distributio etwork, Ackowledgmets This work was supported by the Natioal Research Foudatio of Korea Grat fuded by the Korea Govermet (NRF D00025)ad Itelliget Distributio Maagemet System developmetprogram of Miistry of Commerce, Idustry ad Eergy. Refereces Ilhyug Lim He received his B.E., M.S., ad Ph.D. degrees i Electrical Egieerig at Myogji Uiversity, Korea i 2005, 2007, ad 2010, respectively. Curretly, he is workig as apost-doctoral Fellow ithe Departmet of Electrical ad Computer Egieerig, The Uiversity of Wester Otario, Caada. His research iterests are power system protectio ad cotrol, power automatio system, multiaget applicatio, smart grid, ad IEC 61850/61968/ [1] A.M. Morega, J.C. Ordoez ad M. Morega, "A Costructal Approach to Power Distributio Networks Desig," Departmet of Electrical Egieerig

Il-Hyug Lim, We-Hao Zhag, HamsyahTrirohadi, Myeo-Sog Choi, Seug Jae Lee ad Bok-Nam Ha 333 We-Hao Zhag He received his B.E.

He received his Ph.D. at MyogjiUiversity, Yogi, Korea i 2010. Curretly, he is workig i the Departmet of Electrical Egieerig at Togji Uiversity, Chia.

He received his Ph.D. i Electrical Egieerig from the Uiversity of Washigto, Seattle, USA i 1988.

His major research fieldsicludeprotective relayig, distributio automatio, ad multi-aget applicatios to power systems. HamsyahTrirohadi He received his B.

Hisresearch iterest is Distributio Automatio System. Myeo-Sog Choi He received his B.E., M.S., ad Ph.D. degrees i Electrical Egieerig from Seoul Natioal Uiversity, Korea i 1989, 1991, ad 1996, respectively.

6 Il-Hyug Lim, We-Hao Zhag, HamsyahTrirohadi, Myeo-Sog Choi, Seug Jae Lee ad Bok-Nam Ha 333 We-Hao Zhag He received his B.E. degree i Electrical Egieerig from the Harbi Istitute of Techology, Harbi, Chia i He received his M.S. degree i Electrical Egieerig from Xi a Jiao Tog Uiversity, Xi a, Chia i He received his Ph.D. at MyogjiUiversity, Yogi, Korea i Curretly, he is workig i the Departmet of Electrical Egieerig at Togji Uiversity, Chia. His research iterests are power system protectio ad cotrol, ad power system automatio. Seug-Jae Lee He received his B.E.ad M.S. degrees i Electrical Egieerig from Seoul Natioal Uiversity, Korea i 1979 ad 1981, respectively. He received his Ph.D. i Electrical Egieerig from the Uiversity of Washigto, Seattle, USA i Curretly, he is a Professor at MyogjiUiversity ad a Director at the Next-Geeratio Power Techology Ceter (NPTC). His major research fieldsicludeprotective relayig, distributio automatio, ad multi-aget applicatios to power systems. HamsyahTrirohadi He received his B.S ielectrical Egieerig from GadjahMadaUiversity, Yogyakarta, Idoesia, i 2002.Curretly, he is a M.S studet at MyogjiUiversity ad a employ of PT.PLN (Persero)Natioal Electricity Compay i Idoesia. Hisresearch iterest is Distributio Automatio System. Myeo-Sog Choi He received his B.E., M.S., ad Ph.D. degrees i Electrical Egieerig from Seoul Natioal Uiversity, Korea i 1989, 1991, ad 1996, respectively. He was a Visitig Scholar at the Uiversity of Pesylvaia State i Curretly, he is a Professor at MyogjiUiversity. His major research fields iclude power system cotrol ad protectio, icludig multi-aget applicatios. Bok-Nam Ha He received M.S.E.E degree ad Ph.D. from the Chugam Natioal Uiversity, Korea. He is curretly workig i Korea Electric Power Research Istitute of Korea Electric Power Corporatio sice he joied i He is a deputy researcher ad the leader of distributio automatio group to develop itelliget distributio automatio system sice His research iterests are the applicatio programs of distributio automatio, Smart Grid ad field applicatio.

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