Fifteenth National Power Systems Conference (NPSC), IIT Bombay, December 2008

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1 Fifeenh Naional Power Syses Conference (NPSC, T Boay, Deceer 2008 Seing Direcional Over Curren Relays as he Local Backup of Disance Relays in Power Nework M.M.Ghanarian, F.Kavehnia, A.Kazerooni slaic Azad Universiy, Branch of Kazeroon Asrac- n his paper a new algorih ased on geneic algorih and a new ojecive funcion are used o increase he operaing speed and he seleciviy of power syse proecion relays. n his ehod he opial operaing ie of second zone of disance relays and also he opial operaing characerisic, PSM and TSM of over curren relays are calculaed siulaneously. Finding he asolue opiu poin of he opiizaion prole and iproveen in he speed and coordinaion of power syse proecion relays are he advanages of his ehod in coparison wih he ordinary ehods like siplex or dual siplex. Nuerical resuls oained wih he proposed ehod for a real power syse are presened. Keywords Power syse proecion, Disance relay, Over curren relay, Opial coordinaion 1 nroducion Disance relays are used in power syses as he ain relays o proec lines ecause of heir high speed in clearing fauls and also he easiness of heir coordinaion. Each disance relay has hree zones which second and hird zones operae as he ackup of he forward lines. [1] shows differen ways o se he ipedance and he operaing ie of each zones of disance relays. Despie odern disance relays, direcional over curren (DOC relays are he es choice for local ackup of disance relays fro he econoical and echnical poin of view, Bu i is oo coplicae o coordinae hese relays ogeher. Today opiizaion ehods have een used o coordinae direcional over curren relays ogeher. n his paper, a new ehod ased on geneic algorih and a new ojecive funcion are used o coordinae direcional over curren relays ogeher and also wih disance relays. n opiizaion ehods, a firs, he consrains for coordinaion of each ain and ackup relay are deerined. [1] discusses he process of deerining such consrains. Then, hese consrains are solved y an opiizaion ehod in order o achieve iniu ie seing of each relay. Soe of he opiizaion ehods ha have een used for he aove prole are siplex ehod [2, 3, 4], wo phase siplex ehod [5] and dual siplex [6]. n [7] a arix ehod is used o oain he relay seing. All of he aove approaches consider a predefined characerisic for each DOC relay and hen curren seings and ie seings are oained. Since i is possile o apply differen characerisics on DOC relays, so in his paper we will ry o achieve he opiu operaing characerisic, he opiu ie seing and curren seing of DOC relays and also he opiu ie seing of disance relays' second zone y solving he opiizaion prole. will e shown ha his idea will iprove he speed and coordinaion of proecion syse. n his paper, a firs, he process o oain he consrains of he prole is illusraed and hen we will invesigae he proposed approach for solving hese consrains. Finally he proposed approach will e esed on a real nework and he resuls will e copared wih oher approaches. 2 The consrains o coordinae disance and DOC relays n power syses, DOC relays are used as he local ackup of disance relays. Figure 1 shows his plan Breaker CT Disance DOC Relay Relay PT (Main (Backup Fig 1- DOC relay as he local ackup of disance relay Figure 2 shows a siple ehod for coordinaion of a disance relay and a DOC relay. F 1 Trip Mechanis CT z 2 Trip Fig 2- Coordinaion of a disance relay and a DOC relay 329

2 Fifeenh Naional Power Syses Conference (NPSC, T Boay, Deceer 2008 As figure 2 shows, in order o coordinae one disance relay wih a DOC relay, he operaing ie of DOC relay for faul F 1 should e ore han he second zone operaing ie of disance relay. This inerval should e ore han CT. CT is he ie inerval for coordinaion of ain and ackup relay. So he consrain for coordinaion of disance relay wih DOC relay will e in he for of inequaliies 1 ( F 1 z 2 CT (1 (F 1 is he operaing ie of DOC relay for faul F 1 and z2 is he operaing ie of disance relay second zone. Addiionally, in order o coordinae wo direcional over curren relay [8], one as ain relay ( and he oher as ack up relay (, (i is shown in figure 3, he difference eween he operaing ie of ack up relay and he operaing ie of ain relay for fauls F 1 and F 2 should e ore han CT. F 1 and F 2 are shor circuis a near us and far us of ain relay respecively. Fig 3- Coordinaion of DOC relays So he consrains for coordinaion of DOC relays and will e in he for of inequaliies 2 and 3 ( ( CT (2 ( F2 ( F2 CT (3 (F 1 and (F 1 are respecively he operaion ie of ackup and ain relay for a shor circui in F 1, (F 2 and (F 2 are respecively he operaion ie of ackup and ain relay for a shor circui in F 2. For insance if relays and se on norally inverse characerisics [11], hen inequiies 1, 2 and 3 can e expressed as 3, 4 and 5 z2 CT (4 ( ( F 2, 1, CT, F 2 1, CT (5 (6 and, are currens of ackup and ain relay for faul F 1. F2 and,f2 are currens of ackup and ain CT F2 CT relay for faul F 2. and, are currens of ackup and ain relay. TSM and TSM are ie seing uliplier of ackup and ain relay. For opial coordinaion of power syse relays, a firs, i is essenial o for he coordinaion consrains of all ain and ackup relays. Then he paraeers of he relays should e se such ha for he leas operaing ie of relays, all he consrains e saisfied. 3 Proposed approach for opial coordinaion of disance and DOC relays According wha expressed in he previous secion, we should deerine four paraeers in order o se and coordinae disance and direcional over curren relays a The operaion characerisic of relays should e deerined. To achieve inequaliies 4, 5 and 6, we assued ha he operaion characerisic of DOC relays is norally inverse. Since we can apply several characerisic on a DOC relay, so in his paper we ry o achieve he opial operaion characerisic of relays which iprove he seleciviy and speed of proecion syse. For exaple for SPCS 2D26 relay, which is produced y A.B.B. Copany we can apply six characerisics as expressed in ale 1. Tale 1- Characerisics of SPCS DOC relay Norally nverse Very nverse Exreely nverse Long Tie nverse R-ype RXDG-ype * Ln( TSM * n figure 4, hese characerisics have een drawn for TSM=

3 Fifeenh Naional Power Syses Conference (NPSC, T Boay, Deceer 2008 E V N RXDG R LT Where Char i Characerisic of i' h DOC relay PSM i Curren seing uliplier of i' h DOC relay TSM i Tie seing uliplier of i' h DOC relay z 2 i Second zone operain ie of i' h disance relay n is he oal nuer of DOC relays and is he oal nuer of disance relays. The ojecive funcion which is used in his paper for grading he chroosoes is Fig 4- Differen characerisics of SPCS DOC relay Figure 4 shows ha for soe shor circui currens, a special characerisic can provide a less operaion ie. n his paper we ry o achieve he os suiale operaion characerisic using geneic algorih. Curren seing uliplier (PSM is he oher paraeer ha should e se on DOC relays. This paraeer ha is deerined according o, should e se such ha he relay do no operae for he axiu load curren u operae for he iniu shor circui curren. c Tie seing uliplier (TSM is he oher paraeer for OC relays coordinaion. This paraeer should e se such ha for he iniu TSM value, sufficien ie inerval eween ain and ackup relay is provided. d The operaing ie of disance relays' second zone should e deerined. n his paper, all four paraeers are deerined using geneic algorih. Geneic algorih uses rando nuer (gene for each of variales. A chroosoe is a se of rando nuers produced for all of variales. Therefore each chroosoe is a soluion of he prole. n geneic algorih, a se of chroosoes is provided and hen hey are graded regarding ojecive funcion. Then a nuer of he are seleced which are called he firs generaion. Afer producing he firs generaion, we can use operaors such as crossover and uaion o produce he nex generaion and finally finding he opial soluion. n his paper, each chroosoe conains characerisic, PSM and TSM of over curren relays and also he second zone operaing ie of disance relays as figure 5. Char 1... Char n PSM 1 /... PSM n... TSM n z2,1... z2, TSM 1... Fig 5- Geneic algorih chroosoe OjeciveFuncion N Min{ K * MC K2 * CTNM K3 * Su( n 1 1 OC MC is he nuers of ies ha he ackup relay operae earlier han ain relay, CTNM is he nuer of ies ha ie inerval of ain relay and ackup relay is less han CT and Su( oc is he suaion of he operaing ies of over curren relays and disance relays. K 1, K 2 and K 3 are arirary coefficiens. This ojecive funcion opiizes he operaing speed and he seleciviy of proecion syse siulaneously. So we can e sure ha relays will operae rapidly and coordinaely o clear fauls. 4 Resuls of he proposed approach on a case sudy The proposed approach has een esed on a nework shown in figure 6. This nework consiss of 26 usars, 5 generaors, 43 lines, 7 ransforers, 52 DOC and disance relays. Figure 6- Case sudy The prograed sofware can ge all of he six characerisics, expressed in ale 1. Bu, we ignore using exreely inverse (E.. characerisic since E.. is ofen used in he indusrial neworks o coordinae relays wih fuses. CT value has considered 0.3 seconds. We assue ha TSM varies discreely fro 0.05 o 1 in 0.05 seps, PSM varies discreely fro } (7 331

4 Fifeenh Naional Power Syses Conference (NPSC, T Boay, Deceer % o 200% in 25% seps and z 2 varies coninuously fro 0.3 Sec. o 0.35Sec. Tale 2 shows opial calculaed values for PSM, TSM, characerisics of DOC relays and z 2 of disance relays. Tale 2- DOC and disance relays Seings DOC Relay No. Char. PSM TSM Dis. Relay No. z 2 (Sec 1 N V V N V N RXDG V V V V N V N N V V V V V V R V N V V R V V V V N V V V R N V V V V N N V N N V V RXDG V N V Tale 3 copares oal operaion ie and he percenage of coordinaion consrains which are saisfied in hree cases Case 1 Dual siplex ehod wih he assupion of norally inverse characerisic for all relays. Case 2 Geneic Algorih ehod wih he assupion of norally inverse characerisic for all DOC relays. Case 3 Geneic algorih ehod, which deerines opial operaion characerisic of DOC relays (proposed ehod. Tale 3. Coparison of resuls for he case nework Toal operaion ie of DOC relays (Sec saisfied consrains (% Case 1 Case 2 Case Tale 3 illusraes he advanages of proposed approach. Using Geneic algorih and deerinaion of opial Characerisic, PSM and TSM of relays siulaneously, resuls in a More consrains are saisfied which eans increasing of relays coordinaion and seleciviy of proecion syse. Considerale decrease in he operaion ie of relays, which eans faser operaion of proecion syse. 5 Conclusion n his paper, a new ehod is proposed in order o opiize coordinaion of disance and direcional over curren relays ased on geneic algorih. This ehod can deerine opial operaion characerisic, curren seing uliplier (PSM, ie seing uliplier (TSM of DOC relays and he operaing ie of disance relays' second zone siulaneously. proveen in he coordinaion and he speed of relays, finding he asolue opial poin, no eing rapped in a local opial poin, he ailiy o e applied o large neworks, he ailiy o consider oh linear and nonlinear characerisics of relays are soe of advanages of he proposed ehod. 6 References [1] Seung Jae Lee, Chen-Ching Liu, nelligen Approach o Coordinaion denificaion in Disance Relaying ", EEE Transacion on Power Delivery, Vol. 16, No. 3, July 1996, PP

5 Fifeenh Naional Power Syses Conference (NPSC, T Boay, Deceer 2008 [2] L.Perez, A.J.Urdanea, Opial Copuaion of Direcional Overcurren Relays Considering Definie Tie Backup Relaying ", EEE Transacion on Power Delivery, Vol. 4, No.4, Ocoer 1999, PP [3] L.Perez, A.J.Urdanea, Opial Copuaion of Disance Relays Second Zone Tiing in a Mixed Proecion Schee wih Direcional Relays", EEE Transacion on Power Delivery, Vol. 16, No.3, July 2001, PP [4] A.Urdenaa, H.Resrepo, S.Marques and J.Sanches, Coordinaion of Direcional Overcurren Relay Tiing Using Linear Prograing, EEE Transacion on Power Delivery, Vol. 11, Jan.1996, PP [5] A.J.Urdenaa, R.Nadira and L.Prez, Opial Coordinaion of Direcional Overcurren Relays in nerconneced Power Syse, EEE Transacion on Power Delivery, Vol. 3, July 1988, PP [6] A.S.Braga, J.T.Saraiva, Coordinaion of Direcional Overcurren Relays in Meshed Neworks Using Siplex Mehod, EEE conf. MELECON 96, Vol. 3, No. 3, 1996, PP [7] B.Chaopadhyay, M.S.Sachdev, T.S.Sidhu, An On line Relay Coordinaion Algorih for Adapive Proecion Using Linear Prograing Technique, EEE Transacion on Power Delivery, Vol. 11, Jan. 1996, PP [8] H.A.Ayaneh and R.Keyhani, Opial Coordinaion of Overcurren Relays in Power Syse y Dual Siplex Mehod in Proc AUPEC Conf, Perh, Ausralia, Vol. 3, 1995, PP [9] H.A.Ayaneh, M.Al-Daagh, H.Karegar, A New Opial Approach for Coordinaion of Overcurren Relays in nerconneced Power Syses, EEE Transacion on Power Delivery, Vol. 18, No. 2, April 2003, PP [10] C.W.So, K.K.Li, K.T.Lai, K.Y.Fung, Applicaion of Geneic Algorih o Overcurren Relay Grading Coordinaion, EE Conf. Developens in Power Syse, March 1997, PP [11] H.K.Karegar, H.A.Ayaneh, M.Al-Daagh, A Flexile Approach for Overcurren Relay Characerisics Siulaion", Elecric Power Syse Research, 2003, PP