Backup alternatives for 110 kV lines

POWER ENGINEERING AND ELECTRICAL ENGINEERING VOLUME: 11 |NUMBER: 3 |2013 |JUNE Backup Al e na i es o 110 kV Lines Vi HOUDEK1, S anisla RUSEK1, Radomi GONO1 1Depa men o Elec ical Powe Enginee ing, Facul y o Elec ical Enginee ing and Compu e Science, VSB–Technical Uni e si y o Os a a, 17. lis opadu 15, 708 33 Os a a-Po uba, Czech Republic i .houdek@cen um.cz, [email p o ec ed], [email p o ec ed] Abs ac . The pape desc ibes backup al e na i es o 110 kV lines. Line backup is one o inpu pa ame- e s used o op imise he eno a ion o 110 kV lines. The op imisa ion is based on he p inciple o eliabil- i y cen ed main enance (RCM) which depends on he echnical condi ion and impo ance o a pa icula ele- men . The pape s a s wi h illus a ing he me hod o eliabili y schemes. This me hod enables he e alua ion o ailu e- ee ope a ion p obabili y. The p obabili y o a ailu e- ee ope a ion can be es ima ed o all backup ypes o 110 kV lines exis ing in he dis ibu ion ne - wo k. To compa e di e en backup al e na i es, ype lines we e selec ed and calcula ed wi h. The esul s o he me hod helped es ima e he e ec s o a line ailu e o a pa icula dis ibu ion dis ic . Keywo ds Backup, e ec o ailu e, main enance, RCM, eliabili y. 1. In oduc ion Fo a oday’s consume , a eliable and ailu e- ee op- e a ion o elec ici y ne wo k is a i al and na u al hing. Howe e , o a dis ibu ing company espon- sible o he sa e y and eliabili y o ne wo k, mee ing his need is a complica ed ask liable o he “Regula- ions o dis ibu ion ne wo k ope a ion“. I he powe supply is in e up ed, he dis ibu ion company loses p o i on dis ibu ion and powe supply. Mo eo e , he dis ibu o can be ined o he ene gy unsupplied o consume s. To main ain he eliabili y and sa e y o ope a ion, a dis ibu ion ne wo k mus be egula ly se iced as pe he “Schedule o p e en i e main enance“ [1]. To op imise main enance, eliabili y cen e ed main enance (RCM) seems o be he mos app op ia e ool [2]. I is based on he echnical condi ion and impo ance o he equipmen . The e a e wo inpu pa ame e s which help assess he impo ance o a line. Fi s ly, his pape ou lines he back-up al e na i es o a ailed line. An- o he inpu pa ame e is ansmi ed ene gy [3]. Also, we p esen an e alua ion o one dis ibu ion dis ic . 2. Impo ance o Line The possibili y o a line backup in o ms bes on he impo ance o a line [4]. Howe e , impo ance o a 110 kV line can be also de e mined by i s losses, load o ca ying capaci y. Backup al e na i es o a ailed line mus be speci ied - powe can be supplied by ano he 110 kV line o an MV line. Howe e , some 110 kV lines ha e no backup. I a line ails, localiza ion o a ailu e and manipula ions o deal wi h ailu e, ei he manual o emo e, mus be ca ied ou . In e ms o eliabili y, du a ion o manipula ion is essen ial. 2.1. Reliabili y Scheme Me hod To e alua e backup, we use p obabili y o ailu e- ee ope a ion Rcalcula ed in he ollowing equa ion [5]: R= 1 − λτ 8760.(1) To calcula e he p obabili y o a ailu e- ee ope a- ion, ailu e a e λ(yea −1) and mean ailu e ime τ (hou ) mus be de e mined. The calcula ion is un as pe CEZ 22/80, bu he main enance down imes a e neglec ed. The me hod di e si ies h ee basic ypes o connec ing wo elemen s: •se ies connec ion o elemen s, •pa allel connec ion o elemen s – ho ese e, •pa allel connec ion o elemen s – cold ese e. 1) Se ies Connec ion o Elemen s In se ies connec ion o elemen s ailu e o one elemen causes a ailu e o he whole sys em, e.g. ans o me c 2013 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 169 POWER ENGINEERING AND ELECTRICAL ENGINEERING VOLUME: 11 |NUMBER: 3 |2013 |JUNE and line connec ion: λ=λ1+λ2,(2) τ=λ1τ1+λ2τ2 λ.(3) Fig. 1: Se ial connec ion o elemen s. 2) Pa allel Connec ion o Elemen s – Ho Rese e Ho ese e is a pa allel connec ion wi hou he use o manipula ion. I one elemen ails, ano he elemen akes o e i s unc ion, e.g. wo pa allel ans o me s. To al ailu e a e and mean ailu e ime a e de e mined as ollows: λ=1 8760 (λ1λ2(τ1+τ2)) ,(4) τ=λ1λ2τ1τ2 8760λ.(5) Fig. 2: Pa allel connec ion o elemen s – ho ese e. 3) Pa allel Connec ion o Elemen s – Cold Rese e Cold ese e is a connec ion iden ical wi h he ho e- se e. The connec ion is pa allel and wi h manipula- ion, so manipula ion ime mus be included in he calcula ion. Schema ically, he connec ion is se ial- pa allel. Howe e , in case o a ailu e, he ese e ele- men does no swi ch on immedia ely bu wi h a delay. The ailu e a e o manipula ion co esponds wi h he ailu e a e o he i s elemen . The manipula- ion akes place i he i s elemen ails. Cold ese e equa ions a e a combina ion o ela ions o pa allel ho ese e and se ies combina ion. Fig. 3: Pa allel connec ion o elemen s – cold ese e. 2.2. P obabili y o Failu e-F ee Ope - a ion Inpu pa ame e s o he calcula ion i sel [6], ailu e a e and mean ailu e ime, ha e been upda ed in a long- e m moni o ing o ailu es. The upda ed alues a e in he ollowing Tab. 1 [7]: Tab. 1: Inpu pa ame e s. λ(yea −1)τ(hou ) HV line 100 km 0,282 3,155 MV line 100 km 3,623 18,759 HV/MV ans o me 0,048 74,892 Fi e di e en ypes o connec ions we e used. As we sol e HV lines, he e a e se e al condi ions we mus deal wi h: •no backup, •backup by HV line o he same leng h, •backup by HV line o 1,5 mul iple o i s leng h, •backup by MV line o he same leng h, •backup by MV line o 1,5 mul iple o i s leng h. E e y backup has wo al e na i es – one wi hou ma- nipula ion (ho ese e), he o he wi h manipula ion (cold ese e). Manipula ion imes a e 7 minu es o HV backup lines and 20 minu es o MV backup lines. HV lines o a ype we e calcula ed, he leng h o he o iginal line is 100 km. The backup line is ei he o he same leng h o o he 1,5 mul iple o i s leng h o bo h HV and MV. Al oge he , nine al e na i es we e calcula ed. The calcula ion is o he same leng h o longe , i.e. 150 km. 1) No Backup The scheme has one elemen . To calcula e he p ob- abili y o ailu e- ee ope a ion, pa ame e s o 110 kV line mus be subs i u ed in ela ion R= 0,999898434, 1. c 2013 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 170 POWER ENGINEERING AND ELECTRICAL ENGINEERING VOLUME: 11 |NUMBER: 3 |2013 |JUNE Fig. 4: No backup – powe and eliabili y scheme. 2) Backup by HV Line o he Same Leng h In his case, pa allel connec ion is a ailable. This al- e na i e can be wi h o wi hou manipula ion. Relia- bili y scheme is used o he calcula ion o p obabili y (Fig. 5). Fi s , pa allel combina ion is calcula ed and hen manipula ion is added o o al calcula ion, de- pending on he al e na i e: •no manipula ion: R= 0,999999989, •wi h manipula ion: R= 0,999996234. Fig. 5: Backup by HV line – powe and eliabili y scheme. 3) Backup by HV Line o 1,5 Mul iple o i s Leng h Schemes a e iden ical wi h he p e ious al e na i e (Fig. 5), backup line is longe : •no manipula ion: R= 0,999999985, •wi h manipula ion: R= 0,999996229. 4) Backup by MV Line o he Same Leng h In his connec ion (Fig. 6) he e a e wo ans o m- e s in he backup line in he se ial combina ion. This combina ion is sol ed i s , la e he pa allel line is cal- cula ed and inally he manipula ion depending on he al e na i e: •no manipula ion: R= 0,999999129, •wi h manipula ion: R= 0,999988398. Fig. 6: Backup by MV line - powe and eliabili y scheme. 5) Backup by MV Line o 1,5 Mul iple o i s Leng h The calcula ion is iden ical o he p e ious one (Fig. 6): •no manipula ion: R= 0,999998735, •wi h manipula ion: R= 0,999988004. 3. Backup Ranking Wi h he help o p obabili y o ailu e- ee ope a ion, all he al e na i es o backup we e anked (Tab. 2). The bes backup is p o ided by backup wi hou ma- nipula ion – ho ese e. The second is backup wi h manipula ion - cold ese e. The wo s op ion is a line wi h no backup. The anking illus a es heo e ical assump ions, howe e o he inal e alua ion o op- imisa ion accu a e da a on p obabili y o ailu e- ee ope a ion is needed. Fo me ela i e alues o backup al e na i es we e imp ecise and he e o e eplaced by new ones. The HV abb e ia ion in Tab. 2 means ha he backup is ia HV line, l1=l2means ha he leng hs o c 2013 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 171 POWER ENGINEERING AND ELECTRICAL ENGINEERING VOLUME: 11 |NUMBER: 3 |2013 |JUNE Tab. 2: Backup anking. Ranking Iden i ica ion Backup ype No manipula ion – ho ese e 1. HV l1=l2HV line o same leng h 2. HV l1< l2HV line o 1,5 mul iple o i s leng h 3. MV l1=l2MV line o same leng h 4. MV l1< l2MV line o 1,5 mul iple o i s leng h Wi hou manipula ion – cold ese e 5. HV l1=l2MAN HV line o same leng h 6. HV l1< l2MAN HV line o 1,5 mul iple o i s leng h 7. MV l1=l2MAN MV line o same leng h 8. MV l1< l2MAN MV line o 1,5 mul iple o i s leng h O he 9. No No backup he backed up line and he backup lines a e he same, l1< l2means ha he leng h o he backup line is 1,5 longe han ha o he backed up line. Backups us- ing MV lines a e ma ked MV. The MAN abb e ia ion means ha he backup is wi h manipula ion. Theo e - ical indings o anking o all backup al e na i es can be used o de e mine line impo ance o a pa icula ne wo k. P ima ily i can be used as a weigh c i e ion o he inal algo i hm. 4. E ec o Line Failu e To op imise eno a ion o 110 kV in, algo i hms on he basis o eliabili y cen e ed main enance mus be de e - mined. Backup al e na i es we e de e mined o e e y line in a dis ibu ion dis ic . The abo e men ioned me hod was used o do ha . The possibili y o backup was subs i u ed by he e ec o a line ailu e. This e - ec o ailu e ells us wha happens a e a line ails. In heo e ical analysis educed ansmi ed powe was neglec ed. Howe e , in a inal ield e alua ion his pa- ame e mus be aken in o accoun . Ano he eason o using he e ec o ailu e is ha i gi es a be e pic u e o he line backup. The e ec s o ailu e we e discussed and de e mined by he echnicians ope a ing in he dis ibu ion dis ic and hey co espond wi h he ield p ac ice. The e a e no exis ing lines wi hou a backup in he a ea. Al o- ge he , se en ypes o e ec s o ailu e exis : •1: ”No e ec ” – no manipula ion necessa y, •2: Back-up by 110 kV line o app ox. he same leng h, •3: Back-up by 110 kV line o app ox. he same leng h wi h limi ed powe , •4: Back-up by a longe 110 kV line, •5: Back-up by a longe 110 kV line - limi ed powe , •6: Back-up by MV line, •7: Back-up by MV line - limi ed powe . The e a e o al o 168 powe lines in one dis ibu ion ne wo k. The esul s o e alua ion a e shown in Tab. 3 and in ba g aph (Fig. 7). Ba g aph does no show he e ec numbe 7, because he alue is ze o. Fig. 7: E ec o line ailu e – ba g aph. The e alua ion shows ha app ox. 56 % o lines equi e no manipula ion. In ac , hese lines a e backed up by pa allel lines which a e pe manen ly connec ed. Theo e ically, we speak abou a ho ese e. The e a e 72 lines which equi e manipula ion a e a ailu e, and a e ha ull load can be ansmi ed. Only wo lines a e backed up by lines which ca y educed load. The e a e nine lines ha a e backed up by MV lines. Tab. 3: Inpu pa ame e s. E ec o Failu eCoun [-] Coun [%] 1 94 55,95 2 51 30,36 3 1 0,60 4 12 7,14 5 1 0,60 6 9 5,36 7 0 0,00 To al o : 168 c 2013 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 172 POWER ENGINEERING AND ELECTRICAL ENGINEERING VOLUME: 11 |NUMBER: 3 |2013 |JUNE Also, du ing manipula ion, lines can only ca y e- duced load and he e o e he du a ion o manipula ion is impo an . Backup ia HV line needs max. 20 min. manipula ion and backup ia lowe ol age lines may need as much as minu es manipula ion. 5. Conclusion Theo e ical assessmen o sequencing di e en backups will be used as a weigh c i e ion in he algo i hm o op imised eno a ion o 110 kV line. The line backup is exp essed by he e ec o a ailu e. The weigh will show how impo an a pa icula alue o a ailu e e ec is. In case o he bes backup al e na i e 1, his pa ame e is insigni ican . On he con a y, he alue is i al in case o backup al e na- i e 5. The echnical condi ion is assessed on he basis o he ailu e da abase. Impo ance o a line is de e - mined by ansmi ed ene gy and possibili y o backup. The pape ou lines backup al e na i es o 110 kV lines in one dis ibu ion a ea. This a ea was e alua ed in he p e ious sec ion. O e all, app oxima ely 56 % o lines ha e adequa e backup and he e o e equi e no manipula ion in he dis ibu ion ne wo k. On he con a y, lines wi h dec eased load backup a e ew. Acknowledgmen This wo k was suppo ed by he Czech Science Foun- da ion (No. 102/09/1842), by he G an o SGS VSB- Technical Uni e si y o Os a a (No. SP2013/137) and by he p ojec ENET (No. CZ.1.05/2.1.00/03.0069). Re e ences [1] SKOG, J. E. Main enance ask in e al de e mina- ion. In: 66 h Annual In e na ional Con e ence o Doble Clien s: P oceedings Main enance and Tes Enginee ing. Bos on: M. A., 1999, pp. 158–169. [2] MOUBRAY, J. Reliabili y-cen e ed main enance. 2. ed., [3. e .]. New Yo k: Indus ial P ess, 2000. ISBN 978-083-1131-463. [3] HOUDEK, P., V. KRAL, S. RUSEK and R. GONO. Reliabili y o 110 kV Lines. In: ELNET 2012. Os a a: VSB–Technical Uni e si y o Os- a a, 2012. pp. 1–6. ISBN 978-80-248-2926-5. [4] MARTINEK, Z. and V. KRALOVCOVA. The So- lu ion o Repai able Uni s. In: P oceedings o he 11 h In e na ional Scien i ic Con e ence Elec ic Powe Enginee ing 2010. B no: B no Uni e si y o Technology, 2010. pp. 593–597. ISBN 978-80- 214-4094-4. [5] CHOWDHURY, Ali A. and D. KOVAL. Powe dis ibu ion sys em eliabili y: p ac ical me hods and applica ions. 2. ed., [3. e .]. Hoboken: John Wiley, 2009. ISBN 978-0470292280. [6] BROWN, Richa d E. and D. KOVAL. Elec ic powe dis ibu ion eliabili y: p ac ical me hods and applica ions. 2. ed., [3. e .]. New Yo k: Ma - cel Dekke , 2002. ISBN 08-247-0798-2. [7] TUMA, J. and D. KOVAL. Spolehli os elek- oene ge ice: p ac ical me hods and applica ions. P ague: Czech Technical Uni e si y in P ague, 2006. ISBN 80-239-6483-6. Abou Au ho s Vi HOUDEK was bo n in Ch udim. In 2011 he g adua ed VSB–Technical Uni e si y o Os a a, Facul y o Elec ical Enginee ing and Compu e Science, elec ical powe enginee ing. Today he is Ph.D. s uden in he Depa men o Elec ical Powe Enginee ing, VSB–Technical Uni e si y o Os a a and he applies himsel o he issue o eliabili y o elec ical ne wo ks. S anisla RUSEK was bo n in Ha i o -Sucha. In 1981 he g adua ed VSB–Technical Uni e si y o Os a a, Facul y o Mechanical Enginee ing and Elec ical Enginee ing, powe enginee ing ield. He g adua ed scien i ic pos g adua e a Facul y o Elec i- cal Enginee ing and Compu e Science B no, elec ical machines and de ices, in 1989. Pos -g adua e educa- ion a Facul y o Science Palacky Uni e si y Olomouc in uni e si y educa ion g adua ed in 1991. He was habili a ed a he Facul y o Elec ical Enginee ing and Compu e Science, VSB–Technical Uni e si y o Os a a in 1991. He is p o esso om 2001. Radomi GONO was bo n in Bilo ec. In 1995 he g adua ed om VSB–Technical Uni e si y o Os- a a, Facul y o Elec ical Enginee ing and Compu e Science. He ecei ed his Ph.D. om VSB–Technical Uni e si y o Os a a in 2000. He was habili a ed a Facul y o Elec ical Enginee ing and Compu e Science, VSB–Technical Uni e si y o Os a a in 2008. Today he is ice-head o he Depa men o Elec ical Powe Enginee ing. Resea ch wo k is ocused on eliabili y o elec ic powe sys ems and enewable ene gy sou ces. c 2013 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 173