1.1CC GII PHP CNG NGH CHNH CA CP NGM 1.1.1Thng s thit k c bnin p danh nh: 110kV. in p cc i ca h thng: 121kV. Cp cch in xung c s: 550kV. Tn s h thng: 50Hz. 1.1.2La chn vt liu dn in cho li cp ng v nhm l 2 loi vt liu kim loi thng c s dng cho cu to ca lidnsicpngmdocintrsutnhhncckimloi,hpkimkhc. Do,khichnlavtliunocholidnincacpngmcaothcn phn tch cc yu t sau y:1.in tr DC ca cp in trmt chiu ca cp hp kim nhm bng 61,2%60% so vi cp ng. Do , vi cng mt tr s in tr DC, si cp nhm s c tit din khong 1,6 ln tit din si cp ng. 2.Trng lng cp u im ca vt liu nhm l nh hn, mm hn. Vi cng mt tr s in tr DC,cngchiudithkhilngcalinhmchbng48%khilngli cp ng. Tuy nhin, khi c cch in c bao quanh, u th v trng lng ca cpnhmkhngcn:docpnhmphicthtchcchinbaoquanhdy hn m bo cng kh nng chu lc c hc. 3.Kh nng chuyn ti cng sut Khnngtidngincanhmkmhnving,tythucvochtliu ca hp kim nhm m tr s ny l t 50%60% so vi ng. Do vy, vi cng yu cu v kh nng p ng dng ti cho trc th kch thc si cp nhm s ln hn si cp ng, gy kh khn trong cng tc thi cng lp t, nht l tr ngi do bn knh cong ca cp ti cc v tr cp r gc 90. Tuynhin,khilngsicpngsnnghngn2lnsicpnhm,gy kh khn trong cng tc vn chuyn v lp t. 4.Tn tht in p trn tuyn cp ivisicpctitdinnh,trsinkhngXcgitrrtnhsovi tng tr Z, tn tht in p trn si cp nhm gp 1,6 ln si cp ng c cng tit din. Khititdinln,dohiungmtngoivhcm,trsinkhngXnh hng nhiu n tng tr Z, lc ny, tn tht in p trn si cp nhm gp 1,4 ln si cp ng c cng tit din. 5.Kh nng chu ng dng ngn mch Si cp c lidn bng vt liu ng c kh nng chu ng dng ngnmch tt hn si cp c li dn bng vt liu nhm. 6.c tnh c hc Cp li nhm thng t khic sdng do c tnh c hc kmhn cp li ng. Qua phn tch cc c im ca vt liu ng v nhm, kin ngh chn loi cp ngm cao th c li dn in bng vt liu ng1.1.3La chn s li dn in trong 1 si cp ngm (cp 1 li hay 3 li) Vic chn loi cp 1 li hay cp 3 li ph thuc vo cc yu t nh sau: 1.Tn tht trong cp Tn tht trong v bc thp ca cp 3 li thp hn rt nhiu so vi cp n 1 li: do t trng ca 3 dng in trong 3 li t trit tiu ln nhau do , cp 3 li c th c trang b v bc bng dy thp mm trong khi cp n 1 li yu cu phi c bin php lm v bc thp phc tp. Tn tht thp hn trong cp 3 li cho php vi cngmt cng sut truyn ti, s dng phn li dn in tit din nh hn m vn m bo c kh nng ti. 2.Cng ngh ch to Mtsicp3livnguyntcthnsovitng3sicpn1livc linquanncngnghsnxutcptinhmy.Slngnhsnxutcp ngm cao th 1 li c nhiu d dng trong vic chn nh cp hng.3.Thi cng, lp t cp Mt si cp 3 li c th c lp t theo mt tuyn. Mt nhm cp n 1 li khi thi cng, lp t i hi phi tin hnh tun t tng si cp mt. Cp n 1 li thng c lp t v chn vi thit b nh hn cp ba 3 li v cp c khi lng, cng v bn knh cong thng nh hn. 4.Tnh kh thi ca h thng cp -i vi cp 1 li, trong trng hp c s c lm hng cp, vic cp in c thcphchitrongvngvigibngcchdngsicpdphng. Cp b s c s c sa cha ngay sau ,khi c th. Vic cp in vn in duy tr. -i vi cp 3 li t c mc tiu nh trn cn phi t d thm 1 si cp 3 li. Tuy nhin, iu ny s lm tng chi ph u t. -Cp 3 li c tn tht thp, chi ph lp t t tn km hn cp 1 li, hnh lang tuyn cp hp hn nhng gi thnh t hn so vi cp 1 li. -Cp 3 li c tit din li dn in t 1000mm2 tr ln do qu nng nn kh khn trong vic chuyn ch v lp t. Vi mc tiu d dng trong vic ch to, vn chuyn, thi cng, lp t; ng thititkimchiphvtt,thitb;kinnghchnloicp1lichovic ngmhacctuyn110kVtrongphmvidn,phhpvivicuni vo cc tuyn cp ngm hin hu. 1.1.4La chn vt liu cch in si cp ngm v cu trc lp v 1.Vt liu cch in in nay trn th gii s dng hai loi cp thng dng cho cc ng ti in caothlcpduOilFilledCable-OFvcpkhdngcchin Polyethylene lu ha kh c cc mi lin kt phn t theo chiu ngang PE. i vi cp in p 110kV hin nay a s s dng cp kh cch in PE v nhng l do sau y: -Chi ph u t ca hai loi cp bao gm chi ph u t ban u, chi ph vn hnh v bo tr, chi ph u t cho cc thit b th cp ca cp du t tin hn so vi cp PE -Cp du cn thm nhng thit b vn hnh ph nhiu hn so vi cp PE nh sau: -Cc thit b kim sot; - du; -Thit b b p lc du; - mi ni cp. -n na, tn tht in mi ca cp du cao hn cp PE. -Tngcngttcccchiphlinquan,chiphthchinbngcpdus ln hn cp PE. Do vy, d kin chn cp lp t cho d n l loi cp kh cch in XLPE. 2.Vt liu lp v Cp ngm cao th thng c 3 loi v nh sau: -Cp c v kim loi l bng nhm; -Cp c v kim loi l nhm gn sng; -Cp v ch. o vi cp v kim loi nhm, cp v ch c khi lng ln hn, kh nng chu nhitvckm,gynhhngmitrngvvykinnghkhngsdng loi cp v ch.CutrcinhnhcacpXLPEbaogmcclpcmttheothtt trong ra ngoi nh sau: SttTn giCng dngGhi ch 1Rut dn (li cp) Dn in -Vi tit din di 1,000mm2 li gm cc si ng nh bn xon trn. -Vi tit din t 1,000mm2 tr ln li gm nhiu mi, thng l 4 hoc 5, 6, SttTn giCng dngGhi ch mi mi gm cc si ng nh bn xon li. -Phn khe h gia cc mi c lp y bng vt liu chng thm nc theo chiu dc cp. -Tiu chun p dng cho li cp: IEC 228, tinh khit ca ng l 99.99%, in tr mt chiu max 200C l 0.0113 /km. 2p bn dn Chng phng in cc b -Vt liu ca lp ny l polyethylene bn dn, c tc dng lm gim kh nng gy phng in cc b do b mt li lm ca cp to thnh bi cc si ng nh. -c p n cng lc vi lp cch in 3 v lp bn dn 4.3p cch in PE Cch in cho cp -Croos-linked Polyethylene (XLPE) l loi vt liu cch in c nhiu u im ni bt. -Ch to bng cng ngh p n. - dy ti a 25mm 4p bn dn Chng I-on ha b mt cch in -Vt liu ca lp ny l compound bn dn, c tc dng lm gim kh nng gy I-on ha b mt lp cch in. -c p n cng lc vi lp cch in 3 v lp bn dn 2. -i khi c th thm mt lp bng qun cng tnh cht. 5p chng thm dc Chng nc thm dc theo khe h gia lp (4) v lp 6 -Ch to t vt liu trng n v bo ha nc khi gp nc thm vo, do chng c nc thm dc theo cp. 6V kim loi o v c hc cho cp -Ngoi cng dng bo v c hc cho cp, lp v hoc gip kim loi ny cn ng vai tr tn dng ngn mch khi c s c ngn mch xy ra.-V kim loi cp l loi bng ng hoc SttTn giCng dngGhi ch li ng. 7V ngoio v chung -m bng PVC hoc PE. PE c nhiu u im hn. Chiu dy tnh ton 5.1mm. -C tc dng bo v lp v gip kim loi khi b tc ng n mn in ha ca mi trng. -C th ph thm 1 lp cht bn nhit chng chy v cp khi c ha hon xy ra p dng cho cc on cp tip xc vi khng kh. Vicsdnglpgnsnghaybngquntythucvothitkcanhch to nhng phi c c tnh k thut tng ng nhau. Nhng thun li v kh khn khi s dng cc lp ny ch lin quan n nh ch to. Gii php ni t v cp Phn tch cc gii php V kim loi ca cp cn c ni t mt cch chc chn v l do an ton. Cp n li (Single conductor cable) c mt s tn ti nht nh do cm ng in t t lm xut hin mt in th nht nh trong v cp v mt dng in ng k c sinh ra, lm nng v khi thc hin ni t t nht ti hai im. Do , i vi vic ni t cp mt li cn phi xc nh phng thc ni t ca cp, trncsmboccyutantonctrongchvnhnhbnhthng cng nh s c, tn tht v, chng n mn v cm ng ln ng dy thng tin lin lc i gn.Khidnginchytrongvscmnglnphnvdohintngcmng int.Khivnittimtim,nhthnggptrongthctssinhra mt in th gia v v t ti cc v tr khc nhau ca v v s chnh lch ny ph thuc vo khong cch ti v tr ni t. Do cp s dng hin nay u c bo v chng n mn, khng cn thit phi xem xt n s n mn xoay chiu khi tnh ton in th ln nht cho php ca v. Gi tr in p cho php c xc nh theo ch tiuan ton ca con ngi v chng s nh thng cchin ca lp chng nmnkhi ngnmch cng nhkhixuthinquinpkhquyn,gitrnykhong30-60V.Nht Bn,thngsdnggitr50Vngviquynhvantonvvsinhlao ng.ccnckhcnhaugitrnycngkhacnhau,oaKvAnhi vi phng php ni t mt im ingle Point onding v phng php ni t lin tc (Cross Bonding) cc gi tr in p trn v cho php l 65V v 86V. Tuynhin,vicpctitdinln,trongthctrtkhgiipnggitr inptheogitrtrnhocthn.Dothngsdnggitr100Vhoc ln hn ph hp vi bin php bo v trong nh my in v trm bin p. Cc gii php tip a v cp ca si cp ngm thng s dng hin nay l: ni t1u(single-pointbonding),nit2u(both-endsbonding),nit2 u kt hp o pha v cp (cross-bonding) v ni t 2 u kt hp o pha v cp, si cp (cross-bonding with transposition). Gii phpCch b tru imNhc im - Ni t 1 u (single-point bonding) - Sdngkhi chiudi tuyn cp ngn Ktcunitn gin. Khngcdngcm ngkhnngti casicpcci thin Xuthininp cmng(tlvi chiudisicpv dnginrut cp)tiphakhng nit,cntrangb thitbhnchqu inpmbo an ton - Ni t 2 u (both-ends bonding) Kt cu ni t tng i n gin. inpcmng khng tn ti 2 u si cp an ton Tntidngcm ngtrongvsicp (t l vi dng i qua rutsicptn thtnhitvcp, gimkhnngti ca si cp - Ni t 2 u kthpo phavcp (cross-bonding) - Sdngkhi tuyn cp di. in p v dng in cmngbgiihn, trongtrnghpcc sicpbtrtheo dngtrefoil,kiuni tnystrittiu hontondngcm ng v cp Ktcunitphc tp. inpcmng xut hin cao nht ti ccvtrhpnit o pha - Ni t 2 u kthpo pha v cp, si cp(cross-bondingwith transposition) - Sdngkhi tuyn cp di. in p v dng in cmngbgiihn nhiu,trongtrng hp cc si cp b tr theodngtrefoil, kiunitnys trittiuhonton dngcmngv Ktcunitrt phctpvbtr ophaccsicp rtphctp,khlp t. inpcmngti ccvtrhpnit ophasgimso Gii phpCch b tru imNhc im cpvitrnghpni t2u(cross-bonding) a.Kin ngh Trong phm vi d n, do tuyn cp ngm c chiu di khng ln, n gin trongqutrnhthicnglpt,docthsdngmttronghaigiiphp ni t sau: -Ni t mt u (single-point bonding) -Ni t hai u (both-ends bonding) Da vo cc ch tiu k thut v kinh t tnh ton c s a ra mt phng n hp l nht.1.1.5La chn tit din si cp ngm 1.Hin trng Hinnay,ngdy110kVQun3-AnnangsdngloidyACSR 240/32,khnngtinhmccangdynyl610A.Do,tuyncp ngm 110kV c thay th c kh nng ti c dng tng ng. 2.Chn tit din cp Da vo tiu chun quc tIEC (International Electrotechnical Commicsion):IEC60287,IEC60853,IEC60949vIEC1042csdngphntchn nh nhit ca cp. Dng in nh mc ca cp in xoay chiu c xc nh t phng trnh th hin s gia tng nhit t mi trng xung quanh: ( ) ( ) ( ) ( ) ( )( )2 2 21 1 2 1 2 3 40, 5W 1 W 1 Wd d dR R n R n T Tu A = I + T + I + + TI + + + +IDng in i qua mt dy dn (A); AuMc tng nhit ca dy dn so vi nhit mi trng xung quanh (K); Rin tr n v dng xoay chiu ca dy dn ti nhit lm vic ln nht ca dy dn (O/m); WdTn tht in mi n v ca cch in xung quanh dy dn (W/m); T1in tr nhit n v gia dy dn v lp gip (K.m/W); T2in tr nhit n v gia gip v lp bc (K.m/W); T3in tr nhit n v ca lp v (K.m/W); T4in tr nhit n v gia b mt cp v mi trng xung quanh (K.m/W); NSlngdydndngtibntrongcp(dydncngkchthchoc mang cng ti); 1T l tn tht ca lp gip kim loi vi tng tn tht ca tt c cc dy dn trong cp; 2T l tn tht ca lp v vi tng tn tht ca tt c cc dy dn trong cp. T , xc nh dng in qua dy dn theo cng thc sau: | || |0,51 2 3 41 1 2 1 2 3 4W 0.5 ( )(1 ) (1 )( )dT n T T TIR T n T n T Tu ( A + + +=(+ + + + + + Vi cc thng s u vo tnh ton: Tit din li Dng ling knh li Chiu dy mn chnli Chiu dy cch inChiu dymn chn cch in Chiu dy v ch Chiu dyv bc ng knh tng Khi lng cp in tr DC 200C mm2 mmmmmmmmmmmmmmkg/mO/km 800 Bn nn trn 341,214,01,02,74,086,018,50,0221 1000 Bn r qut 38,71,214,01,02,94,092,011,90,0221 Bng 1.1: Cp in 64/110/123kV: i ng/cch in XLPE/ bc ch/ v bc ngoi PE(PVC) iu kin mi trng Nhit t Nhit khng kh su ca cp Khong cch cp theo phng ngang in tr nhit ca t 0C 0Cmmm 0Cm/W 25401,53001,0 Bng 1.2: iu kin mi trng v phng php b tr cp Hnh 1.1: th ph ti tiu biu Thnh ph Nng thng 7-2010 Da vo phn mm chuyn dng tnh ton cp ngm CYMCAP ca hng CYME International T&D, phng php tnh ton c s dng tun th theo IEC-228. i vi cc phng n khc nhau ta c cc kt qu phn tch nh sau: a.Ni t hai u TheocngthckinhnghimABB,dngtronglicpkhibtrnmngang, nhit li cp 900C c xc nh theo cng thc: . . . . .s d gt tr dg rI k k k k k I = c tnh800mm2 1000mm21200mm2 Dng in nh mc (Ir) - A755800860 H s b mt (ks)-95mm2 0,960,950,94 chn su ca cp (kd)-1,5m0,950,950,95 Nhit t (kgt)-250C0,960,960,96 Nhit in tr t (ktg) 1,20Cm/W 0,930,930,93 Khong cch gia hai tuyn (kdg)0,920,920,92 Dng in trong dy dn (I) - A595,3624671 Do cp la chn cho phng n ni t v ny phi c tit din ln hn 1000mm2. Phhpvicngsutyucucangdy110kV-220kVvtitdinca ngcpngm110kV-220kVhinhu,cpcchnsdngchocng trnh c tit din nh sau: -Cp 220kV: cp 1 li ng 1,600mm2 cch in XLPE. -Cp 110kV: cp 1 li ng 1,200mm2 cch in XLPE. 3.Kh nng chu ng dng ngn mch a.Dng ngn mch trn si cp Cp 220kV 1,600mm2 chn c kh nng chu c dng ngn mch khong 229kA trong thi gian 1s, p ng yu cu v dng ngn mch ca h thng. Cp 110kV1,200mm2c kh nng chu c dng ngnmch khong 172kA trong thi gian 1s, p ng yu cu v dng ngn mch ca h thng. b.Dng ngn mch trn mn chn kim loi Titdinmnchnkimloicacp110kV-220kVhinhuctnhton chn theo dng ngn mch mt pha ln nht ti trm bin p 500kV Tn nh, dngngnmch1phatithanhci220kVl19.8kA,tithanhci110kVl 17.8kA. -Nhit lp gip trc khi ngn mch: 50C. -Nhit lp gip sau khi ct ngn mch: 250C. Chnlpgipbngngctitdin200mm2chocp110kV-XLPEvcp 220kV-XLPE ph hp vi tit din lp gip 200mm2 ca tuyn cp hin hu. i vi tit din mn chn S = 200mm2, tng ng ta c dng ngn mch 1 pha m cp c th chu ng c l 39.6kA, p ng c dng ngn mch 1 pha ln nht ti thanh ci 220kV ca trm Tn nh. ( )0*ln * 1* *CIR tu oo+= Trong : -CNhit dung dy dn (J/cm.0C). -u = 250oCNhit lc xy ra ngn mch. -R0 = 0.0789 (O/km)in tr DC 20oC ca dy dn. -t = 1sThi gian tn ti ngn mch. -o = 0.00411 (1/0C)H s nhit in tr ca kim loi ng. KtqutnhtonchothydytipaM240mbochucdngngn mch 1 pha ca h thng (40kA). 4.Ni t v bo v chng st Mc tiu v yu cu ca h thng ni t l: -An ton cho ngi v bo v thit b trong trng hp s c ngn mch v trng hp qu (hin tng st hoc thao tc ng ngt trong vn hnh). -H thng ni t phi c kh nng chu ng dng s c chm t ln nht m khng b t nng qu mc hoc b nng chy. -Hthngnitphickhnnggiihnvicsinhrainpbc nh gia hai im bt k trn t khng gy nguy him cho ngi. -H thng ni t phi c kh nng ti thiu gia tng in p trn t. B gii hn in p Do in th khc nhau trn v kim loi ca 2 on cp ti im ni cp nn hai v kim loi cp ny phi c cch ly bng vt liu cch in. Khi b s c ca cp c th gy qu p v nguy him n mi ni o pha v. bo v nhng mi ni ny cn lp nhng b gii hn in p ti cc mi ni o pha v. C vi loi b gii hn in p c ch to sn. ngh, cc yu cu k thut ti thiu phi tun th nh sau: -in p phng inin p th nghim 1 chiu ca v kim loi. -oi van in p: nO. Nh ch to cp s phi xc nh loi v tham s cui cng ca van in p. giihninpcchnvikhnnghpthnnglngnhnhtv phi c kh nng hp th nng lng ca 3 xung qu p c lp m khng gy nguy him. in p phng in c la chn theo cch m in p th nghim 1 chiu v kim loi cp c th thc hin m khng ngt b gii hn in p. Nhngthnghimvkimtrathngxuynbgiihninplcnthit cho s an ton v tin cy trong qu trnh vn hnh cp. gii hn in p ny phi c lp t mt cch ring bit vo trong t cross-bonding. 1.Gii php nt t hm cp thngnitcxcnhtheoiukinantonlccgitrinp bcvinptipxcnmtronggitrchophp.Cnchlkhingn mch 1 pha, dng ngn mch ch yu chy trong v kim loi v dy ni t dc tuyn m khng i nhiu vo t. Do in tr ni t ti hm ni cp c th p dng theo quyphm trang b in 11 TCN 19-2006v lygi tr cho php ca in tr ni t l 10Om. Ni t thng c thc hin bng cc in cc ti cc gc ca hm ni t intrtmongmun.Nucn,sucaincccthtcbng cch khoan v h khoan c lp kn bng hn hp bentonite v va bentonite c in tr sut thp lp ynhng ch trng v va lin kt thnhmt khithngnht.Nhnginccnyphicnivinhaubngdydn trn, to ra li ni t ven chu vi hm ni. 2.Gii php chng st Khu vc d n nm trong vng kh hu nhit i nng m, hot ng ging st c cng mnh, mt st vo loi cao so vi cc vng khc. Theo Quy chun k thut quc gia m s QCVN 02:009/BXD (c ban hnh theo Thng t s 29/2009/TT-BXD ngy 14 thng 8 nm 2009 v vic Ban hnh Quy chun k thut quc gia v s liu iu kin t nhin dng trong xy dng), mt st nh c thng k nh sau: -Mt st nh ti th x Th Du Mt, huyn D An, Tn Uyn, Thun An (Bnh Dng): 13,7 ln/km2/nm. -MtstnhtiBnCt,DuTing,PhGio(BnhDng):14,9 ln/km2/nm.Do vy, vic thit k h thng chng st cho cc cng trnh kin trc l iu bt buc. Gii php thc hin: bo v qu in p kh quyn lan truyn t ng dy trn khngvotuyncpngmbngccchngstvanbtrtrnctunicp ngm ng dy trn khng.Chn ccchng st van96kV-10kA bo v cp ngm 110kV. Cc chng st van ny c t trc tip trn ct u ni v ni vo ng dy trn khng trc khi u ni vi cp ngm. Chng st van c ni t bng h thng ring r vi h thng ni t ct in.