Modeling and Simulation Analysis of Power Frequency Electric Field of UHV AC Transmission Line

Transcription

1 (IJACSA) Intrnatonal Journal of Advancd Computr Scnc and Applcatons, Vol., o., Modlng and Smulaton Analyss of Powr Frquncy Elctrc Fld of UHV AC Transmsson Ln Chn Han Collg of Elctronc and Elctrcal Engnrng Shangha Unvrsty of Engnrng Scnc Songang Dstrct, Shangha, Chna Yuchn Chn Collg of Elctronc and Elctrcal Engnrng Shangha Unvrsty of Engnrng Scnc Songang Dstrct, Shangha, Chna Abstract In ordr to study th powr frquncy lctrc fld of UHV AC transmsson lns, ths papr whch modls and calculats usng boundary lmnt mthod smulats varous factors nfluncng th dstrbuton of th powr frquncy lctrc fld, such as th conductor arrangmnt, th ovrground hght, th splt spacng and th sub conductor radus. Dffrnt nflunc of varous factors on th lctrc fld dstrbuton wll b prsntd. In a sngl loop, usng VVV trangular arrangmnt s th most scur way; n a dual loop, th lctrc fld ntnsty usng rvrs phas squnc s wakr than that usng postv phas squnc. Elvatng th ovrground hght and rducng th conductor splt spacng wll both wakn th lctrc fld ntnsty, whl th chang of sub conductor radus can hardly caus any dffrnc. Ths conclusons ar mportant for lctrc powr company to dtct crcut. Kywords boundary lmnt mthod; lctrc fld dstrbuton; powr frquncy lctrc fld; UHV I. ITRODUCTIO Th world's frst UHV AC wth towr of kv n dual loop-anhu Powr Transmsson was offcally put nto opraton on Sptmbr,. Thus th Stat Grd has bult two kv AC and two kv DC procts so far markng th grat nw achvmnts of Chna's UHV constructon. Lu Zhnya sad, "atonal Grd s buldng two kv DC procts and at th sam tm dvlopng th tchnology and qupmnt of kv DC whos transmsson capacty can b.7 mllon klowatts and conomc transmsson dstanc s km. Such procts mak contrbutons to constructng trans-rgonal, transnatonal and transcontnntal transmsson channls. For xampl, f Afrca and th Mddl East can b connctd, South Amrca can buld up a larg powr grd." Wth th rsng voltag lvl and ncrasng currnt of UHV transmsson ln, th ffcts of ts powr frquncy lctrc fld on th surroundng nvronmnt and cology hav attractd growng concrns. UHV powr frquncy altrnatng lctrc fld can not only brng nvronmntal ssus lk th rado ntrfrnc and th audbl nos but also has rathr grat harm on popl s halth and sprt []. ow th powr frquncy lctrc fld dstrbuton nar th UHV AC transmsson ln has bcom on of th ssus that scholars all ovr th world focus on and dscuss. Ths papr basd on boundary lmnt mthod whch s usd for modlng and calculaton on th nflunc of varous factors, th powr frquncy lctrc fld dstrbuton, such as th arrangmnt of conductors, th smulaton of th hght, splt spacng and sub conductor radus. II. THE CALCULATIO METHOD OF THE POWER FREQUECY ELECTRIC FIELD Th boundary lmnt mthod s an accurat and ffctv ngnrng numrcal mthod whch uss th boundary ntgral quaton dfnd on th boundary as govrnng quaton. It transforms boundary lmnt ntrpolaton nto algbrac quaton sts through dscrt mthod [-]. Ths ssay uss ln modl whn smulatng th powr frquncy lctrc fld of UHV transmsson lns, thus rducng th dffculty of modlng as wll as mprovng th opratonal ffcncy. Supposng that all radus of transmsson ln conductor ar r, th charg n th cntr ln of wr s ln charg, th charg s n th form of surfac charg dstrbuton on th surfac of othr dvcs and ts dnsty s, th lctrc potntal of a pont n ths spac can b xprssd as dl P l S ds P In th formula, P s th spac btwn sourc pont and fld pont, S s th surfac ntgral rgon and l s th ln ntgral path. Whn ths formula s dscrt, fld and sourc unts may b thr ln lmnt or surfac lmnt. Thus, formula () can produc knds of dscrt form. Supposng th fld unt s th ln unt and sourc unt s th surfac unt, th formula can b wrttn as l dl ' ' l s P ds' dl In th formula abov, =,,..., m,..., n, corrspondng to dffrnt dscrt nods, whr m s th numbr of conductor dscrt nods, n s th numbr of dscrt nods of calculaton modl, and togthr wth s th ntrpolaton functon. s th nod potntal n whch s th dstny of nod surfac, and ar rspctvly th numbr of fld unt and sourc unt, l rprsnts th ln ntgral path of fld unt and S s 77 P a g

2 lctrc fld ntnsty(kv/m) (IJACSA) Intrnatonal Journal of Advancd Computr Scnc and Applcatons, Vol., o., th surfac ntgral ara of sourc unt. If makng som corrspondng modfcaton to th ntgral path and lctrc charg dstny n th formula (), w can gt th othr knds of dscrt forms. Makng vctors: B,,,,,,,, m m m T n T,,,, m, m, m, n u, A C And th matrx l dl ' l s ' ds' dl P In th formulas abov,,,..., m and,,..., n ar rspctvly th lnar dnsty and lctrc potntal of conductor nod charg; m+ m+,..., n and m+, m+,..., n ar rspctvly surfac dnsty and lctrc potntal of conductor nod charg on th qupmnt s surfac. Thn th formula () can b wrttn as follows: CB Au () Undr th condton of knowng th dvc and th conductor potntal, th surfac dnsty and th ln dstny of conductor quvalnt charg can b obtand. W can smulat dffrnt condtons of UHV transmsson lns accordng to th formula and aftr obtanng and can us th ntgral formula of th lctrc fld to gt th lctrc fld ntnsty of any spac pont r r' ds r r' E ' s r r' l r r ' ' ' dl III. CALCULATIO AD AALYSIS OF POWER FREQUECY ELECTRIC FIELD AROUD THE UHV TRASMISSIO LIE A. Paramtrs of kv AC UHV transmsson ln Chna s kv UHV dmonstraton proct Jndongnan- anyang- Jngmn transmsson ln s all st up n sngl loop. Its full-lngth s klomtrs, transmsson capacty s kva, systm nomnal voltag s,kv and ts maxmum opratng voltag s,kv. Sttng up such a program has far-rachng nflunc on natonal nrgy scurty and rlabl powr supply. At prsnt, UHV transmsson ln systms of our country manly nclud sngl loop (IVI horzontal arrangmnt, VVV horzontal arrangmnt, IVI trangl arrangmnt and VVV trangl arrangmnt) and th common-towr doubl loop (I srs vrtcal arrangmnt and V srs vrtcal arrangmnt). B. Th factors nfluncng th powr frquncy lctrc fld Accordng to th powr frquncy lctrc fld calculaton formula, th charg numbr on th wr surfac, th dstanc btwn wrs and othr factors drctly dtrmn th lctrc fld strngth of th ponts n spac []. Apart from th voltag of both sds, th numbr of charg on wr surfac has rlaton to th arrangmnt, typs and szs of th towr wr. Thrfor, furthr rsarchs ar ndd about th rlatonshp btwn th dstrbuton of powr frquncy lctrc fld undr th transmsson ln and svral factors as th arrangmnt of wrs, th ovr-ground hght, th splt spacng and th sub wr radus. ) Influnc of arrangmnt of wrs a) Dffrnt Arrangmnt of Sngl Loop Supposng th ovr-ground hght of th phas conductor h=m, wth th hght.m and th dstanc from th cntr wr m, th lctrc fld dstrbuton curv undr four dffrnt arrangmnt of wrs can b prsntd as follows: 7 IVI horzontal VVV horzontal IVI trangl VVV trangl Fg.. Th powr frquncy lctrc fld of dffrnt arrangmnt of sngl loop As can b sn from Fg., rgardlss of th arrangmnt, th lctrc fld strngth all rachs th maxmum blow th phas conductor and gradually wakns to both sds. Although th maxmum fld strngth of IVI trangl arrangmnt s a lttl mor than that of VVV horzontal arrangmnt, but th corrspondng hgh fld strngth ara of surpassng kv/m s smallr than th lattr. In gnral, no mattr what th maxmum powr frquncy lctrc fld and th corrspondng hgh fld strngth ara of undr kv/m s, VVV trangl arrangmnt s always bttr than th othr thr arrangmnt. Thrfor, usng trangl arrangmnt can rduc th maxmum fld strngth of th lctrc transmsson ln as wll as th ara undr th covr of hgh fld strngth, thus rducs th constructon rsk and hddn dangr. b) Dffrnt Phas Squnc Arrangmnt of Doubl Loop Doubl crcut arrangmnt of UHV AC can b subdvdd nto four typs: postv and rvrs phas squnc vrtcal arrangmnt of I and V. Supposng th ovr-ground hght of th phas conductor h=m, wth th hght.m and th dstanc from th cntr wr m, th lctrc fld dstrbuton curv undr four dffrnt arrangmnt of wrs can b prsntd as follows: 7 P a g

3 lctrc fld ntnsty(kv/m) lctrc fld ntnsty(kv/m) (IJACSA) Intrnatonal Journal of Advancd Computr Scnc and Applcatons, Vol., o., postv phas squnc I rsrv phas squnc I postv phas squnc V rsrv phas squnc V h=m h=m h=m h=m Fg.. Th powr frquncy lctrc fld of dffrnt arrangmnt of doubl loop As w can s from Fg., th maxmum fld ntnsty of rvrs phas squnc I s.kv/m lss than that of postv phas squnc [-9]. Th maxmum fld ntnsty of rvrs phas squnc V s.kv/m lss than that of postv phas squnc. o mattr usng vrtcal arrangmnt of I or V, th maxmum fld ntnsty and th aras undr hgh fld strngth of rvrs maxmum fld strngth ar much lssr than thos of postv maxmum fld strngth. Thrfor, n doubl crcut arrangmnt, usng rvrs phas squnc arrangmnt s an ffctv way to rduc th ln strngth and th ara undr hgh fld strngth. ) Th nflunc of conductor ovr-ground hght Th changs of th powr frquncy lctrc fld of UHV transmsson ln undr dffrnt conductor ovr-ground hght wll b analyzd takng IVI horzontal arrangmnt for xampl. Supposng th conductor ovr-ground hght h ar m, m, m and m, th dstrbuton curvs of th powr frquncy lctrc fld.m abov th ground can b prsntd as follows: Fg.. Th powr frquncy lctrc fld of dffrnt conductor ovr-ground hght As w can s from Fg., th lctrc fld ntnsty of transmsson ln bcoms mor and mor wak wth th ncrasng conductor ovr-ground hght [-]. Whn th conductor ovr-ground hght ncrass from m to m, th maxmum lctrc fld ntnsty rducs by.9kv/m. f th conductor ovr-ground hght ncrass m ach tm, th maxmum fld ntnsty wll rducs.kv/m and.7kv/m n turn. Thrfor, th dcrasng ampltud of th lctrc fld ntnsty s wakr. Whn th conductor ovr-ground hght h s not so hgh, ncrasng th hght has obvous nflunc on rducng th lctrc fld ntnsty. Wth th ncrasng h, th conomc nput wll gradually ncras n ordr to rduc th sam lctrc fld ntnsty. Thus, w must tak all th rlvant factors nto consdraton whn dsgnng th lns and choos th approprat conductor ovr-ground hght. ) Th Influnc of Splt Spacng Th changs of th powr frquncy lctrc fld of UHV transmsson ln undr dffrnt splt spacng wll b analyzd usng IVI horzontal arrangmnt as an xampl. As s known that th phas conductor of kv UHV transmsson ln has 79 P a g

4 lctrc fld ntnsty(kv/m) lctrc fld ntnsty(kv/m) lctrc fld ntnsty(kv/m) (IJACSA) Intrnatonal Journal of Advancd Computr Scnc and Applcatons, Vol., o., dvson structur, supposng th ovr-ground hght of th phas conductor h s m and th splt spacng ar.m,.m,.m and.m, th dstrbuton curvs of th powr frquncy lctrc fld.m abov th ground s prsntd n th followng fgur. As can b sn, th powr frquncy lctrc fld ntnsty of UHV transmsson lns dcrass wth dcrasng splt spacng. Th maxmum lctrc fld ntnsty dcrass from. to.kv/m whl th splt spacng rducs vry.m. Thrfor, rducng th conductor splt spacng can dcras th lctrc fld ntnsty of th transmsson lns. LGJ-7/ LGJ-/ LGJ-/ LGJ-/.m.m.m.m Fg.. Th powr frquncy lctrc fld of dffrnt splt spacng LGJ-7/ LGJ-/ 7 LGJ-/ LGJ-/ (a) IVI horzontal arrangmnt (b) IVI trangl arrangmnt Fg.. Th powr frquncy lctrc fld of dffrnt sub conductor radus ) Th nflunc of sub conductor radus Th rlatonshp btwn conductor radus and th lctrc fld strngth wll b analyzd usng four typs of sub conductor: LGJ-7/, LGJ-/, LGJ-/ and LGJ- /. In IVI horzontal arrangmnt and IVI trangl arrangmnt, supposng th conductor ovr-ground hght h=m, th dstrbuton curvs of th powr frquncy lctrc fld.m abov th ground s prsntd n th followng fgur. As s shown n th fgur, th nflunc of dffrnt conductor radus on th powr frquncy lctrc fld undr th transmsson lns can b gnord n th two dffrnt arrangmnt []. IV. COCLUSIO Usng boundary lmnt mthod to smulat and calculat th powr frquncy lctrc fld of th kv UHV AC transmsson ln and analyz th dstrbuton of lctrc fld undr dffrnt condtons, th followng conclusons can b drawn: A. Dffrnt factors hav dffrnt ffcts on th powr frquncy lctrc fld dstrbuton of UHV transmsson lns. Th conductor arrangmnt, th ovr-ground hght and th splt spacng all hav a crtan nflunc on th lctrc fld whl th nflunc of th sub conductor radus on th powr frquncy lctrc fld can b narly gnord. Adoptng trangl arrangmnt n sngl loop and rvrs phas squnc arrangmnt n doubl loop all hav grat nflunc on rducng th ground fld strngth. Th ovr-ground hght of phas conductor has grat ffct on th fld strngth and th hghr th ovr-ground hght s, th smallr th ground fld strngth wll b. Howvr, smply rasng th conductor hght wll dfntly ncras th nvstmnt and dffculty of th proct. Thrfor, n ordr to dcras th ground fld strngth and rduc th constructon cost as much as possbl, w must choos th rasonabl conductor ovr-ground hght. P a g

5 (IJACSA) Intrnatonal Journal of Advancd Computr Scnc and Applcatons, Vol., o., B. Th nflunc of th spltd conductors of UHV transmsson lns on th powr frquncy lctrc fld manly dpnds on th conductor radus whl th quvalnt radus s manly dcdd by th conductor splt spacng. Th lctrc fld ntnsty wll dcras wth th dcrasng splt spacng. Th sub conductor radus bascally has no nflunc on th powr frquncy lctrc fld. REFERECES [] Shu Ynbao. Dvlopmnt and xcuton of UHV powr transmsson n Chna[J]. Elctrc Powr,, (): -. [] Kovalv V, Panbratts A, Volkova O t al. Th qupmnt for th AC kv transmsson ln[z]. Moscow: All-Russan Elctrotchncal Insttut (GUP VEI),. [] Shu Ynbao. Currnt status and dvlopmnt of natonal grd n Chna[C]. IEEE/PES T&D Confrnc, Dalan,. [] Okamoto H. Systm dsgn n kv AC transmsson conductd by TEPCO[Z]. [] Wu Jngru, Xu Yongx. Dvlopmnt prospct of UHV AC powr transmsson n Chna[J]. Powr Systm Tchnology,, 9(): -. [] Shao Fangyn. Phas conductor confguraton and powr frquncy lctromagntc nvronmnt of UHV transmsson lns n Chna[J]. Powr Systm Tchnology,, 9(): -7. [7] Zhou Hao, Yu Yuhong. Dscusson on svral mportant problms of dvlopng UHV AC transmsson n Chna[J]. Powr Systm Tchnology,, 9(): -9. [] Zhang Wnlang, Wu Wnng, Hu Y. Study of UHV transmsson tchnology and dvlopng of powr systm n Chna[J]. Hgh Voltag Engnrng,, 9(9): -. [9] Chn Yong. Dscussons on UHV conductors and towr structur n Chna[J]. Hgh Voltag Engnrng,, (): -. [] H Jal, L Yongl, L Bn, t al. Rlay protcton for UHV transmsson lns: Part two dsposton of rlay protcton. Automaton of Elctrc Powr Systms,, (): -. [] Dong Xnzhou, Su Bn, Bo Z Q, t al. Study of spcal problms on protctv rlayng of UHV transmsson ln. Automaton of Elctrc Powr Systms,, (): 9-. [] Frrro RW, Rvra JF, Shahdhpour SM. ADynamc Pro- grammng Two-stag Algorthm for Long-trm Hydro-thrmal Schdulng of Multrsrvor Systms[J]. IEEE Transactons on Powr Systms, 99, () : -. [] M. Duvall and E. Knppng. Envronmntal Assssmnt of Plug-n Hybrd Elctrc Vhcls[R]. w York: EPRI, 7: -7. P a g