Robust and Intelligent Control Methods to Improve the Performance of a Unified Power Flow Controller

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1 rcdng f th Wrld Cngr n Engnrng l II WCE, July 6-8,, Lndn, U.K. Rbut and Intllgnt Cntrl Mthd t Imprv th rfrmanc f a Unfd wr Flw Cntrllr C. BENCHIB, HMED M.. HIDR, M. L. DOUMBI btract Th mprtant factr dturbng th mdrn pwr ytm tday lad flw cntrl. Th Unfd wr Flw Cntrllr (UFC) an ffctv way fr cntrllng th pwr flw and can prvd dampng capablty durng trannt cnn. Th UFC cntrlld cnvntnally ung I cntrllr. Th papr prnt tw rbut cntrllr t mprv th prfrmanc f th UFC. Th frt a RST cntrllr bad n th prncpl f pl placmnt and th cnd an ntllgnt cntrllr bad n th prncpl f fuzzy lgc ptmzd by Gntc lgrthm (G). Indx Trm but Shunt and Sr actv fltr, UFC, I and RST cntrllr, Fuzzy lgc, G I. INTRODUCTION ITH th ncrang cmplxt n pwr ytm wacr th glb and th grwng nd t prvd tabl, cur, cntrlld, cnmc, and hgh-qualty lctrc pwr, n th lat 98 th Elctrc wr Rarch Inttut (ERI) ha ntrducd a nw tchnlgy prgram knwn a Flxbl C Tranmn Sytm (FCTS). In th cntxt th FCTS [], [] cntrllr ar gng t play a crtcal rl n pwr ytm. FCTS dvc nhanc th tablty f th pwr ytm bth wth t fat cntrl charactrtc and wth t cntnuu cmpnatng capablty. Th tw man bjctv f FCTS tchnlgy ar t cntrl pwr flw and ncra th tranmn capacty vr an xtng tranmn crrdr []. Incra n currnt ha ld t th ncra f pwr n a ln ladng t ttal ncra f ytm tranmn l. at rarch had addrd th phnmna n trm f allvatng tranmn l, vltag prfl and vltag tablty mprvmnt. mng th ffctv tchnqu ar ractv pwr upprt chm thrugh th mplmntatn f gnratr ractv pwr upprt and hunt capactr placmnt. On th thr hand, radjutmnt f tranfrmr tap rat and ntallatn f flxbl ac tranmn ytm abl t altr th tranmn ln paramtr whch vntually mprv th pwr ytm prfrmanc n trm Manucrpt rcvd prl, ; rvd ugut,. C. Bnachaba wth th Unvrty f Bchar, LGERI (crrpndng authr t prvd phn: -6678; fax: ; -mal: chllal@ ntcap.nt).. M.. Hadar wth th Unvrty f Malaya ahang, Malaya, - mal: ahmdm@ump.du.my. M. L. Dumba wth th Unvrty f Qubc-Tr-Rvèr, Canada, - mal: Mamadu.Dumba@uqtr.ca. f mnmzng th l, vltag tablty and vltag prfl mprvmnt [4] [7]. Gyugy prpd th Unfd wr Flw Cntrllr (UFC) whch a nw gnratn f FCTS dvc n 99 [8]. It a dvc, whch can cntrl multanuly all thr paramtr f pwr tranmn ln (mpdanc, vltag and pha angl) [9], []. Th dvc cmbn tgthr th fatur f tw thr FCTS dvc: th Statc Synchrnu Cmpnatr (STTCOM) and th Statc Synchrnu Sr Cmpnatr (SSSC). ractcally, th tw dvc ar tw ltag Surc Invrtr (SI ) cnnctd rpctvly n hunt wth th tranmn ln thrugh a hunt tranfrmr and n r wth th tranmn ln thrugh a r tranfrmr. Th ar cnnctd t ach thr by a cmmn DC lnk, whch a typcal trag capactr. Th hunt nvrtr ud fr vltag rgulatn at th pnt f cnnctn, njctng ractv pwr flw nt th ln and t balanc th ral pwr flw xchangd btwn th r nvrtr and th tranmn ln. Thu, th UFC can fulfll functn f ractv hunt cmpnatn, actv and ractv r cmpnatn and pha hftng. B, th UFC prvd a cndary but mprtant functn dampng cntrl t uppr pwr ytm cllatn, thu, mprvng th trannt tablty f pwr ytm. Th UFC ha bn prfundly rcgnzd a n f th mt tchncally prmng dvc n th flxbl ac tranmn ytm (FCT) famly [] []. Th bjctv f FCT dvc t brng a ytm undr cntrl and t tranmt pwr a rdrd by th cntrl cntr, t al allw ncrang f th uabl tranmn capacty t t thrmal lmt. UFC hav th capablty t cntrl vltag magntud and pha angl. B, UFC can ndpndntly prvd thr ptv r ngatv ractv pwr njctn. Many advantag n pwr ytm pratn and plannng can mmdatly b ralzd by achvng th functn f glbally rgulatng th pwr flw and multanuly upprtng th bu vltag. Such advantag nclud th mnmzatn f ytm l wthut gnratn rchdulng, lmnatn f ln vrlad and lw vltag prfl. II. DNMIC MODEL OF THE UFC Unfd pwr flw cntrllr a gnralzd ynchrnu vltag urc, rprntd at th fundamntal frquncy by vltag phar wth cntrllabl magntud ( max) and angl α ( α π), n r wth th tranmn ln. Th UFC cnt f tw vltag- ISBN: ISSN: (rnt); ISSN: (Onln) WCE

2 rcdng f th Wrld Cngr n Engnrng l II WCE, July 6-8,, Lndn, U.K. urcd nvrtr. Th back-t-back nvrtr ar pratd frm a cmmn DC lnk prvdd by a DC trag capactr. Th arrangmnt functn a an dal ac-t-ac pwr nvrtr n whch th ral pwr can frly flw n thr drctn btwn th ac trmnal f th tw nvrtr, and ach nvrtr can ndpndntly gnrat (r abrb) ractv pwr at t wn ac utput trmnal. Th r nvrtr prvd th man functn f th UFC by njctng a vltag wth cntrllabl magntud and pha angl α n r wth th ln va an nrtn tranfrmr. Th njctd vltag act ntally a a ynchrnu ac vltag urc. Th tranmn ln currnt flw thrugh vltag urc rultng n ractv and actv pwr xchang btwn th urc and ac ytm. Th nvrtr gnrat th ractv pwr xchangd at th ac trmnal ntrnally. Th actv pwr xchangd at th ac trmnal cnvrtd nt dc pwr whch appar at th DC lnk a a ptv r ngatv ral pwr dmand. Th bac functn f hunt nvrtr t upply r abrb th ral pwr dmandd by r nvrtr at th cmmn DC lnk t upprt th ral pwr xchang rultng frm r vltag njctn. Th DC lnk dmand f r nvrtr cnvrtd back t ac by hunt nvrtr and cupld t th tranmn ln bu va a hunt-cnnctd tranfrmr. In adn, th hunt nvrtr can al gnrat r abrb cntrllabl ractv pwr, f t drd and thrby prvd ndpndnt hunt ractv cmpnatn fr th ln. Th man cntrl paramtr f UFC ar vltag magntud (), pha angl (α) and ral and ractv pwr. Th cntrl f th paramtr can b achvd by njctng r vltag wth apprprat magntud and pha angl. Th njctd vltag tranfrmd nt dq rfrnc fram, whch plt nt Ed and Eq. Th crdnat can b ud t cntrl th pwr flw. Th cntrllr f UFC fr hunt and r branch SI ar dcrbd blw. Fg.. Equvalnt crcut f th UFC pplyng Krchhff law n quvalnt crcut hwn n Fgur, th thr dynamc quatn f th UFC can b btand a, ISBN: ISSN: (rnt); ISSN: (Onln) d c ch r L d c ch r L d c ch r L Th dynamc quatn f th hunt cmpnatr, d c ch r L d c ch r L () d c ch r L Th dynamc quatn f DC crcut, ddc c c ch cch cch () p Whr, dc : DC vltag : wr abrbd by th r cmpnatr and uppld t th cmmn crcut p : actv pwr prvdd by th hunt cmpnatr and abrbd by th r cmpnatr umng n actv pwr cnumd by capactr and nvrtr, th matrx rprntatn f th quatn ytm ar: Th matrx rprntatn f th r cmpnatr, r L c (4) ch d r. c ch L L r c ch L Th matrx rprntatn f th hunt cmpnatr, r L c ch (5) d r. c ch L L r c ch L Ung ark tranfrmatn, th tw quatn () and (), wll b wrttn a, r d L. r dq L L r d d L d d. r q q L q L cd cq cd cq Th dynamc quatn f th cntnuu crcut ar: ddc cd cqdd q q C dc () (6) (7) (8) WCE

3 rcdng f th Wrld Cngr n Engnrng l II WCE, July 6-8,, Lndn, U.K. Whr, d q Th gnratd and abrbd ntantanu actv and ractv pwr ar gvn blw: Th gnratd actv and ractv pwr ar: Q Th abrbd actv and ractv pwr ar: ch ch () () () () III. UFC CONTROLLER BSED ON OLE LCEMENT Th blck dagram wth a RST cntrllr dpctd n Fg.. c(z) RST U(z) H(z) (z) (9) Th ampld tranfr functn accrdng t (4), :.6 z.6 H (9) Wth, amplng prd h=.5, th factr f amrtzatn a = and th trk f clck k a =5 xpln.55 5 C () Wth, R z, Sz S, z Th Dphantn quatn :.6.6S z.55 z () Thrfr, S nd,.75 T B z z c ' m 8.5 BzT z.45 zrz BzS z z. 55 () Fg.. Blck dagram f RST cntrllr n frm th fg., c(z), U(z) and (z) rprnt rfrnc valu, cntrl valu and ral valu. H(z) dgnat th ampld tranfr functn f th prc t adjut th gvn by th fllwng frmula: H z z Z L G / (4 a) B z H z (4 b) z Th dgr f (z) trctly bggr than B(z). G() th tranfr functn f th ytm that can b adjutd. In gnral th tranfr functn n cld lp gvn by th fllwng rlatn: z z c BzT z zrz BzS z (5) Th plynmal R(z) chn f dgr ρ Rz z r z... r (6) Lt' dnt σ th dgr f th plynmal S(z) z... S z z nd thr τ th dgr f th plynmal T(z) T z t z t z... t (7) Th analgcal tranfr functn f th ytm : 4 G (8) I. UFC FZZ CONTROLER OTMIZED B G Fg. dplay th blck dagram f a G-bad lflarnng fuzzy I cntrl ytm. Th G gnrat a ppulatn uncrtan f chrmm [4]. Th chrmm ar njctd n th fuzzy cntrllr. ftr tag f calculatn (Nrmalzatn, fuzzfcatn, nfrnc, dfuzzfcatn and dnrmalzatn), th cntrllr utput gnal cmmand th ytm. Th G tmat th ftn functn (Mnmzatn f th ttal rrr btwn th actual utput vltag and th rfrnc vltag). ftr th valuatn f all chrmm f th ntal ppulatn a nw gnratn wll b frmd whl applyng th gntc pratr (Slctn, crvr and mutatn). Th prc rpat tlf untl th atfactn f tp crtra f th G. Fg. 4 hw th trangular mmbrhp functn fr ach fuzzy ubt n whch th functn ar ymmtrc functn wth rpct t th vrtcal ax fr th ak f ay mplmntatn. F G Xrf + Fuzzy lant Fg.. Blck dagram f a G-bad lf-larnng ISBN: ISSN: (rnt); ISSN: (Onln) WCE

4 rcdng f th Wrld Cngr n Engnrng l II WCE, July 6-8,, Lndn, U.K. NG NM N EZ (x) M G Ngatv Mdum (NM), Ngatv Small (NS), Zr (Z), tv Small (S), tv Mdum (M) and tv Bg (B). Th actual utput currnt cmpard wth th rfrnc currnt t prduc an rrr gnal and a chang f rrr gnal dfnd a: - x x x x 4 x 5 x 6 x 7 Fg. 4. Trangular fuzzy mmbrhp functn Th paramtr x, x, x, x 4, x 5, x 6, x 7 ar th pck f vry mmbrhp functn rpctvly NB, NM, NS, Z, S, M, B. mmbrhp functn ar ymmtrcal, th nly paramtr that can b dfnd ar x 5, x 6 and x 7, th thr wll b dductd a fllw: x = - x 7 ; x = -x 6 ; x = -x 5 ; x 4 =. ILLUSTRTIE EXMLE In rdr t valuat th prfrmanc f th prpd cntrllr, a mulatn prfrmd ung SIMULINK ftwar prgram fr th UFC ytm hwn n th fgur. Th data f th ytm gv a fllw: Supply ltag: =, Lad vltag : ch = DC vltag : dc =8 Ntwrk frquncy: f=5 Hz Ln rtanc: R=4Ω Ln nductanc: L=.H Shunt fltr rtanc: R p =.Ω Shunt tranfrmr nductanc: L p =.H Cmmn crcut capactr DC: C=µF Fr th purp f cmparn, th ytm rpn ar prntd fr I cnvntnal cntrllr, RST cntrllr and I-Fuzzy bad n G cntrllr. Th charactrtc f ach cntrllr ar prntd blw: Th gan and ntgral tm cntant f th I cntrllr ar K p =.5, T = Th valu f plynmal R, S and T f th RST cntrllr ar R=, S=.75 and T=8.5 Th I-Fuzzy bad n G cntrllr frmd by tw nput rrr () and chang f rrr (Δ) and n utput. Tabl prnt th ptmzd Fuzzy dcn. u TBLE THE DECISION TBLE NB NM NS Z S M B B Z S M B B B B M NS Z S M B B B S NM NS Z S M B B Z NB NM NS Z S M B NS NB NB NM NS Z S M NM NB NB NM NM NS Z S NB NB NB NB NB NM NS Z n frm tabl, ach ntrval f ach varabl dvdd n vn mmbrhp functn: Ngatv Bg (NB), x k k I I () rf k k k (4) Th ftn functn F t maxmz dfnd a n (5), and th tabl dplay G paramtr F n k (5) k aramtr pulatn z Slctn Mutatn rat Crvr rat Gnratn numbr Tlranc TBLE G RMETERS alu 5 Rultt Th fllwng fgur hw rult f th dffrnt cntrllr. Fg. 5 hw th varatn f th actv pwr. Th rpn f th UFC cnvntnal cntrllr (b) prnt amplfcatn t vry varatn f th lad, whl rpn f th thr RST (c) and I-Fuzzy bad n G (b) ar dntcal, mth and prfctly fllw th rfrnc. Th am rmark fr th varatn f th ractv pwr llutratd n fg. 6. Fr drct and quadratc currnt dpctd n fg. 7 and 8 rpctvly, th rpn f th I cnvntnal cntrllr charactrzd by amplfcatn t vry chang f th lad. It ncary t gnal that rpn f th RST and I-Fuzzy bad n G ar dntcal at vry ntant f th mulatn. ( p.u.) (b) (c) and (d) Fg. 5. Intantanu actv pwr f th cntrlld tranmn ln, Rfrnc, (b) I cntrllr, (c) RST cntrllr, (d) I-Fuzzy bad n G cntrllr ISBN: ISSN: (rnt); ISSN: (Onln) WCE

5 rcdng f th Wrld Cngr n Engnrng l II WCE, July 6-8,, Lndn, U.K. Q(p.u.).5.5 (b) (c) and (d) Fg. 6. Intantanu ractv pwr f th cntrlld tranmn ln, Rfrnc, (b) I cntrllr, (c) RST cntrllr, (d) I-Fuzzy bad n G cntrllr r d ( p.u.).5.5 (b) and (c) Fg. 7. Intantanu d-ax currnt cmpnnt, I cntrllr, (b) RST cntrllr, (c) I-Fuzzy bad n G cntrllr r q ( p.u.) (b) and (c) Th can b cnfrmd frm th rult that hw th lmtatn f th cnvntnal I cntrllr whra th cntrllr RST and I-Fuzzy bad n G ar mr ffctv and a prfctly fllw th rfrnc. Thrfr, th cntrl pratn f UFC ar dal frm bth vwpnt. It hwvr t b mntnd that a UFC a vry pwrful dvc ung th ntllgnt cntrllr REFERENCES [] N. G. Hgran, Flxbl C Tranmn, IEEE Spctrum, prl 99, pp [] L. Gyugy, Dynamc Cmpnatn f C Tranmn Ln by Sld-Stat Synchrnu ltag Surc, IEEE, 99, pp [] S. n; J. Cndrn, and T. W. Gdra, n dal tranfrmr UFC mdl, OF frt-rdr ntvt, and applcatn t crnng fr ptmal UFC lcatn, IEEE Tran. wr Syt., vl., n., p.68 75, Fb. 7. [4] Ghadr Radman and Rhma S Raj, wr flw mdl/calculatn fr pwr ytm wth multpl FCTS cntrllr, Elctrc wr Sytm Rarch, lum 77, Iu, Octbr 7, pp [5] E. Ghllpur, S. Saadat, Imprvng trannt tablty f pwr ytm ung UFC, IEEE Tranactn n wr Dlvry, 5, pp [6] H. I. Shahn, G. I. Rahd, and S. J. Chng, Optmal lcatn and paramtr ttng f unfd pwr flw cntrllr bad n vlutnary ptmzatn tchnqu, n rc. IEEE wr Eng. Sc. Gnral Mt., Jun. 4 8, 7, pp. 8. [7] Fujta, H., Watanab,., kag, H., Dynamc Cntrl and rfrmanc f a Unfd wr Flw Cntrllr fr Stablzng an C Tranmn Sytm, IEEE Tran. wr Elct, vl., n. 4, July 6, pp.. [8] L. Gyugy, Unfd wr Flw Cntrl Cncpt fr Flxbl C Tranmn Sytm, IEE rc. art C 9(4), 99, pp.. [9] H. Fujta, H. kag,. Watanab, Dynamc cntrl and prfrmanc f a unfd pwr flw cntrllr fr tablzng an C tranmn ytm, IEEE wr Elctrnc Tranactn, 6, pp.. [] Lütfü Sarbulut, hmt Tk, Mhmt Tümay, Dynamc cntrl f unfd pwr flw cntrllr undr unbalancd ntwrk cnn, Smulatn Mdllng ractc and Thry 9,, pp [] M. Bau, S.. Da, G.K. Duby, Cmparatv valuatn f tw mdl f UQC fr utabl ntrfac t nhanc pwr qualty,, Elctrc wr Sytm Rarch 77, 7, pp [] J. Xa, J.H. Chw,. Edr, B. Fardanh, E. Uzunvc, Tranfr path tablty nhancmnt by vltag-urcd cnvrtr-bad FCTS cntrllr, IEEE wr Dlvry Tranactn 5,, pp [] S. n, J. Cndrn and T.W. Gdra, n Idal Tranfrmr UFC Mdl, OF Frt-Ordr Sntvt and pplcatn t Scrnng fr Optmal UFC Lcatn, IEEE Tranactn n wr Sytm, l., Iu, Fb 7, pp [4] J H. Hlland daptatn n Naturl and rtfcal Sytm, Unvrty f Mchgan r, nn rbr. MI, Fg. 8.Intantanu q-ax currnt cmpnnt, I cntrllr, (b) RST cntrllr, (c) I-Fuzzy bad n G cntrllr I. CONCLUSION Th papr dcu th tplgy and prpd ntllgnt cntrl tchnqu f a UFC that prat n multanu vltag and currnt cntrl md. Frm th prntd rult f cntrllr, t can b cncludd that th UFC ndpnabl qupmnt and can atfy th qualty tandard f nrgy du t th fat dcn and ptmal rpn. ISBN: ISSN: (rnt); ISSN: (Onln) WCE