An Approach to Load Balancing & Unity Power Factor Control in Multi-phase (Six-phase) Load Circuits Using Multi-phase DSTATCOM

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1 An Approh to o Blnng & Unty Powr Ftor Control n Mult-phs (Sx-phs) o Cruts Usng Mult-phs DSTATCOM Zkr Hun, Mmr, IAENG Astrt Mult-phs los, wth phss mor thn thr, splly n orm o nrtr nuton motor rs sut to hgh powr n splz ppltons, r rng growng ttnton n th ltrtur. Ths multphs sour or suh r pplton my r rom trnsormr onnton (3 phs to 6 phs) or y DC lnk sx phs nrtrs. Ths sours wll th prolm o unln, hrmon storton n poor powr tor oprton. In w o ths lopmnts, ths ppr ls wth th supply s lo lnng n powr tor orrton n suh lo ruts. Th propos ompnton shm uss th shunt urrnt sour ompnton whos nstntnous lus r trmn y th nstntnous symmtrl omponnt thory. An l ompntor n pl o physl rlzton o th ompntor hs n propos n th orm o urrnt ontroll oltg sour nrtr. Th ompnton shm lop n th ppr s tst or thr lty on 6-phs ( 6-wr & 7-wr) ruts through xtns smultons or unln long, phs outgs, n non lnr long. Th smulton rsults o th ompnton thory n th l ompntor ry th ompnton mtho. Inx Trms o lnng, Powr tor orrton, Compntor, Sx-phs DSTATCOM, Mult-phs I. INTODUCTION UE to th potntl nts rsultng rom th us o Dphs orr hghr thn thr n trnsmsson, multphs (phs orr mor thn thr) mhn rs r gnng growng ttnton [-3] n rnt yrs, u to thr srl nhrnt nts suh s ru torqu pulton, hrmon ontnt, urrnt pr phs wthout nrsng th oltg pr phs, hghr rllty n nrs powr n th m rm s ompr to thr thr phs ountrprt. Mult-phs nrtr nuton motor rs h n oun to qut promsng or hgh powr rtngs n othr splz ppltons. Th us o suh rs n s prsnt mult-phs lo ruts tht my gt sujt to phs outgs, unln s wll s non-lnr longs smlr to thr thr phs ountr prts. Suh ontons my l to rty o unsrl ts on th supply systm suh s tonl losss n onntng lns n ntrng s, oslltory torqus n mhns, nrs rppl n rtrs, mluntonng n snst qupmnts, hrmon n xss nutrl urrnts t. It s thror sr to h th ln Zkr Hun s wth th Dprtmnt o Eltrl Engnrng, Ntonl Insttut o Thnology Hmrpur (H.P), In (phon: ; x: ; -ml: zhun@ yhoo.om). powr systm oprton wth mnmum lowr orr hrmons n n th prsn o suh oprtons. A urrnt ltrtur sury rls tht numr o mthos h n ol or th ompnton o hrmons n unlns [-] or th onntonl thr phs systms. Th mjorty o th mthos r s on th nstntnous rt powr thory [-8], thory o symmtrl omponnts [6-9], n rrn rm thory [-]. Utlzng ths thortl onpts, thnqus h n lop or lnng thr phs lo [6-7], powr tor orrton [7-8], oltg rgulton [-9] n mtng othr ojts. Ths ppr rsss th prolm o lnng n unln mult-phs lo n powr tor orrton on supply s. It s to not tht t powr ompnton rqurs sour, whh n supply th rl powr to lo. Thortlly lthough possl, ut prtlly powr sour t lo ntr rqurs strut gnrton sours. Ths ppr ssums onntonl powr systm wth ntrl gnrtng stton n thror t powr ompnton s not onsr. Th rt powr ompnton n h y rous Powr ontonng s lk DSTATCOM rlzng rl ptor or nutor wth th lo rut. Th mount o ompnton n th m o ompnton th ontrol strtgy o th powr ontonr. Th rt powr ompnton rqurs th msurmnt o rt powr o th lo rut. Altrntly, n nrt mtho suh s urrnt qulzton or phs onstrnt n mploy to rlz th sr ompnton or th lo ruts. A nw ompnton thnqu hs n propos usng th nstntnous symmtrl omponnts n [-3]. Th propos thnqu ompnts or th rt powr wthout sp msurmnt o rt powr n n ltrnt wy,.. trmnng th rrn urrnt o th shunt urrnt sour ompnt systm y nstntnous symmtrl omponnt. Ths ppr prsnts th shm or ompnton or 6-phs (6-wr & 7-wr) str onnt lo ompnton. Th propos ompnton shm hs n support y smulton o n l swth s ompntor. II. MUTIPHASE COMPENSATO A. Compnton Prnpl Th s ompnton shm or mult-phs (6- phs) lo suppl rom ln st mult-phs

2 sour s shown n Fg. A ompntor rprsnt s urrnt sour onnt n prlll to th lo t th no ll Pont o Common Couplng (PCC) s sgn to supply th rt powr rqur y th lo, whrs th t powr s suppl rom th sour. N s s s s s s s s s s n' Fg. A Conptul Sx-phs, 7- wr ompnton shm l l l l l l o A o B o C o D o E o F Sngl-phs mpnn los onnt n str ormton n rprsnt gnrl sx-phs lo or multphs lo. Th thr nos o th rut rprsnt grphlly n Fg. y n, N n n rprsnt nos t lo, sour n ompntng urrnt sours rsptly. Th no N my thr lotng or onnt wth lo pont n s pr th rqurmnt o th sour n th lo. Conntng n wth n orms lol loop o th ompntor urrnt sours n lo rut. Ths rsults phs ws n npnnt oprton o ompntor rom th supply oltg sours. As onsqun, unln oprton o th ompntor n h,.. th sum o th ompntor rrn urrnts,,, n not zro. Thror, h phs o th ompntor n supply urrnt npnnt to othr phss. B. A Sx-phs Symmtrl Componnt Thory t n unln sx phs nstntnous lo urrnts not y,,,,, n whrs th orrsponng sts o sx ln symmtrl omponnts r rprsnt y,,, 3,, n 5. Th powr nrnt nstntnous symmtrl omponnts o ths urrnts r gn y (). 3 5 = Whr xp ( j / 6 ). All th sx omponnts r grphlly rprsnt n Fg.. () n I 5 I 5 I 5 I 5 I 5 I 5 I 5 I 5 I I I I I I I 3 I 3 () () () I 5 I 5 I 5 I 5 I I I I () () () Fg. Squn omponnts o sx-phs sour () Frst-squn () Son-squn () Thr -squn () Fourth-squn () Fthsqun () Sxth- squn omponnt. Th rst-(post) squn omponnt systm onssts o sx phsors spl 6 rlt to h othr whrs th son-squn omponnt systm onssts o thr phsor spl rlt to h othr, h phsor rprsntng two phss- onsttutng two thr-phs suprmpos post squns. Th thr-squn omponnt systm hs two phsors spl 8 rlt to h othr, h rprsntng thr phss onsttutng two thr-phs zro squns n opposton whrs th ourth- squn omponnt systm s squn n th oppost sns o rotton to tht o th son-squn systm. Smlrly, th th-(ngt) squn omponnt systm s squn o phsors n th oppost sns o rotton to tht o th rst-squn systm. Th sxth squn omponnt lso known s zro squn omponnts hs ll th sx phsors pl t zro gr prt to h othr. It s to not tht th nstntnous tor prs, 5 n, 6 r omplx onjugt prs whrs n 3 r rl quntts, whh s zro, mns urrnts r ln. C Drton o rn Currnts Th m o th ompntor s to mk th sour urrnt ln n oprts t sr powr tor. As rlr, th mount o th shunt urrnt rqur to mk th sour urrnt ln n prsn o unln lo, s rrr s th rrn urrnt. Thr r sx ompntng urrnt n thror sx lnrly npnnt smultnous quton n to ormult n sol. As known rom th symmtrl omponnt thory, ln systm o urrnt, th zro squn omponnts wll h zro summton lu. Aorngly, to pro ln sour urrnts, th zro squn omponnts togthr must zro.. () s s s s s Th gr o ompnton rqur or systm s y shr o th rt powr suppl y th lo wth rspt to mount o rt powr suppl y th ompntor. In most l stuton, th ompntor my rqur to ompnt ompltly th lo rt powr. Howr, ths rqurs lrg sz o ompntng I I I 3 I 3 I 3 I 3 I I I I I I

3 , wstng ompltly th plty o th sour to supply th rt powr. Thror, ll th prt ompntors r xpt to prtlly ompnt. t th sr th powr tor ngl twn n (post squn omponnts), thn th ollowng quton must hol tru. ( ( s s 5 s s s s ) 5 ) s For ln oprton, ll squn omponnts xpt post squn wll zro. For ln rut, th ollowng hols tru. s, s s, s s () t th nstntnous rl powr o th lo gn y ss ss ss s s = p l. (5) / 3 Solng (3), y tkng j w otn / ( A B ) (6) whr, A n B Tkng tngnt on oth ss o (6) n solng togthr () to (6) or s s (3) (,, ); ll th sour urrnts, n th ln oprton o th powr systm, n xpltly n n trms o th othr rls. Phs urrnt s shown n (7) s n xmpl. s s p l (7) Whr, tn n = s s 3 It s to not tht th lult sour urrnts r or ln oprton o n unln lo. I th ompntor s sgn n suh wy tht th unln omponnt o th lo urrnts s suppl y th ompntor n ln omponnt rom th sour, KC t no pont o ommon ouplng (PCC) wll g th rrn urrnt or ompntor (8) to (3) s s pl l (8) s s p l l (9) s s pl l () l l l s s s s s s p p p l l l () () (3) For prtl rlzton o th ompntor, urrnt ontroll oltg sour nrtr n us or th urrnt sour wth th rrn urrnt, r o, trkng. In nxt ston, n l swth n o s ompntor hs n propos or sx-phs lo. III. A SIX-PASE COMPENSATION EAIZATION Currnt ontroll oltg sour nrtr n o prtl rlzton o th ompntor. Usng ths prnpl, n l swth s ompntor s propos. t t ll s sx-phs DSTATCOM s ts rut topology s n xtnson o onntonl thr-phs DSTATCOM. Th topologl srpton o th propos sx-phs DSTATCOM, ts rut nlyss n mthoology o smulton or rton r rly suss s ollows A. Topology o Sx-Phs DSTATCOM Th topology o th propos sx-phs DSTATCOM hs n r rom ts thr-phs ountrprt whr n nrtr rut s mploy wth sl-hrg ptor s DC sour n unln lo rut onnt t PCC s lo to th nrtr. Th propos sx-phs ompntor onssts o sx rms o sngl-phs H- nrtr ruts s shown n Fg.3 wth splt ptor or prong th nutrl pont n o th ompntor. N s s s s s S h h h S h s s s s s s To Error Amplr Choppr V n' V V +V St rn l l l l l l o Z A o Z B o Z C o Z D o Z E o Z F S S S S S S S S S S S S Error Amplr To swth S h n S h o Choppr PI Controllr Fg. 3. Sx-phs 7-wr struton Systm wth DSTATCOM B. Anlyss o sx-phs DSTATCOM To llustrt th workng o th onrtr, phs - o th sx-phs ompntor shown n Fg.3 hs n nlyz. Th qulnt rut o phs '' wth swth S los s shown n Fg.. Th urrnt through th swth S s th srs urrnt, whh n trmn y pplyng KV or th rut. n' V V S S Fg. Equlnt Crut or Phs '' oprton o th onrtr wth swth S los n

4 Th rsultng quton s gn y () V S V S t () Whr S s swthng unton n y (5) n s omplmnt o th swthng unton S. S swth s on othrws (5) Th sours r ssum to l n th mpn loks shown n Fg. xprss los or h phs. For physl rlzton o th onrtr rut, th loss ourrng n ll th lmnts o th ompntor n onntng nutor or trnsormr must ompnt y xhng o rl powr rom sour to DC s ptor o th DSTATCOM. Thror th rrn urrnts xprss n (8-3) r rpl y tonl loss trm ( P loss ) n th powr. Th mo rson or ompntor urrnt or phs- s gn y (6). * l ( s s ) ( P lg P loss ) (6) B. Mthmtl Molng n Smulton or Sxphs DSTATCOM Smultons h n rr out or th propos sxphs DSTATCOM to lt th propos ompnton shm. Th stt sp qutons hs n wrttn n trms o th swthng untons ( S, S ) o th onrtr n ( S u & Sl ) o hoppr o th DSTATCOM n sol y ung-kutt mtho n MATAB y o5 unton. Th stt sp qutons o th sx-phs ompntor systm r gn n (7-). V V s S S t (7) V V s S S t (8) V V s S S t (9) V V s S S t () V V s S S t () V V s S S t () Th hoppr ynms hs n rlz y wrtng th stt sp qutons or th rut shown n Fg. 3. t n th urrnts n rut o th hoppr (Fg. 3), thn (3) n () rprsnts th rlton o ths n trms o swthng unton n th onrtr urrnts. S * (3) S* S* S* S * S * S * () S * S * S * S * S * Th nl xprssons (5) - (7) n otn y pplyng th prnpl o KC n KV. VC h S * S * S * S * S * S * Su * t C C C C C C C (5) VC h S * S * S * S * S * S * Sl * t C C C C C C C (6) h h V V S u S l t (7) h h Th rls us n th xprssons (5)-(7) r nt n th rut grms. Th ptor oltgs ru not ompnt or th losss n th onntng trnsormr/ nutor, whh n ount y hngng th uty yl o th hoppr. Th hng n uty o th hoppr s s on th hng n th ptor oltg rom th st rrn oltg. Th rn n th ptor oltg n st oltg (.. th rror oltg) s put orwr to proportonl-ntgrl (PI) ontrollr. Th PI ontrollr stmts th P loss omponnt s stt n (6) n trmns th uty yl o th hoppr to mntn th ptor oltg t pr sp st rrn oltg. Th st lus r tkn pproxmtly.3 tms th pk AC oltg o th sour oltg or ompntor to work tstorly. IV. SIMUATION STUDIES Th smulton stuy hs n rr out to lt th propos sx-phs DSTACOM or rous ss o unln longs, n phs outgs. Th rsults n nlyss or h s r suss n th stons to ollow. A. Compnton o unln os Th smulton o th onrtr n ompntor hs n rr wth th ollowng prmtrs. Th oltgs sp ( p,,,,, ) n th mpns Z p ( p,,,,, ) ll n ohm or th sx-phs systm r mploy s ollows. s 35.6sn (t * / 3), whr =,,, 3,, 5 orrsponng to phs,,,,, rsptly. Z 5 j5, Z 5 j, Z j, j5, j5, 3 j3 (8) Z Z Th solton trnsormr prmtrs r s ollows: = n = mh. Th ontrol prmtrs or rgultng th ptor oltg o th hoppr r just hurstlly n r gn n (9). K = K = (9) p Th nrtr urrnt n ptor h oltg hystrss n o M n V rsptly. It s sr tht th sour urrnt ln n th sour oprts t unty powr tor unr ths onton. Th systm s run, wth unln lo or on yl (. s) whh ollows turnng on o th DSTATCOM. Th systm s run wth ompntor or nothr thr yls (.8 s). It n h Z

5 sn rom Fg. 5 () n Fg. 5() tht th lo urrnts r hghly unln n qul whn ompntor s not turn on. Atr. s. whn th ompntor s turn on sour urrnts r prtly ln s shown n Fg. 5 (). In orr to ompnt th unln lo urrnts, th ompntor urrnts om unln orngly s shown n Fg. 5(). Fg. 7 ()-() (:7) sl sour oltgs (sh ln), sour urrnts (sol ln) () rton o ompntor urrnts portryng unty powr tor oprton or 6-phs 7-wr supply systm Fg. 5 Vrton o sour oltgs n lo urrnt, sour n ompntor urrnts or 6-phs 7-wr supply systm. Th D.C. lnk ptor mntns th onstnt oltg through th PI ontrollr. Th oltg rton o nul ptor s shown n Fg. 8. Pls not tht th ptor oltg s ssum to ntlly hrg or prhrg Th thr nstntnous powrs nmly sour; lo n ompntor powrs r shown n Fg. 6 () & (), whl two nutrl urrnts (sour & lo nutrl urrnts) r plott n Fg. 6 (). It n sn tht or ompnton, tht s, whn ompntor s swth o, sour powr n lo powr h th m mgntu n r o oslltng ntur s shown n Fg. 6 (). Ths s u to unln n lo urrnts. But tr ompnton (whn ompntor s turn on) th sour powr ttns sty stt lu s n sn rom Fg. 6 () whl lo powr s oslltng Fg. 6(). Moror, th sour nutrl urrnt ttns zro lu s shown n Fg. 6() whn th ompntor s turn on s t lns th sour urrnts. Ths lso mpls tht th sum o th nstntnous ompntor urrnts s qul to lo nutrl urrnt Fg 8 Cptor oltg rton B. o Compnton or phs outgs Th ntgs o los lk motor n ts pty to oprt Th ntg o multphs los lk motor s n ts plty to oprt wth phs outg. Th motor oprts wth gr prormn n sour ss n unln oprton n thror othr los onnt to suh sour gt t. Th propos ompntor hs n tst wth rous omnton o phs outgs n t hs n oun tht t works tstorly n wth thr phss opn (wth phs outg (,, )) n sx phs sour. Th rsult s shown n Fg. 9 & whr th ntr sour urrnts r ln wth ompntor on. Fg. 6 Vrton o powr n nutrl urrnt or 6-phs 7-wr supply systm Th rton o ophsors-oltg n urrnts shows unty powr tor oprton wth ompntor s t s nt rom Fg.7 It n sn rom (8) tht mpns r unln n h ll rt lmnts xpt on, ut th urrnts r not only ln ut lso oprt t unty powr tor wth ompntor Fg. 9 Vrton o sour oltg & rous urrnts or th phs outg (,, ) o th lo or 6-phs supply systm.

6 Fg. Vrton o powrs n nutrl urrnts or phs phs outg (,, ) o lo or 6-phs supply systm Fg. 5 Vrton o powrs n nutrl urrnts wth non lnr long o 6-phs supply systm Fg. ()-() (:7) Sl sour oltgs (sh ln), sour urrnts (sol ln) & () rton o ompntor urrnts portryng unty powr tor oprton or phs outg (,, ) o th lo or 6- phs supply systm. Fg. 6 ()-() (:8) sl sour oltgs (sol ln), sour urrnts (sh ln) () rton o ompntor urrnts portryng unty powr tor oprton or 6-phs supply systm Fg Cptor oltg rton or phs outg (,, ) o th lo or 6-phs supply systm. C. o Compnton or non-lnr lo Th propos ompnton shm hs lso n tst wth nonlnr longs y smultng rtr lo or h phs rwng onstnt.. urrnt rom h phs. Th smulton rsults r prsnt n Fgs A r summry o osrton s s ollows: Volts Amps Amps Amps ()o urrnts ()Sour urrnts ()Compntor urrnts ()Sour oltgs Tm(s) Fg. Vrton o sour oltg & rous urrnts or 6-phs supply systm V. CONCUSION In ths ppr, th prolm o lo lnng n powr tor orrton t th sour s or mult-phs lo ruts n th nt o lnr unln long, phs outgs n non lnr longs h n rss. For th purpos, mult-phs ompntor (6-phs) h n rlz s mult-phs DSTACOM xtnng th pproh lop or thr phs systm n th ltrtur. Th ynm hor o th ompntor s lso smult urng th lo ompnton pross. An lort stuy hs lso n m on sour oltgs, lo urrnts, sour urrnts, n ompntor urrnts urng nonompntng n ompntng pro. Th ptor oltg rtons n th rton o th lo n sour powrs r lso nlyz. Th rton o th ompntor powr t th tm o ts rs hs n xpln. Th nlyss hs onrm unty powr tor oprton o th sour n ll ss s n y th oltg n urrnt worms. An ntrstng spt o th smulton stuy hs n to osr tht mult-phs systms qupp wth mult-phs ompntor n work wth phs outgs s hgh s 3 n 6- phs systm rsptly wthout ny grton n supply systm qulty - tur most lul or mult-phs sours n multphs nuton motor rs. Th nngs o th prsnt stuy r s on th onsrton o only str onnt, - los, howr, othr omnton n mor rlst mol o mult-phs los my nlyz mployng ths lopmnt.

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