ANALYSIS, SIMULATION AND COMPARISON OF CONVENTIONAL AND SVPWM ON STATCOM OPERATION WITH LINEAR LOADS IN POWER SYSTEM

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1 Internatonal Journal of Electrcal Engneerng Technology (IJEET) Volue 9, Iue, March- Aprl 18, pp , Artcle ID: IJEET_9 1 Aalable onlne at ISSN Prnt: an ISSN Onlne: Journal Ipact Factor (16): (Calculate by GISI) IAEME Publcaton ANAYSIS, SIMUATION AND COMPARISON OF CONVENTIONA AND SVPWM ON STATCOM OPERATION WITH INEAR OADS IN POWER SYSTEM Departent of Electrcal Electronc Engneerng, HIT, BBSR, Oha ABSTRACT In th paper the concept of SVPWM (Space Vector Pule Wth Moulaton) extene, n prncple, for the nerter wtchng of a STATCOM (STATc ynchronou COMpenator). A an portant eleent of the STATCOM, the pae coponent play an npenable role n the proce of acte an reacte energy torng an exchangng. Howeer the couplng of the AC nuctance an DC capactance ay lea haronc DC oltage or AC current at the output. The paper focue the effect of ncreae oulaton nex an lower haronc torton ha been tue through ulaton w.r.t. fferent perforance nce an ynac repone of releant arable. A proportonal ntegral controller ha alo been egne for cloe-loop control of the yte. Keywor:- STATCOM, SPWM,SVPWM, PI controller. Cte th Artcle:, Analy, Sulaton an Coparon of Conentonal an SVPWM on STATCOM Operaton wth near loa n Power Syte: Internatonal Journal of Electrcal Engneerng Technology, 9(), 18, pp INTRODUCTION Reacte power copenaton an control ha been recognze [] a an effcent econoc ean of ncreang power yte tranon capablty an oltage tablty. Capactor bank, ynchronou conener an nuctor were ue to upply reacte power to the nterconnecte yte. Power electronc ece later replace thee, naely, TCR (Thyrtor controlle Rectfer) wth fxe or thyrtor wtche capactor. In the ae lne STATCOM ntrouce to a a tatc replaceent of ynchronou conener. Snce t ntroucton oe ten year ago, the GTO bae tatc ynchronou copenator (STATCOM) ha Shown ore an ore eence, both n theory an practce, of the beneft t can brng to power yte [4] but the preent paper eploy VSI (oltage ource conerter) along wth IGBT wtche. The fel current of the ynchronou otor control the aount of VAR aborbe/njecte by the ae. Slarly the frng angle of ntant of the -phae nerter 11 etor@aee.co

2 control the VAR flow nto or out of the STATCOM. So STATCOM ay upply a well a aborb reacte power a an when reure. In [] Moran et. al hae hown n etal how the utlzaton of SPWM (Sne Pule Wth Moulaton) technue reuce the haronc torton. It ha alo been hown that an ncreae of oulaton nex reuce the ze of the lnk reactor an tre on wtche, whch are the gnfcant ue n repect of practcal pleentaton. Further n [] Draon et. al hae oelle the ASVC(Aance Statc Var Copenator) wth SPWM technue to how that a hgher oulaton nex proe the ynac repone of the yte an reuce the ze of the teay tate oltage reure on the c. lnk capactor. Howeer SPWM ha t known ltaton n the oer oulaton range. More portantly the SVPWM ge a uch ore oulaton factor n the uner oulaton a well a the oer oulaton range..e. a uch hgher funaental content. No bulky capactor bank or any other pae eleent reure for t operaton. Only a all capactor proe the reure nerter oltage. PWM (Pule Wth Moulaton) conerter wth hgh wtchng freuency for VAR copenaton reporte n [1]. Hence STATCOM can be regare a an acte energy-exchangng ece. The an crcut of STATCOM contan nucte an capacte coponent, whch uner certan conton uch a torte lne oltage or non-nuoal oulaton functon, wll caue haronc n DC oltage an AC current, whch ay aage the ece an alo lt the capablty of STATCOM. So pae paraeter ealuaton of funaental portance n egn proce of STATCOM. Th paper focue on egnng of nuctor on the ba of ncreang of oulaton nex. It arrange a follow. Secton II ecrbe n etal the plfe atheatcal oel of STATCOM n ynchronou frae. The teay tate an tranent repone are ecrbe n Secton III. The SVPWM coparon wth SPWM an cloe loop control are ecrbe n Secton IV an V repectely.. MODEING AND ANAYSIS A atheatcal oel therefore eelope a n []. Coner Fg.1. The three phae oltage n ecton A ay be wrtten n e(1) an α beng the phae angle between ource oltage an the nerter oltage. Tranforng to - frae ung Park tranforaton atrx an wtchng functon, we obtan the tate pace oel a hown n e(). Where, c the reacte power, X the tate ector an Y the output. Fgure 1 One lne agra of STATCOM V a V b V c V α ) π α ) π + α etor@aee.co

3 Analy, Sulaton an Coparon of Conentonal an SVPWM on STATCOM Operaton wth near loa n Power Syte R V c V c [ Coα Snα ] X ; Y c c R C Snα V Co a + α ( ) c (b) V c. STEADY STATE RESPONSE The teay tate repone of the real an reacte power of the euaton () ulate n MATAB for the yte paraeter V. V, f 5 Hz, R 1 Ω, 5 H, C 5 µf, 1.1/ whch hown n Fg. where the real an reacte power flowng n or out of the STATCOM lnearly araton w.r.t. α. 4. COMPARISON OF SVPWM WITH SPWM AND TRANSIENT RESPONSE In power electronc, nuoal pule wth oulaton (SPWM) an operaton perfore on raw oltage an current waefor to hape ther pectra n a way benefcal to the applcaton uner coneraton. A pectru hapng typcally ean the creaton of a ea ban between wante an unwante pectral Fgure Real an Reacte power on alfa Coponent for a gen wtchng freuency t erable that the oulaton nex houl be n perble lt. SPWM can be operate n uner an oer oulaton regon but t ha t own known aantage n the oer oulaton range ( 1). Alo the funaental content axu 78.5% at 1 w.r.t. funaental content of the uare wae nerter but full of ore haronc. If SPWM of lower oulaton nex apple to the propoe yte then couple nuctor wll be larger n ze an teay tate an tranent repone wll haper a hown n Fg.() Hence the oel ha been aue SVPWM bae wtchng of the nerter. A well known, the pace ector oulaton nole x effecte oltage an two zero ector a hown n Fg.() A reference oltage copoe of te-aerage coponent of two effecte ector ajacent to t an one zero ector. The oulaton nex can be ncreae up to.96 n uner oulaton where the reference oltage ubjecte to trace the nteror of the hexagon an t can be alo ncreae up to.955 n oer oulaton n Moe I an up to 1. n Moe II. Hence the wtchng of nerter n SVPWM wth hgher oulaton nex ecreae the ze an weght of the couplng tranforer an alo c capactor. Th propoe wtchng alo pact greatly n tranent repone of the reacte power n or out whch the an paraeter for controllng the yte oltage a hown n 11 etor@aee.co

4 11 Fg.(4) an (5). In each cae the yte attan table conton after a hort tranent ue to hgher oulaton nex an lower alue of nuctance. Fgure Output oltage of nerter Fgure 4 Tranent repone of current 5. COSED OOP CONTRO It ay be note that the tate euaton (a) an the output euaton (b) nonlnear n alfa. To eploy the cloe-loop control technue aalable n lterature the aboe yte lnearze about an eulbru pont (X o, U o ), an the lnearze oel gen below whch coner the perturbaton to each tate about the operatng pont. Anα, a perturbaton toα, Fgure 5 Tranent repone of reacte power c The nput to the oel [ ] + c c c c C R R X α

5 Analy, Sulaton an Coparon of Conentonal an SVPWM on STATCOM Operaton wth near loa n Power Syte The tranfer functon of the aboe oel foun out a V R + + c ( ) C G ( ) 4 α ( ) R R R C C To proe the tranent repone of the orgnal oel of P-I controller egne whch ha the followng tranfer functon 1 G PI ( ) K T The alue of K an T are choen utably to proe the tranent repone of the yte. The cloe loop tranent repone hown n Fg.(6) how a conerable lowerng n the re te of the ynac repone. Fgure 6 Sulate reacte power repone 6. CONCUSION Coplete analy of the STATCOM preente bae on a tate-pace oel. A PI controller egne to proe the tranent repone. The oulaton nex entfe a an portant paraeter that can proe the ynac repone a well a lower the ze of the nuctor to be ue n the yte. A noel chee of eployng SVPWM wtchng of the conerter propoe whch wll allow ue of 1. REFERENCE [1] Moran..T., P. D. Zoga an G. Joo, Analy an Degn of a Three-Phae Synchronou Sol-State Var Copanator, IEEE Tran. Inu. Appl., Vol. 5, No. 4, pp , [] Rah H. Muhaa, Power Electronc Hanbook, Acaec Pre, 1. [] Shauer C. an H. Mehta, Vector analy an control of aance tatc VAR copenator, IEE Proc, 14, No. 4, July 199. [4]. Gyugy, N.G. Hngoran, an P.R. Nanncry, Aance tatc ar copenator ung gate turn-off thyrtor for utlty applcaton, n CIGRE, eon, pp-, 199. [5]. Gyugy Dynac copenaton of AC tranon lne by ol tate ynchronou oltage ource IEEE Tran. PD, Vol 9, No, pp , etor@aee.co