Analysis and Simulation of Modified Adaptive Perturb and Observe MPPT Technique for PV Systems

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1 J. Suryakumari and G. Sahiti 9 Analysis and Simulatin f Mdifid Adaptiv Prturb and Obsrv MPPT Tchniqu fr P Systms J. Suryakumari and G. Sahiti Abstract: Slar nrgy is a clan and rnwabl nrgy rsurc fr pwr gnratin. Th pwr utput frm a slar phtvltaic systm mainly dpnds n th natur f th cnnctd lad bcaus f nn-linar I- charactristics. In th past yars, P pwr gnratin systm has attractd mr attntin du t th nrgy crisis and nvirnmnt pllutin. Phtvltaic (P pwr g nratin systms can mitigat ffctivly nvirnmntal issus such as th grn hus ffct and air pllutin. Phtvltaic (P ffrs an nvirnmntally frindly surc f lctricity, which is hwvr still rlativly cstly tday. P pwr gnratin systms hav n big prblm that th amunt f lctric pwr gnratd by P mdul is always changing with wathr cnditins i.., irradiatin and tmpratur.. Thrfr, a maximum pwr pint tracking (MPPT cntrl mthd t achiv maximum pwr (MP utput at ral tim bcms indispnsabl in P gnratin systms. Th maximum pwr pint tracking (MPPT f th P utput fr all sunshin cnditins is a ky t kp th utput pwr pr unit cst lw fr succssful P applicatins. Svral tchniqus hav bn prpsd fr maximum pwr tracking. Th mst cmmnly usd tchniqus fr MPPT, ar th Hill Climbing Tchniqus. Ths includ Prturb & Obsrv mthd Adaptiv P&O and mdifid adaptiv P&O tchniqus. It is knwn that th P&O mthd xhibits rratic bhavir undr rapidly changing irradianc lvl that causs incrrct r slw maximum pwr tracking. Th Mdifid P&O (MP&O mthd was prpsd t slv this prblm by dcupling th P pwr fluctuatins causd by hill-climbing prcss frm ths causd by irradianc changing. Kywrds: MPPT (Maximum Pwr Pint Trackr, P&O (Prturb and Obsrv, Phtvltaic systm, Bst Cnvrtr, Hill-Climbing, Adaptiv.. INTRODUCTION As fssil nrgy bcms mr xpnsiv and causs grwing nvirnmntal cncrns, nrgy frm natural rsurcs such as sunlight and wind ar glbally wlcmd t rplac th fssil ful. Amng mthds f gnrating lctric pwr by altrnativ rsurcs, phtvltaic (P has grwn stadily in rcnt dcads as a carbn-fr tchnlgy altrnativ P cnvrts sunlight dirctly int currnt lctricity by mans f th phtvltaic ffct. Sinc cmmn slar clls ar mad frm silicn-basd smicnductrs, th phtvltaic ffct is invlvd with th p-n junctin f th slar clls. First, sunlight prducs J. Suryakumari is wrking as Assciat Prfssr and G. Sahiti is a M. Tch Studnt, bth ar frm Dpartmnt Of Elctrical and Elctrnics Enginring, R.G.M.C.E.T, Nandyal, A.P., India, jdsk.@gmail.cm, sahithy.gmatham@gmail.cm lctrn-hl pairs (EHPs int th cll. Thn, th lctrns mv t th n-rgin and th hls mv t th p-rgin as a rsult f th lctric fild cratd by th junctin. Th lctric chargs cllctd in bth rgins finally flw as lctric currnt int a cnnctd lad. A P systm is a pwr systm that gnrats dirct currnt (DC frm sunlight and prcsss it rquiring DC r altrnating currnt (AC lctricity. Instad f slar clls, th P systm gnrally uss P panl-intrlinkd packags with slar clls-r P arrays-cmbind assmblis f P panls-du t th lw vltag f a singl slar cll. Figur : Blck diagram f P systm As shwn in Figur, th P systm cnsists f thr stags: pwr gnratin, pwr cnvrsin & cnditining, and pwr distributin. In th pwr gnratin stag, th P array gnrats DC lctricity dirctly frm sunlight. Th gnratd DC must b cntrlld and cnductd in th pwr cnvrsin & cnditining stag t suit distributin rquirmnts. This stag uss pwr lctrnic dvics such as DC-DC cnvrtrs and/r DC-AC invrtrs fr prcssing DC frm th array. Th utput pwr f P mdul is nnlinar functin f tmpratur, islatin, and thus linar cntrl thry is nt suitabl fr MPPT. Thr ar a fw MPPT mthds prsntd. Th prturbatin and bsrvatin (P&O mthd with fixd prturbatin stp, which is wll knwn as th hill-climbing mthd, is widly applid. P&O algrithms hav drawbacks such as slw rspns and high scillatins arund MPP. Hwvr, pwr scillatins always appar in this mthd undr stady stat and rduc th fficincy f P mdul. Sm mthds fr aviding th prblms f th P&O mthd hav bn prpsd. This papr prpss a nw mthd fr th MPPT cntrl f P systms. Adaptiv P&O utilizs prturb as varying prturb. Evn thugh varying prturb is usd, but still thr xists scillatin arund MPP. Ths ar vrcm by mdifid adaptiv tchniqu in which autmatic tuning mchanism and cntrl md switching is usd. Owing t changs in th slar radiatin nrgy and th cll prating tmpratur, th utput pwr f a slar array Intrnatinal Jurnal f Emrging Trnds in Elctrical and Elctrnics (IJETEE ISSN: l. 9, Issu., Nv-.

2 J. Suryakumari and G. Sahiti is nt cnstant at all tims. Cnsquntly, during th dsign prcss a simulatin must b prfrmd fr systm analysis and paramtr sttings.. HOW A P CELL WORKS Slar cll cnsists f a p-n junctin fabricatd in a thin wafr r layr f a smicnductr matrial. Phtvltaic clls ar mad f svral typs f smicnductrs using diffrnt manufacturing prcsss.. Th cmmrcial slar cll is mad f wafr-basd tchnlgy f smicnductr matrials, such as Crystallin Si (C -Si and thin film. Diffrnt typs f silicn can b usd t fabricat th slar cll i.. mn-crystallin silicn, ply-crystallin silicn, and amrphus. Th variatin btwn ths typs is distinguishd by th cnvrsin fficincy f th P cll. Fig. rughly illustrats th rprsntd by a simplifid quivalnt circuit mdl such as th n givn in Fig. and/r by an quatin as in (. A phtvltaic cll is basically a smi-cnductr did whs p n junctin is xpsd t light [5], [6]. Mdling is basic tl f th ral systm simulatin. Fr mdling, it is ncssary t analyz th influnc f diffrnt factrs n th phtvltaic clls. Th mathmatical mdls fr phtvltaic clls ar basd n th thrtical quatins that dscrib th pratin f th phtvltaic clls and can b dvlpd using th quivalnt circuit f th phtvltaic clls. Th mst cmmn n is as fllws. Fig.. Equivalnt circuit f P cll Fig..Stuctur f a P cll physical structur f a P cll.. Whn phtns frm th slar nrgy hits th slar cll, with nrgy gratr than band gap nrgy f th smicnductr, lctrns ar knckd ls frm th atms in th matrial, crating lctrn-hl pairs. Ths carrirs ar swpt apart undr th influnc f th intrnal lctric filds f th p-n junctin and crat a currnt prprtinal t th incidnt radiatin. Whn th cll is shrt circuitd, this currnt flws in th xtrnal circuit; whn pn circuitd, this currnt is shuntd intrnally by th intrinsic p-n junctin did. Th rat f gnratin f lctric carrirs dpnds n th flux f incidnt light and th capacity f absrptin f th smicnductr. Th capacity f absrptin dpnds mainly n th smicnductr band gap, n th rflctanc f th cll surfac (that dpnds n th shap and tratmnt f th surfac, n th intrinsic cncntratin f carrirs f th smicnductr, n th lctrnic mbility. Th slar radiatin is cmpsd f phtns f diffrnt nrgis. Phtns with nrgis lwr than th band gap f th P cll ar uslss and gnrat n vltag r lctric currnt. Phtns with nrgy suprir t th band gap gnrat lctricity, but nly th nrgy crrspnding t th band gap is usd th rmaindr f nrgy is dissipatd as hat in th bdy f th P cll. Smicnductrs with lwr band gaps may tak advantag r a largr radiatin spctrum, but th gnratd vltags ar lwr. Slar cll gnratd currnt dpnds n th charactristic f matrial, ag f slar cll, irradiatin and cll tmpratur. A dubl xpnntial quatin may b usd fr th plycrystallin silicn clls. = ph s.(.. ( ( Equatin ( rprsnts utput vltag f a P cll = Output currnt f a P cll Whr, = = ( ( ( = [ + ( 98] ( (5 Th P array pwr can b calculatd using th fllwing quatin = (6. MODELLING OF P ARRAY = ( (7 P arrays ar built up with cmbind sris r paralll cmbinatins f P slar clls, which ar usually Whr, Intrnatinal Jurnal f Emrging Trnds in Elctrical and Elctrnics (IJETEE ISSN: l. 9, Issu., Nv-.

3 J. Suryakumari and G. Sahiti is utput vltag f a P cll ( is utput currnt f a P cll (A is th numbr f mduls cnnctd in sris is th numbr f mduls cnnctd in paralll is th light gnratd currnt in a P cll (A is th P cll saturatin currnt (A is th sris rsistanc f a P cll (Ω A=B is an idality factr =.6 K is Bltzmann cnstant =.85-Nm/K T is th cll tmpratur in Klvin =98K Q is lctrn charg =.6-9 Culmbs is th rfrnc tmpratur =.8K is th P cll shrt circuit currnt N = N f clls is shunt rsistanc f a P cll is th P cll illuminatin (MW/cm is th saturatin currnt at T r E g is th nrgy band gap (v Bth k and T shuld hav th sam tmpratur unit, ithr Klvin r Clsius. Th curv fitting factr A is usd t adjust th I- charactristics f th cll btaind frm th actual charactristics btaind by tsting. Eq. ( givs th vltag f a singl slar cll which is thn multiplid by th numbr f th clls cnnctd in sris t calculat th full array vltag. Sinc th array currnt is th sum f th currnts flwing thrugh th clls in paralll branchs, th cll currnt IC is btaind by dividing th array currnt by th numbr f th clls cnnctd in paralll bfr bing usd in (, which is nly valid fr a crtain cll prating tmpratur T with its crrspnding slar irradiatin lvl Sc. If th tmpratur and slar irradiatin lvls chang, th vltag and currnt utputs f th P array will fllw this chang. Hnc, th ffcts f th changs in tmpratur and slar irradiatin lvls shuld als b includd in th final P array mdl. Th cmplt bhavir f P clls ar dscribd by fiv mdl paramtrs (I ph, N, Is, Rs, R sh which is rprsntativ f th physical bhavir f P cll/mdul. Ths fiv paramtrs f P cll/mdul ar in fact rlatd t tw nvirnmntal cnditins f slar islatin & tmpratur. Th dtrminatin f ths mdl paramtrs is nt straightfrward wing t nn-linar natur f quatin. Fig.. Maximum Pwr Pint ( mp, I mp Charactristic I curv f a practical P dvic and th thr rmarkabl pints: shrt circuit (, I sc, MPP ( mp, I mp, and pn circuit ( c,. Th shrt circuit currnt slightly incrass with cll tmpratur. Fr practical us, P clls can b ampr curv lctrical cnnctd in diffrnt ways: sris r paralll. P clls ar first cnnctd in sris in mst manufacturing mthds t frm P mdul. Mduls can b cnnctd in diffrnt ways t frm P array. This is dn fr th sak f vltag/currnt rquirmnt f th pwr cnditining units (PCU s f th P systm. IRRADIANCE (A Simulatin mdl f P cll Basd n Matlab / Simulink Irradianc P MODEL Ppv pv Ipv Rsistr Fig.5. Simulatin mdl f P cll Th utput charactristic f a phtvltaic (P array is nnlinar and is influncd by slar irradianc lvl, ambint tmpratur, wind spd, humidity, prssur, tc. Th irradiatin and ambint tmpratur is tw primary factrs. T study th utput charactristics f P cll, sm xprimnts basd n simulatin f P cll hav bn dn. Fr cnstant tmpratur (5 C and diffrnt intnsity (- W/m Th P array currnt cnstant up t sm vltag lvl and thn it will b dcrasd. Th P array currnt always incrass with intnsity -.6 OLTAGE.7656 CURRENT.5 POWER Intrnatinal Jurnal f Emrging Trnds in Elctrical and Elctrnics (IJETEE ISSN: l. 9, Issu., Nv-.

4 J. Suryakumari and G. Sahiti W/m 8W/m 5 C 5 C 65 C 6W/m 85 C Currnt(A W/m Currnt(A Fig6(a. I- charactristics f Slar array fr varius irradianc at a cnstant tmpratur f 5 C. Fr cnstant tmpratur (5 C and diffrnt intnsity (- W/m Th P array pwr incrass up t sm vltag lvl and thn it will b dcrasd. Th P array pwr always incrass with lw t high intnsity. 8 Pwr(W ltag( W/m 8W/m 6W/m W/m Fig7(a. I- charactristics f Slar array fr varius tmpratur at cnstant irradianc f W/m. 8 Pwr(W 6 ltag( ltag( 5 C 5 C 65 C 85 C Fig7(b. P- charactristics f Slar array fr varius tmpratur at a cnstant irradianc f W/m. ltag(. BOOST CONERTER Fig 6(b. P- charactristics f Sla array fr varius irradianc at a cnstant tmpratur f 5 C. Frm figur.7 (a I- charactristics fr diffrnt tmpratur and cnstant irradianc th gnratd pwr is gradually dcrasd and maximum pwr availabl mr at lw tmpratur. Th utput vltag can b gratr than th input vltag in (slar array vltag.th switch S prats at high frquncis t prduc a chppd utput vltag []. Th pwr flw is cntrlld by adjusting th n/ff duty cycl f th switching. Th avrag utput vltag is dtrmind by th quatin, Frm figur.7 (b P- charactristics fr diffrnt tmpratur and cnstant irradianc th currnt is cnstant up t sm vltag and thn it will dcras gradually. in T T ff D (8 Intrnatinal Jurnal f Emrging Trnds in Elctrical and Elctrnics (IJETEE ISSN: l. 9, Issu., Nv-.

5 J. Suryakumari and G. Sahiti Fig.8. Bst Tplgy Bst cnvrtr which bsts th vltag t maintain th maximum utput vltag cnstant fr all th cnditins f tmpratur and slar irradianc variatins. A simpl bst cnvrtr is as shwn in Figur9.. MPPT TECHNIQUES.. Opn Circuit ltag mthd This mthd uss OC t calculat MP. Onc th systm btains th OC valu, MP is calculatd by th quatin 9. MP = k x OC (9 Th k valu is typically varis frm.7 t.8. It is ncssary t updat OC ccasinally t cmpnsat fr any tmpratur changs. It uss fractin f pn circuit vltag t dtrmin th mduls vltag at th maximum pwr pint. Th pn circuit vltag algrithm is basd n th bsrvatin frm -I curvs that th rati f th array s maximum pwr vltag ( mp t its pn circuit vltag ( c is apprximatly cnstant. Hr th factr is always <.Th slar array is tmprarily islatd frm th MPPT and a c masurmnt is takn.. Shrt Circuit Currnt mthd Th shrt circuit currnt mthd uss a valu f ISC t stimat IMP. I MP = k x I SC ( This mthd uss a shrt lad puls t gnrat a shrt circuit cnditin. During th shrt circuit puls, th input vltag will g t zr, s th pwr cnvrsin circuit must b pwrd frm sm thr surc. On advantag f this systm is th tlranc fr input capacitanc cmpard t th OC mthd. Th k valus ar typically cls t.9 t.98 Fig.9. Blck diagram f P&O MPPT If th pwr incrasd, th prturbatin is cntinuus in th sam dirctin in th nxt prturbatin cycl, thrwis th prturbatin dirctin is rvrsd. This way, th prating pint f th systm gradually mvs twards th MPP and scillats arund it in stady-stat cnditins. Larg prturbatin stp sizs yild fast tracking f th MPP undr varying atmsphric cnditins but rsult in rducd avrag pwr cnvrsin in stady stat du t larg scillatins arund th MPP. It was prvd that th P&O MPPT cntrl systm smtims dviats frm th maximum prating pint in cas f rapidly changing atmsphric cnditins, such as brkn cluds. Anthr disadvantag is that this simpl tracking mthd has difficulty in prviding gd prfrmanc in bth dynamic and stady-stat rspnss. Hnc th famus tradff prblm btwn fastr rspns and stady-stat scillatins is inhrnt. Mrvr, th prturbatin is nt gnric. In rdr t vrcm all this, high prfrmanc P&O tchniqu is prpsd.. Prturb and Obsrv (P&O mthd A P&O mthd is th mst simpl, which mvs th prating pint tward th maximum pwr pint pridically incrasing r dcrasing th P array vltag by cmparing pwr quantitis btwn in th prsnt and past. Th blck diagram f P&O mthd is illustratd in Fig. 9. Intrnatinal Jurnal f Emrging Trnds in Elctrical and Elctrnics (IJETEE ISSN: l. 9, Issu., Nv-.

6 J. Suryakumari and G. Sahiti r(w w P 5 t(a n r u C.5.5 Fig.Flw chart diagram f P&O MPPT mthd Tim(sc Fig(c. P array utput pwr fr P&O MPPT tchniqu Th rspns with prturbatin and bsrvatin (P&O MPPT Tchniqu wavfrms ar (a P array utput currnt (b P array utput vltag (c P array utput pwr at tmpratur=5 c and slar irradiatin =W/m.. Adaptiv Prturbatin and Obsrvatin mthd (AP&O Th main ida bhind this tchniqu is that at th start f any hill climbing tchniqu, larg prturb stps ar ndd t quickly rach th MPP, and as th MPP is apprachd, th prturb valu nds t b dcrasd t avid larg scillatins arund this maximum utput pwr prating pint. This adaptiv tchniqu utilizs th rrr btwn tw succssiv array pwr signals calculatd frm th masurd array vltag and currnt signals t crat an adaptiv prturb Tim(sc Fig(a. P array utput currnt fr P&O MPPT tchniqu 5 ( g lta Tim(sc Fig(b. P array utput vltag fr P&O MPPT tchniqu Fig.. Blck diagram f Adaptiv P&O MPPT Basically, at th start f th hill climbing prcss, this rrr is larg and dcrass as th maximum pwr prating pint is apprachd at stady stat. Thrfr, this rrr can Intrnatinal Jurnal f Emrging Trnds in Elctrical and Elctrnics (IJETEE ISSN: l. 9, Issu., Nv-.

7 J. Suryakumari and G. Sahiti 5 b tratd lik an rrr signal in a clsd-lp systm that nds t b minimizd at stady stat, prvntd frm vrsht at startup, and fr frm stady-stat scillatins. Th simplst clu t achiv all ths targts is t trat this rrr signal using a cnvntinal PI cntrllr, which is th main cr f this tchniqu. Evn thugh prturb is adaptiv, still thr xists scillatins arund MPP and givs slw rspns. Th flwchart f Adaptiv P&O is shwn in fig ( ( g lta Tim(sc Fig(b. P array utput vltag fr AP&O MPPT tchniqu 8 6 r(w w P.5 Fig.Flw chart diagram f AP&O MPPT mthd Tim(sc Fig(c. P array utput pwr fr AP&O MPPT tchniqu.5 Mdifid Adaptiv Prturbatin and Obsrvatin mthd (AP&O A mdifid adaptiv hill climbing (MAHC MPPT cntrl mthd is intrducd basd n th prvius rsarch and dtaild analysis f th charactristics f P pwr systms. Th mdificatins t th traditinal hill climbing mthd includ autmatic paramtr tuning and Cntrl md switching..5. Prpsd MPPT Tchniqu t(a n r u C Tim(sc Fig(a. P array utput currnt fr AP&O MPPT tchniqu Thr is a tradff btwn dynamic rspns and stady stat prfrmanc du t th slctin f th incrmntal stp f switching duty cycl. Thrugh analysis, it is idal t mak larg switching duty cycl during transint stag and small in stady stat. In th prpsd MAHC mthd, this prblm is slvd by th autmatic tuning f paramtr nlin. Whn th pwr changs in a larg rang primarily du t nvirnmntal variatin, this tunr will chang th switching duty cycl t a larg valu t satisfy th fast rspns rquirmnt during th transint stag. Whn th pwr chang is small, th cntrllr assums that th systm ntrs th stady-stat stag and th valu f "a" bcms small t kp cntrl signal chang smth. With this tuning mchanism, bth dynamic and stady-stat rquirmnts can b cnsidrd in th cntrllr dsign, bcaus th critical paramtr is updatd and adjustd Intrnatinal Jurnal f Emrging Trnds in Elctrical and Elctrnics (IJETEE ISSN: l. 9, Issu., Nv-.

8 J. Suryakumari and G. Sahiti 6 adaptivly.. In sm spcific cass, it was shwn that th P&O mthd culd caus th prating pint t dviat frm th ptimal pint during th prid f rapid islatin changs. This prblm culd b avidd by switching th cntrl md. Th cntrl algrithm can b dmnstratd in flw chart frmat shwn in Fig.8, whr "P" and "D" rprsnt th P pwr lvl and th duty cycl valu rspctivly. n t(a r u C Tim(sc Fig7(a. P array utput currnt fr MAP&O MPPT tchniqu Fig5. Blck diagram f MAP&O MPPT 5 ( g lta Tim(sc Fig7(b. P array utput vltag fr MAP&O MPPT tchniqu 8 6 r(w w P Tim(sc Fig6.Flw chart diagram f MAP& &O MPPT mthd Fig7(b. P array utput vltag fr MAP&O MPPT tchniqu Intrnatinal Jurnal f Emrging Trnds in Elctrical and Elctrnics (IJETEE ISSN: l. 9, Issu., Nv-.

9 J. Suryakumari and G. Sahiti 7 S. N MPPT Tchniqu ltag ( Currnt (A Pwr (W Efficincy (% P & O AP&O MAP&O Tabl5. Cmparisn f MPPT Tchniqus at a tmpratur f 5 C and irradianc f W/m 6. CONCLUSION This papr prpss dsign and mdling f pht vltaic systm, simpl bst cnvrtr and Mdifid Adaptiv P&O MPPT Tchniqu. Th P cll utput vltag varis with atmsphric paramtrs such as tmpratur and irradiatin. In rdr t prat P array at MPP, w nd an intrfac systm btwn P array and lad calld MPPT. Th OC, SC and P&O mthds ar simpl and mstly usd mthds, but d nt accuratly track th MPP. In rdr t vrcm th drawback f abv mthds Mdifid Adaptiv P&O MPPT mthd is prpsd, in which switching duty cycl is usd as cntrl paramtr. Rfrncs []. Dunlp JP, Natinal Jint Apprnticship and Training Cmmitt fr th Elctrical Industry. Pht-vltaic systms. Orland Park, Ill.: Amrican Tchnical Publishrs, Inc.;. [] F.Z. Png, L. M. Tlbrt:Multilvl Cnvrtrs fr Larg Elctric drivs, IEEE Transactins n Industry Applicatins, Jan/Fb 999, vl. 5. [] J. Applbaum: Starting and stady-stat charactristics f DC mtrs pwrd by slar cll gnratrs, IEEE Trans., EC-I ( [] J. A. Rgr: Thry f th dirct cupling btwn DC mtrs and phtvltaic slar arrays, Slar Enrgy, ( [5] J.Surya Kumari, Ch. Sai Babu and J. Yugandhar Dsign and Invstigatin f Shrt Circuit Currnt Basd Maximum Pwr Pint Tracking fr Phtvltaic Systm,Intrnatinal Jurnal f Rsarch and Rviws in Elctrical and Cmputr Enginring (IJRRECE l., N., Jun. [6]. K.E. Yagr, "Elctric hicls and Slar Pwr: Enhancing th Advantags f Elctricity", IEEE Pwr Enginring Rviw, l., N., Octbr 99. [7] K. R and S. Rahman: Tw Lp Cntrllr fr maximizing prfrmanc f a grid-cnnctd phtvltaic ful cll hybrid pwr plant, IEEE Transactins n Industry Applicatins Sptmbr 998. [8] Lai, J., and Png, F.: Multilvl Cnvrtrs- A nw Brd f Pwr Cnvrtrs, IEEE Transactins n Industry Applicatins, May/Jun 996, vl.. [9] L. M. Tlbrt, F. Z. Png: Multilvl Cnvrtrs as a Utility Intrfacfr Rnwabl Enrgy Systms, IEEE Pwr Enginring Scity Summr Mting, July 5-,. Sattl, Washingtn, pp [] Macrci Mnds Casarr, Dnizar Cruz Martins Grid cnnctd PSystm: Intrductin t Bhavir Matching IEEE Transactins n Industrial Elctrnics 8 [] M. Bursch: Phtvltaic Enrgy Systms Dsign and Installatin, McGraw-Hill, Nw Yrk, 98 [ M. Calais,.G. Aglidis, M. Minhardt: Multilvl Cnvrtrs fr Singl-phas Grid Cnnctd Phtvltaic Systms: An Ovrviw. Slar Enrgy. l. 66, N 5. [] Nguyn, D y Lhman, B.:A Rcnfigurabl Slar Phtvltaic Array Undr Shadw Cnditins, Applid Pwr Elctrnics Cnfrnc and Expsitin, pp , 8. [] Srgi Dahr, Jurgn Schmid and Frnand L.M Antuns, Multilvl Invrtr Tplgis fr Stand-Aln P Systms IEEE Transactins n Industrial Elctrnics.l.55, N.7, July 8. [5] Tchnlgy radmap slar phtvltaic nrgy. [Intrnt] Paris: OECD/IEA;. [6] W. Z. Far and M. K. Balahandr: Dynamic prfrmanc f a DC shunt mtr cnnctd t a phtvltaic array, IEEE Trans., EC-( Authrs Prfil: J. Surya Kumari was brn in Kurnl, India in 98. Sh rcivd th B.Tch (Elctrical and Elctrnics Enginring dgr frm S.K Univrsity, India in and th M.Tch (High vltag Enginring frm J.N.T Univrsity, Kakinada in 6. In 5 sh jind th Dpt. Elctrical and Elctrnics Enginring, R.G.M. Cllg f Enginring and Tchnlgy, Nandyal, as an Assistant Prfssr. Sh has publishd svral Natinal and Intrnatinal Jurnals/Cnfrncs. Hr fild f intrst includs Pwr lctrnics, Phtvltaic systm, Pwr systms and High vltag nginring. G. SAHITI was brn in Nllr, India. Sh rcivd th B.Tch (Elctrical and Elctrnic s Enginring dgr frm Jawaharlal Nhru tchnlgical Univrsity, Anantapur in 9 and pursing M.Tch (Pwr Elctrnics frm RGMCET Autnmus, Nandyal. Hr ara f intrst is Pwr Elctrnics, Pht- vltaic nrgy systm fr maximum pwr pint tracking. sahithy.gmatham@gmail.cm. Intrnatinal Jurnal f Emrging Trnds in Elctrical and Elctrnics (IJETEE ISSN: l. 9, Issu., Nv-.