T-S Fuzzy Maximum Power Point Tracking Modelling And Control Of Solar Power Generation

Transcription

1 K. Eugineaj, D. G.Uma /ntenational Jounal of Engineeing Reeach and Application (JERA) SSN: Vol. 3, ue, Januay -Febuay 203, pp T-S Fuzzy Maximum Powe Point Tacking Modelling And Contol Of Sola Powe Geneation K. Eugineaj D. G.Uma 2 Aitant Pofeo, Dept of ECE, SCAD Engineeing College, Tiunelveli Aociate Pofeo,Dept of EEE, College Of Engineeing,Anna Univeity, Chennai Abtact: Thi pape peent maximum powe point tacking (MPPT) contol fo tand-alone ola powe geneation ytem via the Takagi Sugeno (T-S) fuzzy-model-baed appoach. n detail, we conide a DC/DC boot convete to egulate the output powe of the photovoltaic panel aay. Fit, the ytem i epeented by the T-S fuzzy model. Next, in ode to educe the numbe of meaued ignal, a T-S fuzzy obeve i developed fo tate feedback. Then, a fuzzy diect MPPT contolle i popoed to achieve aymptotic MPPT contol, in which the obeve and contolle gain ae obtained by epaately olving two et of linea matix inequalitie. Diffeent fom the taditional MPPT appoache, the popoed T-S fuzzy contolle diectly dive the ytem to the maximum powe point without eaching the maximum powe point and meauing inolation. Theefoe, the popoed method povide an eaie implementation of modeling and contolling of maximum powe tacking of ola powe geneation. Finally, the contol pefomance i hown fom the numeical imulation and expeimental eult. ndex Tem Linea matix inequalitie (LM), maximum powe point tacking (MPPT), photovoltaic (PV) aay, Takagi Sugeno (T-S) fuzzy model.. NTRODUCTON Saving Eath enegy ha become an impotant iue in thi centuy becaue enegy famine will occu afte a few decade. The inteet in ola powe ha been apidly gowing due to it advantage that include: ) Diect electic powe fom; 2) Little maintenance; 3) No noie; 4) No pollution. Since ola powe ue the photovoltaic (PV) effect to tanfom ola enegy into electical enegy, the PV panel i a nonlinea powe ouce. The output powe of a PV panel aay depend on the PV-voltage and unpedictable weathe condition. n ode to optimize the atio between output powe and intallation cot,dc/dc convete ae ued to daw maximum powe fom the PVpanel aay [], [2]. Many appoache have been popoed toadjut the tacking (MPPT), uch a petub-and-obeve method, incemental conductance method, cuve fitting method, fuzzy logic method [6] [9], neual netwok, etc. Mot of MPPT method lack tict convegence analyi, and thu, only appoximate MPPT i achieved. Although neual netwok contol method can povide bette MPPT pefomance than taditional and fuzzy logic contol method, neual netwok contol method equie the meauement of ola adiation and cell tempeatue. n addition, when the dynamic of the convete ae conideed, the maximum powe voltage (MPV) baed appoache have been developed in. The diadvantage i that two contol loop ae equied: fit, the MPV of the PV aay need to be detemined, and econd, the PV aay voltage need to be contolled accoding to the efeence voltage et in the fit loop. Meanwhile, the MPV i difficult to find due to apidly changing atmopheic condition. n othe wod, the implementation of thee MPV-baed appoache i complicated. To emove thee dawback, only one contol loop i ued in by taking the maximum powe condition a the contol objective. Accoding to the Takagi Sugeno (T-S) fuzzy model epeentation [8], [9], nonlinea ytem can be decibed by F THEN fuzzy ule that have local linea dynamic ubytem in the conequent pat. Fom the local linea dynamic model, linea contol theoy i extenively applied to nonlinea ytem by uing paallel ditibuted compenation (PDC). The main advantage i that the contolle gain can be deigned fom linea matix inequality (LM) technique. So fa, the T-S fuzzy-model-baed contol ha become a popula and effective method fo contolling complex nonlinea ytem. Howeve, mot eult focu on the tabilization poblem of nonlinea ytem. Only few of the wok deal with the tacking o egulation contol poblem. Fo example, appoximate tacking contol i achieved by attenuating the eidual tacking eo. The linea egulation theoie and fuzzy PDC ae combined in [9] fo egulation contol. n addition, a nonvanihedbia at the oigin and extenal ditubance 887 P a g e

2 K. Eugineaj, D. G.Uma /ntenational Jounal of Engineeing Reeach and Application (JERA) SSN: Vol. 3, ue, Januay -Febuay 203, pp (whichalway exit in DC/DC convete) will make PDCnontivial, i.e.,the T-S fuzzy-model-baed contol cannot be diectly applied tothe ola powe geneation ytem. To emove thi dawback, acoodinate tanfomation i applied in to the convete fot-s fuzzy MPPT contol of the PV ytem. The main diadvantagei that the opeational point of the MPPT mut be knownduty cycle of the convete fo maximum powe point exactly, in which the deign failed in pactical implementation. Theefoe, all the ealie point motivate thi tudy. n thi pape, we develop an MPPT method fo tandalone ola powe geneation ytem via the T-S fuzzy-model-baed appoach. Hee the output powe of the PV aay i adjuted by a DC/DC boot convete. Fit, the ytem i epeented in the T-S fuzzy model, whee the patial deivative of the PV powe with epect to the PV voltage i taken a the contol output. Since typical fuzzy PDC i nontivial to biae of the buck convete, a fuzzy diect MPPT (DMPPT) contolle i intoduced to cope with the biae and diectly dive the ytem to the maximum powe point. Meanwhile, we develop a fuzzy obeve fo tate feedback unde patial tate meauement. The popoed fuzzy DMPPT contolle povide aymptotic MPPT fo olving an LM poblem. Then, a obut MPPT deign i caied out to achieve ditubance/uncetainty attenuation. The main contibution of thi pape include the following. ) The calculation fo the maximum powe opeational point of the convete i not equied. 2) Coodinate tanfomation i not pefomed fo the T-S fuzzy MPPT contol. 3) Aymptotic MPPT i aued even with apidly changing atmopheic condition. 4) Meauement of inolation i not needed. 5) The method ha a ytematic deign and tict tability analyi. The et of the pape i oganized a follow. Section tat with the T-S fuzzy modeling of ola powe geneation ytem. n Section, we popoe the fuzzy DMPPT contolle deign. To how the contol pefomance, numeical imulation and expeiment ae pefomed in Section V and V, epectively. Finally, ome concluion ae dawn in Section V.. FUZZY MODELNG OF THE SOLAR POWER GENERATON SYSTEM Without lo of geneality, the ola powe geneation ytemconideed hee conit of a PV aay and a DC/DC buckconvete. The ytem i depicted in Fig., and it detailedchaacteitic ae tated in the following ection. A. Sola Photovoltaic Aay Conide a PV panel aay compoed of ola cell aangedin an n p -paallel, n -eie configuation. Let vpv and ipv, epectively,denote the output voltage and cuent of the PVaay. Fig. Configuation of the ola powe geneation ytem. The voltage/cuent chaacteitic equation of the PV aay canbe decibed by a light-geneated cuent ouce and a diode. fthe intenal hunt and eie eitance ae neglected, the outputcuent of the PV aay i given by kpv vpv i pv = n p ph n p (e n ) () wheek pv = q/(pkt) with the electonicchage q = C, Boltzmann contant K = J/K, celltempeatue T, and the ideal p-n junction chaacteitic factop = 5, ph i the lightgeneated cuent, and denotethe evee atuation cuent. Beide, the evee atuationcuent and the light-geneated cuent depend on inolationand tempeatue with the following expeion: = ( T )e qe gp ( T /T)/pK (2) T ph = ( c + K (T T )) λ (3) 00 whee i the evee atuation cuent at the efeence tempeatuet, E gp =. ev i the bandgap enegy of the emiconductomaking up the cell, c i the hot-cicuit cell cuentat efeence tempeatue and inolation, K (in milliampeepe kelvin) i the hot-cicuit cuent tempeatue coefficient,and λ i the inolation (in milliwatt pe quae centimete). The expeion of the aay powe i obtained a follow: P PV = i pv v pv = n p ph v pv n p v pv (e k pv v pv n ) (4) Accoding to thi equation, Fig. 2 depict the chaacteitic ofthe aay powe with epect to the PV voltage, the inolation,and cell tempeatue. t can be obeved that the maximumpowe point i maximized by the PV voltage and i dependenton vaiou inolation and tempeatue.accoding to the aay powe (4) and by taking the patialdeivative of P pv with epect to the PV voltage v pv, we obtain dp PV di pv = i dv pv + v pv PV dv pv dp PV = i dv pv n p k pv PV n v pv e k pv v pv /n (5) The maximum powe point atifie the condition dp pv /dv pv = 0. Howeve, due to the high nonlineaity, the maximum powe point i difficult to be olved fom (5). Thi i the eaon why the MPPT cannot be 888 P a g e

3 K. Eugineaj, D. G.Uma /ntenational Jounal of Engineeing Reeach and Application (JERA) SSN: Vol. 3, ue, Januay -Febuay 203, pp achieved eaily (pactically, dp pv /dv pv = 0 i ued in taditional method [2], [6]). Table Specification of PV Module SP75 Electical Chaacteitic Numeical value Maximum powe (Pmax) 75W Voltage at Pmax (Vmp) 7V Cuent at Pmax (lmp) 4.4A Waanted minimum Pmax 45W Shot-cicuit cuent (c) 4.8A Open-cicuit voltage (Voc) 2.7 Tempeatue coefficient of c 2.06mA / C Tempeatue coefficient of -(0.077)mV/ C Voc Tempeatue coefficient of -(0.5±0.05)%/ C powe B. DC/DC Boot Convete To adjut the PV aay powe, a DC/DC boot convete i connected to the PV aay, a hown in Fig.. The dynamic model of the convete can be decibed by the tate equation. L d L dt = V PV dv O dv O C b dt = d L V O R L Whee d i the contol ignal equal to when the witch i ON and 0 when the witch i OFF. Hee d i the contol ignal equal to when the witch i ON and 0 when the witch i OFF. The contol appoach i to detemine a contol ignal d that achieve a good output voltage egulation in the peence of ditubance uch a tep change in load o in the ouce voltage, and convete paamete change. Alo, it hould impove the damping and educe the ecovey time by deceaing the ovehoot and undehoot. whee v pv i the PV aay voltage on the capacitance C a,i L and v b ae the cuent on the inductance L and the voltage on the capacitance C b, epectively, d i the duty atio of the pule widthmodulated (PWM) ignal to contol the witching MOSFET, R b and R L ae the intenal eitance on the capacitance C b and the inductance L, epectively, V D i the fowad voltage of the powe diode, and i o i a meauable load cuent. n addition, ince the maximum powe point occu at dp pv /dv pv = 0, we take the patial deivative dp pv /dv pv in (5) a the contol output y(t), i.e., y t = dp pv = i dv pv n p k pv pv n v pv e k pv v pv /n (6) C. T-S Fuzzy Model Fuzzy Logic Contolle i one of the mot ucceful application of fuzzy et theoy, intoduced by Zadeh in 965 [6]. t majo featue ae the ue of linguitic vaiable athe than numeical vaiable. The geneal tuctue of the FLC i hown in Fig 2. Fig. 2Stuctue of FLC Now, the ola powe geneation ytem will be epeented in a T-S fuzzy model. The T-S fuzzy model decibe nonlinea ytem by combining local linea dynamic ubytem in F THEN fuzzy ule. i L v O v pv = L RC b 0 C a 0 0 i L v O v pv + L (V D + v pv ) i L v O = x = A x x + B x d + B 0 b d (8) v pv C b C a d + y = 0 G a n p k pv n e k pv v pv /n 0 x = C(x)x (9) h = 0 0 x = Ex (0) 0 0 whee b = i o /i L, G a = i pv /v pv, b d = V D /L, the tate-vaiable vecto i defined a x = [i L v pv v b ] T, and h(t) i a meauable output vecto compoed of the inductance cuent and the PV aay voltage. Accoding to the peviou expeion and the fuzzy modeling method [6], we have to fuzzify the matice A(x), B(x), and C(x) by T-S fuzzy ule. By obeving the function of A(x), B(x), and C(x), the fuzzy pemie vaiable ae choen a z = i L,z 2 = v O, z 3 = Ga, z 4 = v pv, and z 5 = n p k pv n e k pv v pv /n. Then, the ytem (8) (0) can be epeented by the following T-S fuzzy ule. Rule i): F z (t) i F i and and z 5 (t) i F 5i THEN x (t) = A i x(t) + B i d(t) + B 0 b d y(t) = C i x(t) h(t) = Ex(t), i=, 2,..., () WheeF ji (j =, 2,...,5) ae the fuzzy et, i the numbeof fuzzy ule, and A i, B i, C i, and E ae appopiate ubytemmatice. By uing the ingleton fuzzifie, poduct fuzzy infeence,and weighted aveage defuzzifie, the infeed output ofthe fuzzy ytem i, 0 0 V D L (7) 889 P a g e

4 K. Eugineaj, D. G.Uma /ntenational Jounal of Engineeing Reeach and Application (JERA) SSN: Vol. 3, ue, Januay -Febuay 203, pp x(t) = y(t) = i= i= μ i (z(t)) A i x x(t) + B i x d(t) + B 0 b d μ i (z(t)) C i (x)x(t) h(t) = Ex(t) (2). T-S FUZZY DMPPT CONTROL To achieve the MPPT contol, we have to dive the contol output y(t) = dp pv /dv pv to zeo. When the contol output y(t) equal zeo, the ytem achieve the maximum powe opeational point (x d, u d ), which atifie y t = i= μ i z t C i x x t = 0 and x(t) = i= μ i Z d t A i x x t + B i x d t + B 0 b d = 0, whee z d i compoed of the coeponding x d.since the maximum powe opeational point i difficult to finddue to the vaying atmophee, a fuzzy DMPPT contolle iintoduced in the following.fit, due to the fact that only patial tate ae availablein meauement, the following fuzzy obeve i deigned tocomplete the tate feedback. Obeve Rule i) F z (t) i F i and and z 5 (t) i F 5i THEN x(t) = μ i z t { A i x t + B i u t + B 0 b d i= + L i h(t) h t + L i (h(t) h(t))} h(t) = Eh(t) (3) wheex(t)i the etimated tate vecto, h(t)i the etimatedoutput, and L i i an obeve gain that i detemined late. Thefuzzy infeed output i given in the above equation (5). And let u define an etimated eo x(t)= x(t) x(t); then, wecan find the etimation eo dynamic a follow: x t = i= μ i z t (A i L i E)x(t) (4) Obviouly, the etimation eo aymptotically convege to zeoonce L i i deigned uch that i= μ i z t (A i L i E)x(t)i atable matix. Next, baed on the fuzzy obeve (3), the T-S fuzzy DMPPTcontolle i et a follow. Contolle Rule i) F z (t) i F i and and z 5 (t) i F 5i THEN x y t = k y y(t) d t = {K i x t + K 2i x y t }, i=,2, (5) wheex y (t) R p i an integal tate vaiable, ky>0, and K i and K 2i ae contol gain. The fuzzy infeed contolle i obtaineda follow: x y t = k y d t = (6) i= μ i z t C i x(t) i= μ i z t {K i x t + K 2i x y t } V. NUMERCAL SMULATON To veify the theoetical deivation, we cay out the fuzzydmppt contol fo a ola powe geneation ytem. Hee,we ue a Siemen ola PV module SP75, whoe pecificationae tated in Table. The buck convete i compoedof an RFP460 powe MOSFET,.5mH toage inductance,47μf capacitance C a and C b, and a powe ectifie diodembr2045ct. The intenal eitance R b and R L of capacitancec b and inductance L ae 62 mω and Ω, epectively.the fowad voltage of the powe ectifie diode i V D =0.57V. The opeational fequency of the convete i et to50khz.accoding to the fuzzy modeling () and auming thewokpace to be Ω x = {(i L, v pv, v b, i o, T) 5 i L 5, 8 v pv 22, 2 v b 22, 0.8i L i o 0.9i L, K T K}. V. EXPERMENTAL RESULTS Fig. 3 Fuzzy Model Sola PV Powe Geneato. The above fig. 3 how the fuzzy model of ola powe geneation ytem, developed in MATLAB Simulink. To futhe veify the validity of the popoed cheme, evealexpeiment of PV MPPT contol ae pefomed in thi ection.n ou expeiment, the developed contolle i ealized by adsp-baed contol cad (dspace DS04), which take thetms320f240 DSP a the main contol coe. The PV voltage,pv cuent, inductance cuent, and load cuent ae ampled bythe A/D convete and fed into the DSP cad. Afte the contoleffot i calculated fom the feedback, the DS04 cad diectlygeneate a PWMignal to contol the witching MOSFET. Thefequency of the PWM ignal i et to 50 KHz. n addition,the MATLAB Simulink Toolbox and Real-Time Wokhop aetaken a an inteface between oftwae and hadwae. Whenthe contolle block i etablihed by Simulink, the Real-TimeWokhop play the ole of a compile to tanfom the contolleinto a C code, which i downloaded to the DSP cad. Then, theds04 i connected to the buck convete to achieve a cloedloopcontol. 890 P a g e

5 K. Eugineaj, D. G.Uma /ntenational Jounal of Engineeing Reeach and Application (JERA) SSN: Vol. 3, ue, Januay -Febuay 203, pp Fig.4 PV aay chaacteitic with MPPT Fig. 7 Expeimental Gate Pule geneated by Fuzzy. Fig 7 how the expeimental gate pule via the dspace by uing T-S Fuzzy contolle whichcontol the boot convete. Fig. 5 P V diagam of the contolled ola powe geneation ytem via (a) T-S fuzzy DMPPT contol; (b) fuzzy logic contol; (c) neual netwok contol; and (d) P contol. The fig.5 how the compaative tudy of vaiou Maximum powe point tacking contol of ola powe geneation ytem and the fig.6 how the maximum powe tacked by baic P and fuzzy model. Fig. 6 Expeimental P V diagam of the contolled ola powe geneation ytem via the (o) T-S fuzzy DMPPT contol, (*) fuzzy logic contol, and ( ) P contol. V. CONCLUSON Thi pape ha popoed the T-S fuzzy DMPPT contolmethod fo ola powe geneation ytem. The exact MPPT iachieved even when we conide vaying atmophee and patialtate feedback, and when the maximum powe point i notcalculated. n the peence of the ditubance and uncetainty,the obut MPPT i alo aued while the maximum powetacking eo i attenuated to a pecibed level. Diffeent fomtaditional MPPT method, the popoed fuzzy DMPPT methoddoe not equie the maximum powe point to be calculatedunde vaying atmophee. Futhemoe, the popoed methodcan daw moe powe than taditional method (becaue taditionalmethod will lead to powe chatteing phenomenon oappoximate MPPT). n addition, the popoed contolle haa tict tability and pefomance analyi, which i not povidedin taditional wok. Finally, the expected pefomancehave been hown by the expeiment in an eay implementationfom. REFERENCES [] Fancico M. Gonzalez-Longatt, Model of Photovoltaic Module in MATLAB, 2DO Congeoibeoameicano de etudiante de ingenieíaeléctica, electónicay Computación (ii cibelec 2005). [2] TihanEam and Patick.L.Chapman. Compaion of photovoltaic aay maximum powe point tacking technique EEE tanaction on indutial electonic [3] T.J. Liang, Y.C.Kuo AND J.F.Chen. Single phae photovoltaic enegy conveion ytem - EEE tanaction on indutial electonic-200. [4] Mohammed Rahid Powe Electonic Cicuit Device and Application Thid Edition-Peaon Education. 89 P a g e

6 K. Eugineaj, D. G.Uma /ntenational Jounal of Engineeing Reeach and Application (JERA) SSN: Vol. 3, ue, Januay -Febuay 203, pp [5] Rick Zaitu -Undetanding Boot Powe Stage in Switch mode Powe Supplie (SLVA06), Eveett Roge, Texa ntument. [6] Chian-Song Chiu, T-S Fuzzy Maximum Powe Point Tacking Contol of Sola Powe Geneation Sytem, in EEE tanaction on enegy conveion, [7] A. Ramehkumaand S. Aumugam Deign and imulation of fuzzy contolled quai eonant buck convete ARPN Jounal of Engineeing and Applied Science-2009(SSN ). [8] Sofia.Lalouni&Djamila.Rekioua, Modeling and imulation of a photo voltaic ytem uing Fuzzy logic contolle,2009 Second ntenational Confeence on Development in e Sytem Engineeing. [9] XuZhengguang, Membe, nteval T-S Fuzzy Model and t Application to dentification of Nonlinea nteval Dynamic Sytem baed on nteval Data, Joint 48th EEE Confeence on Deciion and Contol and 28th Chinee Contol Confeence Shanghai, P.R. China, Decembe 6-8, 2009(ThAn6.5). 892 P a g e