Photovoltaic Power Control Using MPPT and Boost Converter

Transcription

1 23 Phoovolaic Power Conrol Using MPP and Boos Converer A.Aou, A.Massoum and M.Saidi Absrac he sudies on he phoovolaic sysem are exensively increasing because of a large, secure, essenially exhausible and broadly available resource as a fuure energy supply. However, he oupu power induced in he phoovolaic modules is influenced by an inensiy of solar cell radiaion, emperaure of he solar cells. herefore, o maximize he efficiency of he renewable energy sysem, i is necessary o rack he maximum power poin of he inpu source. In his paper, a new maximum power poin racker (MPP) using Perurb & Observe algorihm is proposed o improve energy conversion efficiency. Maximum power poin racking is an imporan funcion in all phoovolaic (P) power sysems. he simulaion resuls show ha he proposed MPP conrol can avoid racking deviaion and resul in improved performance in boh dynamic response and seady-sae. Index erms Maximum power poin racking (MPP), phoovolaic (P) power sysem, maximum power poin (MPP), swiching mode DC-DC converer, swiching duy cycle, Perurb & Observe conrol. S I. INRODUCION OLAR energy is one of he mos imporan renewable energy sources. Compared o convenional non renewable resources such as gasoline, coal, ec..., solar energy is clean, inexhausible and free. Phoovolaic (P) generaion is becoming increasingly imporan as a renewable source since i offers many advanages such as incurring no fuel coss, no being polluing, requiring lile mainenance, and emiing no noise, among ohers. he phoovolaic array is an unsable source of power since he peak power poin depends on he emperaure and he irradiaion level. A maximum peak power poin racking is hen necessary for maximum efficiency [3,5]. he -I and -P characerisic curves specify a unique operaing poin a which maximum possible power is delivered. A he MPP, he P operaes a is highes efficiency. herefore, many mehods have been developed o Amine AOU, is wih he elecrical engineering Deparmen, Faculy of echnologie, Djillali Liabes Universiy, Sidi-bel-Abbes, 22000, Algeria. ( aouamine@yahoo.fr). Ahmed MASSOUM, is wih he elecrical engineering Deparmen, Faculy of echnologie, Djillali Liabes Universiy, Sidi-bel-Abbes, 22000, Algeria. ( ahmassoum@yahoo.fr ). Mossaab SAIDI, is wih he elecrical engineering Deparmen, Faculy of echnologie, Djillali Liabes Universiy, Sidi-bel-Abbes, 22000, Algeria. ( saidimoss@homail.fr). deermine MPP [5]. In his work, a maximum power poin racker for phoovolaic panel is proposed. dp / d and variaion of duy cycle (ΔD), are used o generae he opimal MPP converer duy cycle, such ha solar panel maximum power is generaed under differen operaing condiions. A phoovolaic sysem including a solar panel, a DC-DC converer and a resisive load is modeled and simulaed [3]. II. MAHEMAICAL MODEL he building block of P arrays is he solar cell, which is basically a p-n semiconducor juncion, shown in Fig.1. he -I characerisic of a solar array is given by Eq. (1) I I sc q ( Rs I Rs I I 0 exp 1 nkk R sh Where: and I represen he oupu volage and curren of he P, respecively. Rs and Rsh are he series and shun resisance of he cell. q is he elecronic charge. I SC is he ligh-generaed curren. I o is he reverse sauraion curren. n is a dimensionless facor. k is he Bolzman consan, and k is he emperaure in o K. + - I sc I d Fig.1 Equivalen circui of P array. Equaion (1) was used in compuer simulaions o obain he oupu characerisics of a solar cell, as shown in Fig. 2. his curve clearly shows ha he oupu characerisics of a solar cell are non-linear and are crucially influenced by solar radiaion, emperaure and load condiion [2,5]. Each curve has a MPP, a which he solar array operaes mos efficienly. R sh R s I pv + - P pv N (1) Copyrigh BAJECE ISSN: X Sepember 2014 ol:2 No:1 hp://

2 24 Swich on off I L I pv ᐃIpv L Fig. 2-I characerisic of a solar cell. pv ou - pv c ou ᐃou Fig. 5 ypical forms wave of boos converer. Fig. 3 -P characerisic of a solar cell. III. BOOS CONERER Consider a boos ype converer conneced o a P module wih a resisive load as illusraed in Fig. 3. pv on (ou pv ) off And, ou Where; on off off pv (2) (3) on off (4) he repor on on is called he duy cycle α and herefore From equaion (3), he volage release can be derived: (5) Fig. 4 Boos converer. he power swich is responsible for modulaing he energy ransfer from he inpu source o he load by varying he duy cycle D [2-4]. where : 1 (6) 1 ou pv ou : ishe oupu volage. pv : is hevolageinpu (solar cell). on : is he duraionof ime whenhe swich is closed. Copyrigh BAJECE ISSN: X Sepember 2014 ol:2 No:1 hp://

3 25 I. PROPOSED MPP ALGORIHM Maximum power poin racking, or MPP, is he auomaic adjusmen of he load of a phoovolaic sysem o achieve he maximum possible power oupu. P cells have a complex relaionship beween curren, volage, and oupu power, which produces a non-linear oupu. his oupu is expressed as he curren-volage characerisic of he P cell. Consan flucuaions in exernal variables such as emperaure, irradiance, and shading cause consan shifs of he I- curve upwards and downwards. A change in emperaure will have an inversely proporional effec on oupu volage, and a change in irradiance will have a proporional affec on oupu curren [1]. he maximum power poin racking (MPP) canbeaddressed by differen ways, for example: fuzzy logic, neural neworks and pilo cells. Neverheless, he perurb and observe (P&O) and Incremenal Conducance (INC) echniques are widely used, especially for low-cos implemenaions. he P&O MPP algorihm is mosly used, due o is ease of implemenaion. I is based on he following crierion: if he operaing volage of he P array is perurbed in a given direcion and if he power drawn from he P array increases, his means ha he operaing poin has moved oward he MPP and, herefore, he operaing volage mus be furher perurbed in he same direcion. Oherwise, if he power drawn from he P array decreases, he operaing poin has moved away from he MPP and, herefore, he direcion of he operaing volage perurbaionmus be reversed [6]. he MPP racker operaes by periodically incremening or decremening he solar array volage. If a given perurbaion leads o an increase (decrease) he oupu power of he P, hen he subsequen perurbaion is generaed in he same (opposie) direcion. In Fig.6, se Duy ou denoes he perurbaion of he solar array volage, and Duy+ and Duy_ represen he subsequen perurbaion in he same or opposie direcion, respecively[ 2,5]. In Fig. 6 i is given a flowchar wich describe he P & O echnique: Sar Se Duy ou Read,I P_new= *I P_new>P_old P_newP_old Duy =Duy + Yes NO Fig. 6Flow char of he P&O algorihm.. SIMULAION RESULS Duy =Duy - he modeling and simulaion of he sysem (phoovolaic generaor, boos converer and MPP algorihm P&O) is hen made wih Malab/Simulink sofware o validae he conrol sraegy and evaluae he performance of he sysem. Fig. 7 represens he model used in he simulaion. P Module E Ipv pv Boos DC-DC MPP Load Duy cycle Fig. 7 Sysem simulaion model. Fig.8 shows hesimulaion resuls. We show ha hemppconrolforces he sysem o work opimally a all imes around he maximum power poin. Copyrigh BAJECE ISSN: X Sepember 2014 ol:2 No:1 hp://

4 26 Power (W) emps (s) Fig. 8 P-Oupu Power of wih MPP. Curren (A) emps (s) Fig. 11 Plo of Cuuren Oupu of P panel. he change in level of irradiance and emperaure are presened in order o show he robusness. Firs, he use of varied levels of irradiaion is presened in he Fig. 9. Fig. 12 Plo of olage Oupu of P panel. Fig. 9. he irradiaion for many levels expressed in Wm 2. For hese levels of irradiaion, he following figure represens he maximum power in he oupu of P array. Fig. 13.Simulaed duy raio response of a P sysem. Fig. 10Power in he oupu of he P array. Copyrigh BAJECE ISSN: X Sepember 2014 ol:2 No:1 hp://

5 27 Efficiency (%) emps (s) Fig. 14. Simulaed he Efficiency response of a P sysem. In Fig.10, he simulaion resuls of he oupu power of he P panel using Perurb an Observe mehod conroller is repored, so we can say i is shown ha he P&O mehod, when properly opimized, leads o an efficiency which is equal o 94 % as shown in Fig. 13. We noe ha a mehod of P & O show converge o he value of MPP a seady sae. However, when he irradiaion changes rapidly he P & O conroller shows a beer ime response mehod. I. CONCLUSION An energy-efficien fas-racking MPP circui P energy harveser is presened in his paper. Firsly he characerisics of P sysem and vecor mahemaical model are presened. he MPP sraegy based on Perurb & Observe mehod is proposed. he resuls obained from simulaion employing P & O approach show he effeciveness of he proposed power racking and conrol sraegies wih quick power racking response and well direc curren oupu. Mehod, IEEE ransacions on Power Elecronics, vol.20, no.4, 2005, pp BIOGRAPHY Amine AOU, he was born in Sidi-bel-Abbes Ciy, in He received he L.S. and M.S. degrees in elecrical engineering from he Universiy of Djillali Liabes, Sidi-bel- Abbes in He is a member in Inelligen Conrol Elecrical Power Sysem Laboraory (ICEPS). Ahmed Massoum, he was born in M sirda Fouaga, lemcen, Algeria, in He received his BS degree in elecrical engineering from he Elecrical Engineering Insiue (INELEC) of Boumerdes 1985 and he MS degree from he Elecrical Engineering Insiue of Sidi-bel-Abbes Universiy in 2004 where he is currenly Professor of elecrical engineering. He is a member in Inelligen Conrol Elecrical Power Sysem Laboraory (ICEPS). Mossaab SAIDI, he was born in SIDA Ciy, in He received he L.S. and M.S. degrees in elecrical engineering from he Universiy of Djillali Liabes, Sidi-bel-Abbes in He is a member in Inelligen Conrol Elecrical Power Sysem Laboraory (ICEPS). ACKNOWLEDGMEN he sudy is seleced from Inernaional Symposium on Susainable Developmen, ISSD REFERENCES [1] A. Barchowsky, J. P. Parvin, G.F. Reed, M. J. Koryowski, B.M. Grainger, A Comparaive Sudy of MPP Mehods for Disribued Phoovolaic Generaion, Conference Publicaions, Innovaive Smar Grid echnologies (ISG), 2012 IEEE PES, 2012, pp.1-7. [2] M.A.Elgendy, B. Zahawi, D.J. Akinson, Evaluaion of perurb and observe MPP algorihm implemenaion echniques, Power Elecronics, Machines and Drives (PEMD 2012), 6h IE Inernaional Conference, IEEE Publicaion, March 2012, pp.1-6. [3] A. Chouder, F. Guijoan, S. Silvesre, Simulaion of fuzzy-based MPP racker and performance comparison wih perurb & observe mehod, Revue des Energies Renouvelables, vol.11, no.4, 2008, pp [4] M. Arrouf, Opimizaion of Inverer, Moor and Pump Conneced wih a Phoovolaic Cell, Ph.D. hesis, Universiy of consanine, Algeria, [5] J.A. Jiang,. H. Huang, Y.. Hsiao and C.H. Chen, Maximum Power racking for Phoovolaic Power Sysems, amkang Journal of Science and Engineering, vol. 8, no 2, 2005, pp [6] N. Femia, G. Perone, Giovanni Spagnuolo, and M. ielli, Opimizaion of Perurb and Observe Maximum Power Poin racking Copyrigh BAJECE ISSN: X Sepember 2014 ol:2 No:1 hp://