Photovoltaic Module Simulink Model for a Stand-alone PV System

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1 Available online at Phyic Procedia () 9 nternational Conference on Applied Phyic and ndutrial Engineering Photovoltaic Module Simulink Model for a Stand-alone PV Sytem Chen Qi, Zhu Ming School of Aeronautic Science and Engineering Beijing Univerity of Aeronautic and Atronautic Beijing, China Abtract PhotovoltaicPV Module i indipenable of a tand-alone PV ytem. n thi paper, a one-diode equivalent circuit-baed veratile imulation model in the form of maked block PV module i propoed. By the model, it i allowed to etimate behavior of PV module with repect change on irradiance intenity, ambient temperature and parameter of the PV module. n addition, the model i capable of function of Maximum Power Point Tracking (MPPT) which can be ued in the dynamic imulation of tand-alone PV ytem. Publihed by Elevier by Elevier B.V. Ltd. Selection Selection and/or and/or peer-review peer-review under reponibility under reponibility of CAPE of Organization [name organizer] Committee. Open acce under CC BY-NC-ND licene. Keyword:PV; MPPT; One-diode equivalent circuit. ntroduction Both reearch and technological development in the area of renewable energy ource are neceary to account for the increae in energy demand and environment problem in the world. Stand-alone otovoltaic ytem are the bet olution uch a communication ytem, water pumping and low power appliance in rural area. Such ytem are coniting of a PV generator, energy torage device, AC or DC conumer and element for power condition. PV module repreent the fundamental power converion unit of a PV generator ytem. The output characteritic of PV module depending on the irradiance intenity and the cell temperature i nonlinear, o it i neceary to model it for the imulation of maximum power point tracking for tand-alone PV ytem. One of the objective of the paper i a review of thoe exiting method and model. The main contribution of the paper i the implementation of a PV model in the form of maked block, and by the model the -V characteritic of otovoltaic module with different combination can be imulated. On the other hand, the veratile model i capable of function of MPPT which i neceary in tand-alone PV ytem Publihed by Elevier B.V. Selection and/or peer-review under reponibility of CAPE Organization Committee. Open acce under CC BY-NC-ND licene. doi:.6/j.pro...5

2 Chen Qi and Zhu Ming / Phyic Procedia () PV generator A PV generator i the whole aembly for olar cell, connection, protective part, upport etc. n the preent modeling, the focu i only on cell and module.. Solar cell Solar cell are in fact large area emiconductor diode. Due to otovoltaic effect energy of light (energy of oton) convert into electrical current. The equivalent circuit for the implet olar cell conit of diode and current ource connected paralleling, a hown in Fig. (a) []. Current ource current i directly proportional to the olar radiation and diode repreent PN junction of a olar cell. Equation of ideal olar cell, which repreent the ideal olar cell model, i: V o exp () AVt i otocurrent (A); o i revere aturation current(a); V i diode voltage(v); V i thermal voltage, V 7.5 mv at 5 t t A i diode ideality factor. On the other hand, Thermal voltage can be calculated in the following equation: kt V t () q k i Boltzmann contant,.8 J K ; T i olar cell temperature (K); 9 q i charge of electron,.6 C. The olar cell temperature, a in () i decribed a []: T..5G G.899T.W 7 a G i irradiance intenity ( W m ); G i erence irradiance intenity, W m ; a: T a i ambient temperature; W i local wind peed ( m ). The otocurrent ( ) in () depend on irradiance intenity and cell temperature, which i decribed G T T c, c G c, i olar cell hort-circuit current at erence condition ( G W m, T Ma = ); () () =5, Air-

3 96 Chen Qi and Zhu Ming / Phyic Procedia () 9 c i the olar cell hort-circuit temperature coefficient. On the other hand, the cell revere aturation current i decribed a: V oc, A T o o, exp qe g T T ka T (5) o, c, exp Voc, AVt i olar cell open-circuit voltage at erence condition; E i band-gap energy in the olar cell, (.-.5eV). g When a erie reitance ( R ) i included, the equivalent circuit i the four parameter model, a hown in Fig.(b)[].The -V characteritic equation of a olar cell can be decribed a[]: V R (7) o exp AVt A modification to four parameter equivalent circuit i accomplihed by adding a hunt reitor ( R h ) in parallel with the diode reulting in the five parameter model, a hown in Fig.(c). The voltage-current characteritic equation of a olar cell i given a: (8) V R V R o exp AVt Rh Single olar cell voltage i too minor to be in real operation, o module i haped of a group of olar cell in erie and parallel, with their protection device.. Module Current-voltage characteritic equation of equivalent circuit for the Photovoltaic module arranged in N parallel and N erie can be decribed a [5]: p M M M M M V NS R Np Np N V R Np Npoexp AVt Rh N i cell parallel number; p N i cell erie number.. Newton-Raon Method A can be een, the incluion of a erie reitance make the olution for current a recurrent equation. One initially applied imple iterative technique only converged for poitive current, but Newton-Raon method ued converge much more rapidly, and for both poitive and negative current [6]-[7]. Equation (7) i alo decribed a: V R () o exp AVt Then, V R () f o exp AVt Solution to current with Newton-Raon method can be decribed a: (6) (9)

4 f f K K ' K K K i Kth iterative current; i K K Chen Qi and Zhu Ming / Phyic Procedia () 9 97 th iterative current. t i well known that PV module power equal to value that voltage multiplie current, and can be decribed a: M M P V () On the other hand, olution to voltage at maximum power point (MPP) for PV module with Newton- Raon method can be decribed a: ' M P V M M K () VK VK '' M P V V K i Kth iterative voltage at MPP; V i K th K K iterative voltage at MPP. () PV model building and imulation The Matlab/Simulink model of PV module illutrate and verifie the nonlinear voltage-current and power-voltage output characteritic of an arbitrary module uing a one-diode equivalent circuit. n addition to that, the model include the function of Maximum Power Point Tracking (MPPT). Model input are the irradiance intenity and ambient temperature. The ubytem for propoed model are implemented and hown in Fig. (a), (b) and (c).the maked model i deign to have a dialog box a how in Fig., in which the parameter of PV module can be configured in the ame way. Reult and Concluion The Solarex MSX6 PV module i taken for example, which provide 6 watt of nominal maximum power, and ha 6 erie connected polycrytalline ilicon cell. The key pecification are lited in Table [8]. The parameter that determine the operation of PV module are lected in their characteritic curve, - V and P-V. For the calculation of two familie of curve, firt the cell working temperature tayed contant at 98K generating a type of curve for irradiance intenity (, 75, 5 and 5W/m ). Later, irradiance intenity maintain contant at W/m calculating the curve for 7, 98, and 8K. Both -V and P-V output characteritic of MSX6 PV module at variou olar irradiance intenity and temperature are carried out and the reult are hown in Fig.-5. t can be een from Fig. (a) and (b) that with increae of the cell working temperature, the hort-circuit current of the PV module increae, wherea the maximum power output decreae. On the other hand, with the increae of irradiance intenity, the hort-circuit current and the maximum power output increae a hown in Fig.5(a)and(b),and in which it i alo hown that current i proportional to irradiance intenity and open-circuit voltage i logarithmically dependent on the olar irradiance. On the other hand, the effect varying with the ideality factor i hown in Fig.6- higher value often the knee of the curve. The erie reitance of the module ha large impact on the lope of the -V curve at open-circuit voltage a een in Fig.7. The main contribution of the paper i the implementation of a PV model in the form of maked block, and by the model that predict the electrical output of an arbitrary module uing a one-diode equivalent circuit or a maximum power point tracking (MPPT) circuit connected to the module the -V characteritic of PV module with different combination can be imulated.

5 98 Chen Qi and Zhu Ming / Phyic Procedia () 9 Reference [] Markvart, Light Harverting for Quantum Solar Energy Converion, Prog. Quantum. Electronic. vol. A, pp. 7, [] A.Al-Amoudi and L.Zhang, Application of Radial Bai Function Network for Soalr-array Modeling and Maximum Power-point Prediction, EEE Power-generation,Tranmiion and Ditribution. vol.7,no.5,may, [] R.Hernanz and C.Martin, Modeling of Photovoltaic Moudle, nternational Conference on Rewable Energie and Power Quality. Granada(Spain), to 5th March, [] Walker,Geoff R, Evaluating MPPT Converter Topologie uing a MATLAB PV Model, Autraliaian Unverity Power Engineer Conference, AUPEC, Bribance, [5] Huan-Liang Tai,Ci-Siang Tu,and Yi-Jie Su, Development of Genereralize Photovoltaic Model Uing MATALB/SMULNK, Proceeding of the World Congre on Engineering and Computer Science. San Francico,USA, to th Oct,8 [6] Wang Xian-nan, The Reearch of The Stand-Alone Photovoltaic Sytem and it Maximum Power Point Tracking(MPPT), Mater Degree Diertation, Nanjing Univerity of Aeronautic and Atronautic,Feb,8 [7] Mao Mei-qin,Yu Shi-jie and Su Jian-hui, Veratile Matlab Simulink Model for Photovoltaic Array with MPPT Function, Jouranl of Sytem Simulation.vol.7,No.5,May,5 [8] TABLE. TYPCAL ELECTRC CHARACTERSTC Parameter Variable value Maximum Power Voltage@ Current@ P P m m Open-circuit Voltage Short-circuit Current Temperature Coefficient of Short-circuit Current P m 6 W V mp 7. V mp.5 A V oc. V c.8 A (.65.5) %/ c Figure. Three Equivalent circuit for olar cell (a) (b) (c) (a) (b.)

6 Chen Qi and Zhu Ming / Phyic Procedia () 9 99 (b.) (c) Figure. Building: (a)maked implementation of PV model;(b)subytem implementation of T and Vt; (c)subytem implementation of PV mode Figure. Dialog box of PV model

7 Chen Qi and Zhu Ming / Phyic Procedia () 9 MSX6 Module, G=W /m, T=7,98,,8K 8 MSX6 Module, G=W/m, T=7,98,,8K 7K.5 98K 7 K 6 7K 8K Module current(a).5 Module Power Output(W) 5 8K K 98K Moudle Voltage(V) (a) Figure. Charactertic with different T: (a)-v output characteritic; (b)p-v output characteritic (b) MSX6 Moudle, T=98K, G=,75,5,5W/m W/m 7 MSX6 Module, T=98K,G=,75,5,5W/m.5 75W/m 6 W/m W/m Module Current(A) 5W/m 5W/m Module Power Output(W) 5W/m 5W/m (a) (b) Figure 5. Charactertic with different G:(a)-V output characteritic; (b)p-v output characteritic MSX6 Module,T=98K,G=W /m, A=.,.,,.8, A=..5 A= Module Current(A).5.5 Figure 6. Effect of diode ideally factor(g= W/m,T=98 K) MSX6 Module, T=98K,G=W/m, R=,5,,5 mohm.5 R= R=5 mohm Module Current(A).5.5 Figure 7. Effect of erie reitance(g= W/m,T=98 K) 5 5 5