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1. 1. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 5, Issue 5, May (2014), pp. 19-27 © IAEME 19 MATLAB BASED MODELING OF A PV ARRAY AND ITS COMPARATIVE STUDY WITH ACTUAL SYSTEM FOR DIFFERENT CONDITIONS S.N.H. Faridi1 , Mohammed Aslam Husain2 , Abu Tariq3 , Abul Khair4 1,2,3,4 Department of Electrical Engineering, AligarhMuslimUniversity (AMU), Aligarh, INDIA ABSTRACT The paper presents the modeling of a photovoltaic array in Matlab/Simulink environment. The model is developed using basic circuit equations of the photovoltaic (PV) solar cells including the effects of solar irradiation and temperature changes. The equations of the model are presented in details. Firstly the mathematical modeling of a solar cell is done, then how a solar module, array and panel is obtained using that cell is shown clearly. Different characteristics of modeled PV panel and practical PV panel have been obtained for different parameters and comparison has been done. Solar PV panel is a nonlinear power source that needs accurate identification of optimal operating point. It is desired to operate Solar Photo Voltaic (SPV) panel at its maximum power output for economic reasons. This paper is useful to model, simulate and study the effect of changing ambient conditions of the photovoltaic arrays. The accuracy of Model is experimentally and practically verified. Keywords: SPV Array, Insolation, Temperature, Modeling, MATLAB Simulation. I. INTRODUCTION With the rapid increase in the demand of energy, it has become the need of time to switch over to the renewable energy sources. Development and utilization of renewable energy and green energy is necessary for sustainable development. The solar energy is the ideal green energy and a photovoltaic system (PVS) is the most simple and reliable way to produce electricity from the conversion of solar energy. The basic building device of SPV system is SPV cell. Many SPV cells are grouped together to form modules.SPV array may be either a module or a group of modules arranged in series and parallel configuration. The output of SPV system may be directly fed to the loads or may use a power electronic converter to process it. To study the converters and other connected performances it is necessary to proper model of SPV systems [2]. INTERNATIONAL JOURNAL OF ELECTRICAL ENGINEERING & TECHNOLOGY (IJEET) ISSN 0976 – 6545(Print) ISSN 0976 – 6553(Online) Volume 5, Issue 5, May (2014), pp. 19-27 © IAEME: www.iaeme.com/ijeet.asp Journal Impact Factor (2014): 6.8310 (Calculated by GISI) www.jifactor.com IJEET © I A E M E
2. 2. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 5, Issue 5, May (2014), pp. 19-27 © IAEME 20 The main task of this paper is to develop a simulation model of SPV cell, module and array to reproduce the characteristics of existing SPV systems. Characteristics of developed models have been shown for different conditions. This text presents in details the equations that form the I-V model. The aim of this paper is to provide the reader with all necessary information to develop photovoltaic array models and circuits that can be used in the simulation for photovoltaic applications. II. MODELING OF PHOTOVOLTAIC CELL 2.1 Photovoltaic Cell The basic equation from the theory of semiconductors [1] that mathematically describes the I- V characteristic of the ideal photovoltaic cell is:       −−= 10 C C PhC kT qV eIII (1) Where: Iph is the short-circuit current that is equal to the photon generated current.         −= 10 kTc qVd d eII (2) Where, dI is the current shunted through the intrinsic diode, The diode current Id is given by the Shockley’s diode equation; Vd is the voltage across the diode (D). k is Boltzmann constant ,q is electron charge , OI is reverse saturation current of diode , CT is reference cell operating temperature (25 °C). 2.2 Modeling the photovoltaic array Practical arrays are composed of several connected photovoltaic cells and the observation of the characteristics at the terminals of the photovoltaic array requires the inclusion of additional parameters to the basic equation [1,11]: Fig.1: Single-diode model of the theoretical photovoltaic cell Fig. 2: Characteristic I-V curve of the photovoltaic cell.
3. 3. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 ISSN 0976 – 6553(Online) Volume 5, Issue 5, May (2014), pp. The net cell current I is composed of the light However, if the load R is small, the cell operates in the region M the cell behaves as a constant current source, almost equal to the short circuit curre hand, if the load R is large, the cell operates on the regions P a constant voltage source, almost equal to the open Fig.3: A typical, current-voltage I-V points: short circuit (0, Isc), maximum = PhC II where Iph and I0are the photovoltaic and saturation currents thermal voltage of the array with Ns cells connected in series. Cells connected in parallel current and cells connected in series provide resistance of the array and Rp is the curve seen in Fig. 3. The equation (3) represents the practical SPV cell. Here the five parameters are RP. This equation can also be used to represent a series/parallel connected module by suitably modifying its parameters [2]. Eq. (3) describes the single- more sophisticated models that present better example, in [3–6] an extra diode is used to represent the a three-diode model is proposed to include the influence of effects which previous models. For simplicity the offers a good compromise between simplicity and accuracy [8] and has been used by several authors in always with the basic structure composed of a current source and a parallel Fig 4: Mathematical Modelling Implementation for Io cal Engineering and Technology (IJEET), ISSN 0976 6553(Online) Volume 5, Issue 5, May (2014), pp. 19-27 © IAEME 21 I is composed of the light-generated current Ipv and the diode current Id. However, if the load R is small, the cell operates in the region M-N of the curve Fig.3, where the cell behaves as a constant current source, almost equal to the short circuit curre hand, if the load R is large, the cell operates on the regions P-S of the curve, the cell behaves more as a constant voltage source, almost equal to the open-circuit voltage. V curve for a solar cell for different load and the three : short circuit (0, Isc), maximum power point (Vmax, Imax) and open-circuit (Voc, 0).       + −         −−         + P SCCAkT RIV q Ph R RIV eI c SCC 10 (3) are the photovoltaic and saturation currents of the array and Vt = thermal voltage of the array with Ns cells connected in series. Cells connected in parallel connected in series provide greater output voltages. Rs is the equivalent series is the equivalent parallel resistance. This equation originates The equation (3) represents the practical SPV cell. Here the five parameters are . This equation can also be used to represent a series/parallel connected module by suitably -diode model presented in Fig.1. Some authors have proposed that present better accuracy and serve for different purposes. 6] an extra diode is used to represent the effect of the recombination of carriers. In [7] model is proposed to include the influence of effects which are not considered by the single-diode model of Fig. 1 is studied in this paper. This offers a good compromise between simplicity and accuracy been used by several authors in previous works, sometimes with simplifications but basic structure composed of a current source and a parallel diode [2,9,10 Mathematical Modelling Fig 5: Mathematical Modeling Implementation for Ipv cal Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), diode current Id. N of the curve Fig.3, where the cell behaves as a constant current source, almost equal to the short circuit current. On the other S of the curve, the cell behaves more as for different load and the three remarkable circuit (Voc, 0). of the array and Vt = NskT/q is the thermal voltage of the array with Ns cells connected in series. Cells connected in parallel increase the Rs is the equivalent series equivalent parallel resistance. This equation originates the I-V The equation (3) represents the practical SPV cell. Here the five parameters are Iph, I0,Vt, RS, . This equation can also be used to represent a series/parallel connected module by suitably diode model presented in Fig.1. Some authors have proposed accuracy and serve for different purposes. For effect of the recombination of carriers. In [7] are not considered by the diode model of Fig. 1 is studied in this paper. This model works, sometimes with simplifications but diode [2,9,10]. Mathematical Modeling Implementation for Ipv