Modeling & simulation of grid connected photovoltaic system

International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Special Issue (November, 2013), © IAEME

International Conference on Communication Systems (ICCS-2013) October 18-20, 2013 B K Birla Institute of Engineering & Technology (BKBIET), Pilani, India Page 128

Modeling & Simulation of Grid Connected Photovoltaic System

Incorporated With Insolation & Temperature Variation

Smita Pareek1, J Sandeep Soni2, Dr. Ratna Dahiya3

1Faculty/Electronics & Communication, BKBIET, Pilani, Rajasthan, India 2Faculty/ Electrical Engineering, BKBIET, Pilani, Rajasthan, India

3Faculty/ Electrical Engineering, N.I.T. Kurukshetra, India

[email protected], [email protected], [email protected]

ABSTRACT: Photovoltaic systems are designed either to feed the grid or for direct consumption. Due to global concerns on environment issues, the 21st century has seen a significant growth of grid- connected installations. Photovoltaic plants connected to the utility grid contain several elements like PV modules, power converters, electric protection apparatus and monitoring devices in order to ensure secure power generation. Since the PV modules produce direct current, an inverter is necessary to interface with the alternative voltage utility grid. The power generated by solar photovoltaic (PV) module depends on surrounding irradiance, temperature and shading conditions. This paper presents modeling of Photovoltaic system of grid connected PV system using MATLAB/Simulink. Each component in the system like boost converter, inverter is modeled and simulated separately and the results are also shown for each model .The complete system model is given at the end with the results. Module model is verified by data given in the literature. The complete system modeled shows voltage output as 220V and 50 Hz frequency. KEYWORDS: Photovoltaic, Module, Model, Grid, Insolation, Inverter, Temperature.

I. INTRODUCTION Photovoltaic power generation is gaining wide acceptance today as a source of clean and pollution free power. Most significantly it is showing exponential growth in grid connected applications [2]. These generators are both grid-connected and stand-alone applications. Fig.1 shows the block diagram of grid connected PV system. DC output from PV module is fed to boost converter and then to inverter to convert it into AC with voltage output as 220V and 50 Hz frequency.

II. MODELING & SIMULATION OF PHOTOVOLTAIC MODULE

The basic device of a PV system is the PV cell. For simplicity, the single diode model as shown in Fig. 2 of practical PV cell including the series and parallel resistances is considered in this

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paper. This model offers a good compromise between simplicity and accuracy, and has been used by several authors in previous works.

Fig.1 Block diagram of grid connected PV system.

Some authors have proposed more sophisticated models that present better accuracy and serve for different purposes. In PV cell, the light-generated current depends linearly on the solar irradiation and is also on the temperature according to the following equation [4]

I = (I , + K ∆T) (1)

Where I , is light generated current at the nominal condition (in amperes), ∆T=T− Tn (T and Tn being the actual and nominal temperatures [in K], G is the irradiation on the device surface (watts per square meters) and Gn is the nominal irradiation (watts per square meters).The saturation current I0 is strongly dependent on the temperature and is given by:

I = (I , + K ∆T)/(exp , ∆ – 1) (2)

Where K and K are current and voltage coefficient.

The basic equation that mathematically describes the I–V characteristic of the ideal PV cell is given by equation 3 as follows:

I = (I − I exp ( ) – 1 − ( ) (3)

Where Ipv and I0 are the photovoltaic and saturation currents, respectively, of the array and Vt = NskT/q is the thermal voltage of the array with Ns cells connected in series. Photovoltaic model is simulated using above three equation and the parameters taken to simulate module are Isc,n=8.21A; Voc,n=32.9V; Kv= -0.1230 V/K;KI= 0.0032 A/K;I , = 8.214A ; Gn =1000W/m2

;a=1.3;Rs=0.221 Ohm =Rp=415.405 Ohm; and total 54 cells are connected in series in a module at nominal operating conditions.

Fig.2. Equivalent circuit of practical PV cell

The current- voltage and power-voltage characteristic of simulated module is shown in Fig.3. As shown the open circuit voltage is 33.1 V, short circuit current is 8.21A. Figure 4 and figure 5



shows the Current- Voltage and Power-Voltage characteristic of the module for temperature variation from 100C to 1000C and insolation variation from 200 W/m2 to 1000W/m2 respectively.

Fig. 3: I-V & P-V Characteristic Curve of Simulated Single Module

Fig. 4: I-V and P-V characteristic for Temperature Variation



Fig. 5: I-V and P-V characteristic for Insolation Variation

III. MODELING OF BOOST CONVERTER

A boost converter converts an input voltage to a higher output voltage. Main purpose of boost converter is to boost the input voltage and make stable output voltage. Figure 6(a) shows the boost converter and Figure 6(b) shows the output waveform of Boost Converter. The voltage has been increased from 33.1 V to 57 V. Since power must be conserved, therefore, the output current is lower than the source current.

Fig. 6: a) Boost Converter b) Output waveform of Boost Converter.

III MODELING OF COMPLETE SYSTEM Centralized architecture, series-connected micro converters, parallel-connected micro converters, and micro inverters are the basic architectures for grid-connected PV systems, as shown in Figure 7[3].In this paper series connected micro-converter architecture is used.



Fig. 7: (a) Centralized (b) Series-Connected Microconverter (c) Parallel-connected Microconverter (d)Microinverter[3]

Fig. 8: MATLAB/Simulink of Complete PV system.

Figure 8 shows the Matlab/Simulink of the complete system and Figure 9 shows the voltage waveform of complete PV system. The voltage output of complete system modeled is 220V and 50 Hz frequency.

Fig. 9: Voltage waveform of complete PV system.



IV. CONCLUSION

Modeling of grid connected PV system has been done using MATLAB/Simulink. Each subsystem of PV system is modeled, simulated and discussed separately. In day time, 9:00 AM to till 5:00 PM, insolation is enough to generate sufficient voltage from PV. During this time, grid will receive the necessary voltage from PV system. Future work includes harmonics reduction of output waveform and to increase current capacity of the system by connecting modules in parallel. REFERENCES [1] Marcelo Gradella Villalva, Jonas Rafael Gazoli, and Ernesto Ruppert Filho “Comprehensive

Approach to Modeling and Simulation of Photovoltaic Arrays” IEEE Transactions on power electronics, Vol. 24, No. 5, May 2009 pp 1198-1208.

[2] Ahmed Sony Kamal Chowdhury, M. Abdur Razzak,” Single Phase Grid-Connected Photovoltaic Inverter for Residential Application with Maximum Power Point Tracking” IEEE 2013.

[3] Ali Bidram, Student Member, IEEE, Ali Davoudi, Member, IEEE, and Robert S. Balog, Senior Member, IEEE “Control and Circuit Techniques to Mitigate Partial Shading Effects in Photovoltaic Arrays” IEEE Journal Of Photovolatics,, Vol. 2, No. 4, October 2012,pp 532-547.

BIOGRAPHY

Smita Pareek, Assistant Professor in Electronics & Communication Department at B.K.Birla Institute of Engineering & Technology. She received B.E. & M.E. degree in 2002 & 2008 respectively .She is currently pursuing Ph.D. from N.I.T. Kurukshetra, Kurukshetra, India. She has also taught at Poornima College Of Enginnering, Jaipur and Government Engineering College Bikaner, Bikaner. She has more than eleven years of teaching experience. She is Co-Author of three books for Engineering Undergraduate Students. She has many

papers in National and International Conferences and Journals of high reputes.

J Sandeep Soni, Asst. Prof. in Electrical Engg. Deptt. at B. K. Birla Institute of Engg. & Tech., Pilani. He obtained Diploma (Electrical Engg.) in 2001 and B.E. Electrical Engg (Hons) in 2004. He worked for more than four years in corporate industries and more than four years in Engineering Education. He has number of papers in National and International Conferences and Journals of high reputes. His research interests are in Power System Automation, Smart Grid Technology, FACTS, Electrical Drives & Control and Renewable Energy &

their Applications.

Dr. Ratna Dahiya received her B.Tech from GBU, Pant Nagar and M.Tech and Ph.D. degree degree in Electrical Engineering from R.E.C, Kurukshetra, Kurukshetra University, Haryana, India. Currently, she is working as Professor in Electrical Engineering Department with NIT, Kurukshetra (Deemed Uni.), Haryana, India. Her research interests include SMES, Electric Power System, Electric Power Quality, Power Electronics & FACTS. She has many papers in National and International Conferences and Journals of high reputes.