# Modeling and Simulation of a Stand-alone Photovoltaic System

ABSTRACT:

In the future solar energy will be very important energy source. More than 45% of necessary energy in the world will be generated by photovoltaic module. Therefore it is necessary to concentrate our forces in order to reduce the application costs and to increment their performances. In order to reach this last aspect, it is important to note that the output characteristic of a photovoltaic module is nonlinear and changes with solar radiation and temperature. Therefore a maximum power point tracking (MPPT) technique is needed to track the peak power in order to make full utilization of PV array output power under varying conditions. This paper presents two widely-adopted MPPT algorithms, perturbation & observation (P&O) and incremental conductance (IC). These algorithms are widely used in PV systems as a result of their easy implementation as well as their low cost. These techniques were analyzed and their performance was evaluated by using the Matlab tool Simulink.

KEYWORDS:

1. Photovoltaic system
2. MPPT
3. Perturbation and Observation
4. Incremental conductance

BLOCK DIAGRAM: Fig. 1. Block diagram of the stand-alone Photovoltaic system.

CIRCUIT DIAGRAM Fig. 2. Model of the photovoltaic module Fig. 3. Schematic diagram of a DC Buck-Boost converter.

EXPECTED SIMULATION RESULTS: Fig. 4. Output current of PV module Fig. 5. Output voltage of PV module Fig. 6 Output power of PV module Fig. 7. Output current of MPPT+DC-DC converter Fig. 8. Output voltage of MPPT+DC-DC converter Fig. 9. Output power of MPPT+DC-DC converter Fig 10 : PV-Output power with and without MPPT+DC-DC converter Fig. 11. Output current of MPPT+DC-DC converter Fig. 12. Output voltage of MPPT+DC-DC converter Fig. 13. Output power of MPPT+DC-DC converter Fig. 14. PV-Output power with and without MPPT+DC-DC converter

CONCLUSION:

In this work, we presented a modeling and simulation of a stand-alone Photovoltaic system. One-diode model for simulation of PV module was selected; Buck-Boost converter is studied and applied to test the system efficiency. Two Maximum Power Point Tracking techniques, P&O and IC, are presented and analyzed. The proposed system was simulated using the mathematical equations of each component in Matlab/Simulink. The simulation analysis shows that P&O method is simple, but has considerable power loss because PV module can only run in oscillation way around the maximum power point. IC method has more precise control and faster response, but has correspondingly higher hardware requirement. In practice, in order to achieve maximum efficiency of photovoltaic  system power generation, a reasonable and economical control method should be chosen. The following of this work is based on optimizing the performance of PV modules and stand-alone systems using more efficient algorithms to minimize the influence of the meteorological parameters on the PV energy production.

REFERENCES:

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