A MODIFIED PERTURB AND OBSERVE ALGORITHM FOR MAXIMUM POWER POINT TRACKING OF PHOTOVOLTAIC SYSTEM USING BUCK-BOOST CONVERTER

Abstract

Perturb and Observe (P&O) maximum power point tracking (MPPT) algorithm is widely applied due to its simplicity, costless and easy implementation. However, P&O tracking algorithm suffers from drift or instabilities due to change of irradiance, and oscillation around maximum power point (MPP) at steady state. Drift occurs due to the incorrect decision taken by the conventional P&O algorithm at the first step change in duty cycle during the change in irradiance. This paper modifies conventional P&O algorithm to overcome these drawbacks and improve MPPT performance of photovoltaic (PV) system and DC/DC converter to supply a resistive load under rapidly change of weather conditions. This modified technique is proposed to avoid the problem of irradiance variation by incorporating the information of voltage, current and power in the decision process for updating the duty cycle of the converter. Simulation results of the proposed algorithm achieved minimum power oscillations with high accuracy, better dynamic response and stability for changes of irradiance, load and temperature. The obtained results are compared with the previous experimental results which are obtained in the literature.