Maximum power point tracking (mppt) technique is invariably used to continuously track the maximum power point of a PV module under fluctuating meteorological conditions. In the classical perturb and observe (P&O) algorithm, the perturbation step-size governs the speed of tracking. A large perturbation step-size speeds up the tracking at the cost of high steady state oscillations around the maximum power point (mpp), whereas, a low perturbation step size decreases the steady state power loss but also slows down the mppt. In this paper, a modified P&O algorithm is proposed that increases the convergence speed while maintaining low steady state power oscillations. The proposed scheme uses, both current and voltage perturbation depending upon the slope of the P-V curve. Two independent PI controllers have been used to ensure fast tracking during system transients, and to simultaneously fulfill the objective of low steady state power losses. The simulations were carried out in MATLAB/Simulink for varying irradiance and temperature conditions. The simulation results show improved steady state and dynamic response with overall increase in output power.
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