Modified perturb and observe MPPT algorithm for drift avoidance in photovoltaic systems

The perturb and observe (PO) maximum power point tracking (MPPT) algorithm is a simple and efficient tracking technique. However, the PO tracking method suffers from drift in case of an increase in insolation (G), and this drift effect is severe in case of a rapid increase in insolation. Drift occurs due to the incorrect decision taken by the conventional PO algorithm at the first step change in duty cycle during increase in insolation. A modified PO technique is proposed to avoid the drift problem by incorporating the information of change in current (Δ I) in the decision process in addition to change in power (Δ P) and change in voltage (Δ V). The drift phenomena and its effects are clearly demonstrated in this paper for conventional PO algorithm with both fixed and adaptive step size technique. A single-ended primary inductance converter is considered to validate the proposed drift-free PO MPPT using direct duty ratio control technique. MATLAB/Simulink is used for simulation studies, and for experimental validation, a microcontroller is used as a digital platform to implement the proposed algorithm. The simulation and experimental results showed that the proposed algorithm accurately tracks the maximum power and avoids the drift in fast changing weather conditions.