Variable Step-size Adaptive Maximum Power Point Tracking Algorithm for Solar Cell Under Partial Shading Conditions

Abstract

The maximum power point tracking concept is essential in PV systems to increase the power transfer capability and efficiency. The conventional methods to track maximum power point perform satisfactorily only under uniform solar irradiation, however under partially shaded conditions, PV array offers several local maxima along with one global maximum power transfer point on the P-V curve. This makes optimal tracking more difficult. This paper proposed an improved adaptive MPPT algorithm with varying step size to track the Global Maximum Power Point (GMPP) under different partial shaded conditions. First, the simulation model has been analyzed which is suitable for partially shaded conditions and then the proposed Variable Step-size Adaptive Maximum Power Point Tracking (VSAMPPT) method has been developed to track the global optimal power point for various irradiations. Here changing the duty cycle is not with fixed step size but with variable step size (Dstep), which depends on the square of the difference between the ratio of voltages to current and makes the proposed algorithm faster. The proposed algorithm keeps on adjusting its tracking strategy to find Global Peak Area (GPA) where the global maximum power point can be tracked down very easily. The proposed algorithm has been validated in the laboratory with dSPACE (DS1103) and tested with different case studies. The results demonstrate the effectiveness of the proposed concept over the existing MPPT methods like P&O method, Incremental Conductance (IC), and Adaptive MPPT methods in terms of speed of tracking global maximum power point, accuracy, and flexibility.