A new modified MPPT algorithm with variable step size for photovoltaic systems under different load and irradiance conditions

The efficiency of PV systems is very important and various algorithms are developed to obtain maximum power from PV systems. Unfortunately, traditional maximum power point tracking (MPPT) algorithms lack efficiency in PV systems. In this paper, a new modified MPPT algorithm is proposed which is more efficient and effective. The proposed algorithm has an improved structure that eliminates the disadvantages of the traditional MPPT algorithm. In addition, the proposed algorithm preserves the simple structure of the traditional MPPT algorithm. In the first step of the proposed modified MPPT algorithm, the regions near and far from the maximum power point (MPP) are determined. In the second step, the step size of the proposed modified MPPT algorithm is calculated according to the determined regions. The proposed algorithm is compared with three different MPPT algorithms, which are traditional P&O, drift-free, and variable step, in the PV system created in MATLAB/SIMULINK. According to the results, the proposed modified MPPT algorithm achieves high convergence by reaching the MPP in a single iteration, whereas traditional methods require multiple cycles. The simulation results demonstrate that the proposed method reaches the steady-state in less than 0.02 s under varying irradiance. Moreover, the steady-state oscillations are reduced by approximately 80% compared to the traditional P&O algorithm, and the overall tracking efficiency is increased to 99.64%. These quantitative improvements confirm that the proposed algorithm provides a more robust performance for PV systems. Calculating the elapsed processing time, the proposed modified MPPT algorithm is about 10 times faster than the other algorithms. Furthermore, the dynamic performance of the proposed method is rigorously validated under the standard EN50530 irradiance test profile.