One novel variable step-size MPPT algorithm for photovoltaic power generation

Abstract

In order to increase the efficiency of photovoltaic (PV) system as much as possible, the maximum power point tracking (MPPT) technology has been paid more attention during the past decades. Among all the maximum power point tracking strategies, the variable step-size MPPT algorithm is widely employed due to its high tracking accuracy and fast speed. However, most of the existing methods are based on perturbation and observation method (P&O), and some essential parameters such as maximum step size and scaling factors are difficult to decide very accurately, due to the fact that the slope of power versus voltage (dP/dU) is asymmetric at the maximum power point (MPP). In order to avoid this defect, a novel variable step-size MPPT algorithm is proposed in this paper, which could adjust the step size online intelligently. Compared with other variable step-size MPPT algorithm, the new method does not need to calculate the maximum step size and speed factor. It can provide a simple and effective way to ameliorate both dynamic and steady state response characteristics. Plenty of theoretical derivation and comprehensive simulation results demonstrate that the new algorithm is much faster and more accurate than those traditional fix step-size methods.