An online maximum power point capturing technique for high-efficiency power generation of solar photovoltaic systems

This paper proposes a novel high-efficiency generation technique for photovoltaic (PV) system, named maximum power point capturing (MPPC) technique. This is an aperiodic perturbation MPPC technique compared to the conventional periodic perturbation maximum power point tracking technique. Firstly, under a closed-loop circuit and an open-loop circuit, the complete I-V curves and P-V curves are defined. Secondly, the proposed MPPC technique is based on the complete I-V curves and a practical model of solar PV systems. The proposed method realizes that maximum power point (MPP) is captured online, and its control strategy is designed to set a steady operating area around MPP. The duty cycle keeps constant when the operating point is within the steady operating area, i.e., aperiodic perturbation, and when the operating point is outside the steady operating area, MPPC is triggered to capture a new MPP with an updated steady operating area. Simulation results demonstrate that no oscillations exist in steady-state; dynamic performances are improved; and only two perturbations are required to capture the new MPP. Using the proposed MPPC method, low voltage ride through and high voltage ride through can be prevented.