Research On Maximum Power Point Tracking Scheme For PV Grid-connected Inverter Under Partially Shaded Conditions

With the proliferation of the world’s population and environmental pollution caused by traditional energy sources, it’s very important to explore green energy. Because of its endless and clean, solar plays a pivotal role in the green energy area. One of the solar applications is photovoltaic (PV) power generation, which has become a major trend. In this paper, a maximum power point tracking system used in single phase two-stage PV grid-connected inverter is designed, focusing on DC/DC converter section, PV cell modeling, maximum power point tracking (MPPT) technology of single peak and multi-peak cases.Firstly, the paper summarizes the background and potential of photovoltaic power generation at home and abroad, analyzes the basic structures of PV system and inverter, and selects Boost circuit as the DC/DC section of single phase two-stage PV grid-connected inverter. Secondly, the thesis analyzes the principle and output characteristics of photovoltaic cell, establishes a Matlab simulation model based on mathematical model to analyze the effects of temperature and irradiance condition on the output characteristics of PV modules, focusing on the dangers of hot spot effect and output characteristics of PV array under partial shading conditions (PSD). The simulation results show that the model can simulate the characteristics of PV array under uniform illumination and partial shading conditions. Finally, the thesis illustrates the basic principle of MPPT and the general MPPT methods. Perturb and observe (P&O) and Incremental Conductance (INC) are discussed in detail, including two key parameters (sampling interval and duty cycle perturbation). A PV array exhibits several local and single global maximum power points under PSD. To track the global maximum power point precisely, a novel global maximum power point tracking scheme is proposed in this paper. In addition, the paper provides the experimental verification with simulation results.According to the theoretical analysis and parameters calculation, an experimental prototype is developed with DSP, and the experiment results are given to verify the theoretical analysis.