Research And Design Of Photovoltaic Power Generation System Based On Multimodal MPPT Control

Study on the maximum power point tracking control technolngy is currently a hot and major topic of photovoltaic power generation system research. The problem of PV array tracking the practical maximum power point difficultly under uneven lighting conditions can be solved effectively by applying multimodal MPPT technology in photovoltaic power generation system. The application of multimodal MPPT technology can also reduce energy consumption and improve energy efficiency of photovoltaic power generation system,which has good prospects for development.Independent photovlotaic power generation pre-stage system is selected as research content. The non-isolated DC/DC converter is proposed to use as system topology and multi-level technology is applied in DC/DC converter. According to the requirements of input voltage range of the converter,which is raised by photovoltaic power generation system,three-level Buck-Boost circuit is proposed to use as converter topology.Working principle and ripple characteristics of the converter is analyzed.Parameters of the circuit is designed and verified by simulation.The simulation results show that the converter can accomplish power converting and voltage gain improving,meanwhile, it has advantages of reducing inductor current ripple and switch voltage stress.For the unbalanced midpoint voltage, midpoint voltage balance strategy based on pulse width modulation is put forward.The results of simulation prove that the policy can effectively maintain the midpoint potential balance.The engineering analytical model of solar cell is built through mathematical derivation.The maximum power point tracking effect of three commonly used single peak optimization algorithm is analyzed and contrasted.After studying the output multimodal phenomenon of PV array,a mathematical expression of PV array output characteristics under any lighting conditions is raised and multimodal simulation model is established.The incremental conductance method is improved,based on this,the multimodal MPPT algorithm is designed.The tracking performance of the algorithm is simulated under uniform and non-uniform lighting conditions.The results indicate that the algorithm has well tracking effect under any lighting conditions.The prototype is designed and produced.The experimental research of photovoltaic power generation sysytem is carried out,which consist of dc converter’s function validating experiment, dc converter’s efficiency mensurating experiment, midpoint voltage regulation experiment and multimodal MPPT algorithm experiment.The experiment’s results prove that the midpoint voltage balance control strategy based on pulse width modulation can adjust the voltage effectively,which owns strong practicality.Besides, the multimodal MPPT algorithm based on mathematical model can accomplish the maximum power point tracking under any lighting conditions and has good tracking performance.