Study On Single-Phase Photovoltaic Grid-Connected Inverter And Maximum Power Point Tracking Control

Grid-Connected Photovoltaic Inverter is the most significant device of the Photovoltaic Power Generation Technology in New Energy Industry,the research directions of related fields has always been focused on lower cost of hardware,advanced control technology,stable work performance and higher energy conversion efficiency.The core research object of the paper is Single-Phase Grid-Connected Photovoltaic Inverter.At the very beginning,the background and meaning of Photovoltaic Power Generation Technology,domestic situation and policy and some other content are introduced,then the research status of the entire system,main circuit topology and control technology are also introduced.After that,the Micro Grid-Connected Photovoltaic Inverter experimental platform and its related content which includes the overall structure of the system,hardware circuit structure,high frequency interleaving SPWM are analyzed.Furthermore,the core content: MPPT control technology is introduced.The feature,modeling and simulation of the photovoltaic modules is researched,the realization principle of MPPT and two normal MPPT technologies(P&O,INC)are also analyzed,the specific process includes the design of DC-bus decoupling capacitor and the estimate of MPPT efficiency is detailed.After all that above,according to the Ripple Correlation Optimum Control Technology,a new type of MPPT control strategy which based on fluctuation of grid-connected output power is proposed,and some related simulation and experiment research is finished.At the last part,the accomplished work of the paper is summarized and the part to be improved is discussed.The proposed new MPPT control strategy which based on fluctuation of grid-connected output power,generally speaking,is derived from the fluctuation of output power and voltage on PV modules when the phases of grid voltage and output current are the same in Single-Phase Grid-Connected Photovoltaic Inverter.After that,the MPPT can be realized.Compared to P&O method,the proposed new strategy has no part of perturbation,and also no wrong decision and fluctuation.It has the advantage of faster speed and high-precision tracking.Besides,based on the design of DC-bus decoupling capacitor and the estimate of MPPT efficiency which considered the output voltage fluctuation of PV modules,the reasonable design of input side decoupling capacitor of the inverter can be realized.The MPPT control strategy,simulation,experimental process,MPPT efficiency estimation,decoupling capacitor design and some other content which proposed in the paper have theoretical and practical value.