Research On Three-phase Photovoltaic Grid-connected Inverter

Due to the rapid growth of human society and economy,energy has become very scarce.In the face of the depletion of energy and the deteriorating environment,renewable energy is highly sought and related technologies are developing rapidly,especially in photovoltaic power generation.Due to the strong influence of environmental factors such as temperature and light intensity,the output voltage and current of the photovoltaic cell are random and intermittent.Therefore,how to realize energy conversion more efficiently in photovoltaic power generation system becomes a core issue,and maximum power point tracking control is a key issue.This paper has carried out a series of researches on various control methods and core theories involved in this topic.The main contents are as follows:1.The basic principle and mathematical model of the photovoltaic cell were analyzed.The simulation model was created in Simulink to study how the light intensity and temperature affect the output characteristics.Based on the research of photovoltaic cells,the principle of maximum power tracking of photovoltaics is illustrated.The advantages and disadvantages of traditional maximum power tracking are analyzed.Based on constant voltage + variable step size,a better performance algorithm is proposed.The simulation model is created.The advantages of the proposed algorithm are verified by analyzing the progress and response speed.2.Introduced the control principle of photovoltaic system inverter and the mathematical model of three-phase grid-connected inverter.A method different from conventional PI control was proposed.A proportional controller was introduced to suppress the gain attenuation of the regulator and realize No static control of the AC signal.The analysis and simulation of the grid-connected control algorithm is completed,and the static-free control without decoupling is realized by the proportional resonance controller.3.The design of the experimental circuit was carried out.Combined with the conclusions of the analysis of the photovoltaic grid-connected inverter and maximum power tracking,photovoltaic maximum power tracking and photovoltaic grid-connected inverter were designed.The photovoltaic maximum power tracking circuit included BOOST main circuit and drive circuit,photovoltaic grid-connected inverter circuit mainly includes three-phase grid-connected circuit,parametercalculation circuit,signal acquisition circuit and drive circuit.The software of the system was designed and analyzed,the main control flow was analyzed,the software of the system can complete the control of the system hardware and complete the functions of MPPT tracking and grid-connected power generation.