Research And Design Of Dual Mode Control In Distributed Photovoltaic System

Since the first industrial revolution,science and technology and economic development is very fast,global energy consumption increased rapidly.Energy demand has been followed,and because of the pollution of the traditional energy consumption is growing,people begin to seek more clean and long-term energy,Thus clean energy into the people's vision,the solar energy resources because of distribution,clean,environmental protection and long-term sustained characteristics is the most concerned in clean energy.Today,solar photovoltaic power generation gradually to the development of small,household type.Distributed photovoltaic power generation is more conducive to the promotion of photovoltaic power generation.Therefore,it is of great theoretical and practical significance to research and utilization the double-mode control strategy in distributed PV system.This thesis focuses on the control of the double mode and the switching process between the two modes.Main contents of several aspects:1.According to the design requirements of photovoltaic system,design and simulation of the MPPT algorithm,the island detection algorithm and PLL control method,they are the foundation of the research.2.By comparison and analysis,choose the topology of the main circuit of photovoltaic system,use push-pull circuit to boost rectifier and the full-bridge circuit for inverter,two circuits are independent of each other to make the switch of the two modes convenient.3.Use output voltage feedback control mode when the PV system in off-grid mode,use output voltage and inductance current close loop control mode when PV system in grid-connected mode,and establish simulation model of the two kinds of control mode,ensure the operation of the system stable and reliable.By analyzing the voltage mutation generated during the mode switching,design the strategy of the switch of the two modes,and establish simulation model to guarantee the voltage mutation in the switching process.4.Design circuit board according to the previous analysis of the thesis.The master chip use the TMS320f2812 of TI.Other hardware includes main circuit,drive circuit and detection circuit and so on.The software includes MPPT,PLL and islanding detection algorithms and so on.5.Overall testing the PV system,make conclusion of several important data and waveforms.And this thesis finally summarized the whole system and pointed out some problems.