Research For Single-Phase Grid-Connected Photovoltaic System

With the continuous development of human society and the continuous improvement of the industrial civilization,The social progress needs to consume large amounts of energy. With the people demand for material things are constantly ascension, the demand for energy is growing.But on the earth,the non-renewable fossil energy reserves are limited,so looking for clean energy instead of fossil energy strategy is more and more urgent.Solar energy as a clean,non-pollution renewable energy in a wide range of applications, Along with the science and technology unceasing development,photovoltaic power generation technology also gradually into the line of sight of people.As photovoltaic cell module cost reduction and photovoltaic power generation technology continues to mature,the photovoltaic power generation technology will more and more attention. Our country has planned to focus on the development of object in the period of the "shi er wu".This paper expounds the small power structure of the solar power system, circuit topology analysis and the control principle design etc. and according to the photovoltaic (pv) grid power system of some detailed analysis such as:Inverter output current waveform of frequency and phase followed grid voltage, Photovoltaic battery cells MPPT tracing control and Photovoltaic power generation system independent power generation and grid generation mode switching etc.The same time, do simulation experiment on photovoltaic inverter control,according to the single current loop control is insufficient,the paper put forward the corresponding double-loop control strategy for photovoltaic (pv) grid system research, has certain reference value.Firstly,this paper mainly makes a brief introduction about the development situation of solar energy current and single-phase photovoltaic (pv) power system structure and given an overall concept;Secondly, research MPPT of the photovoltaic system,and combined with the MPPT conductance incremental approach control strategy, based on Matlab/Simulink build system simulation model and test analysis,and choose 80C196KC single-chip microcomputer chip as the controller of the Boost transform circuit and design the controller hardware circuit and software;Third,According to Solar photovoltaic (pv) grid inverter to the topological structure has made the detailed analysis,and expounds the photovoltaic(pv) inverter between independent working mode and grid work mode of mutual conversion, and Put forward by use of a three-phase inverter modules for realizing inverter and communication system switch function.Finally, The article studied grid inverter control strategy,and put forward the shortcomings of the single current loop control,the paper adopted double-loop control method,and the single current loop control and double-loop control through the PSIM software simulation,test the feasibility study. Due to the simulation results concluded that the output grid current exists ripple problem,The cause of the ripple produce are closely with parameter selection, through mathematics formula deduction and simulation experiment was verified, Draw with the size of the ripple voltage and the inductance side value have close relationship.