Research And Implementation Of Single Phase Photovoltaic Grid-connected Inverter Under High-permeability New Energy

Energy is an important material basis for the survival of human society and economic development.With the shortage of global energy supply and the increasingly serious environmental pollution,clean new energy represented by photovoltaics is receiving more and more attention.Among them,high proportion of new energy in public power grids has gradually formed an inevitable trend.The high permeability photovoltaic power generation has intermittent,random and output power fluctuation,resulting in large fluctuations in the impedance of the public power grid,which brings a severe test to the efficient and stable operation of grid-connected interface components such as photovoltaic grid-connected inverters.In view of this,the research of photovoltaic grid-connected inverter under high permeability of new energy has become an important research direction of photovoltaic power generation.The main research contents are as follows :The overall structure of the single-phase photovoltaic inverter is analyzed.The circuit structure and working principle of the improved Boost converter which suppresses the instantaneous surge voltage and current in the front stage,the Heric inverter which suppresses the common mode leakage current in the rear stage and the LC filter under the weak grid are studied.The control strategy of grid-connected inverter in weak grid environment with high permeability of new energy is studied.The influence of proportional voltage feedforward control strategy on grid-connected inverter system in weak grid environment is analyzed.A multi-resonant feedforward control strategy of photovoltaic grid-connected inverter in weak grid environment is studied.By adding multi-resonant control strategy to the traditional proportional voltage feedforward channel,the influence of grid voltage background harmonics on grid-connected current distortion is effectively suppressed.The stability and adaptability of photovoltaic grid-connected inverter in weak grid environment are improved,and the quality of grid-connected current of photovoltaic grid-connected inverter in weak grid environment is improved.The pre-stage control strategy of photovoltaic inverter is optimized.Aiming at the phenomenon that local shading of photovoltaic array will lead to multiple extreme power points in the output characteristic curve of photovoltaic system,an improved myxobacterial optimization algorithm is proposed.The algorithm uses normal distribution to initialize the population,improves the diversity of the initial population,and applies the Levy flight strategy and spiral search strategy to improve the global optimization ability of the algorithm and effectively prevent it from falling into local optimum.The software and hardware design process of two-stage single-phase gridconnected photovoltaic inverter is introduced,and the experimental prototype of the inverter is developed.