Equivalent modeling and analysis of three-phase LCL grid-connected inverter

Solar energy is one of the hot spots in the field of new energy because of its infinite and clean characteristics. As the most significant application of solar energy, photovoltaic power generation has become the key technology of competing research in various countries. Inverter is the interface of solar system to power grid, and it is an important part of conversion of DC to AC, MPPT, filtering and reducing output power fluctuation. Grid connection control is the key to realize grid connection of inverter to meet the requirements of grid connection. Therefore, the paper analyzes the working characteristics of photovoltaic cells, and establishes the mathematical model of photovoltaic array according to the I-V mathematical function of photovoltaic cells. In addition, based on the structure and working principle of the inverter main circuit, the mathematical model of inverter is deduced by establishing circuit equation. Finally, the coupling of inverter control system is analyzed in different coordinate systems, and the accuracy of the model is verified by simulation.