Design And Optimization Of Main Circuit Of Battery Storage Inverter Based On LCL Filter

In today’s urgent need for new energy, distributed systems based on the new energy has become a hot topic in recent years. As power electronic equipment, the battery storage inverter enables two-way flow of power. It has a tremendous help to improve power quality, improve power supply stability, improve and increase the availability of new energy power generation market value of distributed power. In this paper, T-type three-level grid inverter is the object of study, and the design methods of its main circuit parameters are analyzed, especially the optimal design LCL filter parameters.Firstly, this paper introduces the T-type three-level inverter and its working principles, develops the mathematical model based on its topology in a three-phase stationary coordinate system, combined with the working principle and the mathematical model the parameters of power device, the DC bus capacitor and LCL filter are designed, this paper analyzes the results of design methods by simulating.Secondly, introduce the three-level implementation of SVPWM modulation algorithm and 3MV modulation algorithm. analyzed the inverter output voltage by Fourier analysis. Design the computation method of the output voltage harmonic in both modulation algorithm, and analyze by simulation.Then, analyze the filtering characteristics of the LCL filter, based on the inverter output voltage harmonics, this paper proposes a optimization model of LCL filter which target is the minimum total inductance, constraint condition is to meet IEEE519grid-connected current harmonic distortion standard, based on the characteristics of the optimization model, this paper proposes a searching method of optimal parameters to solve the optimal problem of this paper.Finally, for the LC-LCL filter, through the analysis of its equivalent model at different frequencies, the design method of resonant branch inductance, capacitance and damping resistor are proposed, without increasing the dimension of the search condition,the optimization model and the search method of optimization parameters in this paper are applied to the LC-LCL filter design.In this paper, design methods of parameters of LCL filter and LC-LCL filter are analyzed with both modulation algorithms, find that the design method of this paper can make the grid-connected current harmonic distortion meets the standard by simulationof grid-connected current harmonic distortion of the filters. And analyze the simulation results for the advantages and disadvantages of these two filters in SVPWM and 3MV modulation algorithm. Through the results of the simulation, compared to the traditional LCL filter design methods, design methods in this paper filter can effectively reduce the total inductance, which has a very high practical value.