Research On Control Method Of Three-phase Grid-connected Inverter With LCL Filter

In recent years, while environment pollution is becoming more serious and natural resources is growing shortage, the development and utilization of renewable energy has become the urgent needs for our society. As a necessary interface device connected the grid with renewable energy generation systems, grid-connected inverter has become the grid inverter has become the present research focuses in the power electronic study field.The paper introduces the feasible operation meaning of grid-connected inverter, and current situation of the development in the domestic and international of grid-connected inverter. Then introduces the application within the distributed generation power system. Also introduces the topological structure, control strategy and filter type of three-phase grid inverter, which we present the model and characteristics of three kinds of filters.The main content of this paper is researching the control strategy of three-phase grid-connected inverter with LCL filter, analyzing topological structure and mathematical model of three-phase grid-connected inverter with LCL filter. Analyzing and setting the parameters of filter reasonably, optimizing the control strategy of grid-connected inverter, including the theoretical analysis and verifying by Matlab/Simulink simulation.First we introduce the amplitude-frequency characteristics and phase-frequency characteristics of LCL filter. On the basis of in-depth study of the produce mechanism of resonance, damping control method of LCL filter will be put forward, and the control strategy of the grid-connected inverter will be further analyzed.In addition, the parameters of LCL filter are analyzed and computed in this paper. By analyzing topological structure and mathematical model of three-phase grid-connected inverter with LCL filter emphatically, current double-loop control strategy is identified as the adopted control strategy for this paper. Then design and choose the parameters of three-phase grid-connected inverter system. So we design and choose the parameters of the LCL filter complying with the national standard requirements and the design requirements and verify, it proves the values choose are reasonable and accurate.The simulation analysis of three-phase grid-connected inverter with LCL filter is included in this paper. Mainly do research of the operation of the merged power networks simulation analysis of two kinds of three-phase inverters with L filter and LCL filter, comparing the simulation results, the selection of LCL filter is verified that it is reasonable. Then the dynamic response of three-phase grid-connected inverter with LCL filter is analyzsed and simulated with Matlab/Simulink, the results show that the control system of three-phase grid-connected inverter has a good dynamic and static performance. Then by means of the experimental platform verifies the control strategies.