Research On Stability Control Method Of Grid-connected Converter With Strong Soft Magnetic Characteristic Inductance Filtering

With the continuous growth of energy demand,the traditional primary energy such as coal and oil can no longer meet people’s demand for energy.The development and utilization of renewable energy is an inevitable choice for the development of power resources.As a combination of the power generation system and the power grid,the working state of the grid connected converter determines the quality of the output current.When the filtering inductor is a magnetic particle core inductor,its strong soft magnetic characteristics make the resonance characteristics and stability of the system more complex.Therefore,this article mainly studies the strong soft magnetic inductance filtering grid connected converter,and studies the stability optimization of the grid connected converter caused by inductance nonlinearity after grid connection.The main research content is as follows:Firstly,the design of inductance magnetic materials and the strong soft magnetic characteristics of magnetic cores were studied.Multiple sets of inductors were designed and the strong soft magnetic characteristics of inductors under different initial permeability were verified.The influence of the strong soft magnetic characteristics of inductors on the characteristics of LCL filters was analyzed.Subsequently,a preliminary analysis was conducted on the grid connected converter system,and an impedance model was established under the current control mode on the converter side.Secondly,design the current loop parameters of the PR controller and analyze the impact of strong soft magnetic characteristics on system passivity.Based on impedance stability analysis method,analyze the stability of grid connected converters.Analyze and verify the distribution of system passive intervals through frequency domain passivity theory,and explain the phenomenon of grid connected instability.Using active damping to enhance passivity and enhance the robustness of the system.Finally,simulation and d SPACE platform experiments were conducted in Simulink to verify the effectiveness of the PR controller in suppressing harmonic oscillations.Finally,based on the active damping design,a repetitive controller is used instead of the PR controller in Chapter 3 to achieve better harmonic suppression effect.By analyzing the passivity of repetitive controllers and selecting appropriate repetitive controller parameters based on this analysis.Further comparative analysis was conducted on the suppression effect of repetitive controllers and PR controllers on harmonics caused by inductance nonlinearity.Finally,the simulation model was built in Simulink and validated on the d SPACE experimental platform.