Modeling and Fault Characteristics of Grid-Interfaced Converters in Active Distribution Networks

Abstract

This paper analyzes the control strategy and the fault characteristics of the grid voltage asymmetry through theoretical analysis, establishment of fault control model, simulation verification and other methods. Based on the theoretical analysis, the fault recording of a wind farm in Jiangsu is analyzed. Since the voltage and current have the negative sequence component when the grid has asymmetrical fault, a dual decoupling current control model is established. In the model, the notch filter is used to filter the double frequency component in the current, and the phase angle of the voltage positive sequence component is measured by DSOGI-PLL. Research shows that a notch filter can effectively eliminate the double frequency component, but it will reduce the stability of the system. The DSOGI structure has low-pass filtering characteristics. The problem of oscillation of the instantaneous power injected into the grid can be solved by a control strategy.