Stationary reference frame based current control structure with improved disturbance rejection for grid connected converters

摘要

A proportional resonant (PR) controller is commonly used for tracking the reference current with zero steady state error in the stationary reference frame (abc or αβ) for the voltage source converter. Such a structure suffers from poor disturbance rejection capability when the grid voltages contain harmonic components. This results in higher harmonic distortion in the grid currents which is not desirable. This paper introduces a virtual loop based current control structure for improving the voltage and the current disturbance rejection capability. The virtual loop based current control structure also decouples the reference tracking and disturbance rejection leading to simpler controller designs. Frequency domain plots and analysis have been provided to validate the presented control structure. Detailed circuit simulation results have been used to verify the presented analysis.