Investigation of Limitations in Active Damping Control of LCL Filter Resonance using Inverter Side Current Feedback in Grid Connected Voltage Source Converter

This paper investigates the active damping of LCL filter resonance in a grid connected voltage source inverter. The active damping realized using feedback of inverter side current is considered for analysis. A detailed study showing suitable choice of resistor required for resonance damping in case of the passive and active damping methods is presented. An explicit study showing the limitations of active damping over passive damping for a chosen Switching and resonance frequencies has carried out. The proposed work is simulated using MATLAB/Simulink for the resonance frequency of 1.4kHz and switching frequency of 10KHz. Typical results are reported and analyzed. It is observed from results that the virtual resistor introduced using active damping technique is unlike to the passive damping after a point of Rd values. This issue can be resolved by choosing controller bandwidth adaptive to the changes present in value of virtual resistor.