Strategy for modeling a 3-phase grid-tie VSC with LCL filter and controlling the DC-link voltage and output current considering the filter dynamics

This work presents an analytical and detailed design methodology of the output current controller and DC link voltage controller of the three-phase VSC (voltage source converter) with output LCL filter. Most of inverter-based grid-tie systems use L filters, which present structural simplicity and are easy for modeling and controlling. However, the 3rd order LCL filter mitigates switching harmonic currents and increases bandwidth. Despite its advantages, the LCL filter introduces a resonant peak and reduces damping. This problem can be addressed with active damping techniques. This paper presents an accurate modeling and controlling analysis of the grid-tie VSC taking into account the influence of the dynamic behavior of the LCL filter.