Design and analysis of current controllers with active damped LCL filter for three-phase grid connected solar PV system

This paper discusses three types of current controllers with an active damped inductor-capacitor-inductor (LCL) filter for grid connected solar photovoltaic (PV) system. Grid current is considered as the feedback variable in the first controller. The filter capacitor is divided into two parts and the current between the split capacitor is considered in the feedback to actively damp the resonance peak and regulates the current being injected into the grid. Proportional-integral (PI) and proportional-resonant (PR) controllers are used along with the feedback of the split capacitor current and these are considered as a second and third type of current controllers. The small signal model (SSM) of the three-phase voltage source inverter (VSI) with LCL filter of the system is derived and each type of current controller is separately analyzed and discussed in steady state and also in the transient conditions. The workability and stability of the controllers are analyzed by using Bode diagrams. The proposed controllers are numerically simulated using MATLAB/Simulink and obtained results of the current controllers are analyzed and compared.