Adequate Tuning of LCL Filter for Robust Performance of Converter Side Current Feedback Control of Grid Connected Modified-Y-Source Inverter

In the grid-tied PV inverter systems, the design of a proper power conditioning system is an important issue to ensure high-quality power injection to the grid. Among various control methods for a grid-interfacing inverter with LCL filter, converter-side current feedback (CCF) method has been widely used due to its inherent resonance damping feature. Applying the CCF method requires extra attention to the delay effect of the control system. In such systems, the delay narrows stability region of the resonance frequency of the CCF control method, especially, in the presence of wide variations of the grid inductance. Adequate tuning of the LCL filter and consequently, the proper choice of the resonance frequency can remarkably affect the performance of the CCF control. In this paper, a tuning procedure for the LCL filter has been proposed. Mathematical tuning of the Proportional Resonant (PR) controller parameters has also been included to avoid typical trial and error procedures of tuning. Simulation of the overall system also includes solar panels, maximum power point tracking algorithm, Modified-Y-Source inverter, and LCL filter to model the grid-tied PV system with the most possible details. Simulations are carried out in MATLAB/Simulink, and it has been proved that the proposed control system maintains its stability against grid parameters variations.