An Effective Control Strategy for Single-Phase Single-Stage PV Grid-Tied Inverter Under Abnormal Grid Conditions
Rohit Jain, Venugopal Reddy Barry, Harish Kumar Varma Gadiraju
Abstract
This paper presents a robust and efficient control scheme for single-phase PV grid-tied voltage source inverter. A hybrid phase-locked loop is proposed for grid synchronization and to eliminate the effects of the DC offset and harmonics on the estimated phase and frequency. The integral sliding mode current controller is employed for current tracking and efficient control for quality power injection into the grid in the presence of grid voltage harmonics. The robust sliding mode voltage control is utilized for dc-link voltage tracking. Further, the voltage and current control loop stability are analyzed with the Lyapunov theory. The feasibility and robustness of the proposed control schemes are validated using MATLAB/Simulink and experimental analysis. Comparative studies have been performed among the conventional and proposed methods under varying solar irradiation, frequency variation, dc offset, voltage dip, and distorted grid voltage. The performance of the proposed methods is satisfactory under various dynamic, steady-state conditions, and the injected current THD is < 5%, thus making the system robust and efficient for grid-connected systems.