A Novel Modified Control Scheme in Grid-Tied Photovoltaic System for Power Quality Enhancement

In this article, a modified reduced order generalized integrator-based frequency-locked loop (MROGI-FLL) is proposed for controlling the interfacing inverter of the grid-tied photovoltaic system to mitigate the harmonics. Additionally, a fuzzy tuned PID controller is integrated in the proposed scheme to minimize the steady-state error, which results the voltage level is maintained constant at the common dc-link bus terminals. The MROGI-FLL is designed to evaluate the three-phase reference currents by extracting the fundamental constituents from the load currents and grid voltages. The proposed MROGI-FLL has several advantages such as better harmonic mitigation capability, control adaptivity, adaptive frequency and phase, grid synchronization, and low computation burden. The proposed reference current generator is simulated on MATLAB/Simulink platform under steady state and various transient conditions.The comparative study of proposed scheme is compared with the existing and adaptive control techniques, which assures the potency of the proposed control algorithm in-terms of harmonic mitigation, dc-offset rejection, frequency variation, and computation burden. Finally, the experimental results are verified through an experimental platform by using the dSPACE evaluation kit and both the simulation and hardware characteristics are well justified to the IEEE-519 standard limits.