This thesis presents a Fast Fourier Transform (FFT) based Voltage Reference Configuration (VRC) control algorithm for the three phase Distribution Static Compensator (DSTATCOM) into grid-connected solar photovoltaic system for power quality improvement under nonlinear load and unbalanced load in distribution system. This research aims to address power quality issues characterized by voltage, current, or frequency distortions, which can lead to electrical equipment failures. While conventional utility grids provide clean sinusoidal waveforms for reliable opera-tion, the presence of nonlinear loads introduces harmonic distortions, causing transformer over-heating, grid malfunctions, and more. The FFT extracting the harmonic component from the load current to fed to a hysteresis current controller for the purpose of controlling the Voltage Source Inverter (VSI). The proposed system is modelled and used to simulate the desired responses for various operating conditions which are nonlinear load, unbalanced load, varying solar irradiances and dual mode of grid-connected solar photovoltaic system based DSTATCOM (GCPV based DSTATCOM). The proposed control algorithm performance is simulated in the MATLAB envi-ronment using Simulink. Under steady-state conditions, the DSTATCOM employing the fre-quency domain-based VRC control algorithm demonstrates a significant reduction in harmonic distortion from 20.34% to 1.87%. It also effectively controls disturbances during unbalanced load scenarios, maintaining the Total Harmonic Distortion (THD) below 5% even when a sudden dis-connection occurs in phase ‘b’ load current. The results from the simulations and hardware tests show that the proposed control technique successfully meets the IEEE-519 standard by eliminat-ing harmonics and keeping the THD value within the prescribed limit of 5%. This research con-tributes to the advancement of power quality improvement techniques in photovoltaic systems, ensuring reliable and efficient operation under varying load conditions.
