BPF Based SOGI Controller for Resolving Grid Side and Load Side Abnormalities in a Grid Interfaced PVG-UPQC System

In a photovoltaic generator fed unified power quality conditioner (UPQC) system, the presence of grid side and load side abnormalities deteriorates the power quality of the grid current and load voltage. These abnormalities, which include DC offsets, higher order harmonics, and dominant lower order harmonics, lead to deviations from optimal performance and compliance with power quality standards. To address these challenges, this work proposes a bandpass filter (BPF) based second order generalized integrator (SOGI) control scheme. The presented control methodology is intended to effectively eliminate DC offsets, suppress higher order harmonics, and mitigate dominant lower order harmonics present in grid voltages and load currents. The effectiveness of the presented control methodology is examined using MATLAB/Simulink under various operating conditions, including harmonically distorted grid voltages, unbalanced load conditions, and variations in solar irradiation. Additionally, the presented controller's performance is compared with two existing approaches: a standard SOGI based UPQC and an enhanced SOGI based UPQC. The comparative evaluation demonstrates that the presented controller significantly reduces distortion in grid currents and load voltages. The proposed controller reduces total harmonic distortion in grid currents and load voltages, meeting IEEE Standard 519 limits and improving power quality in PVG-UPQC systems.