Intelligent Control for Power Quality Enhancement and Voltage Stability in Grid-Connected and Islanded Microgrid Operations

A Dynamic Voltage Restorer (DVR) plays a crucial role in improving power quality in both grid-connected and islanded microgrid environments. In the grid-connected scenario, the system is analyzed under both linear and non-linear load conditions. Total Harmonic Distortion (THD) levels are compared for three cases: without DVR, with DVR using a Proportional-Integral (PI) controller, and with DVR employing a Fuzzy Logic Controller (FLC). Simulation results indicate that both PI and FLC-based DVRs significantly reduce THD compared to the case without compensation, with the FLC offering slightly improved performance in harmonic mitigation. In the islanded mode, the DVR controlled by a PI strategy is implemented to address voltage disturbances and harmonics during disconnection from the main grid. The results confirm that the DVR, particularly with intelligent control techniques, is effective in maintaining voltage stability and power quality in both operational modes.