Power quality improvement of microgrids using unified power quality conditioner (UPQC): A scoping review

The growing integration of renewable energy sources into microgrids has heightened the need for effective power quality (PQ) management solutions. This scoping review investigates the deployment of Unified Power Quality Conditioner (UPQC) and its variants as mitigation technologies for power quality disturbances in microgrid environments. A systematic search across major databases was conducted, which yielded 1700 records. From these records, 51 studies met the inclusion criteria based on the population concept context framework. Analysis revealed a predominant focus on grid-connected microgrids, with harmonics, voltage sags, and power factor correction as the most addressed PQ issues. Classical control strategies such as PI and synchronous reference frame control were most common, though intelligent methods like fuzzy logic, ANN, and hybrid approaches demonstrated higher PQ improvement performance. While most studies relied on MATLAB/Simulink simulations, a notable portion also incorporated real-time hardware-based validation using platforms like OPAL-RT and dSPACE. Geographically, research was dominated by contributions from India and China. The review identifies key research gaps in experimental validation, long-term stability assessment, and hybrid microgrid configurations. This synthesis offers a consolidated view of the technical landscape and highlights future research directions in UPQC-based PQ solutions for resilient and efficient microgrids.