Integrating renewable energy resources in power systems is crucial for economic, clean energy, and resilience goals. However, challenges arise due to the variability and uncertainty of renewables and the lack of inherent system inertia. Flexible Alternating Current Transmission Systems (FACTS) and the Unified Power Quality Conditioner (UPQC) are promising solutions for power quality issues. UPQC combines Active Power Filters (APF) and Shunt-APF series to address voltage fluctuations and consumer-related power problems. With two IGBT-based Voltage Source Converters (VSCs), UPQC ensures stable voltage profiles, efficient power generation, and reliable distribution. This review paper highlights UPQC's adaptability, making it a vital tool for modern power systems integrating renewable energy sources.