Power quality problems have become an increasing concern over the last decade in Electrical engineering. There are few techniques have been developed to overcome the power quality issues. The main power quality problems- voltage sag, voltage swell, voltage unbalance, voltage flicker, harmonic distortions. Key Features:- Various types of power quality problems phenomena, Power Quality Standards, Power quality mitigation techniques, Custom Power Devices, Unified Series Shunt compensator, Analysis of a distribution network with Unified Series Shunt compensator.