This paper demonstrates efficacy of the control strategy of Unified Power Quality Conditioner (UPQC) for improvement of three-phase power quality. UPQC contains a couple of active power filters (APF), one is connected in series and another is shunt. Series APF belongs to the Flexible AC Transmission System (FACTS), it is a promising device for the improvement of transmission efficiency. The Voltage Source Converter (VCS) acts as the brain of series APF while the shunt APF is another part of the UPQC. This series-connected component injects the compensating voltages that are generated by voltage source inverter (VSI). The entire system of UPQC (series and shunt APF) deals with the voltage dip and voltage swell on the consumer end of the network. Among the major advantages of the system is that this conditioner can captivate or insert true power. It can inject the voltage from 0°t o 360°as per the phase angle requirement of the base voltage. It is the major reason why it can work in three different modes. This series APF acts as an active power deliverer for sag condition in the aspect of voltage. The Matlab/Simulink software is used to investigate the analysis and results.