<b>Mitigation of Voltage dip in WECS using UPQC</b> Currently, the quality of supplied power is important to several customers. Power quality is a service and many customers are ready to pay for it. In the future, distribution system operators could decide, or could be obliged by authorities, to supply their customers with different PQ levels and at different prices. A new device that can fulfill this role is the unified power quality conditioner UPQC , composed of a power electronic series main unit installed in the medium voltage low voltage LV substation, along with several power electronic shunt units connected close to the end users. The series and parallel units do not have a common dc link, so their control strategies are different than traditional UPQC control techniques. This device can achieve general improvement in power quality, reducing the most common disturbances for all customers that are supplied by the mains by using only the series unit. Additional increments in power quality i.e., mains power interruptions, faults , can be provided to the customers who need it custom power by the shunt units. The UPQC is controlled to mitigate voltage fluctuations and to regulate the WF terminal voltage at PCC caused by pulsating WF generated power and system load changes respectively. Simulation results show that there is reduction in power fluctuations at grid and voltage fluctuations at PCC. The UPQC scheme is validated to mitigate the power quality problems like Voltage Sag, Swell and Harmonics and WF stability. Ancillary services, Frequency response, Emulating inertia, Primary frequency control, Wind turbines 44-49 Issue-4 Volume-2 Sajid Bashir | Gagan Deep Yadav