JIC_V3_N2_RP1 M.S. Sujatha K. Venkateswarlu Journal on Instrumentation & Control Engineering 2321 – 1148 3 2 1 9 Power Quality, Active Power Filter, UPQC, Dq0 Transformation, PI Controller, Fuzzy Logic Controller The power quality has become an important issue in recent years. The aim of this paper, is regulation of source voltage at the distribution side under voltage sag as well as harmonics. The Unified Power Quality Conditioner (UPQC) provides combined features of both series and shunt Active Power Filters (APFs). The cascaded multilevel inverter with sinusoidal switching scheme is employed for low Total Hormonic Distortion (THD) in the output. The UPQC controller is designed based on synchronous dq0 transformation. In this paper, the UPQC performance with Proportional Integral (PI) controller and fuzzy logic controllers under sag and harmonics are analyzed in MATLAB environment. February - April 2015 Copyright © 2015 i-manager publications. All rights reserved. i-manager Publications http://www.imanagerpublications.com/Article.aspx?ArticleId=3534