I J C T A, 9(2) 2016, pp. 741-748 © International Science Press 1 Research Scholar 2 M. Tech student 3 Professor School of Electrical Engineering, VIT University, Chennai- 600 12 E-mails: 1 marshall.arockiadass2013@vit.ac.in; 2 pawaromkar.subhash2015@vit.ac.in; 3 peerfathima.a@vit.ac.in Voltage Sag and Harmonic Compensation of PV Fed Unified Power Quality Conditioner P. Marshall Arockia Dass 1 , Omkar S Pawar 2 and A. Peer Fathima 3 ABSTRACT This paper demonstrates the design of PV fed Unified Power Quality Conditioner (UPQC). Nowadays due to growing applications in power electronics, the power quality problems in the grid interconnected applications take great interest. Hence, mitigation of harmonics and utilisation of clean energy related to power electronics applications became popular worldwide. PV fed UPQC is proposed in the present paper. The unique property about UPQC is it can also export active power. According to the analysis, the proposed UPQC has the capability of eliminating both the supply current distortion, which is a consequence of nonlinear loads and secondly, distortions caused due to the introduction of the fifth and seventh order harmonics to the supply voltage. Also, the proposed UPQC transfers power obtained from PV to the grid using boost converter. The simulation system gives the performance of voltage sag, voltage swell, harmonic distortions and its mitigation and also offers future outlook on UPQC. Keywords: UPQC, Active Power Filter (APF), voltage swell, voltage sag, harmonic mitigation, power quality. I. INTRODUCTION The field of renewable energy resources has undergone many evolutions of the recent society, in the utilisation of clean energy. The PV system is at the zenith of all the solar energy applications because of its versatile attributes such as easy construction, maintenance, and wide applications. As a result of this characteristics, the PV system have been successfully deployed in many of the commercial usage and also some of the technical research [1-3]. The PV based outcomes have been further broadened on their interconnection to grid. Actually the enhancement in the power electronics technology have boosted the utilisation of PV supplied to inverter as that of grid interconnection capabilities efficiently [4-5]. However, the power quality has degraded by switching actions because of the propagation of nonlinear loads, due to their compactness and better controllability. Whenever these power electronics systems are connected to the utility, they cause harmonics, sub harmonics or also at times cause super harmonics in current and voltage patterns. As a consequence of which they can cause malfunctioning in the electrical equipment. To overcome this constrains, different types of filters have been introduced for filtering the harmonics and for reactive power compensation. Also there are some demerits of filter, such as they cause the system to be greater in size and resonant problems, hence gives good margin to carry out research in domain of passive filter. In order to enhance the quality of power, taking into account the voltage and current distortion limits for nonlinear load, numerous system have been proposed. Custom power devices like DVR, DSTATCOM and UPQC have been proposed in recent years for improvement of power quality in the electrical distribution system. Development in manufacturing of power semiconducting devices have led to better characteristics such as higher voltage rating, current rating and at the same time higher switching frequency. In addition to repress voltage and