29 Saurabh S. Jadhao, Gaurav G. Gulhane, Dr. Gajanan M. Dhole, Dr. Mrs. A. U. Jawdekar International Journal of Electronics, Electrical and Computational System IJEECS ISSN 2348-117X Volume 6, Issue 8 August 2017 Unified Power Quality Conditioner for Current Quality Improvement Saurabh S. Jadhao Shri Sant Gajanan Maharaj College Of Engineering, Shegaon, India. Gaurav G. Gulhane Shri Sant Gajanan Maharaj College Of Engineering, Shegaon, India. Dr. Gajanan M. Dhole Gokhale College Of Engineering,Nasik, India. Dr. Mrs. A. U. Jawdekar Shri Sant Gajanan Maharaj College Of Engineering, Shegaon, India. ABSTRACT Presence of power quality disturbances highly influences the performance of power system. Most modern electrical appliances for example industrial drives, electronic ballast fluorescent lights, switching power supplies and so forth are becoming increasingly power electronics based. Whereas these loads possess certain advantages like, enhanced controllability, high power density and so forth, they also bring with them disadvantages which were not there in the early power distribution systems. Some of these disadvantages include increased sensitivity to supply voltage, harmonics and reactive power requirements. These inherent characteristics of power electronic based loads have helped to raise awareness of power quality issues. Most of the word nowadays moving towards the implementation of renewable energy resources to support the rapid increase in load demand. The integration of renewable energies and their accommodation in the existing electricity networks is often a complex issue and is making the electric power distribution networks more susceptible to power quality problems. There are several methods to illuminate all this problems depending upon their severity. One of the best solution for these all power quality issues i.e. unified power quality conditioner is discuss in this paper. A three phase four wire system is analysed in Simulink with different control algorithm. Keywords: Series APF, Shunt APF, harmonic compensation, voltage quality improvement, control strategies. INTRODUCTION In recent year, there is incredible use of complex systems with technologically advanced component such as non-linear load, Uninterruptable power supply, rectifier loads, power electronics devices in domestic as well as industrial area. These components not only affect the source but also impure the power supply inherently. This will replicate the generation of various power quality disturbances such as noise, voltage harmonics, current harmonics, transients, etc. The effect of all these power quality issues are always depends upon cause of disturbances and its occurrence.IEC and IEEE design various international standards for power quality safety and awareness. The solutions to all the power quality obstacles will also depends upon its causes of occurrences, location, time period effect, frequency of occurrence. These all changes in behaviour of supply system also affect on the end users equipment. Today’s power system is usually as three phase three wire or three phase four wire fetching with significant limit to voltage source with source impedance and having a mixture of various types of loads. As per the IEEE standards and view of ideal condition of power systems a pure and balance three phase voltage of constant magnitude should be provided to consumer with as less as possible power quality problems. However with the use of power electronics devices and several non-linear loads,reactive,single phase and unbalance three phase load making structure of system more complex with several power quality issues. At the same side in recent year several active methods of improving power quality have been highlighted with their fast response and