International Electrical Engineering Journal (IEEJ) Vol. 4 (2013) No. 1, pp. 953-961 ISSN 2078-2365 953 NEURO-FUZZY BASED POWER QUALITY IMPROVEMENTS IN A THREE PHASE FOUR WIRE DISTRIBUTION SYSTEM USING DSTATCOM NEURO-FUZZY BASED POWER QUALITY IMPROVEMENTS IN A THREE PHASE FOUR WIRE DISTRIBUTION SYSTEM USING DSTATCOM E.Babu 1 ,R.Subramanian 2 1 , Department of Electrical and electronics engg 2 Department of Electrical and electronics engg 1 babuesec@gmail.com, 2 rama.smani@gmail.com Abstract- This project presents reactive power compensation in a distribution power system. DSTATCOM (distribution static compensator) is a reactive power compensator for power quality improvement in a three phase four wire distribution system. A voltage source converter (VSC) based DSTATCOM with a zig-zag transformer is used for the compensation of reactive power for voltage regulation along with load balancing, elimination of harmonic currents, and also the neutral current compensation at the point of common coupling. The neuro-fuzzy based system is used to control scheme of the VSC. The zig-zag transformer is used for providing a path to the zero sequence current in a three-phase four-wire distribution system. The performance of the proposed DSTATCOM system is verified through simulations using MATLAB software with its Simulink. Keywords- Distribution static compensator (DSTATCOM), voltage-source converter (VSC), zig- zag transformer and neutral current compensation. I. INTRODUCTION The present day ac power distribution systems are suffering from severe power quality problems. These power quality problems include high reactive power burden, harmonics currents, load unbalance and excessive neutral current etc. The power quality at the point of common coupling (PCC) with the utility grid is governed by the various standards and the IEEE- 519 standard is widely accepted. Some remedies to these power quality problems are reported in the literature. A group of controllers together called Custom Power Devices, which includes the DSTATCOM (distribution static compensator), DVR (dynamic voltage restorer) and UPQC (unified power quality conditioner). The DSTATCOM is a shunt connected device, which takes the care of the power quality problems in the currents. Three-phase four-wire distribution systems are used to supply single-phase low voltage loads such as computer loads, lighting