Electrical Power Quality Improvement Assessment Using Multilevel Inverters P. K. Charturvedi 1 and Shailendra Jain 2 1 R/S MANIT Bhopal & Lecturer, Electrical Engg Deptt, SATI, Vidisha, MP, India, e-mail:pradyumnc74@rediffmail.com 2 Assistant Professor, Electrical Engg. Deptt, MANIT, Bhopal, India, e-mai:shailjain02@rediffmail.com Abstract: Recently the issue of power quality has become of growing interest and leads to implementation of standards such as IEEE-519. Therefore, sophisticated electronic equipments used in various industries, commercial and residential applications are looking for pollution free and reliable power supply. The injected harmonics, reactive power burden, unbalance and excessive neutral current due to these nonlinear loads cause low system efficiency and poor power factor. This paper presents the viable solution for power quality improvement in terms of reduced harmonic pollution in electric power supply, improved system reliability and improved electric power quality using a very promising power conversion device i.e. Multilevel Inverter. Key Words: Multilevel Inverters, Power Quality, Total Harmonic Distortion. INTRODUCTION In recent years, Power Electronic Converters are widely employed to control flow of power to almost all types of electrical loads ranging from few watts to megawatts, such as variable speed drives, power supplies, arc furnaces etc. In addition to numerous advantages these power electronic converters suffer from the problem of drawing harmonics and reactive component of current from the source and offer highly nonlinear characteristics. They also cause unbalance, excessive neutral current and disturbance to the other consumers. It has led to distortion of voltage and current waveforms. As a consequence, recently the issue of power quality has become of growing interest and leads to implementation of standards such as IEEE-519. The term ‘Power Quality’ means variation of voltage, current, and frequency of the power system. The increasing use of power electronic equipments in every application increased the amount of non-sinusoidal currents and voltages at customers and utility end. Solid-state power converters are being increasingly used in the developing countries like India. At one end growing industrial environment uses more and more power electronic converters, polluting the quality, on the other hand sophisticated electronic equipments used in various industries, commercial and residential applications are looking for pollution free and reliable power supply. The injected harmonics, reactive power burden, unbalance and excessive neutral current due to these nonlinear loads cause low system efficiency and poor power factor [1-8]. Power quality improvement is receiving a great deal of attention recently at International level, due to the fact that nonlinear loads comprise a larger portion of total connected load It leads to implementation of standards such as IEEE-519-1992 “Recommended Practices for Harmonic Control in Electric Power Systems” Implementation of such standards put certain responsibilities on both utilities and individual consumers to improve the power quality. Advances in Power Electronics have made possible an efficient conversion from DC to AC Power through the use of semiconductor switches. Conventional 2-level inverter with PWM technique is being used widely in various utility applications like harmonic filtering, reactive VAR compensation, voltage regulation, AC Drives, induction heating, standby power supplies and uninterruptible power supply etc [2,3]. With the availability of high-speed semiconductor power devices, the harmonic contents of output voltage waveform can be minimized by various switching techniques using Pulse Width Modulation (PWM). Several Pulse Width Modulation techniques are researched & developed. The sinusoidal PWM technique suffers from harmonic pollution produced due to the presence of converters utilizing high frequency switching devices and results in non-linear behavior of the converter [2-5].