International Journal of Power Electronics and Drive System (IJPEDS) Vol. 10, No. 3, Sep 2019, pp. 1308~1316 ISSN: 2088-8694, DOI: 10.11591/ijpeds.v10.i3.pp1308-1316  1308 Journal homepage: http://iaescore.com/journals/index.php/IJPEDS Energy efficiency enhancement using dynamic voltage restorer (DVR) Muhammad Murtadha Othman 1 , Nik Muhamad Lokman Fahmi Nek Rakami 2 , Zulkiffli Abdul Hamid 3 , Ismail Musirin 4 , Mohammad Lutfi Othman 5 1,2,3,4 Faculty of Electrical Engineering, Universiti Teknologi MARA, Malaysia 5 Centre for Advanced Power and Energy Research and Department of Electrical and Electronics Engineering, Universiti Putra Malaysia, Malaysia Article Info ABSTRACT Article history: Received Jul 27, 2018 Revised Jan 12, 2019 Accepted Mar 15, 2019 Dynamic voltage restorer (DVR) is a device that can compensate harmonic, voltage sag and voltage swell condition that exists in a three-phase system. Other than that, DVR can also be used to enhance the energy efficiency or energy saving by reducing excessive amount of incoming power via the reduction incoming voltage at allowable limit. The DVR can inject the required voltage in the system so that the interruption of supply voltage can be compensated. The compensation of voltage supply interruption is improved based on the hysteresis voltage output of controller used in the DVR to detect the difference between reference voltage and disrupted voltage. The hysteresis voltage control mainly controlled by relays switching so that the signal can be sent to IGBT switches controller. The hysteresis voltage control and unipolar SPWM is supplied to control the IGBT switches by the DC supply for voltage interruption compensation. The unipolar SPWM technique converts the DC supply voltage into AC supplied voltage, thus making the DVR injection become easier to inject the AC voltage into the system to compensate voltage sag and voltage swell. Keywords: Dynamic voltage restorer (DVR) Energy efficiency Harmonic Hysteresis Voltage Control Voltage Sag Voltage Swell Copyright © 2019 Institute of Advanced Engineering and Science. All rights reserved. Corresponding Author: Muhammad Murtadha Othman, Faculty of Electrical Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia. Email: mamat505my@yahoo.com 1. INTRODUCTION Ideally, electricity should be provided efficiently and without any interruptions required or desired by utilities and users. Without the smooth continuity of electricity supply, the consumers may not receive their power demands efficiently [1-5]. However, the utilities may find it difficult to provide a clean and continuous electric supply due to the presence of harmonic distortion, voltage sag and voltage swell. The increasing usage of nonlinear loads in the industry often making the harmonic distortion level becomes critical [6-10]. Consequently, this will introduce inefficient energy consumption to the consumers. In addition, electricity plays an important role in productivity from many industrialized countries. Therefore, the usage of power electronic components used to control the non-linear load in the industrialized countries will also be increased. However, these components are sensitive devices that are requiring a constant of voltage magnitude, voltage frequency and voltage phase [11]. They required a good power quality in order to avoid any failure in the power electronic components and electrical equipment in such a way that it will breakdown in electrical equipment and eventually damage the electrical equipment as well as slowly shorten their lifespan [12]. Therefore, this issue is not a trivial problem for countries that are developing their products in the industry. Voltage sag and swell are the main issue that may cause the power quality problem [13-17]. DVR is one of the wise solutions used to mitigate the power quality problem. It is