International Journal of Power Electronics and Drive System (IJPEDS) Vol. 9, No. 4, December 2018, pp. 1709~1717 ISSN: 2088-8694, DOI: 10.11591/ijpeds.v9.i4.pp1709-1717  1709 Journal homepage: http://iaescore.com/journals/index.php/IJPEDS A Generalized Parameter Tuning Method of Proportional- Resonant Controllers for Dynamic Voltage Restorers Phuong Vu 1 , Ngoc Dinh 2 , Nam Hoang 3 , Quan Nguyen 4 , Dich Nguyen 5 , Minh Tran 6 1,2,3,5,6 School of Electrical Engineering, Hanoi University of Science and Technology, Hanoi, Vietnam 4 Department of Electrical and Computer Engineering, The University of Texas at Austin, Texas, U.S.A Article Info ABSTRACT Article history: Received May 11, 2018 Revised Aug 11, 2018 Accepted Sep 11, 2018 Temporary voltage swells and sags appear with high frequency in electric power systems, and they significantly affect sensitive loads such as industrial manufacturing or communication devices. This paper presents a strategy to design proportional-resonant controllers for three full-bridge voltage-source converters with a common DC-link in dynamic voltage restorer systems. The proposed controllers allow the system to quickly overcome temporary unbalanced voltage sags. Simulation results carried out in MATLAB/Simulink and experimental results implemented in a Typhoon HIL402 device demonstrate the ability of the proposed design method. The results show that the system with the proposed controllers can ride-through single-phase or double-phase voltage sags up to 55% and three-phase voltage sags up to 70% in a duration less than one grid-voltage cycle. Keyword: Dynamic voltage restorer Proportional-resonant controller Hardware-in-the-loop Copyright © 2018 Institute of Advanced Engineering and Science. All rights reserved. Corresponding Author: Phuong Vu, School of Electrical Engineering, Hanoi University of Science and Technology, No.1, Dai Co Viet Road, Hai Ba Trung, Hanoi, Vietnam. Email: phuong.vuhoang@hust.edu.vn 1. INTRODUCTION Power quality disturbances such as voltage sag and swell have been causing serious concerns for modern distribution systems operated at low- and medium-voltage levels. The percentage of voltage sags caused by single line-to-ground fault, double line-to-ground fault, and balanced three phase-to-ground fault in power systems are 68%, 19%, 13%, respectively [1]. Such voltage variations in short durations (less than 60 seconds) lead to improper operation of sensitive loads, while longer voltage variations can result in sustained interruptions or failures. Therefore, mitigating voltage sags and swells in low- and medium-voltage distribution systems is critical. One of the most solution to improve voltage regulation is dynamic voltage restorers (DVRs). The operating principle of DVRs is to inject appropriate voltage in series and synchronism with the distorted AC grid source to compensate for the amount of voltage sag or swell [2]-[4]. A DVR system includes an energy storage, a three-phase voltage-source inverter, and series connected transformers between an AC grid source and a load. Regarding the three-phase voltage-source inverters, it is necessary to control the positive-, negative-, and zero-sequence components to compensate the voltage sag or swell of each phase [5]. Therefore, the control scheme is complicated and insufficiently reliable. To eliminate voltage sags and swells, several alternative topologies of DVR have been introduced such as a three-phase inverters with a neutral point created by a DC-link capacitor, three-phase four-wire inverters, and three single-phase full- bridge inverters with a common DC-link capacitor [6],[7]. The latter is preferred because of the simple pulse- width modulation (PWM) method. In DVR systems using three full-bridge inverters with a common DC-link capacitor, several control approaches have been suggested. A coordination of both feed-back and feed-forward control in