Advantages of the passivity based control in dynamic voltage restorers for power quality improvement Mario González a,⇑ , Víctor Cárdenas a , Gerardo Espinosa b a Universidad Autónoma de San Luis Potosí (UASLP), Centro de Investigación y estudios de posgrado, Facultad de Ingeniería, Dr. Manuel Nava #8, Zona Universitaria, 78290 San Luis Potosi, SLP, Mexico b Universidad Nacional Autónoma De México (UNAM), Facultad de Ingeniería, Ciudad Universitaria, Delegación Coyoacán, 04510 Mexico City, DF, Mexico article info Article history: Received 27 July 2013 Received in revised form 20 June 2014 Accepted 21 June 2014 Available online 17 July 2014 Keywords: Passivity based control PI control Dynamic voltage restorer Power quality Sag Swell Harmonic distortion abstract A better and feasible control strategy for dynamic voltage restorers (DVR) is presented in this paper: the passivity based control (PBC) allows a better compensation performance under transient and steady state operating conditions, and provides tracking with zero error of any reference for linear and nonlinear loads. The closed-loop source-DVR-PBC-load system is asymptotically stable at all operating points, with practically very slight con- straints; its transient response is faster than with classical controllers, and does not present overshoots. These characteristics do not depend on source voltage disturbances, the kind of load, or parameter variations. The PBC uses less digital operations than the PI, and does not require dq transformations. Ó 2014 Elsevier B.V. All rights reserved. 1. Introduction Linear control has always been considered the standard solution to use in static power converters. The PI control and other classical linear controllers have been extensively used in the power quality field to perform online compensation of voltage or current disturbances, aiming to protect critical equipment. The PI control is normally used either in current or voltage loop schemes, but normally a zero steady state error is not fully achieved and the stability is restricted around a region of one operating point. In some power converter applications the system in fact moves the operating point constantly, and then a more suitable controller is needed. One topology for power quality improvement which has received special attention is the dynamic voltage restorer (DVR) (Fig. 1), since it can protect voltage-sensitive equipment from sags and swells [1,2]. The DVR is basically a series compensator equipped usually with energy storage which is inserted between the source and the critical load. With the series scheme, several reported research works have focused only on the compensation of sags with active power (VR), and others are focused only on the active filter function (AF). Since the same series-scheme is used for both the AF and the VR functions, and the functions do not oppose each other, it is theoretically possible to apply both simultaneously; using the fundamental voltage component of the compensator for load voltage regulation, and its harmonic components to cancel the harmonic dis- tortion. To compensate swells, the compensator usually must have regeneration means, a mechanism of dissipation, or the capacity of power absorption. One approach to avoid this is by regulating the load voltage making the compensator use only http://dx.doi.org/10.1016/j.simpat.2014.06.009 1569-190X/Ó 2014 Elsevier B.V. All rights reserved. ⇑ Corresponding author. Tel./fax: +52 (444) 817 33 81. E-mail addresses: gonzalezgm4@gmail.com (M. González), vcardena@uaslp.mx (V. Cárdenas), gerardoe@servidor.unam.mx (G. Espinosa). Simulation Modelling Practice and Theory 47 (2014) 221–235 Contents lists available at ScienceDirect Simulation Modelling Practice and Theory journal homepage: www.elsevier.com/locate/simpat