Generalized proportional-integral controller for dynamic voltage restorers Alfonso Parren ˜o Torres Robotics and Automation Centre, Albacete Science and Technology Park, Albacete, Spain, and Pedro Roncero-Sa ´nchez, Xavier del Toro Garcı ´a and Vicente Feliu Batlle Department of Electrical, Electronics, Control Engineering and Communications, University of Castilla-La Mancha, Ciudad Real, Spain Abstract Purpose – The protection of sensitive loads connected to power distribution grids from the existing disturbances has become an important issue in recent years. This paper aims to evaluate the advantages of a new control strategy, known as the generalized proportional-integral (GPI) control, to compensate voltage sags when using dynamic voltage restorers (DVR). Design/methodology/approach – The DVR application and the principles of the GPI control method are first introduced. In addition, a procedure to adjust the controller for the DVR application is described. Finally, the performance of the controller is extensively tested using the PSCAD/EMTDC simulation software for a variety of conditions including: balanced and imbalanced voltage sags, frequency deviations and parameter variations. Findings – The GPI controller provides an excellent tradeoff between accuracy, response time and robustness. Originality/value – The GPI controller is presented here as a new approach to compensate balanced and imbalanced voltage sags using a DVR. The results obtained with the proposed control system and the described methodology to adjust the control parameters make it a very suitable solution for this application. It is important to note that fast tracking and high accuracy are achieved as illustrated in the control responses. Furthermore, the analysis of the robustness against parameter variations and frequency deviations demonstrates one of the most remarkable advantages of the new control method. Keywords Power quality, Voltage sag, Dynamic voltage restorer, GPI control, Voltage fluctuations, Electric control equipment Paper type Research paper The current issue and full text archive of this journal is available at www.emeraldinsight.com/0332-1649.htm This work has been partially supported by the Spanish Ministry of Science and Innovation in the framework of the National Program of Scientific Research, Development and Technological Innovation (2008-2011) and by the European Regional Development Fund under the Research Project IPT-2011-1468-920000. Additionally, this work has been partially supported by the European Social Fund and the Council of Castilla-La Mancha under the Research Project PII2I09-0088-1366. An earlier version of this paper was selected as a Best Paper of the 7th International Conference-Workshop “Compatibility and Power Electronics” (CPE’ 2011). COMPEL 31,6 1964 COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering Vol. 31 No. 6, 2012 pp. 1964-1984 q Emerald Group Publishing Limited 0332-1649 DOI 10.1108/03321641211267236