Voltage control of emerging distribution systems with induction motor loads using robust LQG approach

N. K. Roy*, H. R. Pota, M. A. Mahmud, M. J. Hossain

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


This paper identifies a new mode called "critical voltage mode in emerging distribution systems. The small-signal stability analysis indicates that load voltage dynamics significantly influence the damping of the newly identified mode. This mode has frequency of oscillation between the electromechanical and subsynchronous oscillation of power systems. A novel voltage controller is designed to damp this voltage mode of the system. The controller is designed using the linear quadratic Gaussian (LQG) method with norm-bounded uncertainty. The approach considered in this paper is to find the smallest upper bound on the H norm of the uncertain system and to design an optimal controller based on this bound. The design method requires the solution of a linear matrix inequality. The performance of the designed controller is demonstrated on a distribution test system for different types of induction motors. Simulation results show that the proposed controller with a careful uncertainty modeling has significant performance to improve the voltage profile of the distributed generation system compared to the conventional excitation controller and standard LQG controller.

Original languageEnglish
Pages (from-to)927-943
Number of pages17
JournalInternational Transactions on Electrical Energy Systems
Issue number7
Early online date26 Apr 2013
Publication statusPublished - Jul 2014
Externally publishedYes


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