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Mathematical Problems in Engineering
Volume 2006, Article ID 90416, 21 pages

Passivity and passivation of interconnected time-delay models of reheat power systems

1C-Group Consultants, P.O. Box 293 Orman, Dokki, Giza 12311, Egypt
2College of Engineering, United Arab Emirates University, P.O. Box 17555, Al-Ain, United Arab Emirates

Received 10 March 2005; Accepted 24 January 2006

Copyright © 2006 Magdi S. Mahmoud and Abdulla Ismail. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This paper investigates the problems of delay-dependent passivity and passivation of a class of linear interconnected time-delay systems with particular emphasis on multiarea reheat power systems. This class contains state delay in the dynamics and observation at the subsystem (local) level. A new state transformation is developed to exhibit the delay dependence in the system dynamics and a less conservative passivity-bounding inequality is incorporated. Through the analytical development, it is established that the passivity condition can be cast in a linear matrix inequality (LMI) format at the subsystem level thereby facilitating decentralized passivity analysis. For state-feedback passivation, it is proven that it is indifferent to use instantaneous or delayed decentralized state feedback. The case of dynamic output-feedback passivation is also treated. The analytical developments are simulated to a typical multiarea power system and the ensuing results show satisfactory performance.