This paper considers the coordinated design of power system stabilizers and
supplementary control of flexible AC transmission systems (FACTS) devices
aiming at the robustness of the control scheme for drastic changes in the o
perating condition. The problem is treated as the design of a single state
feedback controller for the whole power system. The existence of several co
ntrollers is taken into account by introducing structural constraints in th
e design. A design method that explicitly considers both the coordination a
nd the robustness issues is presented. The method is based on the formulati
on and solution of an augmented Riccati equation. A benchmark illustrates t
he limitations of the classical control design and the robustness achieved
by the proposed design method. (C) 2000 Published by Elsevier Science Ltd.