Abstract
In the present work an algebraic and an optimal control method (in connection with linear continuous systems as well as a new optimal multirate control method (in connection with linear discrete systems) are presented and applied, in order to design a suitable excitation controller (analogue and digital type respectively) and thus obtain a pertinent closed-loop system with enhanced dynamic stability characteristics. The obtained computer simulation results, based on a practical power system of the Greek national grid, show clearly the validity-suitability-effectiveness and implementabilitv of the excitation controllers designed using these control procedures.