Habib Rajabi - Electrical Eng. Dept. Ferdowsi University Mashhad IRAN
Modir Shanehchi - Electrical Eng. Dept. Ferdowsi University Mashhad IRAN
Caro Lucas - Elc. & Comp. Eng. Dept. Teheran University Teheran IRAN

this paper effect of changes in the parameters of the power system on the performance of power system stabilizers is investigated and it is shown that these changes can result in system oscillation even in presence of PSS's. The Kharitonov's method of designing robust controllers is explained and shown that this method is not good enough for the PSS design in face wide variation of operating point. A new method for designing robust controllers for the power system is developed that uses the conventional PSS structure and tunes its parameters using a set of varied operating points. This new method is applied to design robust power system stabilizers for a study system and finally the superiority of it is shown.