English title

This paper suggests a method for designing PSS to damp multi-machine power system oscillations.  The method is based on robust control theory. First, the conventional method for designing robust controller in LMI framework is illustrated. Then, the suggested method is given, in which, a PID output feedback controller is tuned using the LMI approach. Mostly, the classical methods are used to tune a PSS, but in this paper a robust approach is investigated to guarantee the robustness of the given PSS. The performance of the controller is tested on a sample power system. Simulation results show the effectiveness, robustness, and good performance of the suggested controller.