design of robust electric power system stabilizers using kharitonov’s theorem

a robust power system stabilizer (pss) is proposed as an effective way to damp-out oscillations in electric power systems. oscillations of small magnitude and low frequency, linked with the electromechanical models in power systems, often persist for long periods of time and in some cases present limitations on the power transfer capability. the proposed pss is designed according to kharitonov’s extremal gain margin theory. it has the following advantages: (i) it is based on simultaneous stabilization of limited number of extreme plants, (ii) the control design can be based on frequency response analysis techniques (root locus diagrams or nyquist plots) and (iii) the resulting controller is a low-order phase-lead compensator, which is robust to the change of operating points. the proposed power system stabilizer is tested through simulation experiments.