INVESTIGATION OF MODAL INTERACTION AND ITS EFFECTS ON CONTROL PERFORMANCE IN STRESSED POWER-SYSTEMS USING NORMAL FORMS OF VECTOR-FIELDS

This paper presents a systematic scheme to evaluate nonlinear modal in teraction in a power system with excitation control and determine the effect of the interaction on control performance using the normal form s of vectors fields. The proposed approach has been applied to a two-a rea, four-generator system. The results obtained showed that the contr ol modes have significant interaction with the inertial modes, especia lly with the so-called interarea modes. The nonlinear interaction betw een modes following the excitation of certain specific modes could res ult in a detrimental effect on control performance when the controls a re designed based on purely linear analysis.