Analysis of structural properties responsible for nonlinear modal behavior of a stressed power system using the normal form technique

In this paper a scanning program is developed based on the normal form technique to analyze the structural properties of a stressed power system. The mathematical model and procedure are presented. Numerical testing on a 17-generator system shows that in the stressed systems, more modes can be strongly excited and new modal resonance phenomenon may occur, which will cause severe nonlinear behavior through modal interaction. The system nonlinearity is not uniformly distributed in various modes. The structural information obtained from the scanning program using the normal form technique makes it possible to efficiently analyze for each mode the dominant modal interaction and the quasi-modal-resonance which lead to the nonlinear modal behavior.