Nonlinear measures of mode-machine participation [transmission system stability]

This work investigates the significance of higher-order terms on the modal behavior of a large, stressed power system´s transient response. Second-order analysis indicates that many more frequencies of oscillation may have significant influence on the power system response. These additional frequencies result from second-order interactions of the linear modes and cannot be studied using linear analysis. A methodology based on the normal-form method is developed and utilized to describe the stressed, nonlinear system response. This methodology is used to extend linear concepts, such as eigenvectors and mode-state participation, to include second-order modal affects on power system performance. Data from the 50-generator IEEE test system is used in this investigation