Comparison of two methods of power systems stability degree assessment

The study focuses on the investigation small-signal stability in power systems using two methods. One of the methods is traditional method of modal analysis investigating behavior of the eigenvalues. Another one is a new sub-Gramians method that was worked out in Institute of Control Sciences (ICS) RAS. The method is based on the application of the so-called sub-Gramians derivable from solving the Lyapunov equations. The comparison of methods was made using the MATLAB software for two test systems: 1) a well-known model of transmission system proposed by P. Kundur, and 2) IEEE 57-bus test model.