Power system stability assessment using sub-Gramian technique

We present the results of comparison of two methods used for examination of the small-signal stability in power systems. One of the methods is based on investigation of behavior of the eigenvalues. Another one is based on the so-called sub-Gramians that represent the eigen-parts in the spectral decomposition of a square H₂ norm of the transfer function. The analysis of behavior of the individual eigen-components allows earlier identification of arising conditions for possible power system instability. The comparison was made using the MATLAB software for two test systems: 1) a well-known model of transmission system proposed by P. Kundur, and 2) a model of power network on Russky Island.