Saddle-node index as bounding value for Hopf bifurcations detection

Some aspects related to modal analysis in voltage stability studies are discussed. The idea is to determine a set of dominant eigenvalues during the voltage collapse path. This set contains the most critical eigenvalues, which are not, necessarily, the least eigenvalues commonly focused in modal analysis. This tool is then used to detect Hopf and saddle-node bifurcations, since the least real part of the eigenvalues are monitored. The results are obtained and discussed with the help of two sample systems with two and nine buses each.