Modified Hopf bifurcation index for power system stability assessment

An index to identify Hopf bifurcation points in power systems is proposed. Two models are used to exploit the method. When the network dynamics are modelled, systems susceptible to subsynchronous resonance are identified. On the other hand, if interactions between the network and generators are not the focus, Hopf bifurcations may be identified as a consequence of generator oscillations. The index proposed is based on the calculation of a reduced set of eigenvalues, rendering the technique effective even for large power systems. Additional analysis is carried out for two techniques previously proposed in the literature, which are based on the calculation of the least singular value of an augmented system matrix, and on its least eigenvalue.