Stability studies of multimachine power systems with the effects of automatic voltage regulators

The stability of power systems including the effects of automatic voltage regulators is studied via Lyapunov's direct method. The multivariable Popov criterion developed by Moore and Anderson is employed in constructing a Luré-type function for a power system consisting of synchronous machines interconnected by a lossless transmission system. The Lyapunov function constructed for the system with only flux decay is regarded as a special case of the result obtained in this paper. The effect of an automatic voltage regulator on power system stability is illustrated by numerical examples, showing some shifts of equipotential curves which are due to changes of voltage regulator gain.