Two reduced-order methods for studies of power system dynamics

The authors present two reduced-order methods, namely second-order aggregation and external system partition, for the analysis of power system dynamics. These methods are developed by the combination of the machine mode associate property with the aggregated model of multimachine systems. An 18-machine and a 9-machine power system are employed to numerically verify the basic concept and the methods. The verification results show that the first method is suited for the computation of all swing modes, while the second method is suited for computing the modes associated with a selected machine group.<>