A generalized Heffron-Phillips model for multi-machine power systems with voltage and frequency dependent loads

In this paper the multi-machine Heffron-Phillips model is generalized to ha n die multi-machine pourer systems with frequency and voltage-dependent loa ds. A systematic method for extracting state equations is proposed which pr eserves structure and is able to account for infinite bus directly. The gen eralized model's block diagram is similar to that of Heffron-Phillips and i s suitable for generalizing dynamic studies of networks with impedance load s to networks with frequency- and voltage-dependent loads. Two applications of this model are presented: (l) studying effects of load model parameters on dynamic stability of a five-bus network, and (2) designing a PSS for a one-machine infinite bus with frequency- and voltage-dependent local load a nd comparing it with a PSS designed based on impedance load.