Cutset stability criterion for power systems using a structure-preserving model

The direct assessment of large-disturbance stability using the model given by Bergen and Hill is studied. this model differs from the usual classical model with constant-impedance loads in that no network reduction is used; the system structure is preserved with the loads modelled as first-order dynamical systems. A new style of stability criterion is suggested which is based on local transient energy flow across network cutsets. This is found to give a more accurate assessment of stability than the usual approach based on total transient energy in the system. The criterion is applied to 5-bus and 14-bus example systems.