STUDY OF FREQUENCY RESPONSES OF GENERATOR ELECTRICAL TORQUES FOR POWER-SYSTEM STABILIZER DESIGN

Frequency response methods based on the concept of damping torque enha ncement have been successfully used in the design of practical power s ystem stabilizers. Central to this approach is the calculation of the frequency response from the automatic voltage regulator input to the e lectrical torque of a generator without the effect of rotor angle feed back. This paper carries out a study to deepen understanding of certai n important properties of the frequency response. It is shown that the frequency response of a generator can be considered as having two com ponents. One component, which depends only on the associated generator , is very significant and has a great effect on the overall frequency response; it has the important propel.ty that its shape is fixed indep endent of the operating condition of the associated generator. The oth er component depends on the associated generator as well as on the ext ernal system. However, this component is found to be not much affected by the dynamics of generators in the external system because of the d iagonal dominance of the reduced admittance matrix of the modified net work with generators lumped into it as dynamic admittances.