Damping and synchronizing torques of closely coupled generators

This paper investigates the effect of the interaction of the various generators installed in a single plant in different configurations, namely, equally loaded similar generators, unequally loaded similar generators and dissimilar generators. The investigation is carried out by using modal analysis and by calculation of the damping and synchronizing torques. To perform the latter, the concept of damping and synchronizing torque of a single-machine infinite-bus system is extended and generalized for the case of a multimachine plant. The paper shows that the single-machine equivalence is only accurate for equally loaded similar generators. Also, it shows that adding more units may decrease the relative stability of the various units in the plant. In this context, the plant which comprises dissimilar units exhibits better values for the damping and synchronizing torque coefficients.