Refinement of conventional PSS design in multimachine system by modal analysis

The design of the lead/lag network in a conventional power system stabilizer (PSS) is intended to provide the correct compensation in order to obtain an electrical torque component in phase with the speed variation. It is shown that, for a multimachine system, the conventional design analysis and synthesis tend to oversimplify the system representation and hence the interaction effects. A more rigorous approach that considers four torque (or power) components instead of the conventional single component is discussed. Using a modal analysis, the significance of these other components is revealed, the more comprehensive treatment using a generalized multimachine representation is justified and a reliable means for optimizing the PSS parameters is presented