Robust Damping Controller for Synchronous Generators under Operational Uncertainties

Power system stabilizers have been widely used to create sufficient damping against low-frequency oscillations. Due to appearing new uncertainties in operational conditions of power systems, robust design of stabilizers and damping controllers is a crucial requirement for small signal stability. In this paper, a robust local damping controller is developed considering the possible uncertainties in operational conditions. The developed damping controller is optimized based on the H-infinity method in presence of uncertainties in electrical variables of the synchronous machine including rotor angle, rotor speed, and terminal voltage magnitude. In the proposed robust damping controller, only the practically available control signals such as the deviation of the rotor speed of the synchronous generators are used. To fulfill the robust and internal stabilities of the damping controller under a given horizon of operational uncertainties, a novel design based on the combination of the developed robust damping controller and the conventional power system stabilizer is introduced. Simultaneous damping of local oscillatory modes and the internal stability of the proposed robust controller is achieved via a multi-objective function. The efficacy of the proposed local damping controller is compared with the conventional stabilizer and a damping controller that is designed using the pole placement approach.