A PSS design using gain scheduling theory and disturbance observer

The conventional PSS is generally designed to be effective in a linearized model at a certain operating point. In the power system, when the state of the system configuration and the power flow change, the performance and stability of PSS are not guaranteed theoretically. In this paper, we propose a designing method of generator control based on the gain scheduling theory which has the robustness for different operating points. Moreover we propose an application of a disturbance observer to the generator control in order to suppress the disturbance and the influence of interaction among generators and to have more robustness for the control. The validity of the proposed generator control is verified using a 3 machine 9 bus system by carrying out nonlinear simulations of a three-phase to ground fault for system condition changes.