Optimal tuning of nonlinear parameters of a dual-input power system stabilizer based on analysis of trajectory sensitivities

This paper focuses on optimal tuning of nonlinear parameters of a dual-input power system stabilizer (dual-input PSS), which can improve the system damping performance immediately following a large disturbance. Until recently, various PSS models have developed to bring stability and reliability to power systems, and some of these models are used in industry applications. However, due to non-smooth nonlinearities from the interaction between linear parameters (gains and time constants of linear controllers) and nonlinear parameters (saturation output limits), the output limit parameters cannot be determined by the conventional tuning methods based on linear analysis. Only ad hoc tuning procedures ('trial and error' approach) have been used. Therefore, the steepest descent method is applied to implement the optimal tuning of the nonlinear parameters of the dual-input PSS. The gradient required in this optimization technique can be computed from trajectory sensitivities in hybrid system modeling with the differential-algebraic -impulsive-switched (DAIS) structure. The optimal output limits of the dual-input PSS are evaluated by time-domain simulation in both a single machine infinite bus (SMIB) system and a multi-machine power system in comparison with those of a sinale-input PSS.