Robust PID power system stabilizer design based on pole placement and nonlinear programming methods

Abstract

Power system stabilizers (PSS) are used to generate supplementary damping control signals for the excitation system in order to damp the low frequency oscillations (LFO) of the electric power system. The PSS is usually designed based on classical control approaches but this conventional PSS (CPSS) has some problems. To overcome the drawbacks of CPSS, numerous techniques have been proposed in literatures. In this paper a new robust hybrid method based on the combination of pole placement and nonlinear programming methods is proposed in order to design a robust power system stabilizer. The classical robust methods usually lead to a high order controller which is expensive, difficult to implement and somehow impossible. As a solution, in this paper a PID type PSS is considered for damping electric power system oscillations. The parameters of this PID type PSS (PID-PSS) are tuned based on pole placement and nonlinear programming methods. Therefore, not only the obtained PID-PSS is low order and easy to implement but also it has robust characteristics like robust controllers. The proposed PID-PSS is evaluated against the conventional and robust power system stabilizers in a single machine infinite bus power system considering system parametric uncertainties. The simulation results clearly indicate the effectiveness and validity of the proposed method. Keywords: Electric power system stabilizer, pole placement, nonlinear programming, robust control, PID controller.