Damped Nyquist Plot for the Phase and Gain Optimization of Power System Stabilizers

Abstract

This paper presents a method to optimize the tuning of a power system stabilizer (PSS) with the objective of simultaneously damping electromechanical poles of different nature. The damped Nyquist plot (DNP) is used to determine the PSS phase and gain compensation requirements to place each pole at a predefined location in the complex plane. A non–linear least–squares curve fitting problem is solved to find the set of PSS parameters that leads to the optimum trade–off for all dominant poles based on a single eigenvalue calculation per operation scenario. The PSS tuning is performed on a two–bus synthetic power system model whose results are validated against a three-machine IEEE benchmark model results. The advantages of using the DNP method together with the synthetic system to perform a PSS tuning in practice are emphasized.