Robust PSS design considering multi-operating conditions

An approach for robust PSS design is presented in this paper, in which multi-operating conditions of a power system is considered by the probabilistic technique. With the assumption of normal distribution, the distribution properties of eigenvalues are obtained by the probabilistic eigenvalue analysis, and described by expectations and variances. To enhance system damping by using PSSs, effects of PSSs on both eigenvalue expectation and variance have been determined, and the conventional eigenvalue sensitivity analysis has been extended to a probabilistic environment. Two types of probabilistic sensitivity indices (PSIs) are formed and employed for robust PSS site selection and PSS parameters adjustment.