Probabilistic eigenvalue sensitivity indices for robust PSS site selection

Probabilistic approach suitable for selecting locations of power system stabilisers (PSSs) is introduced in this paper. When multi-operating conditions of a power system are described by statistical attributes of nodal injections and considered in eigenvalue analysis, the probabilistic distribution of an eigenvalue is expressed by its expectation and variance under the assumption of normal distribution. PSSs will improve both expectations and variances for all concerned eigenvalues. Sensitivities of eigenvalue expectations and variances are calculated by means of the second-order eigenvalue sensitivities with respect to nodal injections and PSS gains. Probabilistic sensitivity indices used for selecting the robust PSS sites are equivalent to the probabilistic representation of the conventional participation factor and the residue. The proposed probabilistic approach is validated on two test systems