“…4 and also far from the region boundary as much as possible. This requirement may be formulated as the following multi-objective function: (10) where σ n,k stands for the real part of n-the eigenvalue of the matrix A k which is obtained by combining matrix A gk with the matrix A p , B p , C p , and D p of the PSS, and ζ n,k denotes the corresponding damping factor. It can be seen that this multi-objective function tends to find PSS parameters such that σ max , the maximum real part of poles of all operating conditions, is minimum, and ζ min , the minimum damping ratio, is maximum.…”