A SPARSITY-ORIENTED TECHNIQUE FOR POWER-SYSTEM SMALL-SIGNAL STABILITY ANALYSIS WITH A PRECONDITION CONJUGATE RESIDUAL METHOD

This paper presents an efficient method for small signal stability assessment in real-size power systems. Eigenvalue analysis based approaches have been studied to evaluate the stability problem. The conventional methods require calculating all the eigenvalues in evaluating small signal stability. Among them, the QR method is widely-used due to its robustness and high accuracy. However, the method has a drawback in that it is not applicable to real-life systems with respect to computational time and storage. Recently, the S-matrix method has been developed to overcome the problem. The idea of the method is based on mapping the most critical eigenvalue from s-plane to z-plane. As a result, the method requires calculating only the most critical eigenvalue rather than all the eigenvalues. Although the method is theoretically elegant, it has a numerical problem. It generates unnecessary fill-in elements which result in increasing computational time since the direct method is used in solving a set of linear equations. That becomes more significant with system size. In this paper, an efficient indirect method is developed using a precondition technique. The proposed method has been successfully applied to several systems. The simulation results indicated that the proposed method is 30 times and 5 times faster than the QR and the S-matrix methods, respectively, for a 46-unit, 191-bus system.