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As the operational conditions of power systems change, the operating point (i.e., the equilibrium point) may approach the small-signal security boundary. Given the current operating condition as well as the load and generation variations, it is meaningful to compute the small-signal security margin (SSSM). In this paper, an effective method that consists of three stages to compute the SSSM is proposed and examined. In the first stage, which is an estimation stage, the critical mode crossing the damping ratio line is estimated. The SSSM is then computed by a test function or by a direct method in the second stage, which is a correction stage. The computational results are then verified in the third stage, which is a verification stage. Numerical results on a 10-machine and a 160-machine system (with the state variables being 1600) show that the proposed three-stage method is efficient and promising. [ABSTRACT FROM AUTHOR]

As power system operation conditions vary, the system may move into critical operating conditions with oscillatory behaviors. In this paper, a generation rescheduling method is proposed for damping critical modes so that oscillations can be suppressed. This proposed method calculates the analytical eigenvalue sensitivity to identify the most effective generators for rescheduling to enhance the damping of the critical mode, thereby suppressing the oscillations. The eigenvalue sensitivity calculation is based on the structure-preserving network representation and the generalized eigenvalue problem. Numerical evaluation of the proposed method is performed with a focus on mode shape and participation factor analysis. The results show that the proposed method is effective in controlling power system oscillations via generation rescheduling. [ABSTRACT FROM PUBLISHER]

This paper investigates a procedure of coordinated tuning of power system decentralized damping controllers based on reduced-order model (ROM). In the paper, the cross-gramian technique is applied to obtain an equivalent ROM for power systems. Once the controllers' locations are selected appropriately, the critical modes are approximated well in the reduced model. The controllers are designed on ROM using search algorithm and then tested on the unreduced system to demonstrate their availability. The benefit of adopting ROM is to decrease the complexity of objective function computation. The proposed method is tested on power systems with 4-machine and 156-machine to validate its efficiency. [ABSTRACT FROM AUTHOR]

This paper describes inexact two-sided Jacobi- Davidson (ITSJD) method to compute the critical (least damping ratio) eigenvalues and corresponding left and right eigenvectors of power systems. Using approximation correction vectors to expand search spaces of two-sided Jacobi-Davidson method leads to ITSJD, which is used to compute eigenvalues closest to the target. Only one LU factorization is needed in whole iteration to improve the computing efficiency. The critical eigenvalues are mapped to extreme eigenvalues of Cayley transformation matrix which can be calculated by using ITSJD. The proposed method has been tested on systems with orders of 493, 1461, and 3781. The results show that ITSJD is effective and able to compute the critical eigenvalues and eigenvectors. [ABSTRACT FROM PUBLISHER]