Abstract
In this paper Eigenvalue estimation method for small signal stability analysis of the electric power systems is proposed. The developed method is named Mode Coupling Method which is the method for estimating the non-linear change of the eigenvalue for the change of parameter, efficiently. The eigenvalue sensitivity analysis method, which has been used to estimate the change of the eigenvalue, is a linear estimation of the change of the eigenvalue. However, the eigenvalue shows a strong nonlinear change frequently. Therefore, the calculating efficiency and the calculating speed were insufficient by the conventional method. In the Mode Coupling Method, at first, it selects the important and most related modes with the major mode for that we pay attention. Next, these two or more selected modes are coupled and a new eigenvalues of the coupled matrix are calculated, those are good estimation of new eigenvalues. The size of the coupled matrix is very small. We can consider mutual interaction between important modes. As a result, it is a powerful method in which nonlinear estimation of the eigenvalue is possible. When QR method is used, the calculation time which is required for eigenvalue analysis, is proportional to the third power of the size of the matrix. The size of the matrix which is used for Mode Coupling Method, is approximately 1/6 of the origin. Therefore, the computing time for eigenvalues estimation becomes less than 1% of computing time of the origin. Concerning the computing accuracy of the proposed method, verification was done with IEEJ standard power system model EAST30.
