A new approach to dynamic contingency selection

A method is proposed for contingency selection for the dynamic security assessment of large power systems. The proposed method iteratively computes the eigenvalues of the system under outage conditions. The initial values for the iterative procedure are the eigenvalues for the normal operating condition (base-case eigenvalues). To reduce the computational burden, the eigenvalues of the system under outage conditions from the first iteration are used for contingency ranking. From the results obtained from a study on the Taiwan power system, it is concluded that contingency ranking using the eigenvalues from the first iteration is both accurate and efficient. It is also found that only the eigenvalues for the worst-damped mode must be considered in contingency ranking. To further improve the efficiency of the proposed method, results obtained from the first iteration of the fast decoupled load flow (FDLF) are also used to model the operating conditions after contingencies. Again, it is observed that satisfactory dynamic contingency selection can be achieved by using the first iteration of FDLF with much less computational effort than that required by full AC power flow