On the effectiveness of applying online dynamic security assessment in power system optimal operation

A method to integrate dynamic security assessment of a power system with the optimal dispatch solution is described. The method is based on a dynamic security monitoring program which assesses the online operating condition of the system. A dynamic security margin that measures the robustness of the system when it is subjected to a selected scenario of contingency is discussed. The method also identifies the critical machine or cluster of machines that may cause transient instability based on certain worst contingencies. Hence preventive control actions are determined to avoid such cascading tripouts that may lead to system collapse. To apply the methodology effectively, the authors also discuss the fast direct methods of dynamic security assessment that may be used. A proposed scheme that uses a reduced dynamic equivalent is hence described and simulation results of sample power systems are presented to demonstrate its effectiveness as a real-time dynamic security monitor in such optimal operational environment