Improved hybrid approach to transient stability assessment

The characteristics of the minimum transient kinetic energy of post-fault trajectories are studied in order to develop a tool for dynamic security assessment during the operation mode analysis of power systems. Using available commercial software a strategy for the transient stability study is introduced to enable harmless contingencies to be screened out and the classification of high-risk and harmful contingencies to be performed. Based on these characteristics, an approach to transient stability assessment is proposed and applied to the assessment at the hybrid transient energy margin for high-risk and harmful contingencies. The significant advantage of this approach is that the identification of a critical machine group is completely unnecessary. Case studies on a small test system, the ten-generator New England test power system and a realistic system, the middle-China power network are presented to verify the effectiveness and efficiency of this method.