A new method for power system transient instability detection

Reliability and computational simplicity are of primary importance in developing on-line instability detection methods. With regard to these requirements, this paper has proposed a new method for instability detection based on generator angles, angular velocities, and their rates of change. According to the developed method, system instability or out-of-step condition is detected by identifying the characteristics-concave or convex-of a surface on which the post-fault system trajectory lies. The variation mode and probabilistic property of the proposed index are investigated by using the 10 machine 39 bus IEEE test system.