Absolute kinetic energy increment of the generator rotor for distinguishing unstable modes

A discrimination index was developed for the unstable modes of complex power system experiencing large disturbances. The swing equation of the generator rotor was used to analyze the physical significance of the integral of the unbalanced rotor power and its relation to the potential energy for transient stability. The analysis was used to define the absolute kinetic energy and relative kinetic energy of generator rotors. Since a generator with large absolute kinetic energy increment is more likely to loss synchronization, an algorithm was developed based on the absolute kinetic energy increment to distinguish the unstable modes. Simulation results for actual power systems verify the accuracy of the algorithm.