Stability analysis of power systems by Lyapunov´s direct method

The Lyapunov direct method is on the verge of being implemented for assessment of online dynamic security. The main bottleneck has been in the proper characterization of the stability boundary and defining the fault-dependent region of attraction locally around the controlling unstable equilibrium points. Now there is a better understanding of this issue, and hence, a number of algorithms have been proposed. Improved generating-unit models and transmission-network models are now being included in the technique. An overview is presented of the theory, practical implementation, and future research.<>