From the Lyapunov general theory to a practical direct method for power system transient stability

The Lyapunov direct method began to be applied to power system transient stability in the early 60's. Since then, a tremendous amount of research has occurred, almost without interruption. This paper traces the milestones of this "Lyapunov adventure" with a threefold objective. First, to describe the main difficulties encountered and identify the types of practical approaches, which eventually emerged. Second, to show that such approaches, though seemingly different from the Lyapunov method, are actually close to it in spirit. Third, to describe one of these approaches, which goes beyond the expectations initially hoped for from the direct Lyapunov method, in particular, by opening up avenues to real-time preventive and emergency control.