Abstract The employment of nonlinear control theories in power system have brought along fruitful results to enhance transient stability. However, from the viewpoint of engineering, it is still a long distance between theoretical analysis and practical implementation. This paper lays emphasis on exploring the gap between the control theory and application in real power system. First, the major approaches applied in power system, including feedback linearization approach, nonlinear robust control, and direct method based on Lyapunov theory, will be reviewed. Then the existing problem and physical constraints in real system will be investigated and summarized.