Stability Analyses of SMIB and Multi-machine Power System Using Energy Function

System stability alert and preventive measures reduce risk of failure. This paper uses Lyapunov method to obtain transient energy function. The variation in the energy function determines the stable characteristic of power system. For large power system, kinetic energy function has been proposed to determine stability of power system. Then simulation on single machine infinite bus system, three-machine power system, IEEE 9-bus, IEEE 39-bus power system and three-area power system have done to validate performance. The plots and table show that krasovskii method is better than variable gradient method for constructing energy function. Further, kinetic energy function is found as good tool for identification of critical machine, group and area. This helps early action over instability in the large power system. Finally, it is observed that the results obtained are very satisfactory and have not been published elsewhere.