ABSTRACT
Power system stability is a vast subject amply covered in the current literature. There are many definitions of the power system stability in the literature; however, with respect to fault disturbances and an initial steady-state equilibrium point, it explores whether the post-fault trajectory will settle down to a new equilibrium point in an acceptable steady state. The small angle stability considers that the disturbances are small and the system equations can be linearized. Sometimes, the small rotor angle stability is termed dynamic stability. The voltages in the system should be controlled following large disturbances, such as faults, loss of generation, or circuit contingencies, which may force the power flow through alternate routes of higher impedances. The term static stability may seem a misnomer for the dynamic nature of the electrical systems. The critical clearing angle is defined as the maximum angle at which the faulty section must be isolated to maintain the stability of the system.
