On the natural frequency of oscillations for synchronous machines

Power system stability is a fundamental concept which is involved in many studies. It includes many sub definitions such as the natural frequency of the machine and the sub-synchronous resonance in addition to many other circumstances of the power system. To get the full picture of these concepts, many models are created and studied through the vast literature sources on power systems. Natural frequency of a machine is a unique and specific property of this machine and it is not considered a fixed parameter for it. It changes according to many factors, such as the machine connection, whether is it connected to an infinite bus network or forms a single stand alone generator supplying local loads or it is connected in parallel with other machines at a power network.