Torque-angle characteristics of synchronous machines following system disturbances

The DETERMINATION of the behavior of synchronous machines during transient conditions subsequent to a system disturbance is becoming increasingly interesting and important. In determining this behavior it is essential to know the torque-angle characteristic of the given machine under conditions resulting from disturbances of various sorts. The most important of such disturbances are variations in mechanical torque, excitation voltage, amount of external reactance, and system voltage. System voltage may vary in either magnitude or angular position.