Power system consist of number of synchronous machine and operating in synchronism under all operating condition.when the system is subjected to electrical fault all of sudden , the system undergoes a transient disturbance as a result the system may become unstable, it may loose synchronism, in order to know the behavior of the system under transient condition which is described by swing equation, which is a non linear differential equation second order which describe the swing of the rotor of synchronous machine.
