The generator in the figure below is operating in steady state, with excitation E' = 1.5pu and initial rotor angle δ0 =36.9°. A three-phase fault occurs at the indicated point, faulting the bus, but the prime mover power and the excitation remain constant.
(a) Calculate the prime mover power pmpu associated with the initial operating point.
(b) Calculate the stable equilibrium. rotor angle after the fault is cleared by opening the breakers and removing the faulted line.
(c) Calculate the maximum rotor angle δ3 to avoid loss of stability (i.e.. the unstable equilibrium rotor angle after the fault is cleared).
(d) Calculate the critical clearing angle δcr so that the rotor angle does not exceed the maximum value δ3.
