Transient response of interconnected power systems to single line-to-ground faults

An interconnected power system containing synchronous and induction machines has been simulated. The total fault current and the behavior of each machine have been calculated under single line-to-ground fault conditions for a fault time of 500 ms. The negative-sequence torque has been calculated for faulted and unfaulted machines. The results show the importance of negative-sequence torque in decreasing the rotor swing amplitudes of synchronous machines during the fault period, while it has a deleterious effect on induction motor speeds which tend to run down, such that they may be unable to recover during the post-fault period