Effect of negative sequence torque on induction motor plant during transient fault conditions

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 the 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