Protection of a embedded generator shaft system from an instantaneous voltage sag

An influence of the voltage sag magnitude and duration on embedded generator's mechanical shaft torque is investigated by simulations using the electromagnetic transients program (ATP-EMTP). Various types of fault are simulated, changing the fault point, the number of faulted phases and the voltage phase angle at the moment of fault occurring. From the simulation results, it becomes clear that the high-speed static switchgear is effective for the stable operation of the embedded generation systems and the critical loads, which are subjected to the voltage sag.