ATP-EMTP study of adjustable speed drive dc link properties during voltage sags

ATP-EMTP simulations of a 3-phase commercial power distribution system containing adjustable speed drive (ASD) driven induction motors in the presence of single-line-to-ground and balanced three-phase voltage sags are described. The simulations show both the dynamic influence of the motor on the temporal evolution of certain sags and the peak ASD dc link voltage and current as functions of fault type, location, and duration. The results show that dc link recovery currents can be several times larger than their nominal values, and that the most severe effect occurs during and after a long (1000 msec) three phase fault at an electrically remote location.