Stator current transient performance of induction motor under different voltage sag conditions

Voltage sag is the common power-quality disturbance and influence the operation performance of motors. The voltage sag consists of two transient processes including the beginning and the end of voltage sag that can cause the inrush current. This paper provided a new method which can also be used in wind turbine control named space vector transform method to calculate the inrush current and then made experiments to verify the results by using a 5.5kW motor. In the end, the influence of voltage sag characteristics including amplitude, duration, initial phase angle and phase-angle jump on stator current of the induction motor with no load are systematically studied and experimental validation is also performed. The results show that peak currents of drop voltage point and recovery voltage point depend linearly on the voltage drop but the onset peak current has a periodic dependence on the sag duration, furthermore, three phase peak currents have a periodical relationship with initial phase and the period is 60°.