Analysis of Different Types of Voltage Sag and Its Effects on Adjustable Speed Drive

Voltage sag continues to be the most common power quality event causing repeated mal-operation of Adjustable Speed Drives (ASD). It either creates speed and torque fluctuations or completely shuts down the operation of ASD. This paper analyze the effects of different types of voltage sag on ASD. The analysis of this phenomenon, including the variation in DC link voltage, input RMS current of ASD, torque and speed of motor due to voltage sag are presented in this paper. A typical ASD with its parameters and different types of voltage sag are also discussed in this paper. To study the performance of the ASD under voltage sag, simulation based study is carried out for symmetrical, unsymmetrical and phase shifted voltage sag and results are presented comparatively. Different voltage sag mitigation techniques for ASD are discussed in brief.