The Tolerance of ASDs to Voltage Sags Based on Mechanical Analysis

Based on quantifying the influence of voltage sags on adjust speed drivers, putting forward relevant suggestions and improvement measures have become important issues for power grid corporations, power consumers and manufacturers. In this paper, with the dynamic equations of DC circuit and dynamic equations of asynchronous drive, mechanism analyses of the sensitivity to internal (i.e. protection system, control strategies) and external (i.e. load and voltage sags characteristic indexes) factors on ASDs were carried out and proposed corresponding measures. Especially combined with undervoltage and overcurrent protection thresholds, the operating ranges under vector control and direct torque control strategies were obtained, which provided the theoretical reference for protection systems setting with different control strategies to voltage sags.