A voltage sag compensation utilizing autotransformer switched by hysteresis voltage control

This paper presents a new voltage sag compensator based on an autotransformer and an IGBT switched by hysteresis voltage control method. Faults occurring in power distribution systems generally cause the voltage sag or swell. Sensitivity to voltage sags and swells varies within different applications. For sensitive loads, even a voltage sag of short duration can cause serious problems. Hysteresis voltage control method suggested in this paper is based on comparing the real voltage of system with a reference voltage. The proposed scheme is able to quickly recognize the voltage sag condition, and it can correct the voltage by boosting the input voltage during voltage sag events. One of the advantages of this topology is that it uses only one controlled switch per phase to boost the input voltage. Different voltage sag events have been simulated by MATLAB/Simulink software. The results of simulations verify the ability of proposed method to mitigate voltage sag events.