This paper presents a voltage swell compensator based on a switched autotransformer by random hysteresis voltage control. The advantage of this compensator is that it uses only one controlled switch per phase with no energy storages. Also the control scheme purposed here distributes the harmonic spectrum of the load voltage and reduces its total harmonic distortion (THD). Different voltage swell events have been simulated by MATLAB/SIMULINK software. The results of simulations verify the ability of proposed method to mitigate voltage swell event.