Quasi Z-Source Inverter Based Dynamic Voltage Restorer for Power Quality improvement of Sensitive Loads in Distribution Grid

Voltage sags and swells in the medium and low voltage distribution grid are considered to be the most frequent type of power quality problems based on recent power quality studies. Their impact on sensitive loads is severe. Different solutions have been developed to protect sensitive loads against such disturbances but the dynamic voltage restorer (DVR) is considered to be the most efficient and effective solution. Its appeal includes lower cost, smaller size and its dynamic response to the disturbance. In this paper, a new topology of quasi Z-source inverter (qZSI) based DVR is proposed. In the proposed system, the size of energy storage element is decreased in compare with the conventional systems where the rating of located power electronics devices is less than the systems using qZSI. This paper described the DVR operation principles and in-phase control method for balanced and unbalanced voltage sags and swells in a distribution system. The Simulation results were presented to illustrate the performances of proposed DVR under voltage sags and swells conditions.

Keywords:

dynamic voltage restorer , quasi Z-source inverter , voltage sag , voltage swell