Voltage Sag Compensation Using Switched-Inductor Z-Source Inverters Based Dynamic Voltage Restorer

This paper presents the application of dynamic voltage restorer (DVR) on Power distribution systems for mitigation of voltage sags at critical loads. DVR is one of the compensating types of custom power devices. The impedance source inverter employs a unique impedance network couple with inverter main circuit and rectifier. In this paper, a new Z-source inverter (ZSI)topology is developed to improve a voltage boost ability ofconventional ZSI.A technique based on Embedded switched-inductor Z-source inverters have become a research hotspot because of their single-stage buck-boost inversion ability, and better immunity to EMI noises. However, their boost gains are limited because of higher component-voltage stresses and poor output power quality .To overcome these drawbacks, a new high-voltage boost impedance-source inverter called a switched-coupled-inductor quasi-Z-source inverter (SCL-qZSI) is proposed. The proposed inverter employs a unique impedance network couple with inverter main circuit and rectifier.  By controlling the shoot through duty cycle, the proposed inverter system provide ride through capability during voltage sags and swells, reduces line harmonics, and improves power factor and high reliability. Simulation results are presented to illustrate and understand the performances of DVR in supporting load voltages under voltage sags conditions.