A Dynamic Voltage Restorer System by Modified Z-Source Inverter to Mitigate Voltage Sag

摘要

Dynamic Voltage Restorer (DVR) is a custom power device used in power distribution networks to protect consumers from sudden sags and swells in grid voltage. On the basis of recent developments in impedance source (Z-source) inverters the present paper proposes an integration of quasi-Z-source inverter (QZSI) with a built-in high frequency transformer. New type LCCT-Z-Source inverters are presented. Proposed inverters characterize continuous input current, improved relationship between boost coefficient and modulation index and improved EMI performance. Application of four element (Inductor - Capacitor - Capacitor - Transformer) LCCT impedance network provides higher voltage gain than obtained in quasi-Z-source inverter. The advantage of proposed topology over other recently developed Z-source inverters is that two built-in capacitors block DC currents in transformer windings and prevents core saturation. Simulation results are shown to verify the proposed topologies.