DC-Link Voltage Balancing and Regulation of Split-Capacitor VSI Based DSTATCOM

In this paper, a modified VSI based Split Capacitor distribution static compensator (SC-DSTATCOM) is presented to ensure the quality of power in a distribution system. The imbalance of voltage across the split capacitors of SC-DSTATCOM is a serious issue when a load current contains dc components. The voltage across the dc-link capacitor is kept at constant value regardless of their connected load. This will increase energy loss across the switches of voltage source inverter (VSI). Therefore, in this paper, SC-DSTATCOM is modified by integrating a bipolar output converter with the conventional SC-DSTATCOM to discuss the aforementioned problem. The bipolar output converter is a combined SEPIC-Cuk (CSC) converter and input dc supply is fed from a renewable energy source (RES). The switching pulses for modified SC-DSTATCOM are generated based on the Instantaneous Symmetrical Component Theory (ISCT). By the proper control of CSC converter integrated SC-DSTATCOM, the voltage balancing and regulation of the dc-link capacitor can be achieved. Therefore, under low load conditions, voltage across dc-link capacitor is adjusted to small value without compromising load compensation and voltage balancing. Finally, the proposed system performance is verified through MATLAB simulation results and some of the results from hardware prototype are also presented.