PV Fed Quasi Z Source Multi Level Inverter Based DVR

This paper presents a photo voltaic fed quasi z source cascaded Multi level inverter based DVR to enhance the quality of power and to compensate the voltage abnormalities seen in the industrial and consumer premises. The Quasi Z-Source structure present in the proposed multilevel inverter performs buck/boost inversion in a single stage with a wide range of gain, assuring reliable operation against short circuit occurrence and leakage current issues faced by the series/multi string PV systems. Switching Frequency Optimal pulse width modulation for enhanced fundamental output voltage has been implemented along with constant boost control for controlling the switches of the proposed nine level inverter. The proposed synchronous reference frame control with PI controller is employed for closed loop operation of DVR to regulate the load terminal voltage during sag, swell in the voltage at the point of common coupling (PCC). The voltage injected by the proposed nine level inverter structure is able to mitigate balanced, unbalanced voltage sag, voltage swell with reduced harmonic content.