Design and control of fully parallel embedded Z-source inverters based flexible photovoltaic systems for grid power quality improvement under distorted condition

This paper presents the design and control of fully parallel embedded Z-source (FPEZ-source) inverter in flexible photovoltaic (FPV) systems. FPEZ-source inverters are one of the Embedded Z-source (EZ-source) inverter topologies with two isolated dc sources embedded with each inductor of X-shaped network in series, so two PV panels can be used in this structure and PV input current flows smoothly during the whole switching period unlike the traditional Z-source inverters without any extra LC filter. Inductor and capacitor of X-shaped impedance network is designed in a way that the ripple of capacitor voltage and inductor current could be put in a desired value. Moreover the corrected p-q control theory and simple MPPT method are used as reference current generator for FPV system that injects maximum available power of PV array and compensates load harmonics, reactive power and imbalance. Finally simulation is performed by PSCAD/EMTDC software, and results are presented to demonstrate effectiveness of proposed concept.