A Switched Z-Source and Switched Capacitor Multi-Level Inverter Integrated Low Voltage Renewable Source for Grid Connected Application

Abstract

Most of the renewable sources generate power at lower voltage levels in the range of 20-50V which cannot be utilized by the loads. Therefore, stacking multiple modules in series increases the voltage level or using conventional boost converter or QZSis helpful. However, due to series stacking and boost converter or QZS there is a great power loss and also have reliability issues.The QZS inverter has very less boosting gain in the range of 2times. Theconventional boost converter or QZSis replaced with SZSC for voltage boosting and inverter operation. The SZSC boosts the voltage 4-5 times to the input voltage level. For further mitigation of harmonics, the conventional 6-switch inverter is replaced with switched capacitor MLI. Multiple renewable sources are at the input which include PV array, battery unit and PMSG wind module. The battery unit is a support to the renewable sources PV array and wind module. The DC link voltage stability is achieved by the battery unit placed in parallel to the renewable sources. The renewable sources share power to the grid through the SZSC and switched capacitor MLI. For DC voltage stability a CV control is integrated to SZSC. And for synchronized power sharing to the grid, a grid voltage feedback synchronization control is included for the control of MLI. A low rating renewable system is modelled and integrated to grid using Simulink MATLAB software. A comparative analysis is carried out operating the system with QZS and SZSC. The performances of the SZSC and MLI are evaluated by the graphs generated by the simulation of the modelled system.