Decoupled control of quasi-Z source inverter for decentralised renewable energy application

Abstract

Decentralised renewable energy (DRE) systems are acclaimed worldwide as it serves as an alternate to the grid extension to remote areas having no access to electricity. The impedance source inverter (ZSI) has overcome the limitations of conventional voltage source inverter (VSI), have buck/boost capabilities. This paper presents an alternative approach of obtaining shoot-through pulses in a quasi-Z source inverter (qZSI) along with decoupled control by keeping dc link voltage constant instead of capacitor voltage. Dynamics of the system are investigated by deriving small signal model, the proposed control methodology uses separate controllers to handle dc and ac side dynamics to get desired shoot-through pulse and modulation index without any overlap, performance of the control methodology is verified under normal condition and under disturbances. Results are obtained using PSIM which verifies the control methodology and depicts the ability of disturbance rejection and effective reference tracking without compromising stability issues.