Simulation performance of grid connected Z source solar inverter with incremental conductance MPPT

Abstract

Z source inverters (ZSI) can perform single stage, buck-boost conversion and have shown to offer slightly higher efficiency over traditional inverters. However, ZSI controller unit becomes more complex when achieving all objectives of Grid connected solar inverter applications where Maximum Power Point Tracking (MPPT), grid synchronization and harmonic reduction from output voltage and current are simultaneously implemented. The control concept used to achieve above objectives is that varying shoot through duty of ZSI while keeping peak DC link voltage at a constant value. Control structure is designed in synchronous reference frame with two cascaded loops as outer voltage control loop and inner current control loop to maintain power balance of ZSI which results constant peak DC voltage. Besides that, incremental conductance algorithm sets shoot through duty of ZSI to extract maximum power from solar panel at a given irradiance and temperature level. In this paper we present a simulation study of a grid connected ZSI along with Incremental Conductance MPPT method. The details of theory, operation, design and simulation results are included in the paper.