Optimization of electricity production in a grid-tied solar power system with a three-phase quasi-Z-source inverter

Solar energy can be harnessed in all areas of the world and directly converted to electricity by means of photovoltaic (PV) systems. This leads to a reduced emission of greenhouse gases such as CO2. In this paper, a grid-tied quasi-Z-source inverter (qZSI) is considered with a PV array connected at the inverter input. The PV array is selected so as to ensure currents and voltages required by the qZSI. A novel maximum power point tracking (MPPT) algorithm, proposed in this study, does not require the measurement of the PV array current and does not oscillate around the maximum power point as opposed to most standard MPPT algorithms. The simulation model of the considered system was built in the MATLAB Simulink environment by using basic Simulink blocks only. The simulation analysis was performed with three PV array models of different complexity to establish the impact of the PV array dynamics on the overall system performance. The operation of the considered system was tested over a wide range of the solar irradiation levels and temperatures of the PV array. The proposed MPPT algorithm is additionally compared with the conventional constant-voltage algorithm, which also requires only measurement of the PV array output voltage. In the considered operating range, the proposed algorithm provides up to 453 W more power from the PV array (i.e., about 7% of the respective nominal power). (C) 2019 Elsevier Ltd. All rights reserved.