Comparative Analysis of Single-Phase Grid-Tied PV Systems with Single and Double Power Conversion Stages

Abstract

This paper presents a comparative analysis of two single-phase grid-tied photovoltaic (PV) systems. The first is deployed employing a single-stage power conversion, while the second a double-stage power conversion is used. In the single stage PV system topology the impedance source inverter (ZSI) is used to perform the maximum power point tracking (MPPT), as well as the control of the active current injected into the grid. On the other hand, in the double-stage PV system a dc-dc boost converter (BC) performs the MPPT, whereas a voltage source inverter (VSI) controls the amount of energy injected into the grid. In both aforementioned PV systems, Perturb and Observe (P&O) based algorithm is employed to perform the MPPT. The comparative analysis takes into account the following aspects: i. converter efficiency; ii MPPT efficiency; iii total harmonic distortion of the grid-tied inverter current; and iv. number of electrical and electronic devices needed to implement the PV systems. Furthermore, the ZSI and BC+VSI modelling and the procedures used to design the controller gains are also presented. Finally, by means of computational simulations, the performance and functionality of the ZSI and BC+VSI PV systems are evaluated.