Dynamic performance comparison involving grid‐connected PV systems operating with active power‐line conditioning and subjected to sudden solar irradiation changes

Abstract

This study presents a comparative performance analysis involving single- and double-stage photovoltaic (PV) systems, which are connected to a three-phase four-wire electrical system by means of a four-leg inverter topology. The double-stage PV system is composed of a step-up DC/DC converter and a four-leg grid-connected inverter, while in the single-stage PV system the PV array is directly connected to the inverter DC bus. In addition to the active power injection into the grid, both PV systems have two attractive features, described as follows: (i) power quality improvement due to their capability to perform active power-line conditioning, such as load harmonic current suppression, reactive power compensation, and load unbalance compensation; (ii) dynamic improvement in the occurrence of abrupt solar irradiation variations, which is achieved through the implementation of a feed-forward control loop (FFCL) acting directly in the inverter DC-bus voltage control loop, resulting in speeding up of the dynamics of both the DC-bus voltage and the injected grid-inverter currents. The referred comparative analysis addresses the static and dynamic performances considering the PV systems operating under the action of the FFCL, as well as performing active power-line conditioning. Simulation and experimental results are presented to evaluate and validate the proposed study.