Soft‐start control strategy for the three‐phase grid‐connected inverter with LCL filter

Abstract

To solve the start-up inrush current existing in the three-phase gridconnected inverter, a soft-start control strategy for the three-phase grid-connected inverter with LCL filter is proposed. The analysis of start-up inrush current is illustrated in detail. The capacitor current of the LCL filter is used to detect the closure of the grid-connected switch, so the closing time of the grid-connected switch does not need to be known. The detailed procedure and flowchart of the proposed soft-start control method are provided. Finally, experimental results of a LCL-type three-phase grid-connected inverter verify the theoretical analysis. The control strategy is easy to implement. The start-up inrush current does not exist in the grid-connected inverter.

A novel soft-start method for SVG based on D-axis orientation

“…Soft-start is a key technology to restrain unfavorable factors such as current impact and DC side voltage overcharge during the starting process, ensuring that the equipment can be started stably and put into operation smoothly. Therefore, soft-start technology is significant and difficult in the design of low-voltage SVG systems [13] . Hence, this paper proposes a new open-loop soft-start method based on the D-axis orientation, which not only realizes the non-impact soft-start of SVG, but also reduces the difficulty of debugging, while being easily implemented.…”