Active disturbance rejection control of LCL filtered grid-connected inverter using padé approximation

In this paper, a simplified robust control is proposed to improve the performance of three phase current controlled voltage source converter connected to the grid with an inductance-capacitor-inductance (LCL) filter. The presence of the LCL filter resonance complicates the control system dynamics and limits its overall performance, particularly when disturbances and parametric uncertainty are considered. To solve this problem, a robust active damping method based on the Linear Active Disturbance Rejection Control (LADRC) is proposed. The simplification is made possible by order reduction in the plant transfer function using Padé approximation. Evaluation results show that the proposed LADRC based active damping control achieves high power quality and good dynamic performance, in the presence of parameters variations as well as external disturbances.