Nonlinear PID DC-link Voltage Control for Hybrid Power Filter Based on Robust Exact Differentiator with Improved Transient Response

Abstract

LC-coupling hybrid active power filter (LC-HAPF) is a cost-effective solution to address power quality issues in low and medium voltage distribution networks. The DC-link voltage controller plays an important role of the LC-HAPF performance. Conventionally, proportional-integral (PI) controller is commonly used for DC-link voltage control due to the ideally zero steady-state error. However, the property of integrator slows down the transient response of DC-link voltage and thus effects the LC-HAPF dynamic performance. In this paper, a nonlinear PID (NPID) controller based on robust exact differentiator (RED) is proposed to improve the transient response of conventional PI controller. First, the parameters of the PID controller are designed by s-domain transfer function analysis. Then, the RED is proposed to replace the linear differentiator, which provides the differential signal fast and accurately. Finally, the advantages of the proposed NPID controller based on RED are verified by simulation results compared with the conventional PI controller.