Study on Dispersing BPF-QPR Harmnoic Current Control for Active Power Filter

Efficient power quality control using active power filters (APFs) is critical to modern power systems. However, most existing harmonic current control techniques use the output of harmonic current detection as the control objective, resulting in a more complex control system. This study proposes a novel APF control system that integrates harmonic current detection and control into the current closed-loop via a band-pass filter (BPF) and quasi-proportional resonance (QPR) control in stationary ABC frames. The proposed harmonic current control algorithm has two control loops: an inner loop that uses proportional feedback of inverter current, and an outer loop that adopts BPF-QPR controllers for each harmonic component. Comprehensive coordinated control of each frequency component current is achieved through independent design of each harmonic controller. A discretization method of the digital signal processor (DSP) controller assists in the practical implementation. Results of the simulation and experimental testing on a 400V/100A module active power filter reveal the feasibility of the proposed harmonic current control technique. The novel control algorithm presented in this study provides high flexibility, requires no harmonic detection, and ensures high compensation accuracy compared to existing techniques.