Adaptive repetitive controller for an active power filter in three-phase four-wire systems

Abstract

Load changing behaviour significantly affects the compensating current control performance of active power filters (APFs). Owing to this effect, harmonic currents at the source can significantly degrade the power quality of the system. This work proposes an adaptive repetitive controller based on a fuzzy logic algorithm to improve current control performance. In addition, a new design approach to fuzzy membership functions is also proposed. The design concept for the adaptive repetitive controller follows a stability analysis of the compensating current control and a mathematical model of the APF. In experimental testing, a power system was implemented with the proposed controller using the processor-in-the-loop technique on an eZdsp™ F28335 board and the MATLAB/Simulink programme. The experimental results indicated that the proposed adaptive repetitive controller would provide better harmonic current-tracking performance compared with conventional repetitive controllers. Also, the APF used in conjunction with the proposed controller would efficiently mitigate harmonic currents even where non-linear loads changed. Moreover, the percentage of total harmonic distortion would be maintained within the IEEE standard 519-2014.