Realization and improvement of repetitive control in rotating frame for active power filter system

The repetitive control, which is based on a delay of fundamental period, is widely used in grid-connected voltage-source converters, such as uninterruptible power supply (UPS), photovoltaic (PV) inverter and active power filter (APF). This paper presents four repetitive controllers in rotating frame for APF system, whose repetitive period is T, T/2, T/3, and T/6 respectively. Compared with traditional repetitive control, these repetitive controllers have fast dynamic response and also have similar structure, which could also be easily implemented in digital processor for APF system. Regeneration spectrum and sensitivity function based analysis methods provide a way for parameters design and performance comparison between each controller. Simulation and experiment results demonstrate the validity and superiority of each controller.