Analysis and realization of a fast repetitive controller in active power filter system

The repetitive control and resonant control are widely used in grid-connected voltage-source converters recently, such as uninterruptible power supplies (UPS), photovoltaic inverter (PV) and active power filter (APF). This paper introduces a new repetitive control strategy in APF system, whose repetitive period is only one half of the traditional and could eliminate all odd harmonics as a bank of resonant controllers. Compared to traditional repetitive control, proposed control strategy has faster tracking speed and smaller steady-state error; Compared to traditional PR control, it could be simply implemented in digital processor. Theory analysis with simulations and experiments demonstrate the validity and superiority of proposed fast repetitive control strategy.