With non-linear loads such as power electronic equipment getting more and more widely used in industrial and civil applications, harmonic current are becoming more damaging to electricity systems on both the power grid side and user side. An effective way to solve the problem is to use the harmonic filter equipments. Active power filter (Active Power Filter, APF) compensates each harmonics simultaneously, is provided with real-time dynamic reactive power compensation and other advantages. Active power filter application is considered the most effective means to treat grid harmonics and improve power quality. In this paper, a shunt 3-phase 3-wire active power filter is researched, using two-level topology. The paper analyzes the main circuit topology and control system principles, and then provides capacitors and inductor selection methods with different power rating. Through real-time detection of load current harmonics, negative-sequence current and reactive current command, the modified prospective proportional resonant method for frequency dividing control and Space Vector Pulse Widths Modulation are used for Controlling APF output current. To further validate the proposed method, a 3-phase 3-wire APF experimental apparatus is built.
