The Research Of Shunt Three-phase Four-wire Active Power Filter

There is a great market demand to utilize the Active Power Filter (APF) to reduce the harmonics of the power system and improve the power quality in China. Therefore it is worthy of research how to correctly choose the control arithmetic and design the parameters of APF to better its performances at the time of reducing its cost.This paper made detail study on the theory and structure of the APF and the three control methods: detecting load current method, detecting system current method and complex control method. This paper also introduced two main circuitries applying to the APF of the three-phase four-wire system. The paper chose i_p-i_q arithmetic of the instantaneous reactive power theory control strategy as the right scheme to produce the instructing current. The paper also validated the probability of applying this theory to three-phase four-wire APF. Also, it analyzed the current control method of hysteresis current control, and gave several key factors which affect performance of the APF.Finally, a model of shunt three-phase four-wire APF was built. Simulation results of this model with the load of three-phase thyristor rectifier and three-pha -se asymmetry load showed that the APF work well suppressing harmonic, thus proved all the validity and reliability hereinbefore.