Research On Harmonic Current Detecting Method And Control System Of Active Power Filter Based On DSP

Active power filte(rAPF)is a new method to realize harmonic elimination and VAR compensation using IGBT or MOSFET. It doesn't have the disadvantages of the traditional method to realize harmonic elimination and VAR compensation which uses the LC filters. A shunt active power filter based on DSP for three-phase four wire systems is studied and designed in this paper.The harmonic current detection is the key element for the active power filter to keep a well dynamic performance. An i_p - i_q detection based on instantaneous reactive power theory is taken as the control strategy in this paper. The traditional i_p - i_q detection is only fit for three-phase three-wire systems, so it is improved in this paper and extended to three-phase four-wire systems by separating zero-sequence current from the load current.A simulation for the system is studied through MATLAB, and an active power filter principle prototype is developed finally.