Three-phase Four-wire Shunt Active Power Filter Based on DSP

The configuration and principle of shunt active power filter is introduced briefly in this paper. A digitally controlled shunt active power filter based on double DSP is designed for the three-phase four-wire system. The main circuit of the shunt active power filter selects a four-leg voltage-source inverter, and a dynamic hysteresis-band current control is used to track the current. A control strategy based on the instantaneous reactive power theory is given in consideration of the source voltage becoming distorted and unbalanced. The facility can compensate harmonic and reactive power completely for three-phase four-wire system. The hardware configuration, flow chart of software, derivation of compensating signal and derivation of PWM waves are analyzed. The validity and correctness of the filter are proved in experiment.