Study on three-leg-based three-phase four-wire shunt active power filter

Power quality problems such as three-phase unbalanced and aberrance, harmonics and so on, have become serious increasingly and the development of APF has been one of the ways to solve these problems. The detection algorithm based-on FBD theory for command current in three-phase and four-wire system, can extract the zero-sequence current and harmonic current from the load current. This algorithm is adopted in the paper to design the main circuit of three-leg with split phase capacitance and hysteresis control is used to regulate the output current. A prototype of APF based-on DSP, which provide experimental environment for high-power, is developed to test the performance of the APF and results have proved that the compensation effect of the device to zero-sequence current, harmonics and reactive power is reliable.