Active Power Conditioner using Fryze-Buchholz-Dpenbrock (FBD) Algorithm

This paper presents a fuzzy logic controlled shunt active power filter used to compensate for harmonic distortion in three-phase four-wire systems. A shunt APF based on FFT for reference compensating current calculation and fuzzy logic current controller has been studied to improve the system power quality by compensating the harmonic line currents and also the neutral current. The APF provides compensation currents in such a way that the utility supplies only the balanced fundamental current at unity power factor, even if the load draws reactive and harmonic currents. The determination of current references for APF with 4-leg inverter is based on linear adaptive notch filter and instantaneous symmetrical components. 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. It is applied by considering a balanced and resistive load as ideal load, so that the voltage waveform injected by the active filter is able to compensate the reactive power, to eliminate harmonics of the load current and to balance asymmetrical loads.