Forghan - Department of electrical and computer engineering, University of Tehran Tehran, Iran
Afsharnia - Department of electrical and computer engineering, University of Tehran Tehran, Iran

In this paper, a novel control technique based on improved FFT (Fast Fourier Transform) algorithm is proposed to overcome the drawbacks of Unified Power Quality Conditioner (UPQC) control technique based on Fourier analysis. Because of the inherent time delay of FFT algorithm based control technique, UPQC (with this control technique) can not be used for compensating variable load current perturbations, whereas, the proposed control technique compensate perturbations of load current in various conditions. By using this novel control technique, DC link voltage variation is not considerable, because the time delay for extracting the fundamental component of load current (which have great effect on DC link capacitor voltages) decreases significantly. Analysis and modeling of the UPQC with FFT control technique and proposed control scheme as well as simulation results are presented. Results show that the accuracy of proposed method is better than FFT control technique and unsymmetrical, dynamic and variable load current can be compensated without any considerable time delay.

power quality, Unified Power Quality Conditioner (UPQC), FFT algorithm, harmonic compensation