UPQC Harmonic Detection Algorithm Based on Improved p -q Theory and Design of Low -Pass Filter

With the development of smart grid, the power quality problems arc getting more and more serious, such as voltage sag/swell, voltage and current harmonic distortion and so on. The unified power quality conditioner (UPQC) has been used to improve multiple power quality problems which is an important developmental trend of current power system. In this paper, a harmonic comprehensive detection algorithm based on improve p-q theory is proposed to be applied to the UPQC. It can quickly and accurately detect a variety of power quality problems such as harmonic currents, voltage sag/swell, unbalanced three-phase voltage. Furthermore, an enhanced low-pass filter is designed to improved accuracy of low-pass filter in this harmonic detection algorithm. Simulation results are presented to verify the rationality of this detection method and the performance of the enhanced low-pass filter.