Research on Compensation Strategy of Unified Power Quality Controller Based on Matrix-type Back-to-back Converter

Aiming at the problems of low power density and high construction and maintenance costs of the unified power quality controller（UPQC） based on the conventional back-to-back converter（BBC）, a UPQC topology based on matrix-type back-to-back converter（MTBBC-UPQC） is proposed. For the series side, a voltage fluctuation and harmonic compensation strategy based on proportional-integral-multi-resonance control is proposed; for the parallel side, a load harmonic and reactive current extraction method based on the FBD theory is used, and a current reactive and harmonic compensation strategy based on improved repetitive control is proposed. Compared with UPQC based on the conventional BBC, MTBBC-UPQC has the advantages of no electrolytic capacitor, high power density and low switching losses. Compared with UPQC based on the conventional matrix converter, the number of switches is reduced from 18 to 12, and the economy and reliability are significantly improved. The Matlab/Simulink results show that the proposed MTBBC-UPQC and its compensation strategy can realize a number of compensation functions, such as voltage fluctuation, voltage harmonics, reactive current, harmonic current, and so on.