An adaptive hysteresis band current controlled unified power quality conditioner

Presence of Harmonics is one of the major power quality problems in the present power system. It is demanded that the utility should ideally provide a balanced and pure sinusoidal three-phase voltage of constant amplitude to the loads. But, with the excessive use of non-linear loads (ASD, Computers, Laser printers, SMPS, Rectifier etc.) power distribution system is getting polluted by harmonics and reactive power disturbances. Harmonics cause a number of undesirable effects like heating, equipment damage and Electromagnetic Interference effects in the nearby communication system. Active power filter (APF) or Active power line conditioner (APLC) is a suitable solution to compensate the adverse effects of harmonics and reactive power simultaneously. There are various topologies of APFs, one of them is Unified power Quality Conditioner (UPQC) which has two inverters connected back to back with same dc link. In this paper a three-phase–three wire UPQC, is proposed for harmonic compensation at point of common coupling (PCC) which are present due to the presence of non-linear load. Reference signals were generated using synchronous reference frame theory (SRF). While the gating signals were generated using Adaptive Hysteresis Band Current Controller (AHCC). Simulation of the proposed UPQC model was done using MATLAB/SIMULINK and result shows that it achieves superior capability of mitigating the effects of voltage sag/swell and reduces the THD of source current within the IEEE standard of harmonic limit. while AHCC successfully maintains the switching frequency almost constant