Power Angle Control-based Method for Interline Unified Power Quality Conditioner and Multi-converter Unified Power Quality Conditioner under Unbalanced and Distorted Load Conditions

This article proposes a new control approach for an interline unified power quality conditioner and a multi-converter unified power quality conditioner to optimize the utilization of the inverters of these structures. In this method, the series active power filter is controlled by the application of a power angle control concept to compensate an unbalanced voltage (asymmetrical voltage sag/swell with or without phase angle jumps) and also partial-load reactive power for power factor correction. Since voltage variation (sag/swell, unbalance, etc.) is a short-duration power quality problem in distribution systems, under normal operating conditions, series inverters are not utilized effectively in conventional methods. By using the proposed method, optimal utilization of series inverters of both structures and also a reduction in the shunt inverter rating of a multi-converter unified power quality conditioner will be achieved. Also, the shunt active power filter is controlled to compensate the unbalanced current, harmonics, and neutral current of a three-phase four-wire system and to take part in power factor correction. The proposed approach is validated through MATLAB/SIMULINK-based (The MathWorks, Natick, Massachusetts, USA) simulation and the results are discussed.