A New Hybrid Unified Power Quality Conditioner for Power Quality Improvement in Electrical Distribution Grids
In this paper, a new hybrid unified power quality conditioner (HUPQC) is proposed to improve current and voltage imperfections in distribution systems. The proposed HUPQC is comprised of the shunt hybrid active power filter (SHAPF), the dynamic voltage restorer (DVR) and the isolated bi-directional DC-DC converter. The main contribution of the study is a new HUPQC topology that enables the reduction in the voltage rating of the DC link capacitor by the help of the SHAPF. The cost and size of the DC link are reduced and switching losses of the voltage source inverter (VSI) is reduced with the low voltage DC link advantage of SHAPF. The DC-DC converter provides isolation and bi-directional power flow between the DVR and the SHAPF during voltage sag and swell. The performance of the proposed HUPQC is evaluated through extensive simulations for mitigating voltage sag/swell and compensating current harmonics by using MATLAB/SIMULINK simulation tool.
 H. Mohamadi, Y. Varjani and H. Mokhtari, "Multiconverter Unified Power Quality Conditioning System: MC-UPQC, IEEE Transaction on Power Delivery, Vol. 24, NO. 3, pp. 1679-1686, March 2009.
 B. Han and G. Jang, “New Configuration of UPQC for Medium-voltage Application” IEEE Transaction on Power Delivery, Vol. 21, NO. 3, pp. 1438-1444, Feb 2008.
 S. Kavanki and K. Boddeti, "A Modified Three-Phase Four Wire UPQC Topology with Reduced DC-Link Voltage Rating," IEEE Transactions on Industrial Electronics, vol. 30, no. 1, pp. 1237-1253, Aug 2016.
 M. Brenna and E. Tironi “A New Proposal for Power Quality and Custom Power Improvement: Open UPQC, “ IEEE Transaction on Power Delivery, Vol. 24, NO. 4, pp. 2107-2116, May 2009.
 A. Take and M. Tumay, “Open UPQC wihte Control based on enhanced Phase Locked Loop” IET Generation, Transmisssion & Distribution, Vol. 7, No. 3, pp. 354-364, Jun 2015.
 G. S. Kumar, P. H. Vardhana, B. K. Kumar, and M. K. Mishra, “Minimization of VA loading of Hybrid unified power quality conditioner (HUPQC) in power system, “ IEEE Transaction on Power Delivery, Vol. 17, NO. 8, pp. 3132–3145 Mar 2012.
 T. Narongrit, K-L. Areerak and K-N. Areerak “The Comparison Study of Current Control Techniques for Active Power Filters” IEEE Transactions On Industry Applications Vol 12, No 34, July 2013.
 V. Khadkikar and A. Chandra, “A new control philosophy for a unified power quality conditioner (UPQC) to coordinate load-reactive power demand between shunt and series inverters, “IEEE Transaction on Power Delivery, Vol. 23, NO. 4, pp. 2522–2534, Oct 2011.