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Advances in Power Electronics
Volume 2013 (2013), Article ID 381581, 13 pages
Research Article

Selection of Design Parameters to Reduce the Zero-Sequence Circulating Current Flow in Parallel Operation of DC Linked Multiple Shunt APF Units

School of Electrical & Electronic Engineering, Dublin Institute of Technology, Kevin Street, Dublin 08, Dublin, Ireland

Received 30 April 2013; Revised 11 October 2013; Accepted 28 October 2013

Academic Editor: Gabriele Grandi

Copyright © 2013 Shafiuzzaman K. Khadem et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Capacity enhancement and operational flexibility are two of the important limitations of the centralized shunt APF ( ) unit. These limitations can be conquered by the operation of multiple APF units in parallel and connected back to back by a common DC link capacitor. In that case, a circulating current (CC) flows within the units. This CC flow becomes out of control when the units operate in hysteresis based current controlled mode. One of the difficulties of this CC flow control or reduction is the variable switching frequency of the units. In this paper, the model for CC flow is derived by the switching dynamics study of the units. It is found that the selection of design parameters plays an important role in the amount of CC flow. Detailed simulation, analysis, and real-time performance show how the selection of design parameters affects the CC flow and the reduction of CC flow can also be achieved at an acceptable level by the proper selection of design parameters.