Differential Power Processing For Solar Photovoltaic Systems: Development and Applications

Abstract: In photovoltaic (PV) systems connected to the ac power grid, PV panels are traditionally connected in series strings with one central converter to control and process the PV’s power. However, imbalances or mismatch in the PV cell characteristics can result in low system efficiency, which can occur due to partial shading, different panel angles, cell aging, etc. The concept of differential power processing (DPP) dc-dc converters are utilized to improve PV power output under mismatched conditions. DPP converters allow for independent MPPT of each PV panel while only processing a portion of the total PV power.
This tutorial introduces the concept of DPP for PV systems and covers the basic architectures, including PV-to-bus, PV-to-PV, and PV-to-isolated-port. Power flow analysis, converter topologies, and basic control methods will be overviewed, along with the advantages and trade-offs of the various techniques. The current challenges of commercialization and steps being taken to overcome these problems will also be discussed and explored through applications examples.

Katherine A. Kim received the B.S. degree in Electrical and Computer Engineering (ECE) from the Franklin W. Olin College of Engineering in 2007. She received the M.S. degree and Ph.D. degree in ECE from the University of Illinois at Urbana-Champaign in 2011 and 2014, respectively. She was an Assistant Professor of ECE at Ulsan National Institute of Science and Technology (UNIST), Ulsan, South Korea, from 2014-2018. Since 2019, she has been an Associate Professor of Electrical Engineering at National Taiwan University, Taipei, Taiwan. Dr. Kim has conducted extensive research on photovoltaic differential power processing techniques and developed a number of new techniques for grid-connected and emerging PV applications.