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Intelligent Solid-State DC Substations - Key Enabling Technologies for Future DC Grids

Rik W. De Doncker, Jingxin Hu, Johannes Voss and Shenghui Cui

Brief Introduction:

    The change of the electrical supply system to more environmental-friendly energy sources require the development of a new grid infrastructure. Next to the increasing penetration of large-scale renewable energy sources such as offshore wind farms, the change of consumer behavior in the distribution grids from consumer into producer due to the installation of decentralized generations will result in a bottle neck in the distribution grids. Local or regional balancing between loads and generations is found to be a cost effective solution for the future electrical grids which can be realized with direct current (DC) technology. Compared to the classical AC technology, DC grids are also less prone to instabilities and more flexible to control via power-electronic based substations.

    The tutorial will focus on intelligent dc substations as the key enabler technology for the future flexible DC grids with renewable energy sources. This tutorial starts with dual-active bridge (DAB) based DC-DC converter topologies for LVDC-MVDC applications, where advanced modulation and control of DAB DC-DC converters will also be discussed. Then, the development and advanced control of an IGCT-based 5 kV, 5 MW DAB DC-DC converter at RWTH Aachen University will be presented including practical techniques to ensure soft-switching and avoid saturation of the employed medium-frequency transformers. The tutorial will then elaborate the operation principle and control of a high step-up ratio TLC-MMC converter for interconnection of MVDC and HVDC grids, which features soft-switching characteristics and fault-tolerant capability. Considering practical demands of interfacing hybrid AC-DC grids, the tutorial will also briefly present the MMC based AC-DC power-conversion techniques with focus on bipolar MVDC grids.

    The last section of the tutorial will deal with the protection of DC grids, including new fast-switching thyristor device for MVDC hybrid circuit breakers and breakless protection schemes enabled by fault ride-through capabilities of AC-DC and DC-DC converters.

image.pngRik W. De Doncker  (F’01) received the Ph.D. degree in electrical engineering from the Katholieke Universiteit Leuven, Leuven, Belgium, in 1986. In 1987, he was appointed as a Visiting Associate Professor at the University of Wisconsin, Madison. After a short stay as an Adjunct Researcher with Interuniversity Microelectronics Centre, Leuven, he joined, in 1989, the Corporate Research and Development Center, General Electric Company, Schenectady, NY. In 1994, he joined Silicon Power Corporation, a former division of General Electric Inc., as the Vice President of Technology. In 1996, he became a Professor at RWTH Aachen University, Aachen, Germany, where he currently leads the Institute for Power Electronics and Electrical Drives. Since 2006, he has been the Director of the E.ON Energy Research Center, RWTH Aachen University. Dr. De Doncker was the President of the IEEE Power Electronics Society (PELS) in 2005 and 2006. He was the founding Chairman of the German IEEE Industry Applications Society PELS Joint Chapter. In 2002, he was the recipient of the IEEE IAS Outstanding Achievement Award. In 2008, he received the IEEE PES Nari Hingorani Custom Power Award. In 2009, he led a VDE/ETG Task Force on Electric Vehicles. In 2010, he received an honorary PhD from TU Riga, Latvia. In 2013, he received the IEEE William E. Newell Power Electronics Award. He is the recipient of the IEEE Medal in Power Engineering in 2020.

    

image.pngJingxin Hu  received the B.S. degree from Northeastern University, Shenyang, China, in 2010, and the M.Sc. degree and Dr.-Ing. degree both with the highest distinction (summa cum laude) from RWTH Aachen University, Aachen, Germany, in 2013 and 2019, all in electrical engineering. During April 2012 – October 2012, he was an intern research engineer at the ABB Corporate Research Center (CRC), Baden-Daettwil, Switzerland. From 2013 to 2014, he worked at the High Power Electronics Laboratory at General Electric Global Research Center (GRC), Munich, Germany. Since October 2014, he joined the Institute for Power Generation and Storage System, E.ON Energy Research Center, RWTH Aachen University, Aachen, Germany, as a research associate, where he is currently working as a senior scientist. Dr. Hu was the recipient of Second Prize Paper Award of IEEE IPEC (ECCE Asia) in 2018 and STAWAG Dissertation Prize in 2019. Besides, he was also an invited lecture instructor in 2019 Asia PhD School on Advanced Power Electronics. His main research interests include solid-state transformers, renewable power generation and dc microgrids.

    

image.png Johannes Voss joined the Institute for Power Generation and Storage Systems, E.ON Energy Research Center, RWTH Aachen University, Germany, in 2012. In 2011, he received the Diploma degree in electrical engineering from the RWTH Aachen University. In 2015, he joined for 8 months the NSF GRid-connected Advanced Power Electronics Systems (GRAPES) at the University of Arkansas as an exchange student. In 2019 he received the Ph.D. degree in electrical engineering from the RWTH Aachen University. He is now with the Research Campus Flexible Electrical Networks and the Institute for Power Generation and Storage Systems. His research interests include the field of power electronics.

    

image.pngShenghui Cui  received the B.S. degree from Tsinghua University, Beijing, China in 2012, and the M.S. degree from Seoul National University, Seoul, South Korea in 2014, and the Dr.-Ing. degree with the highest distinction (summa cum laude) from RWTH Aachen University, Aachen, Germany in 2019, all in electrical engineering. Since March 2015, he joined the Institute for Power Generation and Storage System, E.ON Energy Research Center, RWTH Aachen University, Aachen, Germany, as a research associate, where he is currently working as a senior scientist. Dr. Cui was the recipient of the STAWAG Dissertation Prize in 2019, the Second Place Prize Paper Award of the IEEE Transactions on Power Electronics in 2018, the Second Prize Paper Award of IEEE IPEC (ECCE Asia) in 2018, and the Outstanding Presentation Award of IEEE APEC in 2014.