Opportunities and Challenges of Power Electronics Systems in Future Railway Electrification Luis A. M. Barros Centro ALGORITMI University of Minho Guimarães, Portugal lbarros@dei.uminho.pt Mohamed Tanta Centro ALGORITMI University of Minho Guimarães, Portugal mtanta@dei.uminho.pt António P. Martins SYSTEC Research Center University of Porto Porto, Portugal ajm@fe.up.pt João L. Afonso Centro ALGORITMI University of Minho Guimarães, Portugal jla@dei.uminho.pt J. G. Pinto Centro ALGORITMI University of Minho Guimarães, Portugal gpinto@dei.uminho.pt Abstract— With the continuous expansion of the railway power systems, the integration of high speed locomotives and the need to increase the overhead catenary line power capacity, the main shortcomings of the conventional railway feeding system are becoming more evident. In order to overcome these drawbacks and to contribute to the technological evolution with innovative and electrically more efficient systems, several solutions have been proposed and implemented. In this context, this paper briefly presents a study of different railway power systems, highlighting emerging concepts, such as regenerative braking, energy storage systems, the inclusion of renewable energy sources, bidirectional power flow and wireless power transfer. Some of these concepts can be implemented in short to medium term, or in the long term. Following these concepts, an overview of the power electronics challenges for the implementation of these emerging concepts is presented and discussed. Keywords— Electrical Railway Power Supply Systems, Energy Storage System, Power Electronics, Regenerative Braking, Renewable Energy. I. INTRODUCTION The railway system has maintained its long-standing position as one of the main pillars for passenger and freight transport. This leads to the fact that the railway system may add a distinct footprint for the economy of each country. All these factors have encouraged investment in the railway sector. In fact, the conventional railway system already accounts for almost one-sixth of the long-distance journeys between cities [1]. Nowadays, the high-speed railway system is increasingly attracting interest as a safe, economical and environmentally- friendly substitute for short-haul intercontinental flights. However, and in order to reduce congestion, pollution and travel time in metropolitan areas, the subway is a more interesting service for this requirement. On the other hand, regarding freight transport, rail solutions are equipped to transport large quantities of goods. Overall, the electric railway systems are the most efficient and least CO2 emitting comparing to other transportation modes [1]. The potential of the railway system to meet the forthcoming mobility demand of the future is enormous. This feature is reflected in China's strong bet on high-speed railway systems, moving from a nonexistent infrastructure in 2008 to one with a total length of 41 000 km within 10 years. Worldwide speaking, the metropolitan railway line has a length of 53 000 km and the high-speed railway line has a length of 68 000 km, representing an annual growth of 11 % per year from 2000 to 2016. Despite the truth that people use 5 times more electrified trains than the non-electrified ones, it is important to highlight that almost only 1/3 of the railway systems in the world are electrified [1]. One of the main booster of the railway system in the 21 st century is the financial initiatives of several world nations. For instance, Shift2Rail presents itself as a European organization committed to contributing to technological development in this area, as well as reducing rail life cycle cost by up to 50 %, doubling rail capacity and increasing reliability by up to 50 % [2]. In order to accomplish this objective, it is necessary to develop innovative solutions for railway systems, where power electronics play an important role. To study the opportunities and challenges of power electronics in railway systems, special importance was given to the new concepts of emerging locomotives. Table 1 shows the 11 fastest locomotives to be commercialized in the near future. This paper is structured to give an insight into the challenges and trends for the railway power system. The second Section presents the different emerging concepts that can be integrated into the railway power system. The third Section addresses the power electronics challenges in order to successfully implement the emerging concepts. Finally, Section IV presents the main conclusions of the paper. Luis A. M. Barros, Mohamed Tanta, António P. Martins, João L. Afonso, J. G. Pinto, “Opportunities and Challenges of Power Electronics Systems in Future Railway Electrification”, IEEE CPE-POWERENG 2020 – International Conference on Compatibility, Power Electronics and Power Engineering, Setúbal, Portugal, Jul. 2020, pp.530-537,ISBN: 978-1-7281-4218-0, ISSN: 2166-9546, DOI: 10.1109/CPE-POWERENG48600.2020.9161695.