156 Engineering Rail Power Supply 120 (2022) Heft 4 Smart energy management systems with static energy storage devices René Jenni, Baden (CH), Patrycjusz Antoniewicz, Krakow (PL) Introducing modern rolling stock with more comfort equipment, reducing timetable intervals are possible reasons for inadmissible voltage drops in mature DC traction networks. Static energy storage systems can be considered as efficient alternatives for voltage support in comparison with building new rectifier substations. Intelligente Energiemanagementsysteme mit statischen Energiespeichern Die Einführung von neuem Rollmaterial mit mehr Komforteinrichtungen und die Verdichtung der Fahrpläne sind mögliche Gründe für Spannungseinbrüche in DC-Bahnenergieversorgungsnetzen. Statische Energiespeicher stellen im Vergleich zu klassischen Gleichrichterunterwerken effiziente Lösungen zur Spannungshaltung dar. Systèmes intelligents de gestion de l’énergie avec stockage d’énergie statique L’introduction de matériel roulant moderne avec plus d’équipements de confort, la réduction des intervalles d’horaires sont entre autres des raisons des chutes de tension inadmissibles dans des réseaux de traction à courant continu. Les systèmes de stockage d’énergie statique peuvent être considérés comme alternatives efficaces pour le contrôle de la tension de traction par rapport aux postes redresseurs classique. 1 Introduction Traditionally, Transit Authorities have met the increased power demand by building new, expanding existing substations, or by adding additional conductors to reduce the voltage drop. Also, the energy efficiency in DC railway systems is a concern, minimizing the energy demand and energy loss [1; 2]. Simultaneously recent years have shown a rapid development in energy storage systems [3]. Depending on its technology, batteries can be either directly connected to the DC grid, or through power electronic converter, which allows full control of discharging and charging currents. Further differentiation of lithium-ion cells chemistry [4] allows to tailor battery storage to the particular case. Nevertheless, batteries are still facing limitation on their current capabilities and life span [5]. Another type of storage are electrolytic double layer capacitors (EDLC) which can be used for high energy cases [6; 7]. Also other storage mediums can be found in traction applications like flywheels [8; 9]. That is why Energy Storage Systems (ESS) become an interesting solution to reinforce DC traction power supply networks [10]. ESS can be used to compensate voltage drops [11; 12], reduce peak power demand [13], avoid braking choppers operation, utilize of regenerative energy [14], or emergency power supply. ESS can be installed in the DC traction substation [15; 16; 17], along the track in an e-house, or onboard of electric powered rail vehicles [18; 19; 20]. There is no need of a medium voltage grid connection nor to increase the power demand from the utility. Wayside ESS can feed the railway line when it is required and can be charged from adjacent substations during idle periods, or by using braking energy [21]. Potential benefits of using ESS can be summarized as follows: improved power supply quality to trains, increased energy efficiency by reducing losses Figure 1: Building of Diamond Creek tie station at Melbourne Metro (Photos 1 and 2: ABB).
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