On-Board Energy Storage in DC Traction System

How, Kian Loong (2022) On-Board Energy Storage in DC Traction System. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Most of the trains are equipped with regenerative braking systems. However, the use of this technology is not enough for increasing the overall efficiency of the system if it is not coordinated with other technologies or operation philosophies. One of the technologies included is the on-board energy storage traction system. The project aims to design a realistic on-board energy storage system (OESS) in the third rail traction system. Storage technologies devices are very interesting solutions for improving energy saving and enhancing the electrical characteristics of third rail traction systems. Onboard Energy Storage System (OESS) based on Lithium-ion battery (Li-ion) represent a viable engineering solution for energy saving optimization. An energy saving control strategy that utilizes regenerative braking energy with on-board Li-ion is researched in this paper. The simplified circuit model of the on-board Li-ion is built using MATLAB. After that, the charge and discharge process of the Li-ion is analysed as the speed of the train varies from one station to the other. The regenerative braking had been successfully demonstrated in this paper using three different speed profiles. The SOC recovered for these speed profiles are 0.025%, 0.006% and 0.022% respectively. The energy saved for speed profile 1 ,2 and 3 are 10000J, 1000J and 15000J respectively. This paper also proposed a charge and discharge strategy from the transmission line using bidirectional dc-dc buck boost converter. The charging condition is set to be less than 30% of the battery SOC while the discharging condition is set to be more than 70% of the battery SOC. The simulation had shown that it is a viable energy management system to charge and discharge the battery.