Analysis of energy storage devices in hybrid railway vehicles

This paper presents an analysis of the energy storage requirements for hybrid railway vehicles. Autonomous hybrid railway vehicles combine two power sources. The conventional diesel prime-mover is supplemented with power derived from an on-board energy storage device. The device is dis-charged during high power demand, and may be recharged through regenerative braking. The en-ergy savings that are achievable through the adop-tion of such technology are also dependent on the duty cycle. It is shown that for a given vehicle there is a inter-station distance beyond which the benefits become marginal. The performance of the energy storage device fundamentally affects the whole system perfor-mance and careful consideration is required in de-vice selection. The constrained nature of the rail-way system also presents opportunities for opti-mization of architectures and control strategies. These methods are also discussed in this paper. Fi-nally, a review of practical implementation consid-erations is presented. 1 Hybrid railway vehicles The principle of a hybrid propulsion system is to use more than one power source for vehicle propul-sion. Choices of hybrid architecture and system configuration depend on the vehicle duty cycle, and also depend on issues such as whole life cycle costs and maintainability. For systems with two power sources, the prime mover is usually an internal com-bustion engine, and this is supported by another power source, such as a battery system during pe-riods of high power demand. The path of powe