Design Options for Hybrid Trains Powered by Hydrogen Fuel Cells and Batteries for Routes in the Highlands of Scotland. Results for the case of a three-coach multiple-unit train

Murray-Smith, D. (2020) Design Options for Hybrid Trains Powered by Hydrogen Fuel Cells and Batteries for Routes in the Highlands of Scotland. Results for the case of a three-coach multiple-unit train. Technical Report. Scottish Association for Public Transport, Glasgow.

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This work builds on and extends a report prepared for the Scottish Association for Public Transport in June 2020 entitled Modelling and simulation of hybrid electric trains powered by hydrogen fuel cells and batteries for routes in the highlands of Scotland: Preliminary results. That report discussed some issues arising in the design of powertrain systems for hybrid hydrogen fuelcell/ battery-electric trains and included preliminary simulation results for the case of a two-coach multiple-unit train. The choice of power ratings of hydrogen fuel cell stacks and battery packs, along with battery storage capacity in fuel cell/battery-electric trains is seldom straightforward and requires careful analysis. This design problem is especially challenging for trains intended for use on routes involving significant distances, few intermediate stations and prolonged steep gradients. The work being reported here involves more detailed modelling of on-board power transmission systems and describes the application of model-based analysis methods and simulation techniques to estimate fuel cell and battery power ratings and battery storage capacity. The case considered here involves a three-coach hybrid configuration and differs significantly from that discussed in the previous report in a number of ways. Conventional simulation methods applied to train performance investigations allow estimates to be made of variables such as speed or position, usually as functions of time, for inputs such as tractive force or power. However, an inverse simulation approach is adopted here which provides the tractive force or power at the rail for a given time history of distance travelled as input. This allows direct investigation of power ratings and storage capacity for the fuel-cell stack and battery pack for specified levels of train performance defined by a required schedule. The mathematical model of the train, on which the simulation is based, is considered in two parts. The standard equations describing longitudinal train movement form the first part of the model, with the equations describing the hydrogen fuel-cell stack, battery pack, power electronic components and traction motors forming a separate sub-model. A simple test route is used initially, with several distinct stages. These involve acceleration from rest, steady state running at the line speed limit, a section with a steep rising gradient and subsequent stages involving coasting and braking. From the analysis carried out using this model and the simulation results from the test route, estimates are made of power and stored energy requirements for a specific section of the West Highland line. From the results it is suggested that a specification for a three-coach hybrid unit for use on steeply graded secondary routes could be based on three 250 kW traction motors, a fuel-cell stack providing a maximum power output of 500 kW together with a 375 kW battery pack providing between 210 kWh and 300 kWh of storage. Preliminary weight estimates suggest that this specification could be achieved for a three-coach train for a gross weight of the order of 135 tonnes, although the volume of the necessary equipment could (at the present time) be difficult to accommodate within restrictions imposed by the UK loading gauge. These calculations allow for inclusion of a pantograph and associated equipment for operation from 25 kV supplies on electrified routes. Conclusions are also reached about additional insight provided by the inverse simulation approach compared with conventional simulation methods when applied to powertrain design issues. It is believed that these benefits could apply also to investigations involving other forms of on-board power transmission and energy storage systems

Item Type:Research Reports or Papers (Technical Report)
Additional Information:This is the fourth of a series of technical reports and reviews prepared in 2019 and 2020 prepared for members of the Scottish Association for Public Transport on topics relating to future transport in Scotland and to technical issues associated with the proposed elimination of diesel traction from the rail network.
Keywords:Inverse, simulation, train performance, hydrogen fuel cell, battery, powertrain.
Glasgow Author(s) Enlighten ID:Murray-Smith, Professor David
Authors: Murray-Smith, D.
Subjects:Q Science > QA Mathematics
T Technology > TD Environmental technology. Sanitary engineering
T Technology > TF Railroad engineering and operation
T Technology > TJ Mechanical engineering and machinery
T Technology > TK Electrical engineering. Electronics Nuclear engineering
College/School:College of Science and Engineering > School of Engineering
Publisher:Scottish Association for Public Transport
Copyright Holders:Copyright © 2020 Th Author
Publisher Policy:Reproduced with the permission of the Author

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