In recent years the need to reduce global energy consumption and CO2 emissions in the environment, has been involved even in the railways sector, aimed at the highly competitive concept of new vehicles/transportation systems. The requirements hoped by the operating companies, particularly as concerns tramway and metro-train systems, are increasingly focused on products with so far advanced features in terms of energy and environmental impact. In order to accomplish this possible scenario, this could be put into effects in technological subsystems and critical components, which are able to fulfill not only functional and performance requirements, but also regarding the new canons of energy saving. On the other hand, the regional and national energetic political strategies impose a continuous effort in the eco-sustainability and energy saving direction both for the vehicles and for the infrastructure management.
In this scenario, the thesis aims to fill the gap in the technical literature and deals with improving the energy efficiency of urban rail transport systems by proposing both design methodologies and effective control strategies for supercapacitor-based energy storage systems, to be installed on-board urban rail vehicles or along the rail track.
Firstly, a deep, rigorous and comprehensive study on the factors which affect energy issues in a DC-electrified urban transit railway system is carried out. Then a widespread overview of the currently available strategies and technologies for recovery and management of braking energy in urban rail is presented, also by providing an assessment of their main advantages and disadvantages alongside a list of the most relevant scientific studies and well established commercial solutions.
Afterwards, some effective control strategies for the optimal energy management of the supercapacitor-based energy storage system have been studied. Extensive simulations have been performed with the aim of validating the proposed techniques by employing a methodology which is based on tests carried out by means of scale models of the real systems.
A wide range of experimental tests has been developed and carried out on a laboratory-scale simulator for a typical urban service railway vehicle, in order to fully confirm the theoretical performances, validity, and feasibility of the studied controls, and quantify the technical and economic advantages obtained in terms of global energy saving, voltage regulation, power compensation and infrastructure power loss reduction.
The overall goal of this study is to gain an understanding of the methods and approaches for assessing the use of supercapacitor storage systems in urban rail transit oriented to the optimization of the energy saving and the reduction of the vehicle energy consumption, for whatever technological solutions are adopted
