Assessment of the worthwhileness of efficient driving in railway systems with high-receptivity power supplies

Eco-driving is one of the most important strategies for significantly reducing the energy consumption of railways with low investments. It consists of designing a way of driving a train to fulfil a target running time, consuming the minimum amount of energy. Most eco-driving energy savings come from the substitution of some braking periods with coasting periods. Nowadays, modern trains can use regenerative braking to recover the kinetic energy during deceleration phases. Therefore, if the receptivity of the railway system to regenerate energy is high, a question arises: is it worth designing eco-driving speed profiles? This paper assesses the energy benefits that eco-driving can provide in different scenarios to answer this question. Eco-driving is obtained by means of a multi-objective particle swarm optimization algorithm, combined with a detailed train simulator, to obtain realistic results. Eco-driving speed profiles are compared with a standard driving that performs the same running time. Real data from Spanish high-speed lines have been used to analyze the results in two case studies. Stretches fed by 1 × 25 kV and 2 × 25 kV AC power supply systems have been considered, as they present high receptivity to regenerate energy. Furthermore, the variations of the two most important factors that affect the regenerative energy usage have been studied: train motors efficiency ratio and catenary resistance. Results indicate that the greater the catenary resistance, the more advantageous eco-driving is. Similarly, the lower the motor efficiency, the greater the energy savings provided by efficient driving. Despite the differences observed in energy savings, the main conclusion is that eco-driving always provides significant energy savings, even in the case of the most receptive power supply network. Therefore, this paper has demonstrated that efforts in improving regenerated energy usage must not neglect the role of eco-driving in railway efficiency

Design and Testing of an Innovative Pressure-Controlled Active Pantograph through Hardware-in-the-Loop Experiments

On railways with overhead lines, pantographs play a crucial role in electric trains. Maintaining the contact force between the pantograph and the overhead line is essential to ensure the robustness of the power supply and to minimise mechanical wear. This paper proposes an innovative pneumatic pressure-controlled active pantograph, tested through Hardware-in-the-Loop (HIL) experiments. The proposed easy-to-implement active pantograph is achieved by controlling the air pressure entering the pantograph. The controller design is based on an identified linear model, considering disturbance rejection performance and control input limitations. Experimental results show that the closed-loop active pantograph can robustly and effectively reduce the contact force deviation. This highlights the capability of designing active pantographs through pressure control and model-based design philosophy to achieve improved pantograph–catenary contact performance

Vibration Suppression in Flexible Structures using Hybrid Active and Semi-active Control

This thesis presents a new hybrid active and semi-active control method for vibration suppression in flexible structures. The method uses a combination of a semi-active device and an active control actuator situated elsewhere in the structure to suppress vibrations. The key novelty is to use the hybrid controller to enable the semi-active device to achieve a performance as close to a fully active device as possible. This is accomplished by ensuring that the active actuator can assist the semi-active device in the regions where energy is required. Also, the hybrid active and semi-active controller is designed to minimise the switching of the semi-active controller. The control framework used is the immersion and invariance control technique in combination with a sliding mode control. A two degree-of-freedom system with lightly damped resonances is used as an example system. Both numerical and experimental results are generated for this system and then compared as part of a validation study. The experimental system uses hardware-in-the-loop simulation to simulate the effect of both the degrees-of-freedom. The results show that the concept is viable both numerically and experimentally, and improved vibration suppression results can be obtained for the semi-active device that approaches the performance of an active device. To illustrate the effectiveness of the proposed hybrid controller, it is implemented to keep the contact force constant in the pantograph-catenary system of high-speed trains. A detailed derivation is given after which the simulation results are presented. Then a method to design a reduced order observer using an invariant manifold approach is proposed. The main advantage of this approach is that it enables a systematic design approach, and (unlike most nonlinear observer design methods), it can be generalised over a larger class of nonlinear systems. The method uses specific mapping functions in a way that minimises the error dynamics close to zero. Another important aspect is the robustness property which is due to the manifold attractivity: an important feature when an observer is used in a closed loop control system. The observer design is validated using both numerical simulations and hardware-in-the-loop testing. The proposed observer is then compared with a very well known nonlinear observer based on the off-line solution of the Riccati equation for systems with Lipschitz type nonlinearity. In all cases, the performance of the proposed observer is shown to be excellent

The Shinkansen High-Speed Rail Network of Japan; Proceedings of an IIASA Conference, June 27-30, 1977

The Shinkansen is the peak of railway technology. It travels the 550 km between Tokyo and Osaka 275 times every day at a speed of 210 km/hr. Such a revolution in transportation technology requires very special organization and is bound to have unexpected socioeconomic effects. The Shinkansen has had a large effect on migration patterns in Japan because it has drastically reduced the time it takes to travel from city to city. It has also affected the lives of people who may never use it. Stores in small communities can now offer produce that was too hard for them to obtain before the Shinkansen was built. But travel at high speed creates a great deal of noise, and special care must be taken to keep the tracks clear; at 210 km/hr, a train needs 3 km to stop in an emergency. The IIASA study of the Shinkansen began with this conference. Officials from the Japanese National Railways were invited to describe the development of the Shinkansen, scientists who had studied its effects presented their findings, and members of the IIASA research team outlined the approach that they would use in their study of the Shinkansen. Their papers are collected in this book. After an introductory section describing the history and outlining the plans for the Shinkansen, Sections 2 and 3 deal with the socioeconomic and environmental effects. Section 4 describes the influence the Shinkansen has had on national development. The last two sections deal with the organization of the Shinkansen itself. Section 5 describes the planning and administration of the Shinkansen by the Japanese National Railways, and Section 6 covers the physical requirements of high-speed train operation: the maintenance network and maintenance schedule, vehicle design, accident prevention, the seat reservation system, and other aspects of running a high-speed railroad from day to day

A literature review of Artificial Intelligence applications in railway systems

Nowadays it is widely accepted that Artificial Intelligence (AI) is significantly influencing a large number of domains, including railways. In this paper, we present a systematic literature review of the current state-of-the-art of AI in railway transport. In particular, we analysed and discussed papers from a holistic railway perspective, covering sub-domains such as maintenance and inspection, planning and management, safety and security, autonomous driving and control, revenue management, transport policy, and passenger mobility. This review makes an initial step towards shaping the role of AI in future railways and provides a summary of the current focuses of AI research connected to rail transport. We reviewed about 139 scientific papers covering the period from 2010 to December 2020. We found that the major research efforts have been put in AI for rail maintenance and inspection, while very limited or no research has been found on AI for rail transport policy and revenue management. The remaining sub-domains received mild to moderate attention. AI applications are promising and tend to act as a game-changer in tackling multiple railway challenges. However, at the moment, AI research in railways is still mostly at its early stages. Future research can be expected towards developing advanced combined AI applications (e.g. with optimization), using AI in decision making, dealing with uncertainty and tackling newly rising cybersecurity challenges

Solid-state transformers in locomotives fed through AC lines: A review and future developments

One of the most important innovation expectation in railway electrical equipment is the replacement of the on-board transformer with a high power converter. Since the transformer operates at line-frequency (i.e., 50 Hz or 16 2/3 Hz), it represents a critical component from weight point of view and, moreover, it is characterized by quite poor efficiency. High power converters for this application are characterized by a medium frequency inductive coupling and are commonly referred as Power Electronic Transformers (PET), Medium Frequency Topologies or Solid-State Transformers (SST). Many studies were carried out and various prototypes were realized until now, however, the realization of such a system has some difficulties, mainly related to the high input voltage (i.e., 25 kV for 50 Hz lines and 15 kV for 16 2/3 Hz lines) and the limited performance of available power electronic switches. The aim of this study is to present a survey on the main solutions proposed in the technical literature and, analyzing pros and cons of these studies, to introduce new possible circuit topologies for this application

A systemic framework for monitoring energy performance of urban railways

PhD ThesisGlobal sustainability challenges are particularly acute in urban conurbations which house the majority of the world’s population and where most of the economic activity takes place. Mobility is at the core of this challenge as transport is one of the highest energy consuming and polluting sectors across the globe. Achieving a low environmental impact transport system fit for all is a clear objective. A modal shift to low energy but highly competitive transport modes is a key target. Urban railway systems have the environmental performance and mass transit capability to be the core provider of mobility in metropolitan areas bringing also other benefits e.g. connectivity, cohesion and social inclusivity. Nevertheless, in a very competitive context where all modes are improving their energy performance, it is crucial that urban rail systems enhance their energy conservation levels without jeopardising their service offer. There is a lack of consensus amongst stakeholders on how to assess energy performance of urban rail systems. This void has been extended to the academic literature, where the issue is largely missing. The overall purpose of this thesis is to contribute to energy conservation of urban rail systems by supporting the decisionmaking process leading to the deployment of interventions aimed at improving energy efficiency and optimising its usage. A three-phased methodological triangulation approach has been adopted to address three research questions derived from two research objectives. This research has investigated energy usage, interventions and interdependencies that are governed by the complexity of the socio-technical system that are urban railways. A holistic approach has been developed based on an adaptable systemic monitoring framework and associated methodology enabling i) a multilevel analysis of system energy performance using a set of twenty-two hierarchical indicators and four complementing parameters, ii) an appraisal of candidate energy optimisation interventions and iii) the monitoring of the results of implemented measures. To validate and illustrate its execution, the framework has been applied to five different urban rail systems to assess a total of eleven technical and operational interventions. This has resulted in observing up 3.4% or circa 4 GWh usage reduction at system level when considering the influence of the three technical interventions monitored and up to 4.8% or circa 6.6 GWh when the eight operational interventions are evaluated in conjunction. These outcomes have illustrated the universality of the framework and its adaptability to the particularities of each urban rail system.CleanER-D and OSIRIS grants, both co-funded by the European Commissio

Design of a wing section in ground effect: application to high speed ground transportation

This dissertation attempts to fully explain the aerodynamic ground effect phenomenon, which occurs when a wing flies over a nearby plane. The long-term motivation is to determine the feasibility of a train that achieves aerodynamic levitation above a flat guideway. Such a train would rely exclusively on lifting surfaces, rather than on steel wheels, lifting fans, or magnetic fields.;As a first step in the study of an aerodynamically suspended train, a wing section must be designed. This dissertation focuses on the preliminary design and the experimental investigation of a two-dimensional airfoil in ground effect. For application to high-speed ground transportation, the airfoil is assumed to fly at approximately six degrees incidence and a ground distance of ten percent of its chordlength. Both the theoretical analysis and the wind tunnel experiment utilize two airfoils that are mirror images of one another. The symmetry plane between the two airfoils models the presence of the ground. The theoretical preliminary design makes use of inviscid panel methods.;The work includes chapters on vehicles that use the aerodynamic ground effect, and on high-speed ground transportation systems. Possible directions for future research in the area of aerodynamically suspended trains are also suggested

Finding solutions for complex systems: saving traction energy in rail

Complex optimisation problems, which are concerned with optimising a given aspect of a complex system, such as time or energy, are difficult to solve. Often a range of solutions exist, and the difficulty lies in determining which solutions to implement in which part of the system. Within this work, a novel method is developed that allows the solver to overcome the key challenges for these types of problems, which are: defining the system parts (subsystems); minimising model complexity; quantifying solution effectiveness; and identifying relationships between solutions and subsystems. The method is demonstrated through application to the problem of railway traction energy saving. Subsystems are defined using quantified network and service characteristics. For each subsystem, the trends between six key solutions and the key performance indicators are analysed using multivariate data analysis and visualisation techniques. The relationships between subsystems are then explored at system level. The analysis determines the suitable solutions for each type of railway, providing information for operators about which solutions to target. Based on the results, the implementation of permanent magnet motor technology is considered, illustrating that the method is a suitable tool for informing further studies