Coordinated Energy Management of the Electric Railway Traction System: Croatian Railways Case Study

A railway energy management system based on hierarchical coordination of electric traction substation energy flows and on-route trains energy consumption is presented in the paper. The railway system is divided into energy-efficient individual trains energy consumption management as a lower level, and the energy-cost-efficient electric traction substation energy flows management as a higher level. The levels are coordinated through parametric hierarchical model predictive control with the main goal of additionally decreasing the operational costs of the overall system. Through interactions with the power grid at the higher level, the system can provide ancillary services and respond to various grid requests. At the same time, lower level trains driving profiles are adjusted to attain the minimum cost of system operation with timetables and on-route constraints respected. The developed algorithm is verified against a detailed real case study scenario with the presented results showing significant cost and energy consumption reduction

Coordinated Energy Management of the Electric Railway Traction System: Croatian Railways Case Study

A railway energy management system based on hierarchical coordination of electric traction substation energy flows and on-route trains energy consumption is presented in the paper. The railway system is divided into energy-efficient individual trains energy consumption management as a lower level, and the energy-cost-efficient electric traction substation energy flows management as a higher level. The levels are coordinated through parametric hierarchical model predictive control with the main goal of additionally decreasing the operational costs of the overall system. Through interactions with the power grid at the higher level, the system can provide ancillary services and respond to various grid requests. At the same time, lower level trains driving profiles are adjusted to attain the minimum cost of system operation with timetables and on-route constraints respected. The developed algorithm is verified against a detailed real case study scenario with the presented results showing significant cost and energy consumption reduction

Urban and extra-urban hybrid vehicles: a technological review

Pollution derived from transportation systems is a worldwide, timelier issue than ever. The abatement actions of harmful substances in the air are on the agenda and they are necessary today to safeguard our welfare and that of the planet. Environmental pollution in large cities is approximately 20% due to the transportation system. In addition, private traffic contributes greatly to city pollution. Further, “vehicle operating life” is most often exceeded and vehicle emissions do not comply with European antipollution standards. It becomes mandatory to find a solution that respects the environment and, realize an appropriate transportation service to the customers. New technologies related to hybrid –electric engines are making great strides in reducing emissions, and the funds allocated by public authorities should be addressed. In addition, the use (implementation) of new technologies is also convenient from an economic point of view. In fact, by implementing the use of hybrid vehicles, fuel consumption can be reduced. The different hybrid configurations presented refer to such a series architecture, developed by the researchers and Research and Development groups. Regarding energy flows, different strategy logic or vehicle management units have been illustrated. Various configurations and vehicles were studied by simulating different driving cycles, both European approval and homologation and customer ones (typically municipal and university). The simulations have provided guidance on the optimal proposed configuration and information on the component to be used

Development and experimental evaluation of the control system of a hybrid fuel cell vehicle

This work presents the development and experimental evaluation of a Fuel Cell Hybrid Vehicle, focusing on the control system. The main objective of this paper is to present a real vehicle which has been designed in order to demonstrate the feasibility of the use of hydrogen as an energy source for automotive applications. The paper describes the components that are integrated in the vehicle and presents several experimental results obtained during normal operation. A control system is designed and tested in order to perform all the operations related to the coordinated operation of the fuel cell, the intermediate electrical storage and the power train. Its main task is to compute the power that must be demanded to the fuel cell in real time. This computation is done in order to satisfy the power demand of the electric motor taking into account the state of charge of the batteries and the operating regime of the fuel cell. This is accomplished by manipulating the electronic converter which regulate the current that the fuel cell supplies to the batteries.Ministerio de Ciencia y Tecnología DPI2007-66718-C04-0

Energy Management Systems for Smart Electric Railway Networks: A Methodological Review

Energy shortage is one of the major concerns in today’s world. As a consumer of electrical energy, the electric railway system (ERS), due to trains, stations, and commercial users, intakes an enormous amount of electricity. Increasing greenhouse gases (GHG) and CO2 emissions, in addition, have drawn the regard of world leaders as among the most dangerous threats at present; based on research in this field, the transportation sector contributes significantly to this pollution. Railway Energy Management Systems (REMS) are a modern green solution that not only tackle these problems but also, by implementing REMS, electricity can be sold to the grid market. Researchers have been trying to reduce the daily operational costs of smart railway stations, mitigating power quality issues, considering the traction uncertainties and stochastic behavior of Renewable Energy Resources (RERs) and Energy Storage Systems (ESSs), which has a significant impact on total operational cost. In this context, the first main objective of this article is to take a comprehensive review of the literature on REMS and examine closely all the works that have been carried out in this area, and also the REMS architecture and configurations are clarified as well. The secondary objective of this article is to analyze both traditional and modern methods utilized in REMS and conduct a thorough comparison of them. In order to provide a comprehensive analysis in this field, over 120 publications have been compiled, listed, and categorized. The study highlights the potential of leveraging RERs for cost reduction and sustainability. Evaluating factors including speed, simplicity, efficiency, accuracy, and ability to handle stochastic behavior and constraints, the strengths and limitations of each optimization method are elucidated

Switching nonlinear model predictive control of collaborative railway vehicles in catenary grids

This article contributes to the railway control field by proposing a novel approach capable of making trains collaborate, while also minimizing both traction energy and power line losses in catenary grids. The train dynamics are captured by a combination of four operating modes, so that the formulation of a switched control problem naturally applies. This model is interfaced with that of the catenary grid, consisting of the electrical substations and transmission lines over the track. Relying on these models, an eco-drive control system is proposed based on an original switching nonlinear model predictive control (SNMPC). Being collaborative-conceived, the new SNMPC is compared and evaluated against a noncollaborative version of the controller by means of simulation case studies relying on real-world test data, a validated train model, and measured track topology. We obtain that the proposed SNMPC outperforms the noncollaborative counterpart both in terms of traction energy and energy losses on the train rheostats and over the electrical lines. Thus, we demonstrate that the proposed SNMPC for collaborative eco-drive, based on the energy exchange between trains, has a potential positive impact on railway systems in catenary grids