Sizing and Energy Management of a Hybrid Locomotive Based on Flywheel and Accumulators

The French National Railways Company (SNCF) is interested in the design of a hybrid locomotive based on various storage devices (accumulator, flywheel, and ultracapacitor) and fed by a diesel generator. This paper particularly deals with the integration of a flywheel device as a storage element with a reduced-power diesel generator and accumulators on the hybrid locomotive. First, a power flow model of energy-storage elements (flywheel and accumulator) is developed to achieve the design of the whole traction system. Then, two energy-management strategies based on a frequency approach are proposed. The first strategy led us to a bad exploitation of the flywheel, whereas the second strategy provides an optimal sizing of the storage device. Finally, a comparative study of the proposed structure with a flywheel and the existing structure of the locomotive (diesel generator, accumulators, and ultracapacitors) is presented

A review on power electronics technologies for power quality improvement

Nowadays, new challenges arise relating to the compensation of power quality problems, where the introduction of innovative solutions based on power electronics is of paramount importance. The evolution from conventional electrical power grids to smart grids requires the use of a large number of power electronics converters, indispensable for the integration of key technologies, such as renewable energies, electric mobility and energy storage systems, which adds importance to power quality issues. Addressing these topics, this paper presents an extensive review on power electronics technologies applied to power quality improvement, highlighting, and explaining the main phenomena associated with the occurrence of power quality problems in smart grids, their cause and effects for different activity sectors, and the main power electronics topologies for each technological solution. More specifically, the paper presents a review and classification of the main power quality problems and the respective context with the standards, a review of power quality problems related to the power production from renewables, the contextualization with solid-state transformers, electric mobility and electrical railway systems, a review of power electronics solutions to compensate the main power quality problems, as well as power electronics solutions to guarantee high levels of power quality. Relevant experimental results and exemplificative developed power electronics prototypes are also presented throughout the paper.This work has been supported by FCT-Fundação para a Ciência e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020. This work has been supported by the FCT Project DAIPESEV PTDC/EEI-EEE/30382/2017 and by the FCT Project newERA4GRIDs PTDC/EEIEEE/30283/2017

Electric Traction System Technology as a Solution to African Transportation Industries

The electric traction system in the case of Africa is highly advantageous in terms of transportation. The electric traction system is designed to provide a DC output source from an AC source of 33kV/230V for suitable mobility of tract devices without minimum frequency change. In this work, electric traction system analysis was obtained using mathematical models and simulation of tracts system components using MATLAB. Due to the application of FACTs devices, a 12-pulse thyristor rectifier is used for rectification. The system components are an energy source, harmonic filter, step-down transformer, rectifier substation, and DC load. The maximum current of total harmonic distortion obtained is certified with the IEEE standard 5% total harmonic distortion. the output voltage is purely stable, and the power factor quality is improved.&nbsp

Traction Power Substation Load Analysis with Various Train Operating Styles and Substation Fault Modes

Simulation of railway systems plays a key role in designing the traction power supply 13 network, managing the train operation and making changes of timetables. Various simulation 14 technologies have been developed to study the railway traction power network and train operation 15 independently. However, the inter-action among load performance, train operation and fault 16 conditions have been fully understood. This paper proposes a mathematical modeling method to 17 simulate the railway traction power network with consideration of multi-train operation, driving 18 controls, under-voltage traction, and substation fault modes. The network voltage, power load 19 demands, energy consumption according to the existing operation are studied. The hotspots of the 20 power supply network are identified based on the evaluation of train operation and power demand. 21 The impact of traction power substation (TPSS) outage and short circuit on the power supply 22 network have been simulated and analyzed. The simulation results have been analyzed and 23 compared with the normal operation. A case study based on a practical metro line in Singapore 24 Metro is developed to illustrate the power network evaluation performance

A Review of Developments in Electrical Battery, Fuel Cell and Energy Recovery Systems for Railway Applications: a Report for the Scottish Association for Public Transport

This report outlines the current status of batteries, hydrogen fuel cells and short-term energy storage systems for railway and tramway applications. The report includes discussion of issues associated with regenerative braking and the recovery of energy that would otherwise be dissipated as heat during braking. As well as feeding energy back to the supply grid, as in the case of conventional electrified rail systems, energy recovery may also be achieved using batteries, supercapacitors, flywheels or hydraulic devices and developments in each of these areas are reviewed. The advantages of hybrid systems that involve combinations of different power sources and energy storage methods are emphasised and some associated design optimisation issues are discussed. For each of the developments mentioned, there is a brief account given of some transport applications in the United Kingdom and elsewhere. This is a rapidly developing field and operating experience with vehicles currently entering service in various countries will provide important additional insight within the next two or three years

Power quality phenomena in electrified railways: Conventional and new trends in power quality improvement toward public power systems

Nowadays, railway electrification is the most efficient way to power the trains. However, power quality (PQ) phenomena toward public power systems (PPSs) have always a main concern to the railway operators, especially when the single phase traction power system is interconnected to the three phase PPS. The last decades have witnessed an on going evolution of PQ improvement and traction power supply systems, contributing to diminish the negative impacts of AC railway networks on PQ of the three phase PPS. In this context, this paper presents a global overview of the PQ phenomena in AC railway electrification, as well as the impacts of the potential hazards on the safe operation of electrified railways. The paper also reviews PQ improvement methods from the early use of AC railway electrification until the emergence of the new power electronics devices in railways industry.Mohamed Tanta was supported by FCT (Fundação para a Ciência e Tecnologia) PhD grant with a reference PD/BD/127815/2016. This work has been supported by COMPETE: POCI-01-0145–FEDER–007043 and FCT within the Project Scope: UID/CEC/00319/2013.info:eu-repo/semantics/publishedVersio

Infrastructure performance and reform in developing and transition economies: evidence from a survey of productivity measures

The authors review about 80 studies on electricity and gas, water and sanitation, and rail and ports (with a footnote on telecommunications) in developing countries. The main policy lesson is that there is a difference in the relevance of ownership for efficiency between utilities and transport in developing countries. In transport, private operators have tended to perform better than public operators. For utilities, ownership often does not matter as much as sometimes argued. Most cross-country studies find no statistically significant difference in efficiency scores between public and private providers. As for the country-specific studies, some do find differences in performance over time but these differences tend to matter much less than a large number of other variables. Across sectors, private operators functioning in a competitive environment or regulated under price caps or hybrid regulatory regimes tend to catch up best practice faster than public operators. There is a very strong case to push regulators in developing and transition economies toward a more systematic reliance on yardstick competition in a sector in which residual monopoly powers tend to be common.Enterprise Development&Reform,Labor Policies,Banks&Banking Reform,Environmental Economics&Policies,Economic Theory&Research,Environmental Economics&Policies,Economic Theory&Research,Banks&Banking Reform,Health Monitoring&Evaluation,Health Economics&Finance

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

Power Quality in Electrified Transportation Systems

"Power Quality in Electrified Transportation Systems" has covered interesting horizontal topics over diversified transportation technologies, ranging from railways to electric vehicles and ships. Although the attention is chiefly focused on typical railway issues such as harmonics, resonances and reactive power flow compensation, the integration of electric vehicles plays a significant role. The book is completed by some additional significant contributions, focusing on the interpretation of Power Quality phenomena propagation in railways using the fundamentals of electromagnetic theory and on electric ships in the light of the latest standardization efforts