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Energy savings in public transport

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Abstract

Growing pollution levels and traffic congestion in major cities are becoming delicate issues that could be eased by more efficient public transportation systems. To reduce emissions, electric powered vehicles are in use in many cities. Depending on the number of commuters and on the available infrastructure, different types of electric vehicles (battery electric buses, trolley buses, trams, metro, light rail) can be applied. Although these mass transit vehicles enable large reductions in terms of emissions, their energy efficiency could be significantly improved. This improvement can be reached by the hybridization of their drive train with the inclusion of an energy storage system (ESS) for energy recovery purposes [1], [2]. Recent studies have shown that up to 40% of the energy supplied to electrical rail guided current, and power losses, a model of the tram, network, and substations power flow has been developed in a Matlab/ Simulink environment. Results obtained in energy savings at substation level vary from 24iquest27.6% under the same driving profile and auxiliaries load, while at the endof- life (EoL) of supercapacitors, the range varies from 18.1 - 25.1%, depending on the super capacitor module used and the vehicle load.

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... E LECTRIC vehicles (EVs) have been extensively seen as a favorable option to the conventional combustion engine vehicles [1], [2]. They have advantages such as energy-efficient, environmentally beneficial, silent, and their use decreases oil dependence [3], [4]. Meantime, due to some drawbacks, consumers Manuscript are still not attracted to using EVs. ...
... Having the resistance forces (R x and D A ), it is possible to obtain the total requested torque (T req ) [Nm] in function also of the external radius (r) [m] and the vehicle required acceleration (ẍ req ) [m/s 2 ], as shown in Eq. (3). ...
Article
The hybrid energy storage system (HESS), which is composed of battery and ultracapacitor, is established to enhance the performance of an electric vehicle (EV). Moreover, several studies highlight the gains of split the traction power demand among electric motors (EMs) with different characteristics and drivetrain configurations, allowing these to operate at higher efficiency. In this paper, we unite the advantages of the multi EM drive train with the HESS power split and propose a novel two HESS system, in which each HESS is in charge of one of the drivetrain configurations (front and rear system). The EV is driven by two in-wheel EM at the front wheels and a single EM assembled with a differential transmission that moves the rear wheels. In this paper, a multiobjective optimization, based on a genetic algorithm (GA), is formulated to minimize the HESS sizing and maximize the driving range of the vehicle. Also employing the fuzzy control, this strategy is responsible to split the power between the front and rear wheels systems in a more reasonable way to satisfy the demands of better performance. The complete strategy has been developed under the FTP-75 (urban), HWFET (highway) and the US06 (high speed and required acceleration) driving cycles using the MATLAB/Simulink software environment. As compared to a similar EV with a single HESS system, the proposed dual-HESS configuration was able to improve the driving range in 145.15 km also decreasing 23.93% of the HESS mass.
... Moreover, the diesel engine power has to be sized to provide the maximum traction power, and its best efficient operation point is not often reached. The use of an Energy Storage System (ESS) is a valuable way to reduce the energy consumption of diesel-electric locomotives, but also of electric locomotives [8], [9]. Different hybridizations of diesel-electric locomotive have been developed using battery [10]- [12], supercapacitors [13], [14] and flywheels [15]. ...
... The DC overhead line and pantograph are described with the source DC in Fig. 2. When the pantograph is connected to the DC line (ON) the currents of the DC line and pantograph are determined by the ratio between the voltages applied on the line resistor (8). As the electricity network is considered as irreversible the braking energy cannot be sent back to the electricity network. ...
... As for on-board energy storage, savings are reported at 24% [39] and 18.6-35.6% [40]. These values refer to real-world data and account for phenomena that cannot be properly modelled. ...
... Chymera et al. showed that more than 50% of the energy dissipated in a transit system comes from braking [30], which also sets a limit on the energy that can be recovered through energy storage. The authors of [40] conduct a similar study to ours on a Brazilian route, calculating a theoretical 23.87% energy savings; when introducing the optimal size storage, an energy savings of 15.67% is achieved. [31] shows how coupling a flywheel in a slug car can reduce fuel consumption and NOx emissions by recovering the braking energy; gas emission reduction is another factor to take into account when dealing with ICE locomotives. ...
Article
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In this paper, we looked at the role of electromechanical storage in railway applications. A mathematical model of a running train was interfaced with real products on the electromechanical storage market supposed to be installed at the substation. Through this simulation, we gathered data on the recoverable energy of the system, its advantages, and its limitations. Various storage powers were run along variations in speed and gradient to paint a clearer picture of this application. Throughout these simulations, the energy savings were between 25% and 38%, saving up to 0.042 kWh/(seat km).
... DC MicroGrids are an innovative solution to be used also in transportation systems to integrate the advantages of energy storage utilization [10], [11], [12], [13], [14], [15]. Indeed, they can help to reach the target of increasing the energy saving [16] and the capability to compensate strong perturbations [17]. DC MicroGrids represent also a new possibility of integrating a different kind of energy resource, which is due to the trains' braking energy recovery systems that regenerates this energy by providing negative torque to the driven wheels. ...
... In the same way as for (78) and (80), in the case oḟ W 16 asymptotic stability can be proven by Barbalat's lemma utilization with the calculation ofẄ 16 . ...
Article
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A low-level distributed nonlinear controller for a DC MicroGrid integrated in a Smart Railway Station capable to recover trains' braking energy is introduced in this paper. The DC MicroGrid is composed by a number of elements: two different types of renewable energy sources (regenerative braking energy recovery from the trains and photovoltaic panels), two kinds of storages acting at different time scales (a battery and a supercapacitor), a DC load representing an aggregation of all loads in the MicroGrid, and the connection with the main AC grid. The nonlinear model of the MicroGrid is introduced, and a complete stability analysis is investigated to the purpose to meet power balance and grid voltage stability requirements. An Input-to-State Stability (ISS)-like Lyapunov function is obtained with a System-of-Systems approach, and it is utilized to develop the control laws for the converters in order to fulfill the dedicated objective each of them has. Simulation results, showing the desired grid behavior using the proposed nonlinear control laws, are introduced and compared with classical Proportional Integral (PI) linear controllers, with respect to performances and parametric robustness. The DC MicroGrid is shown to be able to operate braking energy recovery while performing load feeding and renewable energy integration and guaranteeing a proper DC voltage profile.
... Given the advantages of high-transport capacity, punctuality, short isolation distance, and environmental aspects, electric DC railway transportation is a preferred solution in an urban area. However, global warming and the increase in the cost of energy lead to the need to further improve the overall efficiency [1]. Indeed, cost and energy optimisations are more and more expected in the transport sector to reduce its ecological footprint and make its economical aspect more resilient [2]. ...
... T1) is represented by a current source i tot−1 , a coupling element representing the parallel connection on the DC bus with the rheostatic brake (13), and an accumulation element representing the DC bus, which imposes the voltage u f−1 on the DCTN. The brake current i bk−1 is imposed by the braking management strategy (1). The interactions with the DCTN are the voltages u f of the DC buses and the currents i t of the trains. ...
Article
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Simulation tools are crucial to efficiently design the infrastructures and operations of DC electrical railway systems, including potential innovative technologies such as reversible traction power substations and energy storage systems. For this purpose, it is essential to accurately estimate the evolution of the voltage and power flows within the DC traction network, with fast computation time. This study, therefore, proposes a new simulation approach for fast and accurate voltage estimation and power flow analysis of DC railway systems. It is based on the use of non‐linear switched models for traction power substations and trains. The modified nodal analysis is extended to consider such models, including the voltage drop control of the different subsystems, avoiding the necessity to use complex numerical iterative solvers. This new approach is validated and compared to an existing dynamical model and a conventional static model. The comparisons prove the relevance of the new approach, which provides validated and accurate results (<2% error compared to the validated dynamical model) with fast computation time (speed up of 500 compared to the dynamical model). It can, therefore, be used to study, design, size, and optimise DC traction systems with new technologies aimed at saving braking energy.
... By introducing an intelligent energy system for efficient energy processes and mitigation technologies for the reduction of environmental pollutants, many positive environmental, social and economic impacts arise (Barrero et al., 2008;Ozzie, 2012;Yann, 2015). The most targeted measures to reduce pollution should be aimed at transportation emissions since the energy use and greenhouse gas (GHG) emissions are closely related when considering public transport as a major element of urban development (Norman et al., 2006;Schipper et al., 1992). ...
Article
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Many countries face environmental problems along with traffic jams, over-crowded traffic and poor public transportation system. The paper elaborates a project idea of introducing a new sustainable city transport in the capital of Macedonia, based on light and electricity driven monorail system. Yet, the research does not attempt to provide a detailed map applicable to solve pollution problems of Skopje, but rather to suggest framework for serious consideration for answering profound issues, like the nature of urban air pollution, pollution sources, and available resources. Moreover, the study posts some valuable recommendations for developing monorail as probably the only permanent solution that may improve environmental footprint of Skopje. By following many positive world-wide examples, the paper proposes a scheme in which local and central policy makers may approach in selection and implementation of internationally based experiences. It places a special emphasis on how to coordinate policies across many sectors that are closely linked to the mitigation of air pollution from city urban transport, in the first line environment, transport, and energy. Greater use of public transport offers a single most effective strategy currently available for achieving significant energy savings and environmental gains, without creating new government programs or imposing new rules on the private sector. Consequently, Skopje may have fast, reliable, modern, ecologically friendly and long-term sustainable city transport.
... If there is no train in traction and no load on the system to absorb this regenerative energy, the voltage of the DC catenary increases [14]. To overcome this problem, some strategies can either be involved: to optimize the train's operations [16,30] (optimization timetables, efficient energy based driving) or to address an updating of the railway power network by integrating new hardware equipment such as energy storage [6]. Train timetable optimization has been suggested as one of the approaches to increase the recuperation ratio of the regenerative braking energy. ...
Article
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To face environmental issues, SNCF, the French railway, has chosen to improve the energy efficiency of its electrical power system by investigating solutions for regenerative braking. With the contribution of Railenium, a research and test center in railway activities, they aim to recover the braking energy by setting up a reversible inverter in the DC substation ”Masséna”. The issue is to test, implement and compare various control solutions to increase the energy efficiency with minimum impacts on the railway operation. In this paper, a simulation model for studying a reversible power substation is addressed by considering AC and DC equivalent electrical sources. The proposed model provides a reliable tool for analyzing the behavior of the railway electrical network during specially braking mode. In order to validate this model, its simulation results are compared with the ones obtained from Esmeralda, the SNCF professional software. A first configuration is led without the inverter and gives certified Esmeralda results and validates the proposed model despite some gaps in powers and voltages due to differences in input data and models. A second comparison with inverter is presented to highlight the main difference between the proposed model and Esmeralda. In addition, laboratory experimental activities are put forward to investigate the proposed model by using power-hardware-in-the-loop simulations. Finally, a simulation test under MATLAB software with fifty train’s traffic is presented to estimate the energy saving thanks to the installed inverter. For this latter case study, the system sent back to the national AC grid around 6.9% of the total energy consumed by all trains.
... Many urban rail transit systems have been equipped with supercapacitors, such as Brussels tram line, Brussels metro line, Madrid metro line, Blackpool tramway, Mannheim tramway and Paris tram line. The energy saving rate by using supercapacitors ranges from 16% to 35.8% in theoretical assessments [4]- [9]. Electrochemical batteries, such as lead-acid batteries, Ni-Cd batteries, NiMH batteries, Li-ion batteries and so on, are with relatively high energy density leading to large energy-storage capability [1]. ...
Article
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For improving the energy efficiency of railway systems, on-board energy storage devices (OESDs) have been applied to assist the traction and recover the regenerative energy. This paper aims to address the optimal sizing problem of OESDs to minimize the catenary energy consumption for practical train operations. By employing a mixed integer linear programming (MILP) model based on energy flow and the law of conservation of energy, three types of widely used OESD: supercapacitors, Li-ion batteries and flywheels have been studied in a real-world case of Beijing Changping line. Results show that without the constraints of capital cost and volume, the supercapacitor, Li-ion battery and flywheel with optimized capacity can save the catenary energy consumption by 23.6%, 22.9% and 23.7% compared to the cases without OESDs respectively. The minimum catenary energy consumption for each type of OESD has also been found with the constraints of capital cost and volume. The study shows that with a volume constraint less than 0.6 m3 and a higher allowed capital cost more than 20 k$, flywheel tends to achieve the least catenary energy consumption. When the volume is relaxed to go beyond 0.6 m3, supercapacitors always achieve the minimum catenary energy consumption disregarding the constraint of capital cost.
... Real applications of on-board storage systems are the Brussels, Madrid metro and Mannheim tramway lines. The percentage of energy saving reported in [45][46][47] are 18.6% ÷ 35.8%, 24% and 19.4% ÷ 25.6%, respectively. To reach high integration with motor drive control, some research studies are focused on the optimal design, sizing and control of on board energy storage systems [48][49][50][51][52]. Focuses on stationary storage systems, the real implementation of wayside Energy Storage System (ESS), show an increase in energy savings of up to 30%. ...
Article
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The present paper is a review on efficiency issues related to three important sectors of the transportation systems: railways, electrical vehicles, and marine. For the three sectors, the authors, in reference of their knowledge and research area, show the results of a wide literature analysis, in order to highlight which are the measures, in terms of technological solutions and management techniques, which are recently investigated and implemented, for improving the three transportation systems, from the point of view of efficiency. In particular, for the railway transportation sector, a wide analysis is presented, detecting which are the main measures adopted for improving the efficiency, related to the power systems for supplying trains and to the train traffic control, with a focus on the storage system integration. For electric road vehicles the analysis is focused on the plug-in electrical vehicles and on the infrastructure for their recharge, with an emphasis on how these vehicles can support the grid, e.g., through Vehicle to Grid (V2G) applications. Finally, for the marine transport service the review is related to the propulsion systems and on how the different solutions can meet the objective of efficiency.
... It consists of obtaining a way to drive a train on a journey to fulfil a target running time with minimal energy consumption. Eco-driving has the advantage of being a short-term action that requires low investments, while other measures, such as improving the infrastructure [3][4][5][6][7][8][9][10][11][12] or rolling stock [13][14][15][16][17], usually require a significant investment and long/mid-term actions. ...
Article
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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.
... It is important to remark that even though this is a current practice in industry, the formal analysis and explanation of such approach was seldom presented (see Chen et al. (2014); Iovine et al. (2017); Perez et al. (2018b)). of PV generation, a battery and a supercapacitor as a hybrid energy storage system and a DC load, representing the station's own needs as well as charging stations for electric vehicles (bus, taxi, car). The purpose is to allow regenerative braking, such that the surplus energy on the train electric line can be properly absorbed by the MicroGrid, avoiding overvoltage in the trains' line, and then allowing much more electric braking instead of mechanical (see Barrero et al. (2008); Dixon and Ortuzar (2002)). Fig. 1 depicts the proposed DC MicroGrid with the train line connection. ...
Article
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This paper proposes the integration of a train line for regenerative braking into a DC MicroGrid composed of PV generation, hybrid energy storage system (battery and supercapacitor) and DC local load. The energy generated from regenerative braking is absorbed by the supercapacitor, which is able to deal with bursts of power without affecting the stability of the system. The control scheme is based on singular perturbation analysis, where we can split the overall system in two interconnected subsystems with different time-scales dynamics, solving the non-minimal phase problem for DC/DC converters. Therefore, a simplified control strategy is obtained to control the train's converter and to assure stability of the whole MicroGrid. Simulation results show that the proposed control strategy can integrate regenerative braking from train as a renewable source in the MicroGrid.
... and greenhouse gas emission [1]. For these reasons, cleaner tramways, subways, and trains are developed to ensure and increase mobility while limiting environmental impact [2], [3]. Innovative solutions have been proposed to reduce energy consumption, such as vehicle scheduling [4], [5], energy storage systems (ESS) [6], [7], or reversible traction power substations (TPS) [8], [9]. ...
... The braking energy can be stored in stationary or on-board energy storage devices (ESD). The costs of the on-board ESDs may be higher than of way-side ESDs because they have to be embedded on every train instead of being placed at certain stations [9]. The drawback of the stationary ESD [10][11][12] is that the regenerated energy is sent via contact lines, which results in line losses. ...
Article
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This paper presents an analysis on using an on-board energy storage device (ESD) for enhancing braking energy re-use in electrified railway transportation. A simulation model was developed in the programming language C++ to help with the sizing of the ESD. The simulation model based on the mathematical description has been proposed for a train equipped with on-board ESD for analysis of effectiveness of its application. A case study was carried out for a metro line taking into consideration train characteristics, track alignment, line velocity limits and a running time table. This case study was used to assess the energy savings and perform a cost-benefit analysis for different sizes of the on-board ESD by applying the proposed approach. It was shown that when additional environmental benefits (reduction of CO2 emissions) are considered, this may significantly improve effectiveness of the investments due to CO2 European Emission allowances.
... The public transportation such as three-wheelers, mini/micro buses, buses, trolleybuses, trams, trains and ferries is mainly available for use by anyone (Scott and Bloomfi eld, 1990) and generally operates on fi xed routes. Public transportation system has become increasingly important in urban areas due to mass transit and increased awareness to energy-saving methods of transportation (EPA, 1973;Barrero, 2008). During the travel, various components of the vehicle such as seats, handle, door handle are frequently encountered and may act as the important reservoir for transmission of different pathogenic and non-pathogenic microbes (Oranusi et al. 2016). ...
Article
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Objectives: The purpose of this study was to assess microbial load and Methicillin Resistant Staphylococcus aureus from surfaces of public transport vehicle. Methods: The surfaces of public transport vehicle were sampled by swabbing. A total of 56 samples from 28 different vehicles operating in Kathmandu valley were collected and processed according to the standard methodology. The isolates were identified by culture, biochemical tests and subjected to antimicrobial susceptibility testing by modified Kirby-Bauer disk diffusion method following CLSI 2013 guidelines. Methicillin resistant species of Staphylococcus were detected by the virtue of cefoxitin resistance. Results: All 56 samples from the 28 different vehicles were found to have bacterial growth with average bacterial load of 2.47±1.22 x 105 CFU/cm2. The gas vehicles were found to be the most contaminated. Out of 56 samples, 35 (25.9%) were found to be S. aureus growth positive 11 (31.4%) of them being MRSA. Conclusion: The high flow of people with different health conditions in public transport makes the exchange of microorganism more significant. High bacterial load along with MRSA indicates the threats of transmission of infection among travellers. This is of a great public health concern as the mass population of different health condition is in direct exposure and is prone to get infected.
... Therefore, it is usual the situation that this energy must be wasted in on-board resistors (rheostats). Two main solutions have been proposed in the literature, to increase the receptivity of the power supply grid and to maximise the use of regenerative energy: reversible substations [11][12][13][14] and wayside energy storage systems [15][16][17][18][19][20]. Reversible substations improve the receptivity by means of returning regenerated energy to the utility grid. ...
Article
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Transport is a main source of pollutants in cities, where air quality is a major concern. New transport technologies, such as electric vehicles, and public transport modalities, such as urban railways, have arisen as solutions to this important problem. One of the main difficulties for the adoption of electric vehicles by consumers is the scarcity of a suitable charging infrastructure. The use of the railway power supplies to charge electric vehicle batteries could facilitate the deployment of charging infrastructure in cities. It would reduce the cost because of the use of an existing installation. Furthermore, electric vehicles can use braking energy from trains that was previously wasted in rheostats. This paper presents the results of a collaboration between research teams from University of Rome Sapienza and Comillas Pontifical University. In this work, two real European cases are studied: an Italian metro line and a Spanish metro line. The energy performance of these metro lines and their capacity to charge electric vehicles have been studied by means of detailed simulation tools. Their results have shown that the use of regenerated energy is 98% for short interval of trains in both cases. However, the use of regenerated energy decreases as the train intervals grow. In a daily operation, an important amount of regenerated energy is wasted in the Italian and Spanish case. Using this energy, a significant number of electric vehicles could be charged every day.
... Important examples of real world implementation of onboard ESS are Brussel metro and tram lines and Madrid Metro line in Europe that show 18.6%-35.8% and 24% energy saving, respectively [54]- [56]. Japan metro with 8% saving of regenerative braking energy, and Mannheim tramway with 19.4%-25.6% ...
Article
Electric rail transit systems are the large consumers of energy. In trains with regenerative braking capability, a fraction of the energy used to power a train is regenerated during braking. This regenerated energy, if not properly captured, is typically dumped in the form of heat to avoid overvoltage. Finding a way to recuperate regenerative braking energy can result in economic as well as technical merits. In this comprehensive paper, the various methods and technologies that were proposed for regenerative energy recuperation have been analyzed, investigated, and compared. These technologies include: train timetable optimization, energy storage systems (onboard and wayside), and reversible substations.
... This scenario is particularly favorable for the use of regenerative braking systems and, since the lines are usually shorter than conventional railway lines, it is also possible to easily implement innovative customized solutions. For these reasons, the application of energy recovery systems in tramways and light railways has been widely analyzed [10][11][12], considering various energy storage systems locations [13,14], different applications and usage [15][16][17][18], and different storage technologies [19]. Energy recovery in high speed railway systems is still an open field of research and the possibility to obtain significant savings is remarkable. ...
... Many urban rail transit systems have been equipped with supercapacitors, such as Brussels tram line, Brussels metro line, Madrid metro line, Blackpool tramway, Mannheim tramway and Paris tram line. The energy saving rate by using supercapacitors ranges from 16% to 35.8% in theoretical assessments [4]- [9]. Electrochemical batteries, such as lead-acid batteries, Ni-Cd batteries, NiMH batteries, Li-ion batteries and so on, are with relatively high energy density leading to large energy-storage capability [1]. ...
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For improving the energy efficiency of railway systems , on-board energy storage devices (OESDs) have been applied to assist the traction and recover the regenerative energy. This paper aims to address the optimal sizing problem of OESDs to minimize the catenary energy consumption for practical train operations. By employing a mixed integer linear programming (MILP) model based on energy flow and the law of conservation of energy, three types of widely used OESD: supercapacitors, Li-ion batteries and flywheels have been studied in a real-world case of Beijing Changping line. Results show that without the constraints of capital cost and volume, the supercapacitor, Li-ion battery and flywheel with optimized capacity can save the catenary energy consumption by 23.6%, 22.9% and 23.7% compared to the cases without OESDs respectively. The minimum catenary energy consumption for each type of OESD has also been found with the constraints of capital cost and volume. The study shows that with a volume constraint less than 0.6 m 3 and a higher allowed capital cost more than 20 k$, flywheel tends to achieve the least catenary energy consumption. When the volume is relaxed to go beyond 0.6 m 3 , supercapacitors always achieve the minimum catenary energy consumption disregarding the constraint of capital cost. Index Terms-On-board energy storage device (OESD), optimal sizing, electrified railway systems, mixed integer linear programming (MILP), energy-saving
... The problems of energy efficiency and energy saving have been extremely topical lately. So, implementing various systems and devices whose function is not only saving energy, but also generating a certain amount of energy for further use is one of the ways to solve them [1]- [3]. Transport (with its infrastructure) apparently faces the urgency of implementing energy-efficient and energysaving technologies more than any other sector of economy. ...
... Issues related to electromobility in public transport systems and the improvement of the operational efficiency of public transport are currently of interest to many scientists and engineers [1][2][3][4][5][6]. This coincides with the development of devices ensuring passenger comfort, greater passenger comfort expectations and the intensive advancement of technologies involved in the production of traction batteries [7,8], supercapacitors [9][10][11][12], combustion generators and other energy sources [9,13,14]. ...
Article
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When a trolleybus travels through insulated sections of the overhead contact line, it experiences momentary power interruptions, which adversely affect the vehicle’s on-board auxiliary subassemblies. To reduce these negative effects, one can harness energy recovered via regenerative braking. A model power supply circuit diagram for structural systems of the trolleybus is proposed. Simulation tests were carried out to develop a method for analyzing power supply to trolleybus auxiliary devices and verify it in a real-life example. The results allow determination of the limit power that can be generated by the trolleybus drive system to feed auxiliary devices during interruptions in power supply from the overhead contact line. The possibility of powering the on-board auxiliary equipment of a trolleybus using energy from recuperation with a traction motor is presented.
... Surplus energy in braking phases recovered by the installation of onboard or wayside energy storage systems with designing controllers to control charge/discharge process of SCESS suitable for operation characteristic of train. Studies, applications of super capacitor energy storage system with tested to practical utilization (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16) . Iannuzzi et al (5) using onboard SCESS integrated with traction drive system saves energy to 38%, reducing peak power up to 50% in accelerating regime, stabilizing voltage on DC bus to 1%, increasing power supply distance among traction substations ; Dominguez et al released a study of energy consumption reduction to 24% in the Metro de Madrid (7) ; Michael Steiner et al (8) shows Bombardier installed Mitrac energy saver being able to reduce the consumption of the traction energy to 30% and line current peak and voltage drop by 50% ; Diego Iannuzzi, Flavio Ciccarelli, Davide Lauria (12) use stationary ultra-capacitor storage device for improving energy saving and voltage profile of light transportation networks; reversible substations (17,18) ; maximizing the regenerative energy exchange between trains by synchronizing their accelerating and braking phases as much as possible (19)(20)(21) , Fathy Ahmed et al. (22) applied parasitism-predation algorithm (PPA) in the energy management strategy for hybrid photovoltaic/fuel cell/battery/supercapacitor to minimize the hydrogen consumption of fuel cell; Jamadar Najimudin et al (23) developed regenerative braking system (RBS) and braking energy management techniques, considering different driving situations and road conditions which employed in addition to mechanical braking for increasing the braking efficiency of the electric vehicle system. ...
... Energy consumption is a very important aspect linked to the decline in public transport in cities. Increasing levels of pollution, congestion on the roads and energy consumption in cities are becoming sensitive issues that could be mitigated by more efficient public transport systems and an increased share of urban travel by public transport [67]. The epidemic threat has reduced the share of public transport travel, and this reduction occurred drastically during national lockdowns. ...
Article
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Pandemics have presented new challenges for public transport organisers and operators. New diseases (e.g., influenza H1N1, severe acute respiratory syndrome—SARS, as well as, more recently, SARS-CoV-2) increase the need for new protection measures to prevent epidemic outbreaks in public transport infrastructure. The authors’ goal is to present a set of actions in the area of public transport that are adjusted to different levels of epidemic development. The goal goes back to the following question: how can the highest possible level of passenger safety be ensured and the losses suffered by urban public transport companies kept as low as possible? The sets of pro-active measures for selected epidemic scenarios presented in the article may offer support to local authorities and public transport operators. In the next steps, it is important to develop and implement tools for public transport management to ensure safety and tackle epidemic hazards.
... Ordody observed the properties of the existing ventilation system in the Budapest subway and proposed a new economic primary ventilation system considering the technical requirements [|11]. Baerro et al. investigated the use of energy storage systems super capacitors in terms of energy savings and stated that these systems provide about 18 -25% efficiency [12]. Meinert investigated the effects of hybrid energy storage units, and these units provided that energy stored up to 2.5 km and saved up to 10.8% [13]. ...
Article
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Today, reducing the energy consumption of rail systems is one of the issues that attract researchers' attention. There are many methods to reduce energy consumption and coasting control method has been used in this study. The driving modelling of the vehicle has been carried out by considering all parameters. A new objective function has been determined and for optimization, genetic algorithm (GA) and artificial bee colony (ABC) algorithm have been preferred. The study has been tested with the data of Ankaray metro line. When the proposed optimized driving has been compared with practical driving of the vehicle, the energy savings rate is 13.79% in GA and 13.45% in ABC for a driving. Despite these significant savings ratios, the increase in travel time has been calculated at 1.7% in GA and 1.55% in ABC. When the obtained savings rates are considered annually, this study may greatly contribute to sustainable life.
... Microgrids are considered innovative solutions to be used also in transportation systems to integrate the advantages of energy storage utilization [13][14][15][169][170][171]. Indeed, they can help to reach the target of increasing energy saving [172] and the capability to compensate strong perturbations [173]. In urban railways, the power consumption is very high, therefore the optimization of energy consumption in this field means a great contribution for energy efficiency, specially when dealing with braking energy recovery. ...
Thesis
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Microgrids are a very good solution for current problems raised by the constant growth of load demand and high penetration of renewable energy sources, that results in grid modernization through “Smart-Grids” concept. The impact of distributed energy sources based on power electronics is an important concern for power systems, where natural frequency regulation for the system is hindered because of inertia reduction. In this context, Direct Current (DC) grids are considered a relevant solution, since the DC nature of power electronic devices bring technological and economical advantages compared to Alternative Current (AC). The thesis proposes the design and control of a hybrid AC/DC Microgrid to integrate different renewable sources, including solar power and braking energy recovery from trains, to energy storage systems as batteries and supercapacitors and to loads like electric vehicles or another grids (either AC or DC), for reliable operation and stability. The stabilization of the Microgrid buses’ voltages and the provision of ancillary services is assured by the proposed control strategy, where a rigorous stability study is made. A low-level distributed nonlinear controller, based on “System-of-Systems” approach is developed for proper operation of the whole Microgrid. A supercapacitor is applied to deal with transients, balancing the DC bus of the Microgrid and absorbing the energy injected by intermittent and possibly strong energy sources as energy recovery from the braking of trains and subways, while the battery realizes the power flow in long term. Dynamical feedback control based on singular perturbation analysis is developed for supercapacitor and train. A Lyapunov function is built considering the interconnected devices of the Microgrid to ensure the stability of the whole system. Simulations highlight the performance of the proposed control with parametric robustness tests and a comparison with traditional linear controller. The Virtual Synchronous Machine (VSM) approach is implemented in the Microgrid for power sharing and frequency stability improvement. An adaptive virtual inertia is proposed, then the inertia constant becomes a system’s state variable that can be designed to improve frequency stability and inertial support, where stability analysis is carried out. Therefore, the VSM is the link between DC and AC side of the Microgrid, regarding the available power in DC grid, applied for ancillary services in the AC Microgrid. Simulation results show the effectiveness of the proposed adaptive inertia, where a comparison with droop and standard control techniques is conducted.
... 46 Three types of OESDs are commonly utilized in electri-47 fied railway systems, namely supercapacitors, flywheels, and 48 electrochemical batteries. Supercapacitors are widely utilized 49 as the OESD, for example, many urban rail transit systems 50 have been equipped with them, such as tramlines [6] and 51 metro lines [7] in Brussels, Madrid metro line [8], Blackpool 52 tramway [9], Mannheim tramway [10], and Paris tram line 53 [11]. For the flywheel, early in 1988, it has been proposed as 54 an OESD for trains to avoid regenerative braking cancellation 55 and to compensate for voltage drops. ...
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... Most of these research studies estimate a reduction in total energy consumption around 12-35% when using SC. Simulation results reported in the literature show reduction of 33% for a metro line in Brussels [38], 24% for a metro line in Madrid [39], 25% for a tramway in Mannheim [40], or 30% for a Blackpool tramway [41] are reported in the literature. The research presented in [21], oriented to freight trains, shows that using a storage unit to enable regenerative braking reduces up to 25% of the total energy. ...
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Two rating systems assessing the environmental damage caused by vehicles are compared: a Brussels one, ECOSCORE and a European one, CLEANER DRIVE. Both vehicle rating systems were developed for the assessment of vehicles with alternative types of fuels as well as different types of drive train, such as electric, hybrid and fuel cell vehicles. A simplified life cycle assessment following a well-to-wheel approach is used to compare the methodologies. Total emissions involve oil extraction, transport and refinery, fuel distribution and electricity generation and distribution as well as tailpipe emissions from the use phase. Different types of pollution such as acid rain, photochemical air pollution, noise pollution and global warming are examined and their impact on numerous receptors such as ecosystems, buildings and human beings (cancer, respiratory diseases, etc.) are investigated. Examples illustrate both methodologies and sensitivity analysis is used to examine the robustness of the systems.
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Resulting from a Ph.D. research a Vehicle Simulation Programme (VSP) is proposed and continuously developed. It allows simulating the behaviour of electric, hybrid, fuel cell and internal combustion vehicles while driving any reference cycle [Simulation software for comparison and design of electric, hybrid electric and internal combustion vehicles with respect to energy, emissions and performances, Ph.D. Thesis, Department Electrical Engineering, Vrije Universiteit Brussel, Belgium, April 2000]. The goal of the simulation programme is to study power flows in vehicle drive trains and the corresponding component losses, as well as to compare different drive train topologies. This comparison can be realised for energy consumption and emissions as well as for performances (acceleration, range, maximum slope, etc.).
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In order to configure super capacitor based energy storages in hybrid electric vehicles, the required peak power and the total amount of energy are estimated by using our strategies of energy source control and management during typical test cycles. The configuration of the super capacitor based energy storage for a dedicated vehicle has been verified with respect to the voltage variation, maximum current and power losses. The strategies of energy source control and management presented in this paper can be ensure efficiently and safely using the super capacitor based energy storage.
Conference Paper
A supercapacitive-storage based substation for the compensation of resistive voltage-drops in transportation networks is proposed. It allows to feed as a current-source in any voltage conditions of the line. The system has been designed as a compensation-substation to be placed at weak points like end-of-line stations, instead of additional feeding substations. A dedicated power-electronic converter with an associated control system for the stabilization of the voltage level at the point of coupling in case of strong perturbations is proposed. Practical results are also presented, which have been recorded from a reduced-size prototype.
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An ultracapacitor system for an electric vehicle has been implemented. The device allows higher accelerations and decelerations of the vehicle with minimal loss of energy and minimal degradation of the main battery pack. The system uses a DC-DC power converter, which is connected between the ultracapacitor and the main battery pack. The design has been optimized in weight and size, by using water-cooled heat sinks for the power converter, and an aluminum coil with air core for the smoothing inductance. The ratings of the ultracapacitor are: nominal voltage: 300 Vdc; nominal current: 200 Adc; capacitance: 20 Farads. The amount of energy stored allows us to have 40 kW of power during 20 seconds, which is enough to accelerate the vehicle without the help of the traction batteries. The vehicle uses a brushless DC motor with a nominal power of 32 kW and a peak power of 53 kW. A control system based on a Digital Signal Processor (DSP) manipulates all the aforementioned variables and controls the Pulse Width Modulation (PWM) switching pattern of the converter transistors. The car used for the implementation of this system is a Chevrolet LUV truck.
Innovative iteration algorithm for a vehicle simulation program
  • J Van Mierlo
  • G Maggeto
J. Van Mierlo and G. Maggeto, "Innovative iteration algorithm for a vehicle simulation program," IEEE Trans. Veh. Technol., vol 53, no. 2. pp. 401-412, Mar. 2004.