Survey of loss minimization methods in tram systems (original) (raw)
Stationary and on-board storage systems to enhance energy and cost efficiency of tramways
Journal of Power Sources, 2014
One important bonus of tramways comes from the reversibility of electric drives. Braking energy of trams can be recovered in storage systems. High power lithium batteries and supercapacitors have been considered. Storage systems can be installed on-board or along the supply network. A simulation tool has been realised to achieve a cost/benefit analysis.
Tram simulation model for energy balance analyses
2017 21st International Conference on Process Control (PC), 2017
This paper describes a mathematical model of a tramcar which allows to simulate traffic on any tram track and allows to analyze energetic balance on the electrical power link without real energetic data measurement. The described mathematical model could be a useful tool for the design of an energy recovery system for a real tram track. A short description of the tram track model in the city of Liberec is presented together with the mathematical model of the tramcar type T3.PLF that operates on mentioned track. The model simulation results are confronted with data measured during the real tram operation.
2021
Electric trams are one of the standard forms of public transport. They are characterized by large amounts of electric current and electric current gradient from the power grid, especially during acceleration. For this reason, a regenerative braking system is considered with the aim of reducing electric current peaks and increasing energy efficiency by reducing the total energy consumption of the power grid. A supercapacitor module is used as a storage device for storing and utilizing the braking energy. The supercapacitor module and the power grid constitute a hybrid energy system, for which a control algorithm has been developed. The control algorithm takes into account the influence of the elevation profile and the slope of the vehicle route in storing and using the braking energy. The operation of the algorithm was simulated and analyzed using the MATLAB/Simulink software package for tram lines with different elevation profiles.
Energies
Energy savings in electric rail transport are important in order to increase energy efficiency and reduce its carbon footprint. This can be achieved by storing and using the energy generated during regenerative braking. The system described in this paper consists of a supercapacitor energy storage system (SC ESS), a bidirectional DC/DC converter, and an algorithm to control the energy flow. The proper design of the algorithm is critical for maximizing energy savings and stabilizing the power grid, and it affects the lifetime of the SC ESS. This paper presents an energy flow control algorithm based on Pontryagin’s minimum principle that balances maximum energy savings with maximum SC ESS lifetime. The algorithm also performs SC ESS recharging while the rail vehicle stops on inclines to reduce the impact of its next acceleration on the power grid. To validate the algorithm, offline simulations are performed using real tram speed measurements. The results are then verified with a real-...
Energy recovery effectiveness in trolleybus transport
Electric Power Systems Research, 2014
Nowadays the issue of electric energy saving in public transport is becoming a key area of interest which is connected both with a growth in environmental awareness of the society and an increase in the prices of fuel and electricity. One of the possibilities to reduce energy consumption in urban public transport is to increase the extent of regenerative braking energy utilization. This can be achieved by its accumulation in the supercapacitors or a change in the topology of the power supply system in order to facilitate its flow. The article presents an analysis of applying these two options for increasing recovery energy usage on the example of the trolleybus network in the Polish city of Gdynia. For the purpose of the analysis there was used a simulation model of trolleybus traction power system based on the Monte Carlo simulation method. The research results and findings can be applied in other similar trolley or tram networks.
Journal of Rail Transport Planning & Management, 2018
High electric energy consumption is one of the main challenges of metro systems, which the operators deal with. Among several energy saving methods, this paper focuses on the simultaneous application of speed profile optimization and energy storage systems, to efficiently utilize regenerative braking energy. With this approach, a substantial reduction in energy was achieved for the case study of Mashhad LRT Line 1. In addition, because of the simultaneous utilization of the schemes, the required capacity of stationary energy storage systems was decreased in comparison with the case of normal (not optimized) speed profile. To demonstrate the validity of the proposed method, two procedures were done. First, the optimization of stationary supercapacitor energy storage systems was performed by using experimental results (real world, not optimized speed profiles) so that the total input energy would be minimized. In the second procedure, the optimal speed profiles were determined and optimum energy storage was recomputed. The results show a significant reduction of energy in the latter procedure, as well as lower energy storage system costs.
Energy management and hybrid energy storage in metro railcar
2012 International Conference on Renewable Energy Research and Applications (ICRERA)
This paper focuses on the use of modeling and simulation one of renewable energy. In this paper the results of simulation models by Matlab-Simulink for an urban-metro railcar and some newer methods for reducing the need value of capacitance for energy storage are presented. In this research was been investigated the Li-ion battery and the supercapacitor as hybrid energy storing device for the same task and its effectiveness under operation of a suitable energy control system. The available decreasing ratio of the needed energy storage at SCAP is 25 to 40 % with this improved energy control method, which are significant values as decreasing in volume, mass and price. Mass reduction of our hybrid storage system is significant, about 50 to 60%.
Energy and exergy efficiencies in urban electric transportation systems
This paper aimed at examining an underground railway train as a system where different energy forms occur, so that the successive energy conversion chain is emphasized and the energy and exergy efficiencies, respectively, are compared. The study case presented in the paper emphasized the operation of the static converters and the traction induction motors as an assembly, both in the traction regime and in the electric brake regime, for different urban underground metro trains produced by Craiova Electroputere Factory for Bucharest Underground Trasportation System. In this application, the exergy analysis can help improve and optimize the underground transportation system design and operation.
Energy Management System of Fuel-Cell-Battery Hybrid Tramway
IEEE Transactions on Industrial Electronics, 2000
This paper describes the configuration, modeling, and control of a fuel cell (FC)-battery-powered hybrid system for the Metro Centro tramway in Seville, Spain. The proposed hybrid system presents a polymer electrolyte membrane FC as the primary energy source and a nickel-metal hydride cell battery as the secondary energy source, which supplements the output of the FC during tramway acceleration or whenever else needed and cruise and for energy recovery during braking. The tramway presents a traction system which is composed of four traction induction motor drives. The hybrid system also supplies the power for the auxiliary services. The power conditioning system is composed of two converters: 1) a boost-type unidirectional dc/dc converter for the FC and 2) a boost-type bidirectional dc/dc converter for the battery. The energy management system (EMS) of the hybrid tramway determines the reference signals for the electric motor drives, FC, and power converters in order to regulate accurately the power from the two electrical sources. EMS also determines the reference signal for energy dissipation in braking chopper when required during regenerative braking. In this paper, the proposed hybrid system is evaluated for the real driving cycle of the tramway. The results demonstrate the hybrid system capability to meet appropriate driving cycle.