Figure - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
Source publication
The paper proposes a novel approach to modeling electrified transportation systems. The proposed solution reflects the mechanical dynamics of vehicles as well as the distribution and losses of electric supply. Moreover, energy conversion losses between the mechanical and electrical subsystems and their bilateral influences are included. Such a comp...
Context in source publication
Citations
... As can be seen in Figure 3, the first part of the mathematical model concerns the journey of a theoretical rail vehicle, the method and methodology of which is widely known and described in detail, among others in [15,[35][36][37][38][39]. Based on input data regarding the type of vehicle and its traction characteristics, understood as the change in tractive force as a function of speed changes F = f(v), and data on the route and the traction power ...
... As can be seen in Figure 3, the first part of the mathematical model concerns the journey of a theoretical rail vehicle, the method and methodology of which is widely known and described in detail, among others in [15,[35][36][37][38][39]. Based on input data regarding the type of vehicle and its traction characteristics, understood as the change in tractive force as a function of speed changes F = f(v), and data on the route and the traction power network, using the classical equation of motion in accordance with Newton's second law of dynamics, you can receive information about the distance traveled, the power consumption of the vehicle, the load on the power supply system, the vehicle current understood as the current consumed by the vehicle for traction purposes and its own needs, and the charging current of the energy storage tank obtained from braking the vehicle [35,37]. ...
Electric vehicles are increasingly appearing on Polish roads due to a number of technical, legal and marketing conditions. However, electromobility is developing primarily in urban areas, mainly due to the unevenly developed infrastructure for charging vehicle batteries and the power grid. Therefore, solutions should be created that use the existing power infrastructure, including the use of railway power infrastructure (RPI). The railway power network covers a significant part of the country, including forest areas, and, above all, it very often intersects with road infrastructure or runs along roads. This paper raises issues related to the possibility of using RPI to charge the batteries of electric vehicles. After characterizing the technical, operational and legal requirements related to these technical systems, a concept of an electric vehicle charging system using RPI was developed, along with a demonstration of the possibility of its implementation, which was simulated using mathematical models developed by the authors.
... In [10], a modular model was proposed in the Matlab-Simulink environment. Its modularity property still allowed for a simulation of multiple transit trolleybuses and a complex topology, overcoming the difficulties of existing graphical programming-based strategies in modelling the variability across time and space of the OCL electrical resistance as a result of vehicle motion [11]- [15]. The way the methodology adopted in [10] exploits the graphical interface attributes noteworthy flexibility to the respective circuit model. ...
... Similar to the model developed in [10], the goal of the model presented here is to replicate how trolleybus networks behave as a result of changes in vehicle positions over time, while also allowing for some flexibility in the selection of the number of transit vehicles. For this reason, a thorough examination of electrical substations is deemed unnecessary, and the Thevenin equivalent circuit is used to simplify the TPSS architecture [8]- [15]. Furthermore, the novel catenary model is decoupled from vehicle dynamics simulation. ...
The integration of renewable sources to catenary-powered electric traction systems is a paramount step to satisfy sustainability and smart city objectives, albeit necessitating accurate simulations of the infrastructure. This paper presents an innovative trolleybus network simulator, characterised by the modularity of the catenary model and built on an intuitive graphical user interface that offers significant topological change flexibility. The model is distinguished by high precision and moderate processing effort, bridging the gaps of existing block-based simulation tools. A graphical analysis of the voltage distribution evaluated in a section of Bologna’s trolleybus network shows the advances in precision of the proposed model.
... They differ in terms of their level of detail and the quality of the results obtained. For example, Jakubowski et al. [2] propose a model that includes the mechanical and electrical subsystems of a transportation system, based on multivehicle modelling with discreet timestep power integration, to simulate vehicle movement dynamics and energy distribution and losses. But it does not deal with the speed regulator. ...
Estimating the electric power used by railway vehicles is an important factor in the planning of future power consumption, looking for possibilities to reduce the use of electric power and therefore also reduce carbon emissions. To improve the estimation, we used the imperialist competitive algorithm in the optimisation process of a mathematical model of a tram vehicle. Specifically, in the setting of the proportional and summation constant of the vehicle speed controller which emulates the activity of the driver in the simulation. Our work presents a new approach to optimising the estimation of energy consumption in tram transport. The method used is based on mathematical modelling and simulation of social development in human society. To obtain the input data for the simulation, we performed a measurement of the reference speed by means of a GPS receiver located in a sample tram vehicle. Subsequently, to verify the model and energy calculation results, we measured the output currents and voltage from the traction converter station at the corresponding time. Our method achieved a 93 % match between the measured and simulated power consumption.
... The value of the model reported in [5] to simulate the integration of EV chargers and S-ESS is demonstrated in [6]. Another Simulink-based model is explained in [7], where the catenary system supplying both tram and trolleybus services in the city of Pilsen, Czech Republic is analyzed. A literature review highlighting the virtues and limitations of existing modeling techniques is summarized in [8]. ...
... It is important to note the outcomes delivered by a similar work on this topic. The Matlab model presented in [7] provides results of a daily operation of the trolleybus system in the city of Pilsen, Czech Republic, comparing measurements and simulation results of voltage and current in the output of a traction substation. A comparison in the daily energy results in a maximum difference of 5%. ...
In the context of smart cities, direct current overhead contact lines, usually adopted to power urban transportation systems such as trolleybuses, tramways, metros, and railways, can serve as a backbone to connect different modern emerging technologies. Among these, in-motion charging (IMC) trolleybuses with on-board batteries are expected to be very impactful on the DC network’s power flow and may require specific voltage and current control. These factors motivate the development of a simulation tool able to emulate these devices’ absorption and their effect on the supply infrastructure. The main innovative value of the work is to improve a simulation model of a trolleybus grid through a data-driven approach by using measurements of voltage and current output from a traction substation. The measurements are essential for understanding the behavior of vehicle weight variation throughout the day. Thanks to this information, a characterization of the current draw by conventional trolleybuses and IMC trolleybuses is then provided for each trolleybus route in a specific power section of the Bologna trolleybus system. By integrating the variation in vehicle weight within the model, a simulation of a possible daily operation of a trolleybus feeding section has been performed, obtaining a 7% error between the daily energy calculated from the simulation and that obtained through measurements. This analysis demonstrates the feasibility of the adopted simulation tool, which can also be used to evaluate additional hypothetical trolleybus operation scenarios. One of these possible scenarios considers IMC vehicles, and it is also evaluated in this paper.
... In the city of Gdynia (Poland), a converter station that allows the use of a traction system to supply receivers with industrial voltage of 400 V AC was launched in 2021 as a result of the "EfficienCE" project [17]. The converter links a trolleybus overhead line to an electric vehicle charging hub. ...
The development of electromobility involves the development of electric cars charging infrastructure. The increase of the number of chargers poses new demands for the AC power grid, especially in regard to its capacity of delivering high peak power. As an alternative for the public AC power grid, urban electrified transportation systems (trams, trolleybuses, and metro) can be used for supplying electric cars chargers. The article discusses four options of integrating electric cars chargers with a traction power supply system. The option of connecting the charger to the traction overhead supply line has been selected due to the spatial availability of the power source and possibility to use regenerative braking energy for charging. A set of criteria has been developed for analysing the capability of the traction supply system to feed electric cars chargers. An exemplary feasibility analysis was carried out for trolleybus traction supply system in Gdynia, Poland. The impact of installing the charging station on specific traction supply parameters has been predicted using present-state recordings of electrical parameters and assumed charging station power. The study shows that every supply section of the considered trolleybus traction system has the capability of installing a fast-charging station, which provides opportunities of expanding the charging stations network in Gdynia.
More and more often overall energy efficiency of an electrified transportation system appears as target of new constructions, sometimes with incomplete definitions of performance indexes to assess that target has been reached. A worked out example is based on the introduction of reversible substations. Reversible substations are a method to improve energy efficiency, whose application in an existing system can be progressive and does not require large traffic intensity to be effective. Their effectiveness depends on some system parameters (nominal catenary voltage in particular). A simulation model fed with experimental data from a line section of Metro de Madrid is used to demonstrate the operation and optimization of reversible substations.
Background
The ambitious reduction of CO2 greenhouse gas emission within 2050 declared by the European Commission also involves transportation systems. In this context an optimum recovery of the electric braking energy produced by railway vehicles is more and more relevant. Several strategies to completely recover the braking energy are being developed and applied. A methodology that allows the accurate determination of the amount of recovered energy in real operating conditions becomes then a valuable tool.
Objective
Reversible substations are one of the braking energy recovery methods that are widely applicable. Their effect is analyzed in a system perspective, considering them integrated in the transportation system with its dynamics and various operating points. The effectiveness and consequences of the operation of one or more reversible substations are evaluated by identifying relevant system conditions and scenarios.
Methods
An electric network model is provided, fed by measured timetable and traction current. Simulation results are analyzed and compared with some experimental results: simulation configurations will be selected to match those of the available experimental data.
Results
The selected substation no-load output voltage level has a significant effect on efficiency and performance of reversible substations. A reduction of 50 V, from 1700 V to 1650 V produces a decrease of the energy dissipated by the braking rheostat on-board trains of about 13%. The voltage increase caused during braking phases is kept under control better for track positions close to reversible substations: tests show that line voltage increase is 2.5% of nominal value with a reversible substation, and only 0.5% when it is operated. Trimming the thresholds that trigger the operation of the on-board braking chopper (intermingling regenerative and dissipative braking) has a dramatic effect on regenerability: a reduction of 50 V causes an improvement of 19%.
Conclusion
The paper presents a methodology that merges measurements and circuital model to investigate on the energy saving provided by reversible substations supplying railway system. The methodology has been applied to a real case. Preliminary results regarding the impact of supply voltage level, reversible module position and threshold levels of the braking chopper control system on the dissipated braking energy and power quality has been carried out.
