scholarly journals A Dual-Stage Modeling and Optimization Framework for Wayside Energy Storage in Electric Rail Transit Systems

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1614
Author(s):  
Oindrilla Dutta ◽  
Mahmoud Saleh ◽  
Mahdiyeh Khodaparastan ◽  
Ahmed Mohamed
Keyword(s):  
Energy Storage ◽  
Search Space ◽  
Voltage Regulation ◽  
Maximum Energy ◽  
Transit System ◽  
Transit Systems ◽  
Modeling And Optimization ◽  
Optimization Framework ◽  
Dual Stage ◽  
Stage Modeling

In this paper, a dual-stage modeling and optimization framework has been developed to obtain an optimal combination and size of wayside energy storage systems (WESSs) for application in DC rail transportation. Energy storage technologies may consist of a standalone battery, a standalone supercapacitor, a standalone flywheel, or a combination of these. Results from the dual-stage modeling and optimization process have been utilized for deducing an application-specific composition of type and size of the WESSs. These applications consist of different percentages of energy saving due to regenerative braking, voltage regulation, peak demand reduction, estimated payback period, and system resiliency. In the first stage, sizes of the ESSs have been estimated using developed detailed mathematical models, and optimized using the Genetic Algorithm (GA). In the second stage, the respective sizes of ESSs are simulated by developing an all-inclusive model of the transit system, ESS and ESS management system (EMS) in MATLAB/Simulink. The mathematical modeling provides initial recommendations for the sizes from a large search space. However, the dynamic simulation contributes to the optimization by highlighting the transit system constraints and practical limitations of ESSs, which impose bounds on the maximum energy that can be captured from decelerating trains.

scholarly journals Flywheel vs. Supercapacitor as Wayside Energy Storage for Electric Rail Transit Systems

Inventions ◽  
2019 ◽  
Vol 4 (4) ◽  
pp. 62
Author(s):  
Mahdiyeh Khodaparastan ◽  
Ahmed Mohamed
Keyword(s):  
Energy Storage ◽  
Energy Saving ◽  
Voltage Regulation ◽  
Appropriate Technology ◽  
Rail Transit ◽  
Peak Demand ◽  
Transit System ◽  
Transit Systems ◽  
Industrial Sectors ◽  
Demand Reduction

Energy storage technologies are developing rapidly, and their application in different industrial sectors is increasing considerably. Electric rail transit systems use energy storage for different applications, including peak demand reduction, voltage regulation, and energy saving through recuperating regenerative braking energy. In this paper, a comprehensive review of supercapacitors and flywheels is presented. Both are compared based on their general characteristics and performances, with a focus on their roles in electric transit systems when used for energy saving, peak demand reduction, and voltage regulation. A cost analysis is also included to provide initial guidelines on the selection of the appropriate technology for a given transit system.

Analysis of Energy Dissipation in an Electric Transit System

2008 ◽  
Author(s):  
Alasdair C. Renfrew ◽  
Martyn Chymera ◽  
Mike Barnes
Keyword(s):  
Energy Storage ◽  
Energy Savings ◽  
Regenerative Braking ◽  
Energy Prices ◽  
Energy Storage Devices ◽  
Transit System ◽  
Transit Systems ◽  
Storage Devices ◽  
Energy Flows ◽  
Potential Benefits

Reducing energy consumption in electrified transit systems is becoming increasingly important as energy prices rise and environmental concerns become more prominent. In electrified transit systems, significant savings can be accomplished by utilizing braking energy. Energy from regenerative braking can be used to power vehicles via the traction supply system, or stored on board vehicles using energy storage devices. The effectiveness and energy savings of regenerative braking or on board energy storage is dependent on the nature of the system, particularly the vehicle drive cycles and service frequency. The paper describes an analysis methodology developed to consider energy flows in an electrified transit system, hence enabling the potential benefits of regenerative braking and energy storage devices to be assessed.

Developments in Traction Transformer

2012 ◽  
Author(s):  
Subhas Sarkar
Keyword(s):  
Short Circuit ◽  
Real Life ◽  
Voltage Regulation ◽  
Essential Elements ◽  
Circuit Testing ◽  
Transit System ◽  
Transit Systems ◽  
Distribution Transformers ◽  
Draft Standard ◽  
Ordinary Power

Mass transit systems are gaining increased attention and popularity in the country. With this increased activity, more and more lines are getting added under public transit systems in more and more cities. One of the essential elements in the transit system is the traction transformer which powers the trains. With the emphasis on reliability, there is also increased awareness of the energy efficiency required of the traction substation equipments and the transformer in particular. Traction transformers are not ordinary power or distribution transformers. They have to meet several special requirements, including parameters like voltage regulation, impedance, commutation, short circuit withstand, operation with rectifiers, harmonic losses, wide fluctuation of load currents depending on the cyclic nature, etc. The reliability criteria are stringent and the traction transformers have to be properly designed, manufactured and tested, including short circuit testing for validation. Use of modern design tools like electric and magnetic field mapping and estimation of forces and stresses are helpful in computing them accurately. With the extensive use of vacuum circuit breakers, the subject of interaction of transformers and breakers have come to the foreground. New standards (like IEEE C57.142) have come into existence, which recommend methods to mitigate such effects. The author of this paper and his team has successfully applied these techniques in real life situations to solve problems. Work is in the final stages for preparation of a standard specifically for Traction Power Rectifier Transformers for transit applications (IEEE draft standard 1653.1) under the IEEE Vehicle Standards Committee.

Continuous Approximation Model for Hybrid Flexible Transit Systems with Low Demand Density

2021 ◽  
pp. 036119812199713
Author(s):  
Charalampos Sipetas ◽  
Eric J. Gonzales
Keyword(s):  
Agency Cost ◽  
Optimization Techniques ◽  
Optimization Process ◽  
Analytical Models ◽  
Continuous Approximation ◽  
Flexible Systems ◽  
Transit System ◽  
Transit Systems ◽  
Approximation Techniques ◽  
Service Areas

Flexible transit systems are a way to address challenges associated with conventional fixed route and fully demand responsive systems. Existing studies indicate that such systems are often planned and designed without established guidelines, and optimization techniques are rarely implemented on actual flexible systems. This study presents a hybrid transit system where the degree of flexibility can vary from a fixed route service (with no flexibility) to a fully flexible transit system. Such a system is expected to be beneficial in areas where the best transit solution lies between the fixed route and fully flexible systems. Continuous approximation techniques are implemented to model and optimize the stop spacing on a fixed route corridor, as well as the boundaries of the flexible region in a corridor. Both user and agency costs are considered in the optimization process. A numerical analysis compares various service areas and demand densities using input variables with magnitudes similar to those of real-world case studies. Sensitivity analysis is performed for service headway, percent of demand served curb-to-curb, and user and agency cost weights in the optimization process. The analytical models are evaluated through simulations. The hybrid system proposed here achieves estimated user benefits of up to 35% when compared with fixed route systems, under different case scenarios. Flexible systems are particularly beneficial for serving corridors with low or uncertain demand. This provides value for corridors with low demand density as well as communities in which transit ridership has dropped significantly because of the COVID-19 pandemic.

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