Modeling and Simulation of Regenerative Braking Energy in DC Electric Rail Systems

Regenerative braking energy is the energy produced by a train during deceleration. When a train decelerates, the motors act as generators and produce electricity. This energy can be fed back to the third rail and consumed by other trains accelerating nearby. If there are no nearby trains, this energy is dumped as heat to avoid over voltage. Regenerative braking energy can be saved by installing energy storage systems (ESS) and reused later when it is needed. To find a suitable design, size and placement of energy storage, a good understanding of this energy is required. The aim of this paper is to model and simulate regenerative braking energy. The dc electric rail transit system model introduced in this paper includes trains, substations and rail systems

Development of Urban Electric Bus Drivetrain

The development of the drivetrain for a new series of urban electric buses is presented in the paper. The traction and design properties of several drive variants are compared. The efficiency of the drive was tested using simulation calculations of the vehicle rides based on data from real bus lines in Prague. The results of the design work and simulation calculations are presented in the paper

Model-based comparison of hybrid propulsion systems for railway diesel multiple units

In order to reduce operating costs, railway vehicle operators need to find technical solutions to improve the efficiency of railway diesel multiple units on non-electrified railway routes. This can be achieved by hybridization of diesel multiple unit propulsion systems with electrical energy storage systems to enable brake energy recuperation. After highlighting the state of the art of hybrid railway vehicles and electrical energy storage systems, a simulation model of a generic diesel multiple unit in a 3-car formation is developed and equipped with three types of hybrid power transmissions. Simulations on realistic service profiles with different driving strategies show the potential for fuel consumption reduction for the different transmission types. On a suburban service profile, a 3-car diesel multiple unit is able to achieve simulated fuel savings of up to 24.1% and up to 18.9% on a regional service profile

Improvement of the Energy Recovery of Traction Electrical Drives using Supercapacitors

In the paper the possibility of improving the energy recovered during the braking of railway vehicles and reduction of power peaks during accelerating are discussed. The energy available from the regenerative braking of the motor is stored into supercapacitor sets placed on board and reused subsequently for the acceleration of the train. This auxiliary storage system allows the reduction of the losses on the line, because the power peaks are shaved by supercapacitors and, hence, the rms power supplied is reduced. In addition, also the energy consumption of the train can be reduced respect to traditional convoys, especially if the characteristic duty cycle presents many accelerations and braking periods as the case of subways trains. The set of supercapacitors needs the use of an intermediate dc/dc converter in order to harmonize the voltage with that of the dc-link of the drive and control the power flows of the supercapacitors. The mathematical model of the whole system and the control strategy of energy management are presented. The actual possibilities of the energy recovery are shown by means of numeric simulations and expressed in percentage respect to the energy drawn during accelerations. The control strategy has been experimentally validated on a scale system made of an asynchronous drive supplied by a dc source and a set of supercapacitors as auxiliary storage device

Metro de Madrid rolling stock models and comparative studies relating to comfort

This paper presents the work carried out by Metro de Madrid and the Railway Technology Research Centre (Polytechnic University of Madrid), aimed at setting up rolling stock simulation models with a high level of detail. To do this, the features of the SIMPACK simulation tool used to create models have been briefly outlined, explaining the main features of models in two of the series modelled: 7000 and 8000. Finally, the results obtained from comparing comfort in the 7000 and 8000 series are presented

Comparative Energy Consumption Analysis of the Hybrid Diesel Train and the Hybrid Fuel Cell Train

This paper compares train energy consumption of hybrid diesel-electric multiple unit (HDEMU) to hydrogen fuel-cell multiple unit (HFCMU). In the simulation, the parameters of the DMU HŽ7022 train were used for the train model created in Matlab/Simulink environment. Since the train is powered by three diesel engines in original design, it was hybridized by removing one engine and adding a battery and a supercapacitor. For comparison, a train model was made with fuel cells that have rated power of two existing diesel engines, and it was hybridized with a battery and a supercapacitor, as in the simulation with the hybridization of diesel engines. The results are presented by comparing energy consumption for both trains. In addition, voltages, electric current values and power loads of power sources are shown. As the sustainability of the system, the SOC (State of Charge) values of both the battery and the supercapacitor are presented

Preliminary power train design for a state-of-the-art electric vehicle

Power train designs which can be implemented within the current state-of-the-art were identified by means of a review of existing electric vehicles and suitable off-the-shelf components. The affect of various motor/transmission combinations on vehicle range over the SAE J227a schedule D cycle was evaluated. The selected, state-of-the-art power train employs a dc series wound motor, SCR controller, variable speed transmission, regenerative braking, drum brakes and radial ply tires. Vehicle range over the SAE cycle can be extended by approximately 20% by the further development of separately excited, shunt wound DC motors and electrical controllers. Approaches which could improve overall power train efficiency, such as AC motor systems, are identified. However, future emphasis should remain on batteries, tires and lightweight structures if substantial range improvements are to be achieved