Energy Storage System for Traction Energy Recovery

Han, Li Shan (2019) Energy Storage System for Traction Energy Recovery. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

The growing concern of environmental sustainability requires optimization of energy in various sectors. The application of electrical energy storage system in metro system enables the regenerative braking energy to be utilised in order to achieve energy savings. This project developed a strategy to reduce the energy demand of the electrical networks in the metro system using energy storage system for regenerative energy recovery. The strategy to control the energy storage system is developed by using Matlab Simulink. The simulation model consists of two substations, DC transmission lines, a generalised train, and the energy storage system for energy recovery. The substation consists of two step-down star-delta and delta-delta transformer, connected to wye connection capacitors, followed by the rectifier. The DC transmission line is using four variable resistors to model the line resistance between two substations. The train model is simplified into a current equation and is connected to the substation through the DC transmission line. The energy storage system is connected to the DC bus of the substation. It consists of the control system, bidirectional DC/DC converter and energy storage device. The control system determines the current flow between the energy storage device and the DC bus. The PI controller in the converter is used to manipulate the pulses for the insulated-gate bipolar transistor based on the current. The energy storage system is modelled based on supercapacitor and also hybrid energy storage. Both models are simulated with various parameters to determine their energy saved on the traction system. The simulation with and without energy storage system is analysed with the same speed profile of the train to validate the energy savings achieved. It is found that the traction system designed model with the supercapacitor and hybrid energy storage were able to achieve energy saving of approximately 22.7% and 25.1% respectively compared to the system without energy storage system.