Management of Regenerative Braking Energy for Addis Ababa Light Rail Transit System
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Date
2015-04
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Addis Ababa University
Abstract
Addis Ababa light railway is one of the newly constructing railway transport system in Ethiopia.
Urban rail plays a key role in the sustainable development of metropolitan areas for several
reasons such as its high capacity, energy efficiency and lack of local air pollution. Electricity has
become the primary source of traction power in modern railways. DC-electrification is often
used for urban public transport.
Most electric trains in DC-electrified railways are presently equipped with regenerative braking
system. Regenerative braking is a means to save energy and reduce maintenance costs in
railway industry. Ultra-capacitor is a major promising alternative of energy storage
technologies in the urban rail system. Compared to other storage technology, the ultracapacitor
has the advantages of rapid charging and discharging frequencies, a long cycle life
and high power density, which highly match the characteristics of urban rail transit such as
short running time between stations, frequent accelerating and braking and booming power
within a short time.
In this thesis a braking energy recovery system based on super-capacitor is presented for Addis
Ababa light rail transit system. Regenerative brake is preferably applied as service brake for
AART vehicles. Taking the movement of Addis Ababa light rail transit trains between two
stations for design purpose, it is shown that 34 percent of consumed energy can be regenerated
using regenerative braking system. Regenerated energy is fed back to power other train in the
network through brake chopper module or such energy is depleted by brake resistor when
there is no train in the network to consume this energy. The thesis assesses design of onboard
super capacitor based energy storage system for saving energy which is to be depleted by
brake resistor. Based on the design
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capacitance of super capacitor is
required to save regenerated pick energy.
In order to validate the design and do further research, the thesis presents a mathematical
model of the whole system. At the end, the simulation is done, the results of simulation has
been developed in Matlab programs and Simulink with theoretical analysis.
Description
Keywords
Bidirectional DC–DC converter, Energy Efficiency, Light railway transportation, Rail Vehicles, Regenerative braking, Simulation, Stationary Energy Storage, Super capacitor