• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.11
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• pp.639-646
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• 2003

Nowadays traction motors in the urban rail transit vehicle are controlled by VVVF inverter and have capability of regenerative braking. The algorithms to deal with the regenerating vehicle in simulation for the DC traction power supply is introduced in this paper. Substations have to be separated from the system to represent reverse biased rectifiers in substations. The model of the trains in regenerative braking has to be changed from the ideal current source to the constant voltage source since the train input voltage has to be controlled below the certain train maximum voltage. Some mismatches are unevitable because the constraint of the regenerated power can not be imposed with the constant voltage source. The mismatches represent the unused regenerated power. A computer program is developed to verify the validity of the algorithm. The test run result shows the program behaves as it is expected and proves the algorithm's validity.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.4
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• pp.313-321
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• 2002

A braking algorithm for a PM synchronous motor is presented. The resistance of the stator windings operates as a braking resistors and dissipates the regenerated power from the rotor without any braking components including the electronic power components and control circuits. The proposed braking algorithm maximizes the power dissipation in the stator windings and also generates the maximum braking torque under the limit conditions of DC link capacitor voltage and inverter currents so that it can minimize the braking time.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1161_1162
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• 2009

The recent environmental protection trend requires more strict energy saving, therefore every transportation system should reduce energy consumption to the minimum value. High-efficiency operation system, energy saving and $CO_2$ emissions shall be addressed as important issue in railway system. These issues are the most essential factors of railway, compared to major public transportation system. Recently, saving energy in the electric railway system has been studied. For such new energy saving, the energy storage system is considered for saving energy. Energy saving is possible by efficient use of regenerated energy. Regenerated energy is recycled amongst vehicles by mean of charge and discharge corresponding to powering and braking of electric vehicle operations. This energy saving contributes to cut $CO_2$ to reduce greenhouse gas emissions. Recycling regenerated energy demonstrate significant effect on peak cut of consumption energy in railway substation. Absorption of excess energy avoids regeneration failure due to high traction voltage. Therefore, the energy storage system is needed to be adopted to use regeneration energy when the vehicle is braking.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1461-1467
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• 2009

The electric railway is a clean and energy saving system, because it requires relatively less energy than automobiles by transporting the same passengers or goods. Six thousands of vehicles are operated on Korean urban transit system. This system is 95% of regeneration system. Especially, the VVVF-Inverter vehicle has a merit of the highest regeneration rate. Energy consumption is 90% for traction and 10% for auxiliary supply. Braking energy is about 40% of energy consumption. Up to 40% of the tractive power of vehicles capable of returning energy to the power supply can be regenerated during braking and that this energy can be used to feed vehicles which are accelerating at the same time. The energy generated by braking vehicle would simply be converted into waste heat by its braking resistors if no other vehicle is accelerating at exactly the same time. Such synchronized braking and accelerating can not be coordinated, the ESS(energy storage system) stores the energy generated during braking and discharges it again when a vehicle accelerates. This paper presents field tests about the energy saving rate of the developed ESS. when the ESS is on/off, energy saving rate of the ESS is tested. The verification test in the field focused on energy saving.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.11
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• pp.611-616
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• 1999

The introduction of the eddy current braking(ECB) system in HSRT(high speed railway train) is known to be advantageous, in that the system is independent on wheel-rail adhesion coefficient which is greatly affected by weather condition. It also minimize the maintenance of the brake system and does not require any additional electric energy because it is powered form the regenerated power at the time of the braking. In this study, the braking and attraction forces of the ECB are simulated by 2-D FEM and are experimentally verified on a down-scaled prototype. A control algorithm of the ECB is proposed to generate constant braking torque using linear variation of the reference current according to speed. Experimental results shows that the constant torque is generated over all operating speed region by developed control algorithm.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.966-971
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• 2009

The recent environmental protection trend requires more strict energy saving, therefore every transportation system should reduce energy consumption to the minimum value. High-efficiency operation system, energy saving and CO2 emissions shall be addressed as important issue in railway system. These issues are the most essential factors of railway, compared to major public transportation system. Recently, saving energy in the electric railway system has been studied. For such new energy saving, the Energy storage system is considered for saving energy. Energy saving is possible by efficient use of regenerated energy. Regenerated energy is recycled amongst vehicles by mean of charge and discharge corresponding to powering and braking of electric vehicle operations. This energy saving contributes to cut CO2 to reduce greenhouse gas emissions. Recycling regenerated energy demonstrate significant effect on peak cut of consumption energy in railway substation. Absorption of excess energy avoids regeneration failure due to high traction voltage. This paper presents effects by applying the energy storage system to SeoulMetro Line 2.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.3
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• pp.129-133
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• 2012

As people are getting concerned to Environment recently, researches on the environmentally-friendly and effective railway system have been conducted in every aspects. Especially as it became known that the pattern of train driving causes the difference in energy consumption, the researches on the train driving to minimize the energy consumption are gaining a lot of interest. The main study showed the optimal driving to minimize energy consumption while driving after analyzing real driving data measured by EMU of Bundang-line real driving, determining the impact on energy consumption due to train driving pattern changes, executing a variety of simulation on real driving patterns by Matlab Simulink and finally driving between stations by given driving times.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.320-325
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• 2005

Power of fuel cell tram is supplied by only fuel cell system or hybrid system of fuel cell and battery/super capacity. Fuel cell is operated by hydrogen, which is fed directly from hydrogen tank or by reforming gasoline or methanol into hydrogen. Power system is preferred with hybrid of fuel cell and battery/super capacity since it improves total energy efficiency through interaction of hybrid components and restores energy regenerated by braking. Also, power supply system by fuel cell hybrid should be designed to output optimum energy efficiency depending on driving mode of fuel cell tram.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.9
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• pp.85-96
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• 2010

The recent environmental protection trend requires more strict energy saving, therefore every transportation system should reduce energy consumption to the minimum value. High-efficiency operation system, energy saving and $CO_2$ emissions shall be addressed as important issues in railway system. These issues are the most essential factors of railway, compared to major public transportation system. Recently, saving energy in the electric railway system has been studied. The efficient use of regenerated energy is considered to save energy. Namely, Using regenerative energy is that to store the energy generated during braking and discharge it again when a vehicle accelerates. Reusing energy stores and discharges energy, consequently enables a complete exchange of energy between vehicles, even if they are not braking and accelerating at precisely the same time, as is most frequently the case in everyday service. This paper analyzes effects of energy saving and $CO_2$-cut by using regenerative energy of electric vehicles.

• Journal of the Korean Society for Railway
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• v.12 no.4
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• pp.582-589
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• 2009

The energy generated by braking vehicle would simply be converted into waste heat by its braking resistors if no other vehicle is accelerating at exactly the same time. Up to 45% of the tractive power of vehicles capable of returning energy to the power supply can be regenerated during braking and that this energy can be used to feed vehicles which are accelerating at the same time. Such synchronized braking and accelerating can not be coordinated, the ESS(energy storage system, here after) stores the energy generated during braking and discharges it again when a vehicle accelerates. The ESS is able to store and discharge energy extremely quickly, consequently enabling a complete exchange of energy between vehicles, even if they are not braking and accelerating at precisely the same time, as is most frequently the case in everyday service. The energy saving rate is related to the headway. If the headway is long/short, the energy saving goes up/down, When the headway is short, the ESS can not save much regenerative energy. The headway of SeoulMetro line 2 as the worst case is very short in Korea urban transit system. So, the energy saving rate will be very low. If the ESSs are applied to another railway system, we can expect that the effectiveness is better than the results of SeoulMetro line 2. This paper presents effects of energy saving obtained by applying the ESS to SeoulMetro line 2.