• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.836-845
• /
• 2007

In DC 1500V electric traction substations, diode rectifiers are commonly used to supply stable DC power with electric train sets. However, it operates in the first quadrant of the voltage-current plane and thus needs regenerative inverters which transfer the surplus regenerative power caused by regenerative braking of electric train sets into the grid. In order to select the proper capacity and installation position of regenerative inverter, it needs to investigate the consumed and regenerative energy of the electric traction substations in advance. This paper presents an analysis of regenerative energy in two substations operating in Seoul line 2 and Kwangju line 1. DC line voltage and feeder currents are measured for a day to calculate consumed and regenerative power for four feeders. We calculated an amount of regenerative energy consumed in other feeders and estimated the cost reduction in energy consumption due to the reuse of regenerative energy.

• Journal of Power System Engineering
• /
• v.21 no.4
• /
• pp.5-17
• /
• 2017

This study focuses on the application of the PEM Fuel Cell(PEMFC) hybrid system, which includes a regenerative braking system with supercapacitor(SC) and battery. The purpose of this study is to evaluate the characteristics of regenerative energy and to propose solutions to increase regenerative energy via vehicle simulation. To achieve this target, we set the rated motor speed to 3,000/2,500/2,000 rpm. Because the flywheel is directly connected to the motor, the generator activates regenerative braking by using the rotational momentum of the flywheel when the flywheel reaches the set speed after the motor stops. We could then measure the characteristics of regenerative braking of voltage, current, power, energy change, etc. Meanwhile, we calculate the storage efficiency of the SC or the battery. Our results show that the SC stores 18% of the regenerative energy, while battery stores 15% of the energy. Since the regenerative energy decreases with the decrease of the motor rotating speed that 5,027 J and 2,915 J are restored at 3,000 and 2,500 rpm, respectively. The experimental results also prove that regenerative braking energy is able to be obtained if and only if the speed of flywheel is over 2,500 PRM, and the efficiency of the system can be further improved.

• Proceedings of the KIPE Conference
• /
• 2011.07a
• /
• pp.283-284
• /
• 2011

Generally, it is important to use the regenerative energy efficiently for decrease of inverter's consuming energy. From various industry sector (railroad, steel, crane etc), re-uses the regenerative energy which uses the regenerative converter unit, and gets a many profit from whole consuming energy. In this paper, we introduce development of the regenerative converter unit that supply the regenerative energy to power source and main drive inverter, and introduce the instance which is applied in the elevator.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2011.05a
• /
• pp.205-206
• /
• 2011

Various studies on energy saving for construction sites have been carried out and some construction machines using motors have installed regenerative systems such as elevators and excavators. The construction lift also uses motors and generates more regenerative energy when the lifts descend because lifts convey many construction materials and workers. For this reason, it is possible to apply the regenerative system to the construction lift. However, if the system is applied without considering the lift's characteristics, the new development would fail; we therefore need to propose a performance requirement. Thus, the purpose of this study is to propose a performance requirement for the energy-regenerative lift prior to developing the energy-regenerative lift.

• Journal of the Korean Society for Railway
• /
• v.10 no.6
• /
• pp.717-722
• /
• 2007

Most of DC 1500V electric railway substations have adopted diode rectifiers to supply stable DC power. However, the diode rectifiers operate in the first quadrant of the voltage-current plane and thus need regenerative inverters which transfer the surplus regenerative power caused by regenerative braking of electric train sets into the grid. In order to select the proper capacity and installation position of regenerative inverter, it needs to investigate the consumed and regenerative energy of the electric traction substations in advance. This paper presents an analysis of regenerative energy in two substations operating in Seoul Seolleung and Kwangju Yangdong substations. DC line voltage and feeder currents are measured for a day to calculate consumed and regenerative power far four feeders. We calculated an amount of regenerative energy consumed in other feeders and estimated the cost reduction in energy consumption due to the reuse of regenerative energy

• Journal of Electrical Engineering and Technology
• /
• v.8 no.5
• /
• pp.1070-1077
• /
• 2013

Owing to the consistent increase in energy efficiency issues, studies for improving regenerative energy utilization have been receiving attention in the Urban DC railway systems, where currently, the utilization of regenerative energy is low due to the lack of a specific plan for using this energy. The regenerative energy in railway systems has a low efficiency problem which results in the increase of the catenary voltage and a possibility to create problems to the electrical devices connected to the system. This paper deals with the power integration of large urban railway subsystems to improve regenerative energy utilization where the railway subsystems are integrated with other railway subsystems to improve the energy efficiency. Through the case studies, to find the realistic effect of integrated operation, the Seoul Metro subsystems, namely Line 5 and Line 7, has been applied. Also, evaluation for the electricity cost saving has been performed by using KEPCO electricity cost table.

• Journal of the Korean Society of Safety
• /
• v.25 no.5
• /
• pp.15-21
• /
• 2010

Regenerative Energy Storage System(ESS) is a system that saves regenerative energy which generated instantly in the regenerative braking of Electric Multiple Unit(EMU) and disappear, and reuse the stored energy when EMU is in powering. Such system related to a research field of renewable energy which emerged concerning climate change and high oil prices. In the case of existing domestic rolling stock, about 25% to 30% of generated regenerative energy is restored to power source and is regarded as direct factor of raising catenary voltage. Such rapid change of catenary voltage is a cause of the failure of EMU's electronic equipment and lowering its reliability and is also a cause of train's fault occurred by tripping circuit breaker. In this paper, we intend to investigate the effect on blending characteristics of electric-braking and pneumatic-braking whether the regenerative energy storage system is used or not in urban transit DC 1,500V feeding system, while trains run. And we also intend to investigate its effect on stabilization of the blending, fluctuation of catenary voltage and various electric equipments.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.63 no.10
• /
• pp.1479-1484
• /
• 2014

This paper deals with regenerative energy in railway system which one of the largest customer in terms of load capability. Unlike the other loads of power system, loads of railway systems change in time and space. It has a characteristic amount of generating regenerative energy by frequent starting and braking in railway system. Therefore, it is expected higher utilization in railway system than the other systems. The purpose of DC power supply simulation is analyzing backed energy, regenerative energy by each railway vehicle and substation. In this paper, regenerative energy utilization are analyzed using DC power supply simulation and it is performed changing major influence on the design such as the number of installing absorber, internal resistance value, no-load voltage value at substation or operating parameters at regenerative energy utilization. After simulating, results are compared and analyzed.

• Proceedings of the KSR Conference
• /
• 2004.10a
• /
• pp.375-380
• /
• 2004

Vibration of railway vehicle has harmful effect to dynamic performances of railway represented to stability, safety and ride comfort. Hence reduction of vibration has been discussed as an important problem and has been widely investigated. A new technology of vibration control, energy regenerative control, is introduced. Energy regenerative damper using this new vibration control converts vibration energy into other kind of energy that we can utilize. In this paper, this energy regenerative damper is applied to the dynamic absorber and vehicle suspension. And it is evaluated whether the energy regenerative railway vehicle suspension is possible.

• Journal of Drive and Control
• /
• v.9 no.1
• /
• pp.1-9
• /
• 2012

Nowadays, various researches about eco-friendly vehicles such as hybrid electric vehicle, fuel cell vehicle and electric vehicle have been actively carried out. Since most of these green cars have electric motors, the regenerative energy technology can be used to improve the fuel economy and the energy efficiency of vehicles. The regenerative brake is an energy recovery mechanism which slows a vehicle by converting its kinetic energy into electric energy, which can be either used immediately or stored until needed. This technology plays a significant role in achieving the high energy usage. However, there are some technical problems for controlling the regenerative braking and the electro-hydraulic brake during switching at transient region. In this paper, the performance simulator for fuel-cell vehicle is developed and transient response characteristics of the regenerative braking system are analyzed in the various driving situations. And the hardware-in-the-loop simulation of electro-hydraulic brake is performed to validate the transient characteristics of the regenerative braking system for fuel-cell electric vehicle.