• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.354-355
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• 2018

Flywheel energy storage system (FESS) operates motor or generator by utilizing the stored kinetic energy in the rotating mass. Thus, the FESS can support the frequency control of the power system. However, the FESS is disabled when the rotor speed reaches to its minium value. Thus, the second frequency dip occurs in the power system. This paper proposes the frequency control scheme of FESS based on a variable gain depending on the rotor speed and frequency deviation. The proposed scheme prevents the second frequency dip because the variable gain decreases depending on the stored in the FESS. The performance of the proposed scheme is investigated for the IEEE 14-bus system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.7
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• pp.1045-1052
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• 2013

In this study we deal with design procedures for the flywheel energy storage system that has the capacity to store the regenerative energy produced from the railway vehicles. The flywheel energy storage system (FESS) stores the regenerative electrical energy into the high speed rotational flywheel, by conversion the electrical energy into the mechanical rotational energy. Thus the FESS is composed of the energy conversion components, such as the motor and generator, mechanical support components, such as the rotational rotor, the magnetic bearings to support the rotor, and the digital controller to control the air gap between the rotor and the magnetic bearings. In this paper the design procedures for the rotor operating at the rigid mode and the magnetic bearings to support the rotational rotor without contact are presented.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.485-490
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• 2004

Flywheel Energy Storage System(FESS) consists of a high speed flywheel with an integral motor/generator suspended on non contact bearings and in an evacuated housing. Permanent magnet machines as the FESS motor/generator are a popular choice, since there are no excitation losses which means substantial increase in the efficiency. In this paper, the structural design method of rotor retainer for a high speed motor/generator are presented.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1051-1053
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• 2003

Flywheel Energy Storage System (FESS) consists of a high-speed flywheel with an integral motor/generator suspended on magnetic bearings and in an evacuated housing. Permanent magnet (PM) machines as the FESS motor/generator are a popular choice. since there are no excitation losses which mean substantial increase in the efficiency. In this paper, the basic design and the steady-state performances of a permanent magnet synchronous high speed motor/generator for FESS are presented.

• Journal of KSNVE
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• v.9 no.5
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• pp.891-898
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• 1999

The purpose of Superconducting Magnetic Bearing Flywheel Energy Storage System (SMB-FESS) is to store unused nighttime electricity until it is needed during daytime. An analytical model of the SMB-FESS is necessary to identify the system behavior. At first, we have to model the superconducting magnetic bearing. Modeling the SMB is same as estimating the bearing parameter. The theoretical modal parameter is calculated through the equation of motion and the experimental modal parameter is estimated through the impact testing (modal testing). The bearing parameter is searched by using the non-linear least square method until the theoretical result corresponds to the experimental result. The suggested modeling method is verified by comparing experimental and analytical frequency response function.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.235-236
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.927-928
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• 2012

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.11
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• pp.1757-1763
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• 2010

Flywheel energy storage system (FESS) is defined as a high speed rotating flywheel system that can save surplus electric power. The FESS is proposed as an efficient energy storage system because it can accumulate a large amount of energy when it is operated at a high rotating speed and no mechanical problems are encountered. The FESS consists of a shaft, flywheel, motor/generator, bearings, and case. It is difficult to simulate rotor dynamics using common structure simulation programs because these programs are based on the 3D model and complex input rotating conditions. Therefore, in this paper, a program for the FESS based on the 2D FEM was developed. The 2D FEM can model easier than 3D, and it can present the multi-layer rotor with different material each other. Stiffness changing of the shaft caused by shrink fitting of the hub can be inputted to get clear solving results. The results obtained using the program were compared with those obtained using the common programs to determine any errors.

• Journal of KSNVE
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• v.8 no.1
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• pp.81-86
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• 1998

A 500Wh class high-speed Flywheel Energy Storage System (FESS) driven by a built-in BLDC motor/generator has been designed, which runs from 30000 to 60000rpm nominally. Due to the motor/generator inside, the flywheel rotor made of composites supported by PM/EM hybrid bearing system has a shape of bell or pendulum and thus requires accurate rotordynamic analysis and prediction of its dynamic behavior to secure the operating reliability. Rotordynamic analyses of the flywheel rotor-bearing system revealed that the bell shaped rotor has two conical rigid-body modes in the system operating range and the first conical mode, of which nodal point lies in the radial EM bearing position, can adversely affect the dynamic response of the rotor at the corresponding critical speed. To eliminate the possibility of wild behavior of the rotor, two guide bearings are adopted at the upper end of the rotor and motor/generator. It was also revealed that the EM bearing stiffness if 0.5~1.0E+6 N/m and damping of 2000 Ns/m are favirable for smooth operation of the system around the 2nd critical speed.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1362-1363
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• 2011

본 논문은 250[kVA]의 용량을 갖는 Induction machine을 이용하여 FESS(Flywheel Energy Storage System)를 PSCAD/EMTDC를 통하여 전동모드(Motoring mode)와 발전 모드(Generating mode)에 관하여 시뮬레이션 한 논문이다.