• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1021-1022
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• 2011

This paper presents the double side PM synchronous motor/generator for core loss reduction in flywheel energy storage system. The use of double PM rotor causes the elimination of core loss in no-load state of machine. Because flywheel rotational speed is reduced by core loss, double PM rotor is very effective in flywheel system. This paper suggests two types of double side PM rotor, Halbach magnetized array and parallel magnetized array. And characteristic comparison according to thickness of rotor back core is performed.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.4
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• pp.343-347
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• 2019

When referring to weight, volume, and efficiency, a SuperConducting Synchronous Generator (SCSG) is definitely superior to conventional generators as a large-scale wind power generation system. The SCSG is connected to a full power converter that transmits the energy from the SCSG to the power grid. To reduce the current stress and system cost, the SCSG which has nine-phase armature windings with three converters is used. This paper deals with a comparative analysis of 10 MW superconducting wind power generators with three-phase and nine-phase armature windings. The stator windings of SCSGs are of various types. Using the finite element method, SCSGs are analyzed and compared in terms of the weight and volume of SCSGs, the total length of the superconducting wire, harmonics, torque performance, and efficiency. The analyzed results will be effectively utilized to design large-scale superconducting generators for wind power generation systems.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.402-403
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• 2011

This paper presents an active and reactive power compensator for the wind power system with multi-polar synchronous generator. The proposed compensator is composed of a charge/discharge PWM converter and battery. The output power of a wind power system changes irregularly according to the variation of wind speed. The developed system is able to continuously compensate the active and reactive power. The operational feasibility of the proposed model was verified by simulations with PSCAD/EMTDC.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1612-1620
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• 2016

This paper presents the dynamic excitation control of a siphon-turbine coupled pico-hydro powered cage rotor induction generator and load matching for off-grid electricity generation. Through the proposed dual-role of the current-controlled voltage source converter (VSC), acting as static synchronous compensator and load controller, real and reactive power are dynamically controlled in a decoupled manner with a self supported DC-bus. The proposed scheme entails minimal computation for ensuring the rated (set) capacity of real power. The scheme also exhibits fault immunity for protection, thus enabling the effective handling of constant power electrical loads presented by base telecom station towers in remote locations. The performance of the system is evaluated under MATLAB/Simulink and is experimented through a developed hardware prototype. Simulation and experimental results show close conformity and validate the effectiveness of the proposed scheme.

• Journal of Power Electronics
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• v.10 no.5
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• pp.555-562
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• 2010

This paper presents the development of a hardware simulator for a 3-parallel grid-connected PMSG wind power system. With the development of permanent magnetic materials in recent years, the capacity of a PMSG based wind turbine system, which requires a full-scale power converter, has been raised up to a few MW. Since it is limited by the available semiconductor technology, such large amounts of power cannot be delivered with only one power converter. Hence, a parallel connecting technique for converters is required to reduce the ratings of the converters. In this paper, a hardware simulator with 3-parallel converters is described and its control issues are presented as well. Some experimental results are given to illustrate the performance of the simulator system.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.512-513
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• 2011

본 논문에서는 PMSG(Permanent Magnet Synchronous Generator)의 가변속-고정피치(Variable-Speed Fixed-Pitch) 풍력발전시스템을 위한 FLC를 기반으로 하는 최대 전력점제어(MPPT) 알고리즘을 제시한다. 최근에는 풍속변화에 대응하여 최대전력을 발생할 수 있는 가변속 풍력발전 시스템에 대한 연구가 활발히 진행 중이다. 국내의 지형적 조건에 따른 바람의 영향으로 풍력발전 시스템의 MPPT제어가 반드시 필요하다. 종래의 풍력발전 MPPT 제어는 응답속도 등에 대한 문제점이 나타난다. 따라서 본 논문에서는 이러한 문제점을 해결하기 위해 파라미터 변동에 강인한 FLC를 기반으로 하는 최대 전력점 제어(MPPT)를 제시한다. 또한 본 논문에서 제시한 알고리즘은 시뮬레이션 결과를 통해 타당성을 입증한다.

• Journal of Electrical Engineering and Technology
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• v.10 no.2
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• pp.529-538
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• 2015

Due to the high efficiency and compact mechanical structure, direct drive variable speed generators are used for power conversion in wind turbines. The wind energy conversion system (WECS) considered in this paper consists of a permanent magnet synchronous generator (PMSG), uncontrolled rectifier, dc-dc boost converter controlled with maximum power point tracking (MPPT) and adaptive hysteresis controlled voltage source inverter (VSI). For high utilization of the converter's power capability and stabilizing voltage and power flow, constant DC-link voltage is essential. Step and search MPPT algorithm which senses the rectified voltage ($V_{DC}$) alone and controls the same is used to effectively maximize the output power. The adaptive hysteresis band current control is characterized by fast dynamic response and constant switching frequency. With MPPT and adaptive hysteresis band current control in VSI, the DC link voltage is maintained constant under variable wind speeds and transient grid currents respectively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.44-50
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• 2002

Theoretical analysis on the transient torsional vibration was started from early 1960's for high power synchronous motor application. As for marine engineering, simulation and measuring techniques of transient torsional vibration have been steadily studied by manufacturer of flexible coupling and designer of four stroke marine diesel engine. In this paper, the simulation method of transient torsional vibration for four stroke marine diesel engine application using Newmark method is introduced.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.8
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• pp.1146-1158
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• 1993

In this paper, parallel scrambling techniques are considered for practical use in the SDH transmission and the ATM transmission. In the ATM transmission, there are two ways of transmitting ATM cells - the SDH-based and the cell-based - and the corresponding scrambling techniques differ accordingly. For the SDH transmission and the SDH-based ATM transmission, the FSS (frame synchronous scrambling) is applied to the STM frames : while for the cell-based ATM trans-mission, the DSS(distributed sample scrambling) is used on the ATM cell stream. The parallel scrambling techniques are examined for the FSS and the DSS, and applied to achieve the parallel FSSs for use in the SDH and the SDH-based ATM transmission along with the parallel DSS applicable to the cell-based ATM transmission. The resulting(8, 4) PSRG(parallel shift resister generator) and (8, 16) PSRG based parallel scramblings are directly applicable for the STM-1 rate processing of the STM-4 and STM-16 scramblings, respectively. Likewise, the resulting (1, 8)PSRG and double-sampling-double-correction based parallel scrambling techniques can be practically used for a low-rate processing of the SDH-based and the cell-based ATM signal scrambling respectively.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.17-20
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• 1988

The most important thing in design procedure of SCG is the exact estimation of the electromagnetic force acting on the field and amature winding. Until now, equivalent circuit method was used for the analysis or electric and magnetic performance. This paper sheds the leo dimensional analysis of electric and magnetic characteristics of SCG by Finite Element Method(FEM). Analysis by FEM provides more areolate results than that of equivalent circuit method because harmonics field generated by field current can he considered. Circuit and field equations are combined together in a equation and solved simultaneously.