• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1053-1055
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• 1998

Using EMTP model which describes bipolar HVDC system, switching level simulation results are presented in this paper. Voltage synchronization at point of common coupling, gate pulse generation and current control loops are represented in TACS module. The system consists of 100 km submarine cable rated 300 MW and 12 pulse rectifier and inverter stations which are connected to equivalent three-phase sources and loads through the 154 kV AC lines, respectively. In convertor stations, harmonic filters and capacitor banks are equipped to cancel out the harmonics generated by converters and to supply the required reactive power.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.403-404
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• 2014

전기 자동차 및 하이브리드 자동차는 차량의 12V 부하에 전원을 공급하고 12V 배터리를 충전시키기 위해 DC/DC 컨버터를 사용한다. 이 DC/DC컨버터를 LDC(Low voltage DC/DC Converter)라 한다. 본 논문에서는 Active Clamp 방식의 포워드 컨버터를 이용하여 소용량 LDC를 개발한 내용을 소개 하였다.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.155-157
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• 2005

This paper analyzed the adoption possibility of a low cost single phase active power filter as the neutral current reduction device in three-phase four-wire power system with the balanced or/and unbalnaced nonlinear load conditions. Proposed system can make neutral line current to within rated vale without the phase current THD change of the installed phase line.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.3
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• pp.409-413
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• 2016

The 500 MW rated steam turbine model in coal fired power plant is developed to be used for validation and verification of controller rather than for the education of operator. The valve, steam turbine, reheater and generator are modeled and integrated into the simulator. And the data from the plant heat balance diagram are used for estimation of the model parameters together with actual operating data. It is found that the outputs of model such as pressure, temperature and speed are similar to the operating ones. So, it is expected that the developed model will play a very big role in controller development.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.477-478
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• 2016

This paper introduces a repetitive controller in low switching frequency applications. Generally, A high power UPS system has a high rated current. And the system usually consist of high power IGBT has a tail current. So the high power UPS system operates in low switching frequency because of this tail current. The repetitive controller improve THD of output voltage or current by reducing the steady state error. The effect of the repetitive controller is proved by simulations.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.453-454
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• 2016

The ESS(Energy Storage System) connected with distributed generation is drawing attention due to improving the quality load leveling, peak shaving for enhancing reliability of the power grid. The grid-connected inverter makes frequency adjustment to the active power's charge discharge according to the load variation. In addition, the inverter is possible to act as a reactive power compensation device to eliminate harmonic operates as power factor change inhibiting, anti-transient voltage fluctuation, active filter. In this paper, we propose a design method of igbt stack considering the reactive power supply capacity to improve the quality and reliability of the inverter. Moreover, the grid-connected inverter considering the four-quadrant rated operation designed stack and verified the feasibility of the design through a thermal analysis.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.519-523
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• 2004

In this paper, a simple power control scheme of Class-D inverter, which is varied duty cycle of fixed frequency to desired output power. It is more suitable and acceptable for high-frequency induction heating (IH) jar applications. The proposed control scheme has the advantages of not only wide power regulation range but also ease to control output power. Also it can achieve the stable and efficient Zero-Voltage-Switching (ZVS) in whole load range. The control principles of proposed method are described in detail and its validity is verified trough simulations results on 38.5kHz IGBT for induction heating rated on 1.6kW with constant frequency variable power.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.1
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• pp.7-11
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• 2008

A new continuously variable transmission (CVT) for electric bicycles was developed using a traction drive mechanism with inner and outer spherical rotors. This electric bicycle CVT permits three propulsion modes: human-power only, motor-power only, or a combination of motor power and human power. In addition, the electric bicycle CVT has high power efficiency, large torque capacity, improved drivability, and good packageability. A prototype was manufactured based on a conceptual design, a performance analysis, and a detailed design. This prototype has a rated power of 250 W and input motor speed of 20 rad/s for an overall speed ratio in the range 0.3-1.2. A bench test was conducted to measure the power transmission performance of the prototype.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1311-1318
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• 2015

This paper introduces a novel topology and an effective control strategy for a shunt hybrid power filter (SHPF) to simultaneously compensate harmonic currents and reactive power. The proposed SHPF topology is composed of an LC passive filter tuned to the 7^th harmonic frequency and a small-rated active filter connected in parallel with the inductor L_pf of the LC passive filter. Together with the SHPF topology, we also propose a control strategy, which consists of a proportional-integral (PI) controller for DC-link voltage regulation and a PI plus repetitive current controller, in order to compensate both the harmonic current and the reactive power without the need for additional hardware. Thanks to the effectiveness of the proposed control scheme, the supply current is sufficiently compensated to be sinusoidal and in-phase with the supply voltage, regardless of the distorted and phase lagging of the load current. The effectiveness of the proposed SHPF topology and control strategy is verified by simulated and experimental results.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.1-11
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• 2003

The service reliability of power plants strongly depends on the excellent performance and integrity of hydrodynamic bearings. Consequently, the bearings must be properly designed so as to control vibration amplitudes of rotor due to mass unbalance in passing critical speeds and also suppress self-excited vibrations of rotor even over maximum rated speeds. Furthermore, the bearings must be designed so as to maintain required tribological performance even under severe operating conditions. However, various tribological troubles have been experienced in power plants in Japan. The actual troubles are analysed, focusing on not only direct mechanical causes but also specific bearing designs that surfaced the troubles. Furthermore human factors that decided such designs are also studied. The powerful database of troubles and analyses will contribute greatly to designing advanced power plants with enhanced service reliability in the future. To this end, trouble information should be disclosed, shared and transferred limitlessly. Cooperation of users of power plants is essential to making more advanced design specifications, because no one has easier access to operating and trouble information of power plants than users.