• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.2
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• pp.201-208
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• 1999

This paper presents the degradation of the system performance according to the vmiation of the rotor time constant. The algorithm for the on-line estimation of rotor time constant is proposed. which is applied to the consistent relationship between the tangent torque angle of the synchronous reference frame and that of stationary reference f frame. For the purpose of the validity of proposed algorithm. the computer simulation and the experiments have been p performed.

• Proceedings of the KIEE Conference
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• 1990.11a
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• pp.73-77
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• 1990

In this paper we describe the solid-state ac-circuit breaker which has the characteristic of both a half cycle circuit breaker and a current limiting circuit breaker. This circuit breaker has a current limiting resistor in order to surprises the fault current to a certain level and discharge the energe included in circuit inductor. We explain the effect of circuit parameter on transient phenomena of switch device by using EMTP and finally design the control circuit consisted synchronous closing circuit, over- current detecting circuit and sensing circuit of rate of rise of fault current.

• Proceedings of the KIEE Conference
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• 2008.04c
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• pp.103-105
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• 2008

본 논문에서는 동기좌표계를 이용한 단상 계통연계형 태양광 인버터의 새로운 전류제어 기법을 제시한다. 기존의 정지좌표계 단상 인버터 전류제어 방법인 PI제어기와 PR제어기를 먼저 알아보고, 기존의 가상 2상 전류 생성기를 통해 단상 시스템을 동기좌표계 모델에 적용하는 전류제어기법을 기술한다. 그리고 가상 2상 전류 생성기의 새로운 방법을 제안한다. 제안된 전류 생성기는 지령 전류를 이용하여 새로운 전류를 생성하는 것으로 시스템의 안정도와 과도상태 응답특성을 개선하였다. 모의실험을 통해 기존의 방식과 제안된 방식을 비교함으로써 그 우수성을 입증한다.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.55 no.1
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• pp.21-25
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• 2006

This paper describes the novel control techniques design of VSC(Voltage Sag Corrector) for the purpose of power line quality enhancement. A fast detecting technique of voltage sag is implemented through the detection of instantaneous value on synchronous rotating do-reference frame. The first order digital filter is added in the detection algorithm to protect the insensitive characteristics against the noise. The relationship between the total detection time and cut-off frequency of the filter is described. The size of the capacitor bank used as the energy storage element is designed from the point of view of input/output energy with circuit analysis. Finally, the validity of the proposed scheme is proven through the simulated results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.6
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• pp.1000-1006
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• 2007

This paper presents a methodology to calculate an optimal solution of equilibrium to differential algebraic equations for power systems. It employs a nonlinear interior point method to solve the optimization formulation which includes dynamic equations representing the two-axis synchronous generator model with AVR and speed governing controls, algebraic equations, and steady-state nonlinear loads. This paper also adopts two algorithms for the improvement of solution convergence. In power system analysis and control, equilibrium optimization (EOPT) is applicable for diverse purposes that need the consideration of dynamic model characteristics at a steady-state condition.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.5
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• pp.250-256
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• 2003

In this papur, the STATCOM (STATic synchronous COMpensator) application for efficient operations of wind farm is described. The wind farm connected with the electric power network is one of good alternative energy sources. However, it would be also highly possible that interconnection of wind farm causes unwanted influences on distribution system operation, protection and control. This paper proposes the STATCOM application for reducing the negative effects from interconnection of wind farm with distribution networks. The simulation results show that STATCOM would be on effective and useful device to resolve the bad influences from wind farm on distribution networks and improve the operational efficiency of wind farm. In the simulation, the radial distribution network of IEEE 13 bus was modeled using PSCAD/EMTDC.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.361-363
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• 1996

The output of solar cell should be operated in the maximum power point, since it is greatly fluctuated by insolation and temperature. Also, since the output of solar cell is a DC power, it needs the inverter to interact with utility line. In this paper, we made composed of PV system with a chopper that control the maximum power point and the inverter that drive to the high power factor and low harmonic by use of defected and compensated utility line voltage for synchronous phase with utility line.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.65-69
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• 1997

Generally, we often use a speed sensor based on a rotary encoder and we can obtain a speed information by counting the increased or decreased number of encoder pulses in a sampling period. However, these speed measurement systems do not inherently produce a true, instantaneous speed information and them the speed ripple is generated by speed measurement errors. In order to overcome this problem, speed observer is used for the accurate speed measurement and improvement of speed ripple for Permanent Magnet Synchronous Motor (PMSM) in this paper. Speed observer estimates the instantaneous speed at each sampling instant. This estimated speed signal is then used as the speed feedback signal for the speed loop control. The proposed speed observer system is proved simulation using SABER simulation S/W.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.485-489
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• 2003

This paper presents the method of speed measurement for permanent magnet synchronous motor(PMSM) with the full-order observer using reduced-order state equation. This Is able to improve the operating performance at low speed. Therefore, by the proposed technique, a low resolution encoder can be used. Because it make the system improve the performance of speed response. The proposed method is verified to simulation and experiments.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.557-560
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• 2005

The Korea Multi-Purpose SATellite-2 (KOMPSAT -2) will be launched into a circular sun synchronous orbit in Dec. 2005. For the mission operation of the KOMPSAT-2 satellite, KARl Ground Station (KGS) consists of the Mission Control Elements (MCE), Image Reception & Processing Elements (IRPE) and the overseas stations. For the oversea stations, the Kongsberg Satellite Services (KSAT) is the prime supplier of support service. KSAT has the capability to provide Tracking Telemetry and Commanding (TT&C) nominal, contingency and anomaly support for every single orbit for most polar orbiting satellites. Also KSAT provides nodal service through the network management functionality for all oversea ground stations. This paper describes the oversea stations and the support for Launch and nominal TT&C services for KOMPSAT-2 and the operation plan for KOMPSAT-2.