• Journal of Electrical Engineering and Technology
• /
• 제13권1호
• /
• pp.78-88
• /
• 2018

The liberalization of electricity market and environmental concerns are the major driving forces for the development of Distributed Generation (DG). The mode of grid-connected wind power generation is becoming popular and has matured as a reliable DG technology. The voltage generated by the wind generator is stepped up to the higher voltage by the transformers before connecting to the grid. Operating algorithm of the differential relays for transformer protection used in the wind farms need to be modified to take care of the dynamic nature of fault current caused by the intermittent nature of the wind power. An algorithm for the differential relay is proposed in which dual slope characteristics are adjusted with varying fault level situation according to the wind generator in service as well as with the wind speed. A case study conducted for a typical wind farm shows that the proposed method avoids mal-operation of the differential relay in varying wind power conditions.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2001년도 전력전자학술대회 논문집
• /
• pp.348-351
• /
• 2001

In this paper, voltage-fed high frequency resonant inverter of instantaneous current phaser control method used to DC voltage source separated is proposed. In the output control method, a novel circuit type of phase shift driving signal method with CVCF illustrated, also the operation principle of the proposed circuit is described in detail and its characteristics are presented as to normalized parameters. According to the each mode, in order to the circuit analysis and characteristic evaluation of the state equation are derives and present used to normalized parameter. In the future, this proposed inverter show that it can be practically used as power source system for the lighting equipment of discharge lamp, DC-DC converter etc.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1997년도 추계학술대회 논문집
• /
• pp.77-79
• /
• 1997

A 5Gbps LiNb $O_3$ optical phase modulator was packaged and described. A APE(annealed proton exchange) method was employed for the optical waveguide and the electrode of ACPS (asymmetric coplanar strip) type was formed by electro-plating on LiNb $O_3$ fort applying microwave signal. The resulted phase modulator exhibited a single mode at a 1550nm wavelength and Its modulation bandwidth, Insertion loss and driving voltage showed 7$^{GHz}$, 3. $O^{dB}$ and 6V. respectively.y.

• 대한전기학회논문지
• /
• 제41권6호
• /
• pp.588-599
• /
• 1992

This paper describes the variable speed drive of an induction motor by the line commutated inverter, which is operated in the forced commutation mode from start-up to operating point of load commutation. A novel forced-commutation circuit is proposed in this paper. The selection range of leading condenser to decide load commutation starting point is simulated by the sampling data of a general purpose IM and a high speed IM. The experiment to drive IM by a line commutated inverter with the proposed forced commutated circuits is performed. There was no problem in driving IM from standstill to starting point of load commutation by a line commutated inverter with forced commutation.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2007년도 하계학술대회 논문집
• /
• pp.356-358
• /
• 2007

최근 개발된 평판 타입 면광원의 경우, 전면방전을 위해서는 방전수축이 아닌 글로우 방전을 이용하게 된다. 본 논문은 면광원 피드백 구동 시스템에 관한 것으로서, 구체적으로는 면광원의 동작시간이 길어짐에 따라 방전수축 상태로 천이하거나 방전수축 상태에서 점등하는 것을 방지하고 안정적으로 동작하도록 하는 피드백 구동 시스템에 관한 것이다. 면광원에 흐르는 전류의 값을 측정하여 면광원 구동 회로를 피드백 제어하는 시스템을 구성함으로써, 면광원 램프에 흐르는 전류의 값을 목적하는 범위 이내에 유지할 수 있어 방전수축상태로 천이하지 않는 안정적인 면광원 구동회로를 구성한다. 실험을 통하여 제안된 방식의 타당성을 검증 하였다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2002년도 춘계합동학술대회 논문집
• /
• pp.62-67
• /
• 2002

A single-phase power factor corrected converter for switched reluctance motor driving is presented to achieve sinusoidal, near unity power factor input currents. Because it combines a power factor corrected converter and a conventional asymmetric SRM driver into one power stage, the configuration has a simple structure resulted in low cost. A prototype to drive 6/6 poles SRM employing a parking magnet is designed to evaluate the proposed topology. The characteristics and operational mode will be discussed in depth, and the validity of proposed driver will be verified through the experimental results.

• 전기학회논문지
• /
• 제57권8호
• /
• pp.1356-1361
• /
• 2008

A switched reluctance generator(SRG) has simple magnetic structure, and needs simple power electronic driving circuit. But, a SRG are no windings or permanent magnets on the rotor, and there are concentrated windings placed around each salient pole on the stator. Because of the characteristics of time-sharing excitation, the control of SRG is very flexible. And there are several parameters for controlling SRG, such as switch turn-on angle, switch turn-off angle, and exciting voltage and controlling mode, all these will affect the generation greatly. A SRG has positive torque at increasing inductance region and negative torque at decreasing inductance region. In this paper, we studied characteristics about the switch turn-on and off angles according to switch method for constant output voltage of the fixed speed SRG. It is the acoustic noise and torque ripple characteristics. Characteristics for a switch angle and method are presented by experiment using a 50W SRG with 12/8 poles.

• 한국안전학회지
• /
• 제15권3호
• /
• pp.45-51
• /
• 2000

This paper studies the effect of vibrational characteristics of the various tubes analyzed though experiment. By an experiment analysis we found out that the factor of system vibration is fluid-structure interaction of tube line. In fluid-filled tube system we study on the influence that the natural frequency of system and the frequency of wave motion produce upon through three experiments. Three experiments are modal test on each tube, FRF in continuous system, and vibrating tests when the system is driving on. From the results of the experimental studies, we obtained that the natural frequencies of system are very important than wave induced vibrations. and according to the variation of configuration, the frequencies are different each other. And we found that though fluid passed away through the tube, the tendency of system vibration level was similar with the mode shape at the simple system.

• 한국정밀공학회지
• /
• 제17권11호
• /
• pp.81-87
• /
• 2000

A new resonator that is fabricated by single polysilicon layer process is presented. The resonator can move in two orthogonal direction on the plane parallel to the substrate. And the resonant frequencies of the two modes are intrinsically designed to be identical since the overall structure of the resonator is symmetric about the two directions of motion. Since the resonator ideally has two identical vibration mode, it can be applied to various micro-devices that requires multi DOF motion, especially to microgyroscopes. To investigate the feasibility of application of the resonator, dynamic model of the resonator including the nonlinear behavior of driving electrodes is derived and evaluated with the fabricated one, and the self-tuning characteristics are proved though experiments.

• 융복합기술연구소 논문집
• /
• 제4권1호
• /
• pp.9-13
• /
• 2014

The purpose of this study is analysis to vehicle's fuel economy and emission gas characteristics by fuel type. The test vehicle were selected to similar weight and performance, the test vehicle was used three representative mode(CVS-75, HWFET and NEDC) in order to evaluation fuel economy and emission gas. For reference, environment pollution cost was calculated on the basis of the exhaust emissions occurred in the test in progress.