• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 제38회 하계학술대회
• /
• pp.602-603
• /
• 2007

In this paper, the RCF method is applied to analyze small signal stability of power systems including thyristor controlled FACTS equipments such as SVC. The eigenvalue sensitivity analysis algorithm in discrete systems by the RCF method are presented and applied to the power system including SVC. As a result of simulation, the RCF analysis method is very powerful to calculate the newly generated unstable oscillation modes precisely after periodic switching operations of SVC. Also the RCF analysis method enabled to precisely calculate eigenvalue sensitivity coefficients of dominant oscillation modes after periodic switching operations. These simulation results are very different from those of the conventional continuous system analysis method such as the state space equation method.

• 전기학회논문지P
• /
• 제57권4호
• /
• pp.388-394
• /
• 2008

The purpose of this paper is concerned with a battery type powered handpiece drive system for surgical operation. Battery type powered surgical handpiece is suitable for delicate surgical operating. The conventional air-type handpiece has a mechanical noise, a strong oscillation and a danger of infection. And the conventional contact switching type handpiece has problems that is restricted by surroundings. By reason of this kind, we studied noncontact switching type surgical handpiece to change conventional air type surgical handpiece and contact switching type. Also in this paper we develop the battery type power handpiece drive system for surgical operation using controller IC UC3625 of UNITRODE CO. Finally some experimental and simulation results are provided to demonstrate the validity of the proposed battery type power handpiece drive system.

• Journal of Power Electronics
• /
• 제4권1호
• /
• pp.46-55
• /
• 2004

This paper presents a high-frequency ZVS-PWM boost chopper-fed DC-DC converter with a single active auxiliary edge resonant snubber in the load-side which can be designed for power conditioners such as solar photovoltaic generation, fuel cell generation, battery and super capacitor energy storages. Its principle operation in steady-state is described in addition to a prototype setup. The experimental results of ZVS-PWM boost chopper-fed DC-DC converter proposed here, are evaluated and verified with a practical design model in terms of its switching voltage and current waveforms, the switching v-i trajectory, the temperature performance of IGBT module, the actual power conversion efficiency and the EMI of radiated and conducted emissions. And then discussed and compared with the hard switching scheme from an experimental point of view. Finally, this paper proposes a practical method to suppress parasitic oscillation due to the active auxiliary resonant switch at ZCS turn off mode transition with the aid of an additional lossless clamping diode loop, and reduced the EMI conducted emission in this paper.

• Journal of Power Electronics
• /
• 제17권6호
• /
• pp.1694-1706
• /
• 2017

Models and experiments for magnetic resonance coupling wireless power transmission (MRC-WPT) topologies such as the chain topology and branch topology are studied in this paper. Coupling mode theory based energy resonance models are built for the two topologies. Complete energy resonance models including input items, loss coefficients, and coupling coefficients are built for the two topologies. The storage and the oscillation model of the resonant energy are built in the time domain. The effect of the excitation item, loss item, and coupling coefficients on MRC systems are provided in detail. By solving the energy oscillation time domain model, distance enhancing models are established for the chain topology, and energy relocating models are established for the branch topology. Under the assumption that there are no couplings between every other coil or between loads, the maximum transmission capacity conditions are found for the chain topology, and energy distribution models are established for the branch topology. A MRC-WPT experiment was carried out for the verification of the above model. The maximum transmission distance enhancement condition for the chain topology, and the energy allocation model for the branch topology were verified by experiments.

• 한국원자력학회:학술대회논문집
• /
• 한국원자력학회 2001년도 추계학술발표회요약집
• /
• pp.118-118
• /
• 2001

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1998년도 추계종합학술대회 논문집
• /
• pp.633-636
• /
• 1998

In this study, power AlGaAs/InGaAs/GaAs PM-HEMT's for mm wave's were fabricated using Electron beam lithography and air-bridge techniques, and so on. DC and AC characteristics of the fabricated power PM-HEMTs were measured under the various bias conditions. For example, DC and RF characteristics such as S21 gain of 3.6 dB at 35 ㎓, current gain cut-off frequencies of 45 ㎓ and maximum oscillation frequencies of 100 ㎓ were carefully analyzed for design methodology of sub-mm wave power devices.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
• /
• pp.226-228
• /
• 1999

This paper presents a dynamic simulation algorithm for studying the effect of Unified Power Flow Controller(UPFC) on the low frequency power system oscillations and transient stability studies. The algorithm is a Newton-type one and gives a fast convergence characteristics. The algorithm is applied to inter-area power oscillation damping regulator design of a sample two-area power system. The results show that UPFC is very effective for damping inter-area oscillations.

• Wind and Structures
• /
• 제23권3호
• /
• pp.211-229
• /
• 2016

In recent years, the frequency and duration of supply interruption in electric power transmission system due to flashover increase yearly in China. Flashover is usually associated with inadequate electric clearance and often takes place in extreme weathers, such as downbursts, typhoons and hurricanes. The present study focuses on the wind-induced oscillation of conductor during the process when a downburst is passing by or across a specified transmission line. Based on a revised analytical model recently developed for stationary downburst, transient three-dimensional wind fields of moving downbursts are successfully simulated. In the simulations, the downbursts travel along various motion paths according to the certain initial locations and directions of motion assumed in advance. Then, an eight-span section, extracted from a practical 500 kV ultra-high-voltage transmission line, is chosen. After performing a non-linear transient analysis, the transient displacements of the conductors could be obtained. Also, an extensive study on suspension insulator strings' rotation angles is conducted, and the electric clearances at different strings could be compared directly. The results show that both the variation trends of the transient responses and the corresponding peak values vary seriously with the motion paths of downburst. Accordingly, the location of the specified string, which is in the most disadvantageous situation along the studied line section, is picked out. And a representative motion path is concluded for reference in the calculation of each string's oscillation for the precaution of wind-induced flashover under downburst.

• 조명전기설비학회논문지
• /
• 제16권2호
• /
• pp.45-53
• /
• 2002

본 논문은 두 지역 간에 직렬로 연결된 HVDC 연계시스템의 전력계통 안정화장치와 전력변환기의 적정 파라메터 선정기법을 다루었다. PSS파라메터 선정기법은 구하고자 하는 진상이 되도록 극좌표를 이동시키고, 충분한 댐핑을 얻도록 이득을 조절하는 고전적인 기법이다. 전력변환기의 적정 파라메터는 근궤적기법을 근거로 하여 기준 값의 변화와 시스템의 동요에 충분한 속응력과 안정도를 고려하여 산정한다. 이들 기법으로 구판 제정수로 소신호 및 과도안정도 분석결과는 사례연구시스템의 고유동요 주파수에 적절한 댐핑 효과를 보여주었다. 본 논문에서 사용한 프로그램은 MATLAB을 근거로 한 PST이다.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
• /
• pp.79.2-79.2
• /
• 2011

플라이 휠 에너지 저장장치(Flywheel Energy Storage System: FESS)는 전기 에너지를 회전 운동 에너지로 저장하였다가 필요시 회전 운동에너지를 전기 에너지로 변환하여 재사용 가능한 에너지 저장장치 이다. 최근 전력 변환 기술의 발전으로 인하여 플라이휠 에너지 저장 장치의 에너지 입출력 속도가 빨라지고 대용량의 에너지를 저장할 수 있게 되었다. 본 논문에서는 이러한 플라이휠 에너지 저장 장치의 전력 입출력 특성을 이용하여 전력 시스템에서 발생하는 저주파 진동(Low frequency oscillation)을 억제하는 방안을 제시 하여 안정도를 향상 시키고자 하였다. 전력 시스템은 발전조건, 전송조건, 부하조건에 따라 동작 조건이 지속적으로 변하고 있다. 이러한 동작 환경 변화는 전력 시스템에 대한 수학적인 표현과 실제 전력계통간의 차이가 발생하기 때문에 정확한 제어 목적을 달성하기가 힘들다. 따라서 본 논문에서는 제어기 설계 단계에서 전력 계통의 불확실성을 고려할 수 있는 $H_{\infty}$ 제어 기법을 이용하여 플라이휠 에너지 저장장치를 위한 강인 제어기를 설계 하였다. 제안한 플라이휠 에너지 저장장치의 강인 제어기의 유용성을 입증하기 위하여 1기 무한대 모선에 적용한 결과를 비선형 시뮬레이션을 통하여 다양한 외란이 발생한 경우에 외란 억제 성능과 강인성에 대하여 고찰 하였으며, 제안한 방식이 기존의 전력계통 안정화 장치(Power system stabilizer: PSS) 보다 효율적이며 전력계통의 안정도 향상에 크게 기여함을 보이고자 하였다.