• 소음진동
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• 제8권1호
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• pp.112-121
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• 1998

In this report, Experimental analysis for main factors and analyzing methods of electro-magnetic noise and no loading noise was conducted because of noise of AC generator, which is peripheral equipment by reduction of engine noise that would be the main cause of vehicle radiation noise. In addition, This is intended to suggest the noise reduction development basis of AC generator for actual fan and electro-magnetic noise by making-analyzing-testing it's sample.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권12호
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• pp.609-615
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• 2005

A 30kW electrical power conversion system is developed for a variable speed wind turbine. In the wind energy conversion system(WECS) a synchronous generator with field current excitation converts the mechanical energy into electrical energy. As the voltage and the frequency of the generator output vary according to the wind speed, a 6-bridge diode rectifier and a PWM boost chopper is utilized as an ac-dc converter maintaining the constant dc-link voltage with only single switch control. An input current control algorithm for maximum power generation during the variable speed operation is proposed without any usage of speed sensor. Grid connection type PWM inverter converts dc input power to ac output currents into the grid. The active power to the grid is controlled by q-axis current and the reactive power is controlled by d-axis current with appropriate decoupling. The phase angle of utility voltage is detected using software PLL(Phased Locked Loop) in d-q synchronous reference frame. Experimental results from the test of 30kW prototype wind turbine system show that the generator power can be controlled effectively during the variable speed operation without any speed sensor.

• 대한전자공학회논문지SD
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• 제39권11호
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• pp.1-6
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• 2002

본 논문에서는 High speed DRAM의 speed 특성을 향상시키기 위한 Laser_Repair Condition 최적화의 한 방안을 구현하였다. 구현 방법은 먼저 Wafer내의 개별 Die별 DC Generator level을 확인하고 최약 DC Generator를 파악한 후 AC parameter의 margin을 check하고 AC parameter의 특성을 개선시킬 수 있는 DC Generator level을 forcing하여 test하여 개선 효과를 곧장 확인하였고 그에 대한 Fuse cutting inform을 생성하여 Laser_Repair 공정에서 적용하여 Post_Laser test시 개선 효과를 확인하였다.

• 동력기계공학회지
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• 제11권3호
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• pp.3-8
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• 2007

The emergency AC power supply system of the nuclear power plant is designed to supply the power to the nuclear reactor at the emergency operating condition. The safety function of the diesel generator at the nuclear power plant is to supply AC electric power to the plant safety system whenever the preferred AC power supply is unavailable. The reliable operation of onsite emergency diesel generator should be ensured by a conditioning monitoring system designed to maintain and monitor and forecast the reliability level of diesel generator. To do this kind of diesel generator condition monitoring we reviewed several operating factors and history of the wolsong unit 3 diesel generator and selected the proper conditioning monitoring operating factors.

• Journal of Electrical Engineering and Technology
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• 제9권1호
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• pp.280-285
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• 2014

In order to evaluate the insulation deterioration in the stator windings of five gas turbine generators(137 MVA, 13.8 kV) which has been operated for more than 13 years, diagnostic test and AC dielectric breakdown test were performed at phases A, B and C. These tests included measurements of AC current, dissipation factor, partial discharge (PD) magnitude and capacitance. ${\Delta}I$ and ${\Delta}tan{\delta}$ in all three phases (A, B and C) of No. 1 generator stator windings showed that they were in good condition but PD magnitude indicated marginally serviceable and bad level to the insulation condition. Overall analysis of the results suggested that the generator stator windings were indicated serious insulation deterioration and patterns of the PD in all three phases were analyzed to be internal, slot and spark discharges. After the diagnostic test, an AC overvoltage test was performed by gradually increasing the voltage applied to the generator stator windings until electrical insulation failure occurred, in order to determine the breakdown voltage. The breakdown voltage at phases A, B and C of No. 1 generator stator windings failed at 28.0 kV, 17.9 kV, and 21.3 kV, respectively. The breakdown voltage was lower than that expected for good-quality windings (28.6 kV) in a 13.8kV class generator. In the AC dielectric breakdown and diagnostic tests, there was a strong correlation between the breakdown voltage and the voltage at which charging current increases abruptly ($P_{i1}$, $P_{i2}$).

• 한국전기전자재료학회논문지
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• 제33권2호
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• pp.130-134
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• 2020

Metal oxide varistors (MOVs) protect circuits and devices from transient overvoltages in electric power systems. However, a MOV continuously deteriorates owing to manufacturing defects or repetitive protective operations from transient overvoltages. A deteriorated MOV may result in a short circuit or a line-ground accident. Previous studies focused on the analysis of deterioration mechanisms and condition diagnosis techniques for MOVs owing to their recent growth of use. An accelerated deterioration experiment under the same conditions in which a MOV operates is essential. In this study, we designed and fabricated a surge generator that can apply a surge current to a MOV connected to AC mains. The coupling network operates at a low impedance against the surge current from the surge generator and transfers the surge current to the MOV under test. It also acts as a high impedance against AC mains for the AC voltage not to be applied to the surge generator. The decoupling network operates at a high impedance against the surge current and blocks the surge current from AC mains. It also acts as a low impedance against AC mains for the AC voltage to be applied to the MOV under test. The prototype surge generator can apply the 8/20 us up to 15 kA on AC voltages in the approximate range of 110~450 V, and it fully operates on a LabVIEW-based program.

• 전기학회논문지P
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• 제57권2호
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• pp.102-108
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• 2008

AC generator plays an important role of power system. The large AC generator fault may lead to large impacts or perturbations in power system. And then the protection of a generator has very important role in maintaining stability in a power system. In present, the DFT(discrete Fourier transform) based RDR(ratio differential relay) had been widely applied to a internal fault of a generator stator winding. But DFT has a serious drawback. In the course of transforming a target signal to frequency domain, time information is lost. DWT uses a time-scale region. This paper proposes an advanced fault detection algorithm using DWT(discrete Wavelet transform) to enhance the drawback of conventional DFT based relaying. To evaluate the performance of the proposed relaying, we used the test data which were sampled with 720 [Hz] per cycle and obtained from ATP(alternative transient program) simulation. And we made a comparative study of conventional DFT based RDR and the proposed relaying.

• 한국산학기술학회논문지
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• 제14권6호
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• pp.2979-2984
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• 2013

본 논문은 도서지역에서 운용되고 있는 풍력-디젤 하이브리드 발전시스템의 풍속변화 등으로 인한 주파수변동 문제를 해결할 수 있는 플라이휘일 저장장치의 모델링 및 제어기 설계 방법을 제안하였다. 플라이휘일 저장장치는 효율측면에서 유리한 영구자석 동기기형 플라이휘일로 선정하여 모델링하였고, 주파수보상 제어기는 AC/DC/AC 양방향컨버터로 구성하되 동기기측 컨버터는 연계계통의 주파수변동에 대하여 충방전운전을 하도록 하고, 계통측 컨버터는 직류버스전압 일정제어를 통하여 출력을 하도록 설계하였다. 제안된 모델링 및 제어기 설계방법을 풍력-디젤 하이브리드 독립운전계통에 적용한 결과 풍속변화에 따른 주파수변동을 적정범위내로 유지할 수 있었다.

• 동력기계공학회지
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• 제17권4호
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• pp.31-35
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• 2013

The emergency AC power supply system of the nuclear power plant is designed to supply the power to the nuclear power plant at the emergency operating condition. The safety function of the diesel generator at the nuclear power plant is to supply AC electric power to the safety system whenever the preferred AC power supply is unavailable. The reliable operation of onsite standby diesel generator should be ensured by a condition monitoring system designed to maintain, monitor and forecast the reliability level of diesel generator. The purpose of this paper is to improve the existing ultrasonic sensor used for condition diagnosis of engine fuel pump and cylinder head for the accurate diagnosis in actual engine condition of emergency diesel generator(EDG). As a result of this study, we could design and develop much more reliable ultrasonic sensor than existing ones.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 V
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• pp.2769-2772
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• 2003

This paper presents results of the development of the Turbo-generator system with structure which is HSG(High Speed Generator) installed to high speed gas-turbine engine directly. Turbo-generator with high speed motor-generator directly has many advantages aspects of weight, size, lubrication system and complexity of the system compared of conventional turbo-generator system with gear-box. But because of direct high speed operation of the high speed generator, we have to need stable high speed motor driving algorithm for perfect engine ignition when gas turbine starting. Also we have to need design of the PCU(Power Conditioning Unit) for converting high speed AC output power to conventional AC power or needed DC power.