• The Transactions of the Korean Institute of Electrical Engineers
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• v.37 no.7
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• pp.434-441
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• 1988

This paper proposes a new invention of the integrated generator converter system for the HVDC transmission. And it analyses the general formula for eddy currents in the rotor iron using the double Fourier series in order to trace the smallest eddy current losses of the system which connects a new designed synchronous generator windings or conventional synchronous generator windings with the v Graetz bridges.

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.69-70
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• 2017

This paper presents design of control system for permanent magnet synchronous generator(PMSG). The gas engine make rotating mechanical energy from gas fuel energy. The rotor of synchronous generator is connected to axis of engine. And it converts the mechanical energy to the electrical energy. The control system of PMSG helps the electrical energy to flow to grid. the single phase pfc rectifier controls the DC-link voltage by controlling the current of filter inductor. If the DC-link voltage is higher than the voltage reference, the filter current could be controlled to flow to grid. The three phase inverter controls the stator current of generator. The direction of the current is controlled depends on motoring or generating mode. The feasibility of the grid-connected PMSG is verified by the experimental results with 1kW prototype.

• Journal of Electrical Engineering and Technology
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• v.10 no.6
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• pp.2271-2276
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• 2015

A superconducting synchronous generator (SCSG) can be expected to decrease the size and weight compared to conventional tidal current generators. This paper proposes an optimal design of a 2 MW class SCSG for a tidal current power generation system. The proposed optimal design of the SCSG will reduce the length of the high-temperature superconducting wire as well as the weight and volume of the SCSG. The 3D finite element method is used to analyze the magnetic field distribution. The optimized 2 MW SCSG is compared with a 2 MW conventional generator. As the optimized SCSG is more compact and lighter than a conventional generator, it will be efficiently applied to practical tidal power systems.

• Journal of Power Electronics
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• v.8 no.4
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• pp.345-353
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• 2008

In this paper, a novel loss minimization of an induction generator in wind energy generation systems is presented. The proposed algorithm is based on the flux level reduction, for which the generator d-axis current reference is estimated using support vector regression (SVR). Wind speed is employed as an input of the SVR and the samples of the generator d-axis current reference are used as output to train the SVR algorithm off-line. Data samples for wind speed and d-axis current are collected for the training process, which plots a relation of input and output. The predicted off-line function and the instantaneous wind speed are then used to determine the d-axis current reference. It is shown that the effect of loss minimization is more significant at low wind speed and the loss reduction is about to 40% at 4[m/s] wind speed. The validity of the proposed scheme has been verified by experimental results.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.304-310
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• 2001

A numerical model which simulates the heat and mass transfer processes within a counter-current plate type generator for ammonia/water absorption refrigerators was developed. Ammonia/water solution flows downward under gravity and ammonia/water vapor generated by flow boiling flows upward. The flow pattern within the generator was assumed to be a bubbly flow, and the liquid and vapor phase were assumed to be saturated. It was shown that the boiling of ammonia occurred mainly in the upper part of the generator. The effects of the generator length, the wall temperature and the mass flow rate of ammonia/water solution into the generator on the generation of ammonia/water vapor were investigated.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.2047-2052
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• 2004

Inconel-600 alloy has been used as steam generator tube material for current pressurized water reactors (PWRs). The long-term operation of steam generators showed that the use of this material induced localized corrosion damages and increased tube wear of steam generator. To protect these problems, steam generator tube material is being changed to Inconel-690 alloy. Based on the current trend, we have chosen Inconel 690 as the Advanced Power Reactor 1400 (APR1400) steam generator(SG) tube material and performed the design optimization of preventive measure against tube fretting wear for the APR1400 steam generator. In this paper, we examined the technical consideration in this modification : the selection of material, wear characteristics, effect of the Egg-crate Flow Distribution Plate installation, and effect analysis of vertical strip installation.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.5
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• pp.163-169
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• 2003

Modeling of engine-generator system and its control responses are investigated using high performance generator controller. The nonlinear engine is modeled using mean torque production model based on experimental engine map. In case of diesel engine. the amount of injected fief is decided by engine controller depending on the APS(Acceleration Position Sensor) value. An electromechanical generator model contains electrical circuits and moment of inertia. The generator controller maximizes the performance of generator using decoupling and linearized current feedback control. The generator control system consists of 3-phase IGBT inverter and controller board based on 32 bit floating point DSP. Field oriented control algorithm with digital current feedback control at 10kHz sampling enabled high performance torque and speed control of induction machine. Not only the steady state but also the transient state responses can be evaluated through a batch test of the engine generator system. Developed engine and generator modeling and control can be utilized in various applications such as Series Hybrid Electric Vehicle(SHEV), engine-generator for emergency, and other hybrid generation systems.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.2
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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.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.43.1-43.1
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• 2011

The detail simulation modeling of fully-fed induction generator is investigated through PC based MATLAB/Simulink environment. Generator's stator currents are controlled by indirect vector control method. In this method, generator side converter controls the maximum excitation (air gap flux) by stator d-axis current and controls generator torque by stator q-axis current. Induction generator speed is controlled by tip speed ratio (TSR) upon the wind speed variations in order to generate the maximum output power. The generator torque model is specified as a 3-blade wind turbine with rating, then, the model is simulated under normal operating condition and three different fault conditions. The matlab model designed for fully-fed induction generator based wind farm provides good performance under normal and grid fault conditions. It provides good results for different pwm techniques and fault conditions except the single-phase line to ground fault, which should be verified with real time data from wind farms.

• Journal of Power System Engineering
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• v.16 no.1
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• pp.19-23
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• 2012

This thesis is the result of conducting an analysis to find the solution to the phenomenon of power stoppage due to the disconnection of a CT (Current Transformer) because of vibration. The CT which measures the most essential current is used in power industries as part of a generator protection relay. When it comes to the bottom plate of a CT, nonconductor; such as bakelite and laminates; these material elements should be used because it is impossible to utilize the conductor when measuring the current of a generator which carries a high current if you use other materials. These nonconductor's material properties are irregular and interpretation errors often occur because the weight is light. In addition, since the change of dynamic characteristics which are related to the temperature often occur, it is important to match the real situation by considering an error of interpretation rather than selecting the quality of the material. Lastly, the conclusion that the study drew is that it is possible to avoid the resonance by utilizing three changes to the components to solve the problem concerning the high vibration which is caused by non-conductive objects. These changes are the most crucial points in this thesis: First, material changes to the Plate. Second, weight changes to the Coil. Third, thickness changes to the Plate.