• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.7
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• pp.645-649
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• 2007

Partial discharge(PD) test for simulated insulation defects of used hydro generator stator winding was conducted to analyze the PD Parameters. Simulated insulation defects are classified by 5 types corona, slot, internal, multi and aging defect. Phase resolved partial discharge, statistical parameter (skewness, kurtosis), PD magnitude as a function of the test voltage(Q-V curve) and PD magnitude change under test voltage for 2 minutes are used as PD parameters. The analysis of PD parameters by 4 types are proved to be useful methods. In particular, PD parameter characteristics of aging defect could help to assess the aging condition of stator winding because aging defect has more weak insulation strength than other insulation defects : PD distribution is wide and flat, PD rises rapidly near $0^{\circ}\;and\;180^{\circ}$ and Q-V curve rises sharply and then gently drops.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.9
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• pp.17-24
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• 2008

Recently, the importance of supplying the reliable electric power is increasing. therefore, the importance of diagnosis of power equipments is increasing also. Breaking insulation of stator windings is major cause of faults in high voltage generators. On-line PD (Partial Discharge) detection using Capacitive Coupler at stator windings is used widely to diagnose high voltage generator. However, precise PD(Partial Discharge) detection is impossible if detected signals are mixed with PD and noise signal. In this paper, we analyze detected signals using Capacitive Coupler at 13[kV] hydroelectric generator stator winding and suggest not hardware method but noise elimination algorithm for detecting PD of generator stator winding considering relation of periphery signals.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.5
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• pp.97-107
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• 2001

Many power plants in the thermal and hydraulic utilities, the pulp and the paper industry are faced with high maintenance and down time due to the aged excitation system. For the life extension of the aged power plants, the static excitation system of triple module redundancy type had been developed by KEPRI(Korea Electric Power Research Institute). This paper will discuss the design conception and the application results of system which includes the power control devices(thyristors, GTO), power potential transformer(excitation transformer) and triple module redundancy controller(voltage regulator).

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.480-485
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• 2009

Offshore wind energy is gaining more attention. Ensuring proper design of offshore wind turbines and wind farms require knowledge of the external conditions in which the turbines and associated facilities are to operate. In this work, a three-bladed 5MW upwind wind turbine, which is supported by the monopile foundation, is studied by use of fully coupled aero-hydro-servo-elastic commercial simulation tool, 'GH-Bladed'$^{(R)}$. Specification of the structures are chosen from the OC3 (Offshore Code Comparison Collaboration) under "IEA Wind Annex XXIII-subtask2". The primary external conditions due to wind and waves are simulated. Design Load case 5.2 is investigated in this work. The steady state power curve and power production loads are evaluated. Comparison between different codes is made.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.579-582
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• 1989

The air-cooled waterwheel generator has a fan connected to waterwheel shaft or motor driven fan or fans. The fans are operated at constant speed, constant input, regardless of generator loss which is varied according to generator output and coolant the perature. Energy savings may he possible if the cooling air flow is controlled according to generato output and air temperature depending on season. The simulation and experience have been done on the 22.6 KVA Waterwheel generator by using AC variable speed drive. The results gave us los cut of generator.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.194-196
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• 1989

The production costing plays a key role in power system expansion and operations planning especially for the calculation of expected energy, loss of load probability and unserved energy. Therefore, it is crucial to develope a probabilistic production costing algorithm which gives sufficiently precise results within a reasonable computational time. In this respect, a number of methods of solving production simulation have been proposed. In previous paper we proposed the method used Fast Hartley Transform in convolution process with considering only the thermal units. In this paper, the method considering the scheduling of pumped-storage plants and hydro plants with energy constraints is proposed.

• Journal of the Korean Solar Energy Society
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• v.29 no.5
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• pp.73-80
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• 2009

A tidal current turbine is designed and analyzed numerically by using blade element momentum theory. The rated power has a limitation because the diameter of the tidal current turbine cannot exceed the depth of sea water. This study investigates a horizontal axis tidal-current turbine with a rated power of 500 kW. NACA-6 series laminar foil shape is used for basic airfoil along the blade span. The distributions of chord length and twist angle along the blade span are obtained from the hydrodynamic optimization procedure. Prandtl's tip loss correction and angle of attack correction considering the three-dimensional effect are applied for this study. The power coefficient curve shows maximum peak at the rated tip speed ratio of 6.0, and the maximum torque coefficient is developed at the tip speed ratio of 4. The drag coefficient reaches about 0.85 at the design tip speed ratio.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1769-1773
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• 1996

The remaining life of generator stator winding has been the controversial issue amomg many experts in this area. The report from Japan claims that they can predict the remaining life of generator winding, while the North American has the negative opinion about it. This study aimed at verifying the validity of both Japanese criteria and North American argument on evaluation of generator winding insulation. Non destructive and destructive tests were performed on two hydro-generators. The test results showed that the trend analysis of stator winding insulation was the better option.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.2
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• pp.74-80
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• 2014

Generator protection device has to detects an internal fault conditions in generator and abnormal operating conditions must be due to the hazards. Loss of excitation may cause generator itself failure as well as serious operating problem in power system, and then requires an appropriate response of generator protection device. Details modeling of generator control system and analysis of transient states in generator are important for optimal operation in power plants. In addition, the fault simulation data are also used for testing the characteristics of IED. In this paper, the hydro generator control system using PSCAD/EMTDC, visual simulation for power systems, was modeled. The generator control system which is composed of generator, turbine, exciter, governor was implemented. The parameters of generator control system model were obtained from field power plant. Loss of excitation simulations were performed while varying the fixed load. Several signals analysis were also performed so as to analyze transients phenomena.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.2
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• pp.294-300
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• 1996

In hydro-generator, a groundwall insulation of stator windings gradually deteriorates due to mechanical, thermal, electrical and environmental stresses. These stresses combine to result in loose windings, delamination of the stator insulation and/or electrical tracking of the endwinding, all of which can lead to stator insulation failures. Conventionally, off-line tests such as partial discharge measurement, DC/AC current and .DELTA.tan.delta. tests has been used for estimation of winding condition. However, off-line test requires large power supply and generator outage. In addition, major cause of insulation problems such as loose wedges and slot dischages may not be found with off-line diagnoses. This paper introduces the on-line partial discharge measurement techniques using frequency spectrum analyzer(FSA) for the generator stator windings. The experimental results from the UIAM #1 hydro-generator confirms a optimistic application of on-line generator diagnosis method as a reliable tool for evaluation of winding condition.