• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.345-346
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• 2015

In this paper, we study the generator capability curve about the relay coordination on the basis of generator protection and control developed by NERC.

• Journal of Electrical Engineering and Technology
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• v.5 no.3
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• pp.371-378
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• 2010

Most modern wind turbines employ a doubly-fed induction generator (DFIG) system due to its many advantages, such as variable speed operation, relatively high efficiency, and small converter size. The DFIG system uses a wound rotor induction machine so that the magnetizing current of the generator can be fed from both the stator and the rotor. We propose a protection algorithm for a DFIG based on a d-q equivalent circuit in the time domain. In the DFIG, the voltages and currents of the rotor side and the stator side are available. The proposed algorithm estimates the instantaneous induced voltages of magnetizing inductance using those voltages and currents from both the stator and the rotor sides. If the difference between the two estimated induced voltages exceeds the threshold, the proposed algorithm detects an internal fault. The performance of the proposed algorithm is verified under various operating and fault conditions using a PSCAD/EMTDC simulator.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.12
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• pp.2173-2178
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• 2008

A doubly-fed induction generator(DFIG) system has been widely used in the modem wind turbines due to variable-speed operation, high efficiency and small converter size. It is well known that an inter-turn fault of a generator is very difficult to be detected. The DFIG system uses a wound rotor induction machine so that the magnetizing current of the generator can be fed from both the stator and the rotor. This paper proposes a protection algorithm for a DFIG using the d-q equivalent circuit in the time domain. In the case of a DFIG, the voltages and currents of the rotor side as well as the voltages and currents of the stator are available. The proposed algorithm estimates the instantaneous(i.e., converted into the stationary frame) induced voltages from the rotor and the stator sides. If the difference between the two estimated induced voltages exceeds the threshold, the proposed algorithm detects the inter-turn fault. The algorithm can detect a inter-turn fault of a winding. The performance of the proposed algorithm is validated using a PSCAD/EMTDC simulator under inter-turn fault conditions and normal operating conditions such as an external fault and the change of the wind speed.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.1
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• pp.35-40
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• 2015

Generators are the most complex and expensive single element in a power system. The generator protection relays should to minimize damage during fault states and must be designed for maximum reliability. A conventional CDR(Current Differential Relaying) technique based on DFT(Discrete Fourier Transform) filter have the disadvantages that the time information can lead to loss in the process of converting the signal from the time domain to the frequency domain. A WT(Wavelet transform) and WT analysis is known that it is possible with the local analysis of the fault and transient signal. In this paper, to overcome the defects in the DFT process, an application of WT for fault detection of generator is presented. This paper describes an selection of mother Wavelet to detect faults of generator. Using collected data from the fault simulation with ATPdraw, we analyzed the several mother Wavelet through the course of MLD(multi-level decomposition) using MATLAB software. Finally, it can be seen that the proposed technique using detail coefficient of Daubechies level 2 which can be fault discriminant of generator.

• Journal of Electrical Engineering and Technology
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• v.6 no.4
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• pp.466-473
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• 2011

This paper proposes a protection algorithm for a wind turbine generator (WTG) in a large wind farm. To minimize the outage section, a protection relay for a WTG should operate instantaneously for an internal fault or a connected feeder fault, whereas the relay should not operate for an internal fault of another WTG connected to the same feeder or an adjacent feeder fault. In addition, the relay should operate with a delay for an inter-tie fault or a grid fault. An internal fault of another WTG connected to the same feeder or an adjacent feeder fault, where the relay should not operate, is determined based on the magnitude of the positive sequence current. To differentiate an internal fault or a connected feeder fault from an inter-tie fault or a grid fault, the phase angle of the negative sequence current is used to distinguish a fault type. The magnitude of the positive sequence current is then used to decide either instantaneous operation or delayed operation. The performance of the proposed algorithm is verified under various fault conditions with EMTP-RV generated data. The results indicate that the algorithm can successfully distinguish instantaneous operation, delayed operation, or non-operation depending on fault positions and types.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.6
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• pp.415-423
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• 2018

We herein investigate the E1 pulse for evaluating the conducted performance of transmission lines connected to the electromagnetic pulse protection facilities against a conducted high-altitude electromagnetic pulse threat exposed to an external electromagnetic environment. The existing E1 pulse generator uses the Marx generator high-voltage step-up method; however, in this research, we used the Tesla transformer method to easily change the broadband output voltage(30 to 350 kV). We also analyzed the controller, power supply, high-voltage booster, and pulse-shaping device. The E1 pulse performance using the Tesla transformer was predicted through simulations and validated by measurements.

• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.75-77
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• 2007

Current percentage differential relaying has been recognized as the principal basis of main protection for stator windings of AC generator. The DWT has merit of obtaining frequency characteristics in time domain. In order to compensate for DFT's defects, we proposed fault detection algorithm using DWT. This paper describes a comparative analysis about conventional DFT-based DFR and advanced DWT-based relaying.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.522-524
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• 2000

The installation of small sized Embedded Generator(EG) in parallel with the utility supply was required several technical complications for protection of the system. One of the most important protection is to provide protection against islanding and out of synchronism reclosing with the utility source. This paper explains several current methods of detecting 'Loss Of Mains'(LOM). But they have not proved completely dependable, in particular when the islanded load's capacity matches that of the EG. A new loss of mains protection algorithm is presented in this paper which based on measurement of the reactive power and node voltage for detecting the islanding condition even though the EG operate in the capacity.

• Journal of Radiation Protection and Research
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• v.14 no.2
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• pp.1-9
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• 1989

An analytic method for quantitative comparisions between the alternatives for radiation protection optimization is required to aid the decision making process. This paper introduces the dynamic Markov model to evaluate the effect of inservice inspection, testing, and repair activities of the plant on radiation protection. In the example to put the Markov model into practice, the steam generator inspection intervals which minimize expected cost and total exposure dose were determined using the data for Kori-2 unit and foreign plants. The results show that the effect of the radiation exposure on the steam generator inspection interval is determined by the cost rather than the radiation exposure. The Markov model used in the example can be applied easily to the domestic NPPs by replenishing the data and also can be used in evaluating the comparative priority between various alternatives for radiation protection optimization.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.6
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• pp.897-902
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• 2011

This study incorporates a welder and a generator as needed while using the generator to be used as a welder is to configure the system. As such, in order to offer an integrated system to prevent the rapid charging process to manage the power state information, system configuration is the most important. Ideally, the random controls the flow of charge is ideal for that. When charging is good as long as possible, less current. However, In this study, the most ideal fusion welder and generator as required by the generator or welder can be used as a system is proposed. Specifically, the damage can be caused by carelessness, so short-circuit protection, overload protection, reverse polarity protection, automatic charging system is all about, including the ability to adjust.