• 한국ITS학회:학술대회논문집
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• 2008.11a
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• pp.181-184
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.589-590
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• 2010

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.4
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• pp.62-68
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• 2015

Subsynchronous Resonance is a condition where the electrical power systems composed of generator and transmission line exchange energy with mechanical turbine-generator system at the frequency of the combined below the subsynchronous frequency. Therefore, the frequency of power systems should be associated with the subsynchronous resonance. This paper describes subsynchronous resonance by flexible frequency operation. It focuses on the characteristics and behavior of subsynchronous resonance. The subsynchronous resonance is being conducted by real-time digital simulator and the IEEE benchmark model for subsynchronous resonance have been utilized for the test systems.

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.95-99
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• 2001

Frequency is the unique physical value for all the interconnected systems. Therefore. the load frequency control is in the responsibility of all members in the interconnection power unbalance in one of the interconnected system can cause the problems in others. In the following text a brief description and the role of frequency in an interconnected system will be presented. Following is the short description of the Balkan Interconnection (UCTE Second Synchronous Zone) with schematic diagram. A Power-Frequency (P-f) dynamic model of a control area wil1 be shown. Model gives the analytical solution for frequency change versus a time after outage of a generator in the power system. This model will be applied to the Balkan Interconnection and compared with numerical approach. Advantages and drawbacks of the analytical method will be discussed Purpose of using this model is to investigate if the pumps in reversible hydropower plant will be underfrequency shed after the outage of the biggest generator unit in the interconnection, according %o (n-1) security postulate.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1752-1758
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• 2015

This paper presents partial discharge localization in stator winding of generators using multi-conductor transmission line (MTL) and RLC ladder network models. The high-voltage (HV) winding of a 6kV/250kW generator has been modeled by MATLAB software. The simulation results of the MTL and the RLC ladder network models have been evaluated with the measurements results in the frequency domain by applying of the Pearson’s correlation coefficients. Two PD generated calibrator signals in kHz and MHz frequency range were injected into different points of generator winding and the signals simulated/measured at the both ends of the winding. For partial discharge localization in stator winding of generators is necessary to calculate the frequency spectrum of the PD current signals and then estimate the poles of the system from the calculated frequency spectrum. Finally, the location of PD can be estimated. This theory applied for the above generator and the simulation/measured results show the good correlation for PD Location for RLC ladder network and MTL models in the frequency range of kHz (10kHz<f<1MHz) and MHz (1MHz<f<5MHz) respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.997-999
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• 2013

In this paper, the frequency monitoring system for the small AC generator having two or more generator is designed and implemented to synchronize a voltage, phase and frequency for stable power supply. CT sensor is used to measure the amount of current flowing in the power line, and PT sensor is used to measure the amount of voltage across the power line. The experimental results show that the power frequency can be measured using the power frequency monitoring system developed in this paper. The frequency monitoring system proposed in this paper will be able to control the power generation system using two or more small generator efficiently.

• Journal of Power Electronics
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• v.16 no.3
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• pp.1176-1189
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• 2016

In this paper, a novel quasi-direct power control (Q-DPC) scheme based on a resonant frequency adaptive proportional-resonant (PR) current controller with a variable frequency resonant phase locked loop (RPLL) is proposed, which can achieve a fast power response with a unity power factor. It can also adapt to variations of the generator frequency in T-type Three-level shaft synchronous generator (SSG) converters. The PR controller under the static α-β frame is designed to track ac signals and to avert the strong cross coupling under the rotating d-q frame. The fundamental frequency can be precisely acquired by a RPLL from the generator terminal voltage which is distorted by harmonics. Thus, the resonant frequency of the PR controller can be confirmed exactly with optimized performance. Based on an instantaneous power balance, the load power feed-forward is added to the power command to improve the anti-disturbance performance of the dc-link. Simulations based on MATLAB/Simulink and experimental results obtained from a 75kW prototype validate the correctness and effectiveness of the proposed control scheme.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_3
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• pp.1155-1163
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• 2022

This study proposes a technology to ensure the seismic stability of a 1,000 kW diesel engine-type emergency generator by applying a seismic isolated bed system. The technology allows the static analysis by making the first natural frequency of the installed entire emergency generator larger than the earthquake cutoff frequency of 33 Hz. First a three dimensional model for the generator was made with simplification for mode analysis. A new bed system with springs, shock absorbers, stoppers was then devised. Next, The mode analysis for the finite element model equipped by the bed system was performed. the 1^st natural frequency above 33 Hz, the seismic safety cutoff frequency, was calculated to be 152.92 Hz. Finally, based on the seismic stability theory, the von-Mises equivalent stresses derived by structural analysis under the Upset and Faulted conditions were 0.01603 Mpa, and 32.06 Mpa, respectively. so seismic stability was confirmed.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.580-582
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• 2008

The object of this paper is develope the PC based controlled high voltage power supply and studies 1.2kW(120kV, 10mA) pulse power X-ray generator possible to adapt fluoroscopy of Dental CT X-ray generator and industrial X-ray pulse power equipment. The developed pulse power X-ray generator consisted of mono-block tank include X-ray tube and high voltage X-ray power supply circuit and high voltage control unit with RS232C/422 communication port. The PC control program of pulse power X-ray generator uses LabVIEW, and the size of high voltage transformer and high voltage generator is minimized by high voltage high frequency inverter has 100kHz switching frequency. Also this paper shows result of X-ray tube voltage and tube current correspond to variable load.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.10
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• pp.1399-1411
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• 2012

The grid frequency is controlled cooperatively by the governor of the Turbine-Generator and the automatic generation controller(AGC) of the KPX(Korea Power Exchange). It is a basic requirement that the reliability of the governor is verified to enhance the power system stability but it is not easy to confirm the response characteristics of the governor because all generators are operated in the grid system that has the constant voltage and frequency. Therefore, it is necessary to study a new test method in order to examine the governor dynamic characteristic in the similar fault conditions. A study has shown that it is verified to simulate the turbine-generator power control system, the governor response characteristic under limited conditions and contribution of AGC with the gas turbine generator simulation model as well as demonstrate the dynamic response of the governor with the developed governor dynamic characteristic tester based on digital controller while the turbine-generator is connected to the grid system. This tester is constructed by the built-in functions of the turbine-generator main controller. In this treatise, the theoretical background, development method and the results of both simulations and demonstrations are described as another way to verify the turbine-generator governor dynamic characteristics.