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박철원(Chul-Won Park) 대한전기학회 2018 전기학회논문지 P Vol.67 No.3
Recently, LVDC distribution network and DC microgrid with many advantages are being built. However, this LVDC distribution is an IT grounded or ungrounded system, and it is difficult to detect a ground fault because the fault current is small. In this paper, we propose a signal injection method for unipolar LVDC distribution network to detect ground fault in ungrounded LVDC distribution, and various analyzes were performed for ground fault detection.
765㎸ 모델링 데이터에 의한 개선된 주파수 추정기법의 성능 평가
박철원(Chul-Won Park) 대한전기학회 2010 전기학회논문지 P Vol.59 No.3
The frequency is an important operation parameter for the control, protection, and stability of a power system. The frequency as a key index of power quality can be indicative of system abnormal conditions and disturbances. Due to the sudden change in generation and loads or faults in power system, the frequency is supposed to deviate from its nominal value. It is essential that the frequency must be maintained very close to its nominal frequency. An accurate monitoring of the power frequency is essential to optimal operation and prevention for wide area blackout. As most conventional frequency estimation schemes are based on DFT filter, it has been pointed out that the gain error could cause defects when the frequency is deviated from nominal value. This paper presents an advanced frequency estimation technique using gain compensation to improve the performance of DFT filter based techniques. To evaluate performance of the proposed algorithm, the 765㎸ T/L system in Korea is simulated by EMTP-RV software. The proposed technique can reduce the gain error caused when the power system frequency deviates from nominal value.
박철원(Chul-Won Park) 대한전기학회 2013 전기학회논문지 P Vol.62 No.1
Fault currents are expressed as a combination of harmonic components and exponentially decaying DC offset components, during the occurrence of fault in power system. The DC offset components are included, when the voltage phase angle of fault inception is closer to 0° or 180°. The digital protection relay should be detected quickly and accurately during the faults, despite of the distortions of relaying signal by these components. It is very important to implement the robust protection algorithm, that is not affected by DC offset and harmonic components, because most relaying algorithms extract the fundamental frequency component from distorted relaying signal. So, In order to high performance in relaying, advanced DC offset removal filter is required. In this paper, a new DC offset removal filter, which is no need to preset a time constant of power system and accurately estimate the DC offset components with one cycle of data, is proposed, and compared with the other filter. In order to verify performance of the filter, we used collecting the current signals after synchronous machine modeling by ATPDraw5.7p4 software. The results of simulation, the proposed DC offset removal filter do not need any prior information, the phase delay and gain error were not occurred.
통증 완화 치료기용 인체 부하 변동에 따른 피드백 제어가 가능한 고주파 회로 설계
박철원(Chul-Won Park),원철희(Chul-Hee Won) 대한전기학회 2013 전기학회논문지 P Vol.62 No.1
High frequency system has been used for the purpose of skin care and obesity treatment, by high-frequency energy is applied to the human body generates deep heat. Conventional high frequency system could not selection control by depending on the body load fluctuations. Such as burns and side effects have been reported by system instability and then therapeutic effect is insufficient. During treatment, objective information about the status of the patient was no. Because of treatment methods are subjective, and so tailored treatments were impossible. In this paper, high frequency medical system with sinusoidal frequency characteristics without distortion of the Push pull switching scheme for pain relief therapy was designed. And control circuit that was designed by feedback using the output changes according to the body-load fluctuation. Last, power circuit for efficient control the heat generated from the hardware was proposed.
Digital Generator Protection System의 성능 시험을 위한 발전기 사고모델링
박철원(Chul-Won Park),반우현(Woo-Hyeon Ban) 대한전기학회 2011 대한전기학회 학술대회 논문집 Vol.2011 No.11
최근 전원개발과 그 신뢰성 확보를 위하여 발전소 보호제어시스템에 대한 국산화의 필요성이 제기되었다. 이에 발전소 보호제어시스템의 효율적인 운용과 차세대 ECMS와 DGPS의 성능 시험을 위하여 발전기의 상세 모델링과 내부권선 사고 모의에 관한 연구가 선행되어야 한다. 본 연구에서는 현재 알려져 있는 여러 가지 발전기 사고모델링 기법을 소개하고 과도현상해석 도구인 ATPDraw 5.7p4 버전에 의한 CT 단자의 내부사고와 외부사고 모델링 방법을 자세히 기술한 후, 시뮬레이션을 수행하여 고장전류의 과도현상을 분석하였다.
박철원(Chul-Won Park),오용택(Yong-Taek Oh) 대한전기학회 2013 전기학회논문지 P Vol.62 No.3
Large generator of power plant is very important. In order to protect large generator from faults, digital protective relay or IED is required. However, all protective relays for generators of the domestic power plant are operated by foreign products. And now, for technological independence from foreign and improvement of import substitution effect, IEDs using domestic technology are being developed. To evaluate performance of developing next-generation power devices, the study of the dynamic characteristics of the power plant, generator system modeling, fault simulation and analysis, should be considered. Specially, To obtain IEEE Standards COMTRADE format for relay operation test, generator system modeling and fault simulation using PSCAD/EMTDC tools must be preceded. Until now, a complete modeling of generator internal windings and fault simulation techniques dose not exist. In this paper, for evaluation performance of relay elements of developing IED, the generator system modeling and various faults simulation using PSCAD/EMTDC tools were performed. And then, the various transient phenomena through obtained relaying signal of developed modeling were analyzed.