• 대한전기학회논문지:전력기술부문A
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• 제53권2호
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• pp.111-120
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• 2004

This paper presents an application of Unified Modeling Language(UML) software technique for developing transmission pricing evaluation package. Also, this paper describes a transmission pricing algorithm applicable to a large-scale power system. The usage-based transmission pricing mechanism is very complex since it requires power flow analysis, fault current analysis, sensitivity evaluation of a transmission line, penalty factors calculation, transmission asset databases, and cost allocation rules, etc. For the efficient and flexible development of the transmission pricing package, a UML. approach is applied, which is composed of a use-case diagram, interaction diagram, class diagram, and package diagram using Rational Rose Unified Process(RUP). The designed transmission pricing package can be efficiently modified and reused as the market environments evolves since it is designed by Object-Oriented Programming(OOP).

• KIEE International Transactions on Power Engineering
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• 제4A권3호
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• pp.141-145
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• 2004

FACTS devices, such as the Thyristor Controlled Series Compensator (TCSC) and Static Var Compensators (SVC), can help increase system load margin to improve static voltage stability. In power systems, because of the high cost and the effect value, the optimal placement for FACTS devices must be determined. This paper investigates the use of the series device (SVC) and the parallel device (TCSC) from the point of load margin to increase voltage stability. It considers the sensitivity of load margin to the line reactance and eigenvector of the collapse. The study has been carried out on the IEEE 14 Bus Test System to verify the validity and efficiency of the method. It reveals that incorporation of FACTS devices significantly enhance load margin as well as system stability.

• 전기학회논문지
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• 제66권11호
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• pp.1641-1646
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• 2017

This paper presents a fast method to identify an area of severity which is a network area leading to voltage sags at multiple sensitive load points, simultaneously. To assess voltage sag performance considering various sensitive loads, it is need to determine an area of severity for the load points. The area of severity can be calculated by overlapping areas of vulnerability for each sensitive load. However, as the number of sensitive loads increases, computational complexity and time for determining an area of severity are highly increased. In this paper, an efficient scheme based on line division is described. The proposed method is useful for identifying an area of severity and assessing voltage sag performance considering multiple loads together.

• 대한전기학회논문지
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• 제43권5호
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• pp.703-710
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• 1994

This paper describes for the applicability of optimal PID controller to the load frequency control of 2-area power systems. The proposed optimal PID controllers are designed by the optimization technique of P.I.D's gain coefficients using the relatively ingeneous simplex method, and we have considered the system sensitivity for the optimal gains and the stable effects of systems to speed regulation changes. This PID controller for load frequency control systems with exciter shows better performances and robustness than conventional tie-line bias controller.

• Nuclear Engineering and Technology
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• 제55권12호
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• pp.4628-4636
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• 2023

Cables are indispensable in nuclear power plants for transmitting data measured by various types of detectors, such as self-powered neutron detectors (SPNDs). These cables will generate disturbing signals that must be accurately distinguished and eliminated. Given that the cable current is not very significant, previous research has focused on SPND, with little attention paid to cable evaluation and validation. This paper specifically focuses on the quantitative analysis of cables and proposes a theoretical model to predict cable noise. In this model, the reaction characteristics between irradiated neutrons and cables were discussed thoroughly. Based on the Monte Carlo method, a comprehensive simulation approach of neutron sensitivity was introduced and long-term irradiation experiments in a heavy water reactor (HWR) were designed to verify this model. The theoretical results of this method agree quite well with the experimental measurements, proving that the model is reliable and exhibits excellent accuracy. The experimental data also show that the cable current accounts for approximately 0.2% of the total current at the initial moment, but as the detector gradually depletes, it will contribute more than 2%, making it a non-negligible proportion of the total signal current.

• 한국산학기술학회논문지
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• 제18권2호
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• pp.6-13
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• 2017

본 연구에서는 혼화기의 혼화성능과 압력손실을 개선하기 위해 오리피스의 형상과 개수에 따른 영향을 해석하였다. 물의 정수에서 중요한 과정은 물속의 이물질을 포집하는 응집 과정이고 응집제가 얼마나 물속에 고른 분포를 가지고 물속에 혼화되어 있는 지가 정수에 큰 영향을 미친다. 기계식 혼화방식이 갖는 정수과정에서의 긴 체류시간, 기계 소음, 과다한 에너지의 소비 및 높은 유지관리 비용 등의 단점을 보완하기 위해서 최근에는 응집제가 원수에 주입됨과 동시에 가능한 한 빠르게 수중에 확산시킬 수 있는 장치로서 관내혼화장치의 도입이 증가추세에 있다. 본 연구에서는 관내 혼화기의 혼화성능과 압력손실을 개선하기 위해 오리피스의 유무, 형상과 개수에 따른 약품의 체적분률, 관내 압력손실 등 유동특성과 체적분률이 수치해석에 의해 계산된다. 관내 혼화장치에 장착된 오리피스는 혼화정도를 향상시키나 압력손실이 증가되므로 오리피스의 개수를 제한하여야 한다. 주요 인자에 대한 민감도 분석을 통해 가이드 베인을 장착한 오리피스 1개를 사용하여 약품의 체적분률과 압력손실이 개선된 관내 혼화장치를 제안하였다.

• 전기학회논문지
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• 제59권4호
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• pp.728-732
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• 2010

GIS(Gas insulated switching gear) is power equipment with excellent dielectric strength and is economy merit in high confidence and stability. Recently, because equipment of GIS was occurring problem of confidence used for a long time, partial discharge on-line diagnosis systems have been importantly recognized. Partial discharge (PD) detection is an effective means for monitoring and evaluation of dielectric condition of gas insulated system (GIS). The ultra-high-frequency (UHF) PD detection technique can detect and locate the PD sources inside GIS by detecting electromagnetic wave emitted from PD source. Therefore, real-time diagnostic system using UHF detection method has been developed for this application is being expanded gradually. However, the signal of partial discharge occurring in SF6 gas is very weak and susceptible to external noises which mainly consist of PD in air. Thus, it is important to distinguish the PD in SF6 gas more sensitively from the external noises. Unfortunately, these external noise signals and the partial discharge signals have very similar characteristics. Therefore, to solve this problem, we need the signal processing method for distinguish partial discharge signals with external noise signals for improvement of SNR(signal to noise ratio) and sensitivity. In this paper, we proposed internal signal processing method for removing external noise signals with built-in pre.amplifier and frequency conversion circuit.

• 조명전기설비학회논문지
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• 제18권5호
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• pp.169-173
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• 2004

본 논문은 전력계통의 전압 안정도 제약 문제를 해결하는데 고온 초전도 케이블을 적용하기 위한 기법을 제시하였다. 대전력계통의 유효 송전용량은 종종 전압 안정도 제약에 의해 결정된다. 기존의 초전도 케이블 응용 연구는 주로 도심지역의 고밀도 전력 수송 문제를 해결하는 대안으로 연구의 초점을 두어왔지만, 고온 초전도 케이블의 선로정수 개선효과를 이용하면 전압 안정도로 제약된 계통의 송전용량을 증가시킬 수 있어 그 응용 범위가 확대될 수 있다. 전압 안정도에 의한 최대 수송전력을 결정하는 데는 IPLAN에 의한 P-V곡선을 이용하였고, 대체 대상선로는 부하 증가시 무효전력 손실감도가 가장 큰 선로로 하였다. 결과의 타당성을 검증하기 위해 IEEE 14모선 계통을 사용하였으며, 적용결과 Case II는 70[%], Case III에서는 160[%]의 추가 수송 능력 증가를 가져올 수 있었다.

• 동력기계공학회지
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• 제12권6호
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• pp.70-77
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• 2008

The purpose of this study is to compare the quality of digital radiography image with that of classical film images for welded structure in power plants. The CMOS(Complementary Metal Oxide Semiconductor) flat panel detecter and Agfa D5 film are used to image flaw specimens respectively. In the test, CMOS flat panel detector has been determined to have a better image than that of film image. In the IQI(Image Quality Indicator) transmission test, one or two more line can be seen in digital image than in film image. Digital Radiography Test enabled to successfully detect all defects on the weld specimens fabricated with real reheat stem pipe and boiler tube as well. In the specific comparison test, Digital radiography test detected micro flaws in the size of 0.5 mm in length by 0.5 mm in depth. However, film test has limited it to 1.0 mm in length by 1.0 mm in depth. As a result of this study, digital radiography technology is estimated well enough to perform the inspection in the industry with far more cost effective way, compared to the classical film test.

• 에너지공학
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• 제12권2호
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• pp.93-100
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• 2003

An estimation methodology of the mass and energy (M/E) release due to the main steam line break (MSLB) has been developed with the RETRAN-3D code. In the case of equipment qualification (EQ), the over-estimated temperature would exceed the design limits of some cables or valves. In order to have a more flexible EQ profiles from the MSLB M/E release, the methodology with the best-estimated code was used. The major conditions affecting the MSLB M/E were found to be the initial SG level, heat transfer between primary and secondary sides, power level, operable protection system, main or auxiliary feedwater availability, and break conditions. The RETRAN-3D models were developed for the Kori unit 1 (KRN-1) which is typical two loop Westinghouse (WH) designed plant. Particularly, a detailed model of the steam generators was developed to estimate a more realistic two-phase heat transfer effect of the steam flow. After the modeling, the methodology has been developed through the sensitivity analyses. The M/E release data generated from the analyses have been used as the input to the inside containment pressure and temperature (P/T) analysis. According to the results at the point of view containment P/T, the Kori unit 1 can have more margin of 5∼15 ㎪ in pressure and 8∼15$^{\circ}C$ in temperature.