• 조명전기설비학회논문지
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• 제17권3호
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• pp.127-137
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• 2003

논문에서는 대규모 계통의 미소신호안전도 평가 및 해석을 위해 고유치 감도/perturbation 이론에 근거한 상정사고 지표를 제안하였으며 이를 실제 계통에 적용한 결과를 기술하였다. 선로정수와 제어기점수에 대한 미소신호 안정도 상정사고 지표를 제시하였고 이로부터 심각한 저주파진동 문제를 발생할 수 있는 파라메타들을 선택하였다. 또한 각 발전기의 발전량 증감에 대한 고유치 변화로부터 미소신호안정도 상정사고를 일으킬 수 있는 발전기들을 선택하였다. 이 논문에서는 모든 결과들을 2000년 KEPCO 실계통의 시간영역해석과 비교 검증하여 제안한 미소신호안정도 상정사고 해석법이 정확함을 확인하였다.

• 전기학회논문지
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• 제63권1호
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• pp.1-9
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• 2014

The parameters of electromechanical modes offer considerable insight into the dynamic stability properties of a power system. This paper describes an initial result for extraction of dynamic parameters from synchrophasor measurements collected on the KEPCO system. Dominant modes of the system are estimated by oscillation detecting program in K-WAMS. The critical wide-area modes of KEPCO system have frequencies in the 0.4 to 0.7Hz range. And the local mode causing the low frequency oscillation of generators located on the west coast area has in the frequency 0.97 and 1.25 Hz, respectively. This results can serve as a reference in the future for reliable system operation in KEPCO system.

• Nuclear Engineering and Technology
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• 제54권6호
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• pp.2147-2155
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• 2022

Nuclear safety-related underground liquid storage tanks, such as those used to store fuel for emergency diesel generators, are critical components for safety of hundreds of existing nuclear power plants (NPP) worldwide. Since most of those NPP will continue to operate for decades, a beyond design base (BDB) seismic screening of safety-related underground tanks in those NPP is beneficial and essential to public safety. The analytical methodology for buried tank subjected to seismic effect, including a BDB seismic evaluation, needs to consider both soil-structure and fluid-structure interaction effects. Comprehensive analysis of such a soil-structure-fluid system is costly and time consuming, often subjected to availability of state-of-art finite element tools. Simple, but practically and reasonably accurate techniques for seismic evaluation of underground liquid storage tanks have not been established. In this study, a mechanics based solution is proposed for the evaluation of a cylindrical underground liquid storage tank using hand calculation methods. For validation, a practical example of two underground diesel fuel tanks in an existing nuclear power plant is presented and application of the proposed method is confirmed by using published results of the computer-aided System for Analysis of Soil Structural Interaction (SASSI). The proposed approach provides an easy to use tool for BDB seismic assessment prior to making decision of applying more costly technique by owner of the nuclear facility.

• Nuclear Engineering and Technology
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• 제24권2호
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• pp.154-162
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• 1992

원전 증기발생기 2차측 화학세정시 두가지 주요 목표는 슬러지 제거를 효과적으로 하는 것과 모재금속의 부식을 최소화하는데 있다. 본 연구에서는 전기화학 실험과 슬러지 용해 실험을 통하여 제동공정 중에 어떤 인자들이 중요한 역할을 하는지 확인하고 외국에서 개발된 두가지 제동공정에 대하여 안전성 측면과 슬러지 제거 효과를 비교. 평가하고자 하였다. 38$^{\circ}C$에서 EDTA, NH$_4$OH. EDA를 사용하는 제동공정에 있어서 $H_2O$$_2$는 구리슬러지 제거에 적합한 전위구역으로 구리의 전위를 높여주는데 매우 효과적이었다. 이런 전위구역에서 SA 285 Grade C와 Alloy 600 재료의 부식속도는 매우 작았다. 그러나 전위가 -450 mV 이하로 유지될 때 SA 285 Grade C 재료의 부식속도 증가가 예상된다. 6$0^{\circ}C$에서 EDA, (NH$_4$)$_2$CO$_3$를 사용하는 공정은 구리의 부식전위가 -200 mV이상으로 유지될 때 효과적인 제동이 가능하였으나 전위를 공기주입과 용액교반으로 이 구역으로 올리기는 매우 어려웠다.

• 한국산학기술학회논문지
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• 제20권9호
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• pp.541-550
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• 2019

소방용 비상발전기는 화재 시 인명과 재산을 보호하는 소방 시설에 전원을 공급하는 중요한 설비이다. 이러한 중요성에 따라 관련 법규에서는 의무적으로 비상발전기에 비상용 부하를 연결하여 시험하도록 규정하고 있다. 그러나 실 계통에서는 비상전원계통의 부하운전 시험을 위해 상용 전원을 차단하는 경우 저압기기의 파손, 병원과 같은 중요시설의 응급부하 정지 등 심각한 문제점이 발생할 수 있어, 무부하로 비상발전기를 형식적으로 시험하고 있는 실정이다. 따라서, 본 논문에서는 상기의 문제점을 개선하기 위하여, 상용 전원의 차단 없이 비상발전기에 전기저장장치를 연계하여, 비상용부하의 동작특성과 동일하게 ESS가 충전동작을 수행함으로서 비상발전기의 성능 및 상태를 시험할 수 있는 방안을 제시한다. 또한, 배전계통 상용 해석 프로그램인 PSCAD/EMTDC를 이용하여, 비상발전기, 비상용부하, ESS 부하시험장치로 구성된 비상전원계통의 모델링을 제시하고, 20kW급 ESS 부하시험장치를 구현하여, 이를 바탕으로 다양한 시나리오에 따른 시뮬레이션과 시험을 수행하여 본 논문에서 제안한 ESS 부하시험 장치와 모델링의 유용성을 확인한다.

• 대한기계학회논문집
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• 제15권6호
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• pp.1948-1966
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• 1991

본 연구에서는 2상 횡유동을 받는 튜브군의 진동 메카니즘을 규명하기 위한 실험계획의 일환으로 실시된 실험으로부터 튜브군의 유체탄성 불안정성 상수에 관해 고찰하였다. 실험은 먼저 p/d=1.47 및 1.32 튜브군에 대해 수행되었는데, 이들 튜브 군의 결과는 참고문헌에 발표하였다. 본 논문은 후속 실험으로 수행된 p/d=1.22인 튜브군을 사용하여 유체탄성 불안정성 상수를 고찰한 참고문헌의 후속논문이다. 실 험은 액체상태로 부터 99% 보이드율(void fraction)까지 변화된 2상 유동에서 튜브가 유체탄성 불안정성 상태에 도달할 때까지 점진적으로 증가하였다.실험결과는 p/d= 1.32 alc 1.47 튜브군의 유체탄성 불안정성 결과들과 종합. 비교되었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.941-945
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• 2006

In the development of electricity generating wind turbines for wind farm application, only two types have survived as the methods of power regulation; stall regulation and fun span pitch control. The sound measurement procedures of IEC 61400-11 are applied to field test and evaluation of noise emission from each of 1.5 MW and 660 kW wind turbine generators (WTG) utilizing the stall regulation and the pitch control for the power regulation, respectively. Apparent sound power level, wind speed dependence and third-octave band levels are evaluated for both of WTGs. It is found that while 1.5 MW WTG using the stall control is found to emit lower sound power than 660 kW one using the pitch control at low wind speed (below 8 m/s), sound power from the former becomes greater than that of the latter in the higher wind speed. Equivalent continuous sound pressure levels (ECSPL) of the stall control type of WTG vary more widely with wind speed than those of the pitch control type of WTG These characteristics are believed to be strongly dependent on the basic difference of the airflow around the blade between the stall regulation and the pitch control types of WTG. These characteristics according to the methods of power regulation lead to the very different noise emission characteristics of WTG depending on the seasons because the average wind speed in summer is lower than the critical velocity over which the airflow on the suction side of blade in the stall types of WT are separated. These results propose that, in view of environmental noise regulation, the developer of wind farm should give enough considerations to the choice of power regulation of their WTG based on the weather conditions of potential wind farm locations.

• Smart Structures and Systems
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• 제6권3호
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• pp.183-196
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• 2010

Monitoring and economical design of alternative energy generators such as wind turbines is becoming increasingly critical; however acquisition of the dynamic output data can be a time-consuming and costly process. In recent years, low-cost wireless sensors have emerged as an enabling technology for structural monitoring applications. In this study, wireless sensor networks are installed in three operational turbines in order to demonstrate their efficacy in this unique operational environment. The objectives of the first installation are to verify that vibrational (acceleration) data can be collected and transmitted within a turbine tower and that it is comparable to data collected using a traditional tethered system. In the second instrumentation, the wireless network includes strain gauges at the base of the structure. Also, data is collected regarding the performance of the wireless communication channels within the tower. In both turbines, collected wireless sensor data is used for off-line, output-only modal analysis of the ambiently (wind) excited turbine towers. The final installation is on a turbine with embedded braking capabilities within the nacelle to generate an "impulse-like" load at the top of the tower. This ability to apply such a load improves the modal analysis results obtained in cases where ambient excitation fails to be sufficiently broad-band or white. The improved loading allows for computation of true mode shapes, a necessary precursor to many conditional monitoring techniques.

• Journal of Electrical Engineering and Technology
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• 제4권1호
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• pp.55-65
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• 2009

Due to the rapid increase of electricity demand, consideration of environmental constraints in optimal power flow (OPF) problems is increasingly important. In Algeria, up to 90% of electricity is produced by thermal generators (vapor, gas). In order to keep the emission of gaseous pollutants like sulfur dioxide (SO2) and Nitrogen (NO2) under the admissible ecological limits, many conventional and global optimization methods have been proposed to study the trade-off relation between fuel cost and emissions. This paper presents an efficient decomposed Parallel GA to solve the multi-objective environmental/economic dispatch problem. At the decomposed stage the length of the original chromosome is reduced successively and adapted to the topology of the new partition. Two subproblems are proposed: the first subproblem is related to the active power planning to minimize the total fuel cost, and the second subproblem is a reactive power planning design based in practical rules to make fine corrections to the voltage deviation and reactive power violation using a specified number of shunt dynamic compensators named Static Var Compensators (SVC). To validate the robustness of the proposed approach, the algorithm proposed was tested on the Algerian 59-bus network test and compared with conventional methods and with global optimization methods (GA, FGA, and ACO). The results show that the approach proposed can converge to the near solution and obtain a competitive solution at a critical situation and within a reasonable time.

• 전기학회논문지
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• 제66권7호
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• pp.1032-1038
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• 2017

Recently, regulation on carbon emissions has been strengthened according to the new climate change convention (COP21) held in Paris, and then Korea has decided to reduce CO2 emissions by 37% until 2030. As one of countermeasures, the government has energetically performed demonstration projects of island micro-grid including solar power, wind power and energy storage system. However, in order to smoothly introduce island micro-grid, it is a critical issue to carry out the economic evaluation for power utility aspect and independent power producer aspect. Therefore, this paper proposes economic evaluation algorithms of island micro-grid which are based on the present worth method, considering cost and benefit factors in the aspect of both sides. Firstly, in case of power utility this paper proposes algorithm to estimate a period of return on investment according to the introduction capacity of distributed generators replacing diesel generator. And also, in case of independent power producer, this paper proposes evaluation algorithm to estimate weighting factor of SMP and benefit rate based on break-even point related with cost and benefit. From a case study result on real island micro-grid model, it is confirmed that proposed algorithms are useful and practical for the economic evaluation of island micro-grid.