• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.2
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• pp.97-104
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• 2004

As a device that returns surplus energy, regenerated from trains to d.c. source, to a.c. system and reuses it, the thyristor Inverter has been widely used. Because the conventional thyristor inverter is a unidirectional phase-controlled device, it Is Impossible to control the power factor of its output. Moreover, harmonics emission is high and it needs to take a additional filter. In this paper, to solve the problems stated above, the inverter, which can control real and reactive power by adopting IGBT modules as switching elements and being controlled by means of space vector PWM, is developed. Considering high economical efficiency and reliability in order to apply to the system for commercial use, the developed inverter is equipped with fully digital control system and low pass filter, and reduces harmonics and has compact size. The detail description about the developed inverter is stated in various respects: design criteria, technical description, power circuits, control techniques, the developed system, test results, etc.

• Journal of Korea Water Resources Association
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• v.34 no.6
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• pp.617-625
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• 2001

Peace dam constructed against the water attack had stopped in the first step, linked with Hwacheon dam through bypass tunnels and had an effect of flood surcharging in its pocket on Hwacheon dam downstream. To study the utility of Peace dam, the flood control effects of Peace dam and the restricted water level (RWL) in Hwacheon dam were reviewed and identified with operating Hwacheon dam system. Analysing the results the ideas of expanding the usability of the water resources in Hwacheon dam system were suggested. To do that, the criteria and the model of reservoir operation were established frist and the optimization of the operation have done. Based on the results the performance of the optimization was evaluated as an reference coefficient with relative value of the registered data to the optimized. And examining several alternatives for the RWL in Hwacheon reservoir operation made more feasible RWL suggested. And its economic benefit was also reckoned.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.236-236
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• 2016

현재 댐운영 계획 수립 시 매월 유지해야 하는 저수량의 범위를 나타낸 기준수위가 사용되고 있으며 매년 홍수기 말에 현재의 수문 상황과 장래의 전망을 통한 시기별 연간, 월간 댐운영 계획을 수립하고 있다. 물관리의 이수측면에서 댐수위 운영계획 수립과 홍수기 운영목표 수위를 결정하는데 활용하기 위해서는 계절단위, 연단위의 기상정보가 필요하다. 본 연구에서는 기상청에서 운영하고 제공하는 전지구 계절예측시스템 GloSea5(Global Seasonal forecasting system version 5)자료를 활용하여 금강유역에 적용하고자 하였다. GloSea5는 전지구계절예측시스템으로 대기(UM), 지면(JULES), 해양(NEMO), 해빙(CICE)모델이 서로 결합되어 하나의 시스템으로 구성되어 있으며 공간 수평해상도는 N216($0.83^{\circ}{\times}0.56^{\circ}$)으로 중위도에서 약60km이다. Hindcast자료는 유럽중기예보센터(ECMWF)에서 생산된 ERA-Interim 재분석장을 대기 모델의 초기장으로 사용하며 기간은 1996~2009년의 총 14년이다. 예보자료의 검증은 예보의 질을 결정하는 과정으로 Brier Skill Score (BSS), Reliability Diagrams, Relative Operating, Characteristics (ROC)등을 통해 정확성과 오차에 의한 예보의 성능을 검증하였다. 또한 Glosea5의 통계적 상세화를 수행하여 다양한 변수가 갖는 계통적인 지역 오차를 보정함으로써 자료의 신뢰도를 향상시키고자 하였으며 이는 이후 수문모델과의 연계 시 보다 정확하고 효율적인 댐운영에 활용할 수 있는 기후예측정보를 제공할 수 있을 것으로 판단된다.

• Journal of the Korean Institute of Gas
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• v.21 no.6
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• pp.23-29
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• 2017

Solar and wind energy among the renewable energy produce irregular power because resource is difficult to control. When connected to grid have unstable. However, when the fuel cell system is connected to grid more stable because regular frequency and output power based on controllable hydrogen energy. To using fuel cell system in the household, it is important that the safety performance of power conditioning system(PCS) and it is important that evaluation method of electromagnetic compatibility(EMC). In this study, we consider that introduce power-frequency magnetic field immunity test before analyzed that compare with the EMC of the international standards and KGS AB 934 PC53. Also, we conduct that actual assessment and study on available the quantitative analysis as using complementary indicator.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.587-593
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• 2021

Since 2017, a total of 29 fire accidents have occurred in energy storage systems (ESSs) as of June 2020. The common mode voltage (CMV) is one of the electrical hazards that is assumed to be a cause of those fire accidents. Several cases of CMV that violate the allowable insulation level of a battery section are being reported in actual ESS operation sites with △-Y winding connections. Thus, this paper evaluates the characteristics of CMV. An ESS site was modeled with an AC grid, PCS, and battery sections using PSCAD/EMTDC software. As a result of a simulation based on the proposed model, it was confirmed that characteristics of CMV vary significantly and are similar to actual measurements, depending on the grounding method of the internal transformer for PCS. The insulation level of the battery section may be severely degraded as the value of CMV exceeds the rated voltage in case of a grounding connection. It was found that the value of CMV dramatically declines when the internal transformer for PCS is operated as non-grounding connection, so it meets the standard insulation level.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.6
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• pp.584-591
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• 2000

Power Quality Compensator(PQC) has been installed to protect the sensitive loads against the voltage disturbances, such as voltage sag and interruption. In general, static switch is used for the purpose of link between utility and PQC. So transfer operation of the static switch play a important part in the PQC. Many studies on the structure and control of PQC have been progressed in active, but these researches have been rarely mentioned about any voltage-disturbances-detection method to start the PQC operation. In this paper, a new voltage-disturbances-detection algorithm for computer application loads using the CBEMA/ITIC curve is proposed for transfer operation of the static switch. The proposed detection algorithm is implemented to get fast detecting time through the comparison of instantaneous 3-phase voltage values transferred to DC values in the synchronous reference frame with the operating reference values. To get the robust characteristics against the noise, a first order digital filter is designed. The magnitude falling and phase delay caused by the filter are compensated through the error normalizing and numerical analysis using transfer function, respectively. Finally, the validity of the proposed algorithm is proved by ACSL simulation and experimental results.

• Journal of IKEEE
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• v.26 no.1
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• pp.1-9
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• 2022

In order to secure the reliability of the power system and to increase the penetration level of distributed energy resources (DERs), requirements such as IEEE 1547 have been revised to strengthen the grid connection standards for DER. This paper proposes a control scheme for smart inverter functions based on IEEE 1547-2018 that satisfy these standards, and introduces a power HILS-based test platform built for verification of smart inverter. Among the smart inverter functions, Volt-var and Frequency-watt allow the curve to be set from the upper level to comply with the interoperability and operation time of enable signals for each function are controlled by references from the upper level. According to the requirement, Volt-var and Frequency-watt are performed via power HILS platform and verified through the measurement results that all of the specified type tests were satisfied.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.381-381
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• 2021

영산강 유역은 타수계에 비해 농경지 비율이 높으며, 영산강 하류에는 나주평야 등 논농사를 하고 있어 농업용수 위주의 물이용율이 높다. 또한 4대호(광주호, 장성호, 담양호, 나주호) 이외의 대규모 다목적댐이 없어 수자원 확보에 어려움이 있다. 섬진강 유역은 유역변경으로 대부분 타수계로 물 공급이 이루어져 하천유량 부족, 섬진강 하류 생태계 피해로 물문제가 지속되고 있다. 이러한 물문제를 해결하기 위해 물관리 일원화에 따른 물이용, 수량, 수질 등을 모두 고려한 효율적인 통합 물관리 방안이 제시되고 있다. 통합 물관리를 위해 유역 내 수자원 이용현황과 물 문제해결 등을 고려한 용도별 최적 물이용 계획 및 효율적인 물관리 운영방안이 중요시되고 있다. 이를 위해서는 지역의 여건 및 특수사항을 고려한 장래 물공급량 변화 및 과부족량에 대해 분석하는 것이 필요하다. 이에 본연구에서는 대상지역인 영산강·섬진강 유역 특성 및 물공급체계를 파악하고 이를 반영한 물수지 분석체계를 구축하여 유역 내 수자원 현황을 파악하고자 한다. 본 연구에서는 실제 물이용체계를 반영하고 용수계통에 따라 자기유역 내 또는 타수계에 대해 용도별 수요량에 따른 공급량, 부족량을 산정하여 그 적용성을 평가하고자 한다. 이를위해 1) 하천수는 유수와 저수로 구분하고 유수는 하천 취수시설의 실사용량을 유역단위 수요량으로 추정, 저수는 다목적댐은 계약량, 농업용저수지는 필요공급량을 개별시설의 수요량으로 설정하여 각각의 수원(저수/유수)에 대한 수요량 대비 공급량과 부족량을 분석하였다. 2) 댐과 저수지는 용수공급조정기준에 따라 공급량을 탄력적으로 적용하고 농업용저수지는 가뭄등급에 따라 하천유지용수를 고려하였다. 3) 주암본댐과 섬진강댐은 송정 수위관측지점의 유량 상황에 따라 환경대응용수를 고려하였다. 4) 주안본댐과 주암조절지댐의 연계 운영을 고려하였다. 물수지 분석 결과 검증을 위해 주요 지점의 관측유량과 물수지 분석을 통해 계산된 유량을 비교하여 적용성 분석을 진행한 결과 상관관계가 높게 분석되었다. 본 연구 결과를 바탕으로 영산강·섬진강 유역 내 효율적인 물관리 방안 수립에 활용될 수 있을 것으로 판단된다.

• Journal of the Korean Association of Geographic Information Studies
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• v.21 no.2
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• pp.1-23
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• 2018

This study aims to propose a way for evaluating thermal environment vulnerability associated with policy to improve thermal environment. For this purpose, a variety of indices concerning thermal vulnerability assessment and adaptation policies for climate change applied to 17 Korean cities were reviewed and examined. Finally, 15 indices associated with policies for improving thermal environment were selected. The selected indices for thermal vulnerability assessment were applied to Daegu Metropolitan City of South Korea as a case study. As results, 15 vulnerability maps based on the standardized indices were established, and a comprehensive map with four grades of thermal vulnerability were established for Daegu Metropolitan City. As results, the area with the highest rated area in the first-grade(most vulnerable to heat) was Dong-gu, followed by Dalseo-gu and Buk-gu, and the highest area ratio of the first-grade regions was Ansim-1-dong in Dong-gu. Based on the standardized indices, the causes of the thermal environment vulnerability of Ansim-1-dong were accounted for the number of basic livelihood security recipients, the number of cardiovascular disease deaths, heat index, and Earth's surface temperature. To improve the thermal environment vulnerability of Ansim-1-dong, active policy implementation is required in expansion and maintenance of heat wave shelters, establishment of database for the population with diseases susceptible to high temperature environments, expansion of shade areas and so on. This study shows the applicability of the vulnerability assessment method linked with the policies and is expected to contribute to the strategic and effective establishment of thermal environment policies in urban master district plans.

• Journal of the Korean Society for Railway
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• v.19 no.5
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• pp.592-599
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• 2016

In the 21st yearly session of the Conference of the Parties (COP 21) of the 2015 United Nations Climate Change Conference, held in Paris, France, in December 2015, the "Paris Agreement" was negotiated; this is a new global agreement on the reduction of climate change, which encourages every country to participate in countermeasures for global climate change. Along with such movements, the electric railway sector has also been actively engaged in low carbon technology. This paper studied the building of a 1.5MW photovoltaic power generation system using the rooftop of the Gwangmyeong Station Building, which is the largest roof among the high-speed railway station buildings in Korea; this station has passenger traffic that reached about 7 million in 2014. For this study, we configured an optimized photovoltaic (PV) power generation system and then estimated the expected annual energy production by using PV system software; we also calculated the expected revenue that could be obtained by linking this source to the power distribution system. The obtained data were used to analyze the contribution of low-carbon energy that could be obtained by introducing a PV power generation system on the roof of an electric railway station building.