• 한국초전도ㆍ저온공학회논문지
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• 제19권4호
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• pp.40-44
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• 2017

This paper analyzed the fault current limiting characteristics of the previously proposed transformer superconducting fault current limiter (TSFCL) interruption system according to its transformer type. The TSFCL interruption system is an interruption technology that combines a TSFCL, which uses a transformer and a superconductor, and a mechanical DC circuit breaker. This technology first limits the fault current using the inductance of the transformer winding and the quench characteristics of the superconductor. The limited fault current is then interrupted by a mechanical DC circuit breaker. The magnitude of the limited fault current can be controlled by the quench resistance of the superconductor in the TSFCL and the turns ratio of the transformer. When the fault current is controlled using a superconductor, additional costs are incurred due to the cooling vessel and the length of the superconductor. When the fault current is controlled using step-up and step-down transformers, however, it is possible to control the fault current more economically than using the superconductor. The TSFCL interruption system was designed using PSCAD/EMTDC-based analysis software, and the fault current limiting characteristics according to the type of the transformer were analyzed. The turns ratios of the step-up and step-down transformers were set to 1:2 and 2:1. The results were compared with those of a transformer with a 1:1 turns ratio.

• Journal of Electrical Engineering and Technology
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• 제12권6호
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• pp.2146-2156
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• 2017

When a failure occurs in active distribution system, it will be isolated through the action of circuit breakers and sectionalizing switches. As a result, the network might be divided into several connected components, in which distributed generations could supply power for customers. Aimed at decreasing customer interruption cost, this paper proposes a theoretically optimal island partition model for such connected components, and a simplified but more practical model is also derived. The model aims to calculate a dynamic island partition schedule during the failure recovery time period, instead of a static islanding status. Fluctuation and stochastic characteristics of the renewable distributed generations and loads are considered, and the interruption cost functions of the loads are fitted. To solve the optimization model, a heuristic search algorithm based on the hill climbing method is proposed. The effectiveness of the proposed model and algorithm is evaluated by comparing with an existing static island partitioning model and intelligent algorithms, respectively.

• 전기학회논문지P
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• 제63권3호
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• pp.163-168
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• 2014

In this paper, when photovoltaic systems are connected to distribution system, most effective capacity and location of PV system are studied considering customer interruption costs of power distribution system. The reliability model of PV system considering the duration of sunshine, the model of time-varying load and Roy Billinton test system (bus2 model) are used. To simulate the effects of PV system, various cases are selected; (1) base case which is no connection of PV system to power distribution system when faults are occurred, (2) 3MW case which is 3[MW] connection of PV system (3) 4[MW] case, and (4) 20[MW] case which is 20[MW] connection of PV system to the bus of power distribution system. The capacity limit of connected PV system is settled to 14[MW] for all cases except case 4. The reliability and customer interruption costs for residential, general, industrial, and educational customer is evaluated.

• 조명전기설비학회논문지
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• 제21권8호
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• pp.81-86
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• 2007

본 연구에서는 현 직접부하제어사업의 실태 및 문제점을 도출하고 국내 실정에 맞는 직접부하제어 활용 및 개선을 위하여 직접부하제어 사업 계약자를 대상으로 제도 개선사항, 지원금액 개선사항 및 제도 실시 등에 대한 설문조사를 하였다. 대표적으로 개선되어야 할 방안으로는 직접부하제어사업 참여 업체 증가를 위하여 기본지원금 및 제어지원금의 검토 방안과 소비자의 의견을 반영한 수요측 입찰 실시 방안이 필요하며, 시장운영과 계통운영에 있어서 페널티, 차단시간, 차단 횟수, 통보시간, 계약기간 등에 대한 기준을 정립할 필요가 있음을 확인하였다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권11호
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• pp.519-526
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• 2005

This paper presents computer simulation results for developing new type of SF$_{6}$ Circuit Breaker in terms of cold gas flow after small current interruption. This cold gas flows down a nozzle into the chamber of a circuit breaker. There are many difficult problems in analyzing the gas flow due to complex geometry, moving boundary, shock wave and so on. When predicting the dielectric capability of a gas circuit breaker after interruption, the gas pressure and density distributions due to the cold gas must be considered in addition to the electrical field imposed across the gas. A self-coded computational fluid dynamics (CFD) program is used for the simulation of cold gas flow in order to evaluate the electrical field characteristic across open contacts and transient characteristics of insulations after small current interruption.

• 가정과삶의질연구
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• 제29권1호
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• pp.21-40
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• 2011

This research is intended to find out the causes of the career interruption of highly-educated housewives, their experiences of caring for their children after career interruption, their psychological conflicts and coping strategies, and their attitudes toward reemployment. The participants were university-graduated housewives in their thirties who have pre-school children older than 2 years. The participants in this research consisted of twenty-nine participants. The essence of this study is the belief system that career and maternal roles are not compatible. Specifically, the participants possessed a certain motherhood ideology, so they gave up working in order to care for their children, deferring their careers for a while. The participants had ambivalent feelings about working mothers, and described their children by highlighting their negative aspects. Additionally, the participants experienced persistent conflicts about developing their careers and caring for their children during their period of career interruption. The participants seemed to possess a vague sense of hope about their careers, and their attitudes toward their careers were ambiguous in the past, present, and even in the future.

• 전기학회논문지
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• 제67권9호
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• pp.1159-1164
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• 2018

Vacuum circuit breakers(VCB) are widely used for current interruption of high-voltage inductive loads such as induction motors. This VCB can be chopped off before the current zero due to its high arc-extinguishing capability. One of the outstanding features of VCB is that it can cut off high frequency re-ignition current more than other circuit breakers. If the transient recovery voltage generated in the arc extinguishing is higher than the dielectric strength of the circuit breaker, a re-ignition phenomenon occurs. The surge voltage of the re-ignition is very high in magnitude and the steepness of the waveform is so severe that it can act as a high electrical stress on the winding. If the high frequency current of one phase affects the other two phases when the re-ignition occurs, it may cause a high surge voltage due to the virtual current chopping. If the magnitude of the voltage allowed in the motor winding is high or the waveform level is too severe, it may lead to insulation breakdown. Therefore, it is necessary to reduce the voltage to within a certain range. In this study, we briefly explain the various phenomena at the time of interruption, analyzed the magnitude of the dielectric strength and the transient recovery voltage at the simultaneous three-phase interruption that can give the greatest influence to the inductive load, proposed a method to reduce the impact.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2006년도 춘계학술대회 논문집
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• pp.365-369
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• 2006

It is concentrated on a methodology to establish a scheme of investment on power distribution systems of components. This paper provides a methodology to estimate the scheme as using a customer interruption cost regarding reliability indices in power distribution systems. The proposed method basically uses the failure rate depending on time for explaining the deterioration of a component. Therefore, the theory of the sensitivity is used for deciding the precedence of the investment to consider an effect of each component's failure rate on the system reliability. After Estimating the sensitivity on component investment cost making incremental reliability level is produced by component's investment cost accumulated according to the precedence of the sensitivity. After that, the failure rate corresponding with reliability level on the curve of investment cost is used as producing the curve of customer interruption cost. Two curves have the crossing point that is proposed to acceptable reliability level for customer and utility. In this paper, the acceptable reliability level for customer with the utility is assessed to analyze customer interruption cost and sensitivity of reliability indices. In conclusion the result of investment based on this method is shown to the reliability level with two cost.

• 자원리싸이클링
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• 제30권5호
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• pp.3-9
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• 2021

우리나라에서 연, 아연, 동, 주석, 니켈, 알루미늄 등의 베이스메탈의 수급구조는 양극화된 특성을 지니고 있다. 연, 아연, 동 등은 국내에 세계적 규모의 생산기업이 있는 반면, 주석, 니켈, 알루미늄 등은 국내 생산기업이 전무하거나, 생산량이 미비하여 내수량의 대부분을 수입에 의존하고 있다. 따라서 베이스메탈의 수입중단 또는 국내생산기업의 생산 중단 등의 공급중단에 따른 리스크에 대한 대비가 필요하다. 본 연구에서는 베이스메탈 6종(구리, 연, 아연, 알루미늄, 니켈, 주석)을 대상으로 수입중단 리스크 발생 시 대응이 필요한 물량과 시장이 대응할 수 있는 물량, 정부가 대응해야 하는 물량(전략비축)을 정량화하였다.

• 조명전기설비학회논문지
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• 제23권4호
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• pp.47-55
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• 2009

본 논문에서는 해석적방법론에 의한 산업용 수용가의 공급지장비를 산정할 수 있는 방법론을 개발하기 위해 산업용 수용가 1,026호를 방문하여 설문조사를 수행하는 미시적 접근법을 사용하여 산업용 수용가의 종별 공급지장비를 표준산업분류에 의한 18개의 업종으로 조사하였다. 얻어진 조사결과를 계층화의사 결정법(AHP; Analytic Hierarchy Process)으로 최적의 공급지장비용 함수(SCDF; Sector Customer Demage Function)를 선정하였다. 이를 통하여 배전계통에서의 신뢰도 가치평가(VBDRA; Value Based Distribution Reliability Assessment)를 위해서 주어진 배전계통 예상 공급지장에너지(EENS; Expected Energy Not Supply), 정전비용기대치(ECOST; Expected Interruption Cost), 차단에너지비율(IEAR; Interrupted Energy Assessment Rate)을 계산하여 그 가치를 평가하였다. 이를 배전계통에 적용하기 위해서 사례연구로 적용하고 공급지장비용을 도출하여 그 특성을 분석하였다.