• 전기학회논문지
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• 제62권4호
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• pp.467-473
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• 2013

The addition of disconnect switches to a distribution feeder or the replacement of the manual switches with the automatic switches do, in general, increase reliability by decreasing the duration of the outage of many to the customers on the feeder and reducing the outage section. However, the improvement of reliability in power distribution system causes an increase of the investment cost, for example, replacement costs, labor costs, and so on. For this reason - the balance between investment and reliability improvement - many studies about the appropriate level of investment have been conducted. In this paper, we suggest the algorithm for determining the reasonable switch automation rate in the power distribution system. We evaluate the customer interruption cost and reliability for several cases - these cases relate with the switch automation rate - in the domestic metropolitan power distribution system, estimate the effectiveness of changing the manual switch to automatic switch quantitatively. These results can help the determining on the disconnect switch's automation rate.

• 한국통신학회논문지
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• 제35권12A호
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• pp.1198-1206
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• 2010

최근 스마트폰 및 타블릿 PC가 차세대 통신단말롤 급부상함에 따라 멀티미디어 서비스에 대한 사용자의 요구 또한 급격히 증가하였다. 기존의 통신네트워크사업자는 셀 용량의 증설을 위해 값이 저렴한 중계기의 도입을 적극 검토하고 있다. 그러나 중계기의 도입은 셀 내의 간섭을 심화시키고 이는 사용자 서비스 품질에 악영향을 미치며 서비스 불능(outage) 비율을 증가시키게 된다. 본 논문에서는 중계기를 사용하는 다중흡 셀룰러 네트워크에서 OFDMA에 적합한 효율적인 주파수 재활용 방법을 제안하여 서비스 불능 확률을 감소시키면서 동시에 데이터 수율을 증가시키고자 한다. 또한 동적 전력제어를 통해 추가적인 성능향상을 보장하며, 셀 전체의 데이터 수율과 서비스 불능 비율의 비교를 통해 성능을 검증한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1340-1343
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• 1999

This Paper Presents a new analytic load decrement method for the evaluation of avoided generation costs of independent power producers (IPPs), named as probabilistic load decrement method. Unlike conventional load decrement methods, the proposed method exactly consider the random outage characteristic of a generating unit, economic dispatch order, and the resulting loss of load probability. Therefore, we can Provide the exact generation avoided costs of an IPP by applying the developed method. In the case studies, we have shown the correctness and effectiveness of the method, and compared with conventional load decrement methods.

• Journal of Electrical Engineering and Technology
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• 제7권6호
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• pp.814-823
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• 2012

Electric power transmission utilities make an effort to maximize profit by reducing their electricity supply and operation costs while maintaining their reliability. The development of maintenance strategies for aged components is one of the more effective ways to achieve this goal. The reliability centered approach is a key method in providing optimal maintenance strategies. It considers the tradeoffs between the upfront maintenance costs and the potential costs incurred by reliability losses. This paper discusses the application of the Particle Swarm Optimization (PSO) technique used to find the optimal maintenance strategy for a transmission component in order to achieve the minimum total expected cost composed of Generation Cost (GC), Maintenance Cost (MC), Repair Cost (RC) and Outage Cost (OC). Three components of a transmission system are considered: overhead lines, underground cables and insulators are considered. In regards to aged and aging component, a component state model that uses a modified Markov chain is proposed. A simulation has been performed on an IEEE 9-bus system. The results from this simulation are quite encouraging, and then the proposed approach will be useful in practical maintenance scheduling.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 A
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• pp.95-96
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• 2006

As the power industry moves towards open competition, there has been a call for methodology to evaluate distribution power system reliability by using customer interruption costs. Accordingly, it is increased for methodology to evaluate distribution power system reliability in power supply zones under competitive electricity market. This paper presents algorithm to evaluate system average interruption duration index. expected energy not supplied and system outage cost taking Into consideration failure rate of distribution facility and industrial customer interruption cost. Also, to apply this algorithm to evaluate system outage cost presented in this paper, distribution system of a dual supply system consisting of mostly high voltage customers in industrial complex in Korea is used as a sample case study. Finally, evaluation results of system interruption cost, system average interruption duration index and expected energy not supplied in sample industrial complex area are shown in detail.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.895-904
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• 2015

This paper presents a probabilistic approach of reliability evaluation and economic assessment for solving transmission network expansion planning problems. Three methods are proposed for TNEP, which are reorganizing the existing power system focused on the buses of interest, selecting candidates using modified system operating state method with healthy, marginal and at-risk states, and finally choosing the optimal alternative using cost-optimization method. TNEP candidates can be selected based on the state reliability such as sufficient and insufficient indices, as proposed in this paper. The process of economic assessment involves the costs of construction, maintenance and operation, congestion, and outage. The case studies are carried out with modified IEEE-24 bus system and Jeju island power system expansion plan in Korea, to verify the proposed methodology.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전력기술부문
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• pp.239-242
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• 2001

This paper presents a windows program package for solving security constrained OPF in interconnected power systems, which is based on the combined application of evolutionary programming(EP) and sequential quadratic programming(SQP). The objective functions are the minimization of generation fuel costs and system power losses. The control variables are the active power of the generating units, the voltage magnitude of the generator, transformer tap settings and SVC setting. The state variables are the bus voltage magnitude, the reactive power of the generating unit, line flows and the tie line flow. In OPF considering security, the outages are selected by contingency ranking method. The resulting optimal operating point has to be feasible after outages such as any single line outage(respect of voltage magnitude, reactive power generation and power flow limits). The OPF package proposed is applied to 10 machines 39 buses model system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.515-517
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• 2001

The efficient and rational transmission rate system is one of the crucial factors in creation of fair and competitive electricity market. Transmission charge can be largely categorized into the line usage charge, system reliability maintenance charge, access charge and others. Therefore, transmission rate structure should be able to reflect these cost components reasonably. This Paper suggests an approach that could be used for the reasonable calcuation of transmission reliability costs with reflection of line sensitivity and line outage rate.

• 조명전기설비학회논문지
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• 제25권6호
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• pp.90-99
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• 2011

As power industry evolves into Smart Grid scheme, previously closed power systems are being integrated into public communication networks. It increases the controllability and efficiency of the system, but also accompanies many cyber threats having existed in the Internet to the SCADA system. Therefore it is required to apply security countermeasures to the Smart Grid, which brings about investment costs. There have been few approaches to assess risks from cyber attack especially in electric power industry. So this paper proposes a methodology to assess quantitative impacts of various types of cyber attacks to a power system, and also shows the feasibility of the method through a case study.

• 대한전기학회논문지
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• 제41권1호
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• pp.9-17
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• 1992

Proper resource allocation is also a very important topic in power system problems, especially in operation and planning. One such is optimal maintenance problem in operation and planning. Least cost and highest reliability should be the subjects to be pursued. A probabilistic operation simulation model developed recently by authors is applied to the proboem of optimal maintenance scheduling. Three different methods are compared, marginal maintenance cost, levelized risk and maintenance space. The method by the marginal maintenance costs shows the least cost, the highest reliability and the highest maintenance outage rates. This latter characteristics may considerably influence the results of genetation planning, because the usual maintenance outages obtained from the other methods have shown to be lower.