• 대한전기학회논문지:전력기술부문A
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• 제48권9호
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• pp.1073-1080
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• 1999

Optimal routing of distribution networks can be attained by keeping the line power capacity limit to handle load requirements, acceptable voltage at customer loads, and the reliability indices such as SAIFI, SAIDI, CAIDI, and ASAI limits. This method is composed of optimal loss reduction and optimal reliability cost reduction. The former is solved relating to the conductor resistance of all alternative routes, and the latter is solved relating to the failure rate and duration of each alternative route. The routing considering optimal loss only and both optimal loss and optimal reliability cost are compared in this paper. The case studies with 10 and 24 bus distribution networks showed that reliability cost should be considered as well as loss reduction to achieve the optimal routing in the distribution networks.

• 대한전기학회논문지
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• 제40권1호
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• pp.1-9
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• 1991

This paper describes a new method of calculating expected energy generation and loss of load probability (L.O.L.P) for electric power system operation and expansion planning. The method represents an equivalent load duration curve (E.L.D.C) as a mixture of cumulants approximation (M.O.N.A). By regarding a load distribution as many normal distributions-rather than one normal distribution-and representing each of them in terms of Gram-Charlier expansion, we could improve the accuracy of results. We developed an algorithm which automatically determines the number of distribution and demarcation points. In modeling of a supply system, we made subsets of generators according to the number of generator outage: since the calculation of each subset's moment needs to be processed rapidly, we further developed specific recursive formulae. The method is applied to the test systems and the results are compared with those of cumulant, M.O.N.A. and Booth-Baleriaux method. It is verified that the M.O.C.A. method is faster and more accure than any other method.

• 대한전기학회논문지:전력기술부문A
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• 제51권9호
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• pp.425-432
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• 2002

This Paper illustrates a method for evaluating nodal probabilistic production cost using the CMELDC. A new method for constructing CMELDC(CoMposite Power System Equivalent Load Duration Curve) has been developed by authors. The CMELDC can be obtained by convolution integral processing between the probability distribution functions of the fictitious generators outage capacity and the load duration curves at each load point. In general, if complex operating conditions are involved and/or the number of severe events is relatively large, Monte Carlo methods are more efficient. Because of that reason, Monte Carlo Methods are applied for the construction of CMELDC in this study. And IEEE-RTS 24 buses model is used as our case study with satisfactory results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.360-362
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• 2003

In operation of distribution system, DGs(Distributed Generations) are installed as an alternative of extension and establishment of substations, transmission and distribution lines according to increasing power demand. Optimal capacity and allocation of DGs improve power quality and reliability. This paper proposes a method for determining the optimal number, size and allocation of DGs needed to minimize operation cost of distribution system. Capacity of DGs for economic operation of distribution system can be estimated by the load growth and line capacity during operation planning duration. DG allocations are determined to minimize total cost with failure rate and annual reliability cost of each load point using GA(Genetic Algorithm).

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.79-82
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• 2002

The addition of switches to a distribution feeder does, in general, increase reliability by decreasing the duration of the outage of many to the customers on the feeder. To cover its service area so that feeder-level delivery reaches sufficiently close to all customers, feeders typically split their routes many times, in what is often called a lateral feeder. It is interesting to note, however, that the effectiveness of a switch is very much dependent on the types of lateral feeder. The types of lateral are classified into two types. The first is loop lateral feeder that can connect its load to an adjacent feeder through a tie line in case that a fault occurs in its feeder and it is laid out so that every feeder has complete fault backup through re-switching of its loads to other sources like a main feeder. The second is the radial lateral feeder cannot connect its load to an adjacent line, no provision is made for contingency backup of feeders. There are no other circuits in the radial lateral feeder form which to restore power. In this study, we evaluate the effectiveness of a switch installation between on the radial and loop lateral feeders to increase reliability by decreasing the duration of the outage. These results can help power utility to design the switch layouts on the radial and loop lateral feeder system.

• 한국정밀공학회지
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• 제16권5호통권98호
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• pp.175-185
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• 1999

Acoustic emission(AE) measurement was carried out to evaluate the fracture behavior of high tension steel. Fracture toughness $K_{AE}$ could be determined reasonably by using the load value corresponding to an abrupt change of the accumulated AE counts AE emitted from the test specimens. AE characteristics of the base metal, the weld metal and the heat-affected zone could be distinguished using a constant value b which represented the AE amplitude distribution, Consequently the structure integrity can be evaluated by variation of the constant b at the load level. In addition it was found that AE signals due to crack growth have high amplitude but low rise time and duration.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.206-209
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• 2001

This paper illustrates a new method for reliability evaluation at load points in a composite power system. The algorithm includes uncertainties of generators and transmission lines as well as main transformers at substations. The CMELDC based on the new effective load model at HLII has been developed also. The CMELDC can be obtain from convolution integral processing of the outage capacity probabilistic distribution function of the fictitious generator and the original load duration curve given at the load point. The CMELDC based on the new model at HLII will extend the application areas of nodal probabilistic production cost simulation, outage cost assessment and reliability evaluation etc. at load points. The characteristics and effectiveness of this new model are illustrated by a case study of a small test system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 D
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• pp.1003-1005
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• 1997

To evaluate the quality of a system or its ability to perform a required function, it is necessary to quantify the reliability of that system. The reliability techniques are based on the concept of expected failure rate and average-outage-duration method. For each load point, the expected failure rate, average outage duration and average annual outage time are evaluated. This paper deals with the reliability evaluation for distribution system including the protection relay system. In evaluating the reliability, it suggests a method for the analysis of protective system reliability, that provides a probabilistic measure of the success of the protective apparatus to perform its intended function. The analysis shows the dependency of success on the reliability of many components, and the way this reliability may be enhanced by redundancy.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.111-112
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• 2008

Although two types of uncertainty such as randomness and fuzziness simultaneously exist in power systems, yet they have been treated as distinct fields to evaluate the power system reliability. Thus, this paper presents a reliability assessment method based on a combined concept of fuzzy and probability. To reflect the two-fold uncertainty, a modified load duration curve(MLDC) is proposed using the probability distribution of historical load data in which a fuzzy model for the peak load forecast is embedded. IEEE RTS system was used to demonstrate the usefulness and applicability of the proposed method, and the reliability indices were obtained using the proposed MLDC. The results show a wider insight into impact of load fuzziness on uncertainties of reliability indices for power systems.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 하계학술대회 논문집
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• pp.154-157
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• 1990

This paper describes a new method of calculating expected energy generation and loss of load probability (L.O.L.P) for electric power system operation and expansion planning. The method represents an equivalent load duration curve (E.L.D.C) as a mixture of cumulants approximation (M.O.C.A), which is the general case of mixture of normals approximation (M.O.N.A). By regarding a load distribution as many normal distributions-rather than one normal distribution-and representing each of them in terms of Gram-Charller expansion, we could improve the accuracy of results. We developed an algorithm which automatically determines the number of distribution and demarcation points. In modelling of a supply system, we made subsets of generators according to the number of generator outage: since the calculation of each subset's moment needs to be processed rapidly, we futher developed specific recursive formulae. The method is applied to the test systems and the results are compared with those of cumulant, M.O.N.A and Booth-Baleriaux method. It is verified that the M.O.C.A method is faster and more accurate than any other methods.