• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1281-1286
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• 2009

As a general radial configuration of power distribution system, the various researches have being studied to change a radial configuration to network one such as smart, intelligent and micro grid for loop operation. If a radial configuration changes to network, protective coordination comes to the biggest problem. When a typical protective algorithm is applied to loop distribution system protection, the interrupted section is expanded, therefore, reliability grows worse. This paper presents the new protective method being able to apply to loop distribution system with Distribution Automation System (DAS) which separate the minimal faulted section. Through contingency analysis of the sustained and momentary fault, we analyzed the influence for radial configuration and loop configuration using interrupted area and proved the effectiveness of proposed method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1270-1275
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• 2009

The structure of a power distribution system will change in a loop configuration such as in the case of a smart grid. If power distribution system changes radial to loop form, the structure may have to be changed significantly. Therefore, we analyzed the reliability indices and calculated a CIC(Customer Interruption Cost) for the loop power distribution system. The power distribution system reliability depends on the protection scheme. This study is applied to the current protection scheme method and is compared with each model. When the CIC was evaluated, most studies performed calculations only for sustained interruptions. However, in actuality, momentary interruption frequencies occurred more than sustain interruptions. Thus, it is occurred the CIC additively. Therefore, we evaluated a CIC including momentary interruption, for each model, and then compared with MAIFI(Momentary Average Interruption Frequency Index)

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.11
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• pp.1942-1948
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• 2010

Recently, the radial distribution system is operating as one-way power flow. These are popular because of their simple design and relatively low cost. However, radial systems are sensitive to outages due to single contingencies. Also, reliability of supply is becoming increasingly important. Accordingly, an appearance of the loop distribution system is inevitable and the other countries such as Macau, Florida, Taiwan are actively working on. The reliability of distribution system is estimated with reliability indices. In this paper, comparing with the radial distribution system, we evaluate and analyse the reliability of loop distribution system quantitatively considering directional relay.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.1
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• pp.26-31
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• 2011

In this paper, we focused on the loop distribution system to solve the international issues of energy depletion and global warming. The conventional method of reconfiguration of distribution system was moving open points of switches from an actual switch position to another, while an appropriate switch must be opened to preserve the radial structure and this procedure is continued til there is no further loss reduction. However, the loop distribution system is the best optimization method to minimize loss than the other methods which is preserving radial structure. So we analyzed 3 types of loop distribution system upgraded from radial distribution system by changing normally open switch to normally closed switch. The simple 3 types of model system for simulation were composed, and each types of loop system were simulated in accordance with varying parameters. As a result of simulations, the loss reduction was different for each types of loop distribution system and each loop types have constraints for composing loop distribution system. The algorithms propose the method how to construct loop distribution system regarding constraints. Type I that needs least requirements get least loss reduction and Type III that needs most requirements get maximum loss reduction. On the other hand, Type I was most feasible distribution system to be realized.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.2042-2048
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• 2014

In medium voltage electrical distribution networks, reforming the loss reduction is important, and in line with this, the issue of system engineering and use of proper equipment Expansion of distribution systems results in higher system losses and poor voltage regulation. Therefore, an efficient and effective distribution system has become more important. So, proper selection of conductors in the distribution system is crucial as it determines the current density and the resistance of the line. Evaluation of aging conductors for losses and costs imposed in addition to the careful planning of technical and economic networks can be identified in the network design. In this paper the use of imperialist competitive algorithm; genetic algorithm; is proposed to optimal branch conductor selection and reconstruction in radial distribution systems planning. The objective is to minimize the overall cost of annual energy losses and depreciation on the cost of conductors to improve productivity given the maximum current carrying capacity and acceptable voltage levels. Simulations are carried out on 69-bus radial distribution network using genetic algorithm approaches to show the accuracy as well as the efficiency of the proposed solution technique.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.8
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• pp.1472-1478
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• 2009

The domestic power distribution system is operating in an open loop mode; however, it already has a loop structure. Power distribution systems must be changed for bi-directions power supply for smart networks due to a changing of paradigm in electric power industry. The simplest bi-directions distribution networks can make it closing of normally open switch. However, bi-directions power supply is very difficulty to be operated and there are many parts which it must study. This paper presented various models that are able to change a radial system for loop structures. Further, we compared the reliability index for each model by evaluating the amount of improvement reliability required in radial power distribution system. In addition, we calculated CIC(Customer Interruption Cost) for each model by comparing and analyzing.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.3
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• pp.397-403
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• 2016

Generally, an electrical distribution configuration is a radial system with one-way current in a distribution management system (DMS). All feeders in a DMS have tie-switches to make radial system. Sometimes, DMS should change a tie-switch for operation. In that case, the tie-switch has to be closed first; then a switch is opened as another tie-switch in order to prevent blackout for customers. At the moment when the tie-switch is closed, distribution system is operated in a loop state, not radial. Before the loop operation, DMS operator has to check any expected events for stable distribution system operation; and the most important event is a mis-operation of a protection relay. In addition, DMS operator should check voltage profile violation but a calculation method of section voltages had not been used. Thus, this paper proposes a calculation method of section voltages at a loop operation in a DMS. The proposed calculation algorithm is verified by Matlap Simulink.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.488-490
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• 2001

It is important to catch or classify fault types by any detecting technique for distribution protection. This paper proposes the technique to classify the fault types using wavelet transform in radial distribution line. Modeling of the radial distribution line is simulated using PSCAD/EMTDC and wavelet transform is performed in the Matlab program.

• KIEE International Transactions on Power Engineering
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• v.2A no.4
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• pp.166-173
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• 2002

Dispersed Generation (DG) units significantly effect the existing distribution protection practices. Therefore, new protection practices of the distribution system interconnected with DG units should be reevaluated and developed. In this paper, a new inter-tie protection scheme of DG units for distribution automatic reclosing is proposed. The impact of DG units on existing radial-sectionaliser coordination is analyzed. And the effects of the distribution reclosing type (radial and passive reclosing) on DG dynamics are analyzed and classified. From the results of the DG dynamic responses by the reclosing type, i.e. radial and passive reclosing, the inter-tie protection schemes of DG are introduced to improve the reliability and availability of utility interactive DG. The proposed schemes are proved and evaluated by a case study using PSCAD/EMTDC simulation.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.83-86
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• 2002

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.