• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.530-532
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• 2001

This paper illustrates a method for evaluating nodal probabilistic production cost using the CMELDC. A new method for constructing CMELDC(the equivalent load duration curves of composite power system) was 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. Monte Carlo Methods are applied for the construction of CMELDC on this study. And IEEE-RTS 24 buses model is used as our case study with satisfactory results.

• Proceedings of the KIEE Conference
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• 2001.07a
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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.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.2
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• pp.107-113
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• 2003

In a deregulated electric power market, a demand function to consider the characteristics of electric power consumers should be required. It is essential that the optimal power flow algorithm with object function of social welfare maximization using the demand function for a competitive electric power market is applied to resolve in a point of economic benefits as well as the security of power systems. Therefore, in this paper, we implement the optimization problem based on linear programming to consider the characteristics of electric power consumers using the demand function and analyze not only the nodal cost for generations and demands but also the variation of demands as a function of the characteristics of electric power consumers through numerical studies.

• Tunnel and Underground Space
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• v.11 no.1
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• pp.36-41
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• 2001

It is often said that the supply of fossil fuels in use for energy source will last only for 40 years. Futhermore, statistics shows that most of the fuels are imported from outside and that 30-40% of total cost for housing in Korea. One of those methods for reducing the energy cost for housing is to use underground space. Being used well, it may bring a considerable saving of energy since the underground space keeps its air cool in summer and warm in winter. To use underground space, we need to analyse its temperature first. For this purpose, what is generally used is the numerical analysis with the use of nodal system. That is, we can calculate a specific underground temperature with the matrix of thermal resistance after we make a nodal system. However, the existing numerical analysis programs need usually high cost and require a computer with large capacity. So they are seldom used in practice. Considering such problems, this study seeks to find a method for making the matrix of thermal resistance operatable on PC level.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.574-575
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• 2007

This paper proposes a method for choosing the best transmission system expansion plan using nodal/bus delivery marginal rate criterion ($BMR_k$) defined newly in this paper. The objective method minimizes a total cost which is an investment budget for constructing new transmission lines subject to the $BMR_k$ which means a nodal deterministic reliability level requirement at specified load point. The proposed method models the transmission system expansion problem as an integer programming problem. It solves for the optimal strategy using a branch and bound method that utilizes a network flow approach and the maximum flow-minimum cut set theorem. Test results on an existing 21-bus system are included in the paper. It demonstrated the suitability of the proposed method for solving the transmission system expansion planning problem in competitive electricity market environment.

• Journal of Agricultural Extension & Community Development
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• v.5 no.1
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• pp.93-102
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• 1998

The objectives of the study were 1) to make the reasonable standard, 2) to select the objective and scientific method and process for the location-allocation of a new provincial capital city. The Main standard of location-allocation were suggested as follows ; 1) Integration of province 2) Convenience of Administration service 3) Accomodations of new provincial capital city 4) Balanced development by region. The validity of location-allocation were reviewed the population potentials and nodal accessibilities. The population potential was examined to find the maximum point of administrative demand, and the locationallocation model was examined to find the minimum point of the aggregated travel-cost to a proposed provincial government office. The nodal accessibilities measured in travel-time distance and actual values. Two major concerns in locating public facilities are efficiency and equity.

• Journal of Power System Engineering
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• v.2 no.1
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• pp.59-66
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• 1998

The authors have studied vibration analysis algorithm which was suitable to the personal computer. Recently, we presented the transfer stiffness coefficient method(TSCM). This method is based on the concept of the transfer of the nodal dynamic stiffness coefficients which are related to force and displacement vectors at each node. In this paper, we describes the general formulation for the longitudinal and flexural coupled vibration analysis of a beam type structure by the TSCM. And the superiority of the TSCM to the finite element method(FEM) in the computation accuracy, cost and convenience was confirmed by results of the numerical computation and experiment.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.6
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• pp.259-264
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• 2001

The electric utility industry around the world is undergoing a revolutionary transition from vertically integrated monopoly structures to a competitive structures. Competition in an open transmission access(OTA) makes the market participants access easily the transmission system in a non-discriminatory and equitable manner. The competitions of suppliers and customers make the electric market price change every hour. This paper presents a web program in the internet environment with a function of optimal power flow(OPF) calculation. The Web program gives the nodal marginal cost and the congestion charge using the shadow prices resulted from OPF. This web program is realized by a Perl and JAVA languages, and using the common gateway interface(CGI).

• Proceedings of the KIEE Conference
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• 2006.11a
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• pp.275-278
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• 2006

This paper describes a probabilistic annual congestion cost assessment of a grid at a composite power system derived from a model. This probabilistic congestion cost assessment simulation model includes capacity limitation and uncertainties of the generators and transmission lines. In this paper, the proposed probabilistic congestion cost assessment model is focused on an annualized simulation methodology for solving long-term grid expansion planning issues. It emphasizes the questions of "how should the uncertainties of system elements (generators, lines and transformers, etc.) be considered for annual congestion cost assessment from the macro economic view point"? This simulation methodology comes essentially from a probabilistic production cost simulation model of composite power systems. This type of model comes from a nodal equivalent load duration curve based on a new effective load model at load points. The characteristics and effectiveness of this new simulation model are illustrated by several case studies of a test system.

• KIEE International Transactions on Power Engineering
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• v.3A no.1
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• pp.17-26
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• 2003

In this paper, the comparative steady-state operating performance analysis algorithms of the stand-alone single-phase self-excited induction generator (SEIG) is presented on the basis of the two nodal admittance approaches using the per-unit frequency in addition to a new state variable de-fined by the per-unit slip frequency. The main significant features of the proposed operating circuit analysis with the per-unit slip frequency as a state variable are that the fast effective solution could be achieved with the simple mathematical computation effort. The operating performance results in the simulation of the single-phase SEIG evaluated by using the per-unit slip frequency state variable are compared with those obtained by using the per-unit frequency state variable. The comparative operating performance results provide the close agreements between two steady-state analysis performance algorithms based on the electro-mechanical equivalent circuit of the single-phase SEIG. In addition to these, the single-phase static VAR compensator; SVC composed of the thyristor controlled reactor; TCR in parallel with the fixed excitation capacitor; FC and the thyristor switched capacitor; TSC is ap-plied to regulate the generated terminal voltage of the single-phase SEIG loaded by a variable inductive passive load. The fixed gain PI controller is employed to adjust the equivalent variable excitation capacitor capacitance of the single-phase SVC.