This paper covers general recommendations for top-oil temperature rising of mineral-oil-immersed power distribution transformer rated 100kVA and less, manufactured in Korea. In order to analyze the top-oil temperature rising due to the distribution transformer loading we performed experiments for oil-immersed distribution transformer, manufactured in domestic at KERI(Korea Electrical Research Institute) from December 2000 to May 2001. The magnitude of loading were changed, and the top-oil temperatures for each time were measured. Finally, we present the overload criteria of distribution transformer for summer and winter season in domestic. respectively.

On the side of that necessity, it is known that the development of Amorphous metal take effects on lowering eddy current loss in a core system. If a amorphous transformer and a motor to which "Amorphous Metal" is applied be widespread, electricity saving should be enormous with the several hundreds billion won of economic effects like cutting the cost of power plants and the unhealthy gases. This paper carried out general evaluation about the characters of Amorphous metal, the expected energy saving effects of a amorphous transformer, the environmental contribution, the increasement of electricity quality, and the features of harmonic.

본 논문에서는 한전에서 강진변전소에 파이롯플랜트로 설치 중에 있는 80MVA 용량의 3-레벨 12-펄스형 UPFC의 EMTDC 모델링에 대해 기술하고 있다. UPFC의 EMTDC를 이용한 시뮬레이션 모형은 그 목적에 따라 상세 정도가 상이한 다양한 형태가 존재하나 본 연구에서는 향후 RTDS에 연계하여 전력계통과의 동적 성능 평가에 적용 가능하도록 인버터를 스위칭 레벨 다중펄스 전압원으로 모델링하였다. 개발된 시뮬레이션모형의 타당성은 정현파 이상진원을 사용한 시뮬레이션 분석결과와 비교검토 하여 검증하였다. 개발된 시뮬레이션모형은 UPFC의 성능분석과 전력계통과의 동적응동 해석에 유용하게 활용 가능하고 또한 UPFC 운전자에게 동작특성과 초보적인 운전특성을 교육하는데도 활용가능 할 것으로 보인다.

본 논문은 대용량 전력을 사용하는 철강산업 전력계통에서 고조파 전압과 전류 등을 현장 실측하여 고조파 발생 설비를 모의하여 고조파를 해석한 실계통 적용 연구 사례로 전력계통 전반에 나타나는 고조파 전압과 전류 분포를 분석하고 고조파 억제용으로 설치되어있는 고조파필터용 콘덴서의 공진 가능성 등을 검토한 것이다.

This paper discussed for harmonic analysis of 154kv system in Kwangyang steel works. The harmonic modelings are developed by harmonic measurement for scores of days in a 154kv substation at a same time. In this paper, the measurement values of harmonic are compared to the analysis results in incoming line. Case studies are presented to predict harmonic distortion of the future system.

Sheath circulating current results from the change of sheath mutual impedance which is caused by unbalanced cable system, and different section length between joint boxes. If circulating over current flows in sheath, it produces much sheath loss which reduces the transmission capacity. And also such large sheath current influences severely on the operator. Recently, large sheath circulating current was partially measured in underground cable system of KEPCO. Accordingly, actual schemes to reduce sheath circulating over current is urgently required for installed cable system as well as newly-constructing cable system. This paper describes the analysis of sheath circulating current and various schemes to reduce the large circulating current in case of operating cable system using EMTP/ATPDraw. And also, possible schemes are proposed through a detailed analysis regarding cable systems by considering various electrical and environmental factors. It is evaluated that the proposed reduction schemes can be effectively applied to reduce the large sheath circulating over current with the minimized electrical problems.

This paper evaluate reliability indices of a part of transmission network of KEPCO system. Quantitative evaluation of transmission system reliability is very important because successful operation of an electric power system in the deregulated electricity market depends on transmission system reliability management. Monte Carlo methods are often preferable, when complex operating conditions are involved and/or the number of sever events is relatively large. Monte Carlo simulation methods and CMELDC(CoMposite power system Effective Load Duration Curve) were used in this paper.

경쟁적 전력시장의 도입으로 시장의 모든 참여자들은 자신의 효용이나 수익을 극대화하게 된다. 이에 따라 수용가들은 효용극대화 및 비용최소화를 위한 적극적인 전력소비전략을 필요로 하게 되며, 이를 위해 경쟁적 시장의 부하관리 시스템에 대한 관심이 증가하고 있다. 본 논문에서는 경쟁적 전력시장의 에너지비용절감을 위한 부하관리시스템의 국내외 연구 동향 및 사례들을 조사 분석하였으며 이를 바탕으로 국내 적용 가능성 등을 연구하였다.

In a competitive environment of electric power industy, the level of uncertainty increase due to generation investment decisions creating new challenge to transmission system planner. The use of a locational signal and the provision of a indicative plan to control the generation investment reasonably is very important in the viewpoint of a regulator. The main target of this stuty is to emphasize on the necessity for considering simultaneously both generation and transmission expansion plan. This paper demonstrate the many case studies to make certain of the necessity for the interconnection between generation and transmission planning. In addition to, the planning in Korea power industry is considerd.

Recently, electric heating using midnight power has brought a rapid increase. due to a rise of oil price and a low tariff of midnight power. Therefore, the increase of midnight power use has much influenced on midnight load pattern. This paper estimates the load pattern due to midnight power equipments, analyzes the influence of the spread of midnight power equipments on midnight load and suggests reasonable spread level of equipments.

전력 수요 예측은 전력 수급 안정과 양질의 전력을 공급하기 위한 필수 기법이며 경쟁적인 전력시장에서 전력요금과 밀접한 관련이 있다. 그러므로, 경쟁적인 전력시장 구조하의 시장 참여자에게 있어서 전력 수요 예측은 매우 관심 있는 사항이다. 최근의 전력 수요 예측 기법으로 예측한 오차율을 살펴보면 평일과는 다르게 특수일의 전력 수요예측은 평균 5%를 상회하는 수준으로 예측의 정확도가 평일 예측에 비해 크게 낮은데 이유는 특수일이 평일에 비하여 부하의 크기가 다소 낮게 나타나고 특수일 마다 계절적인 차이가 있으며 각각의 특수일 마다 고유한 부하의 특성이 있으므로 과거 데이터를 이용할 때 동일 특수일을 이용하게 되며 따라서 평일과는 다르게 일년 단위로 과거 데이터 값들이 취득되므로 오차율이 커진다. 따라서 데이터들을 퍼지화하여 선형계획법을 수행하여 평균 $2{\sim}3%$ 정도의 우수한 결과를 도출한 바 있다. 본 논문에서는 퍼지 선형회귀분석법을 이용한 예측 기법에 최소자승법을 도입하여 특수일 전력 수요예측의 정확도를 개선하였다.

매년 전력사용량은 증가하고 있으나 발전 공급량은 수요의 증가분을 따라가기는 힘들다. 수요관리(DSM)는 소비자의 전기사용 패턴을 합리적인 방향으로 유도함으로써 부하율 향상을 통한 원가절감과 전력수급 안정에 기여한다. 국내의 전력산업 특성상 DSM은 규제에 의한 DSM이었다. 규제된 DSM 덕택으로 부하율 향상과 에너지이용효율향상을 위한 수요관리 프로그램을 전력회사는 꾸준히 추진해 왔다. 그러나 전력산업의 구조개편후 규제가 완화되면서 전력회사는 수지 타산에 맞는 DSM만 선호하게 될 것이다. 전력회사의 이익에 맞지않는 DSM은 구조개편후 경제원리에 의해 사라져야만 하는가? 비록 전력회사에게는 이익이되지 않지만 사회적으로는 많은 편익을 주는 DSM 프로그램도 상당수 있다. 이 논문에서는 그러한 프로그램의 대표적인 예제라 할 수 있는 고효율 유도전동기에 대해서 DSM프로그램의 각 참여자 입장에서 비용효과적인지를 분석하였다. 그리고 구조개편후 이러한 DSM프로그램이 어떻게 유지되어야 타당한지를 밝히려 한다. 효과분석에서 사용되어지는 소프트웨어 패키지로는 미국의 EPRI연구소에서 개발한 DSManager를 사용하였다.

The restructuring of power industry is still going on all over the world for last several decades. Many kinds of restructuring model has been studied, proposed, and applied. Among those models, power pool is more popular than others. This paper assumes the power pool market structure having competitive generation sector and a new method is presented to build bidding strategy in that market. The utilities participating in the market have the perfect information on their cost and price functions, but they don't know the strategy to be chosen by others. To define one's strategy as a vector, we make utility's cost/price function into discrete step function. An utility knows only his own strategy, so he estimates the other's strategy using stochastic methods. For considering these conditions, we introduce the Bayesian rules and noncooperative game theory concepts. Also additional assumptions are included for simplification of solving process. Each utility builds the strategy to maximize his own expected profit function using noncooperative Bayesian game. A numerical example is given in case study to show essential features of this approach.

This paper shows the optimal bidding strategy determination method using Nash equilibrium concept by defining bidding strategy vector. This vector is 2-dimension vector whose components are generation amount and generation cost. Thereby we are able to make all possible strategies and their's payoff table. And then we erase dominated strategies one by one so that we obtain Nash equilibrium, the optimal bidding strategy of generation bidding game.

In the Poolco model, the bidding game is executed periodically. The player participating to the bidding game accumulates the information of others' strategies and payoffs through the repeated process. Thereby, he is able to map out how he gets his maximum profit, and proceed to the optimal strategy region. This paper shows the algorithm for a player to determine his strategy in t period based the information of the game results of t-1, t-2 period. And this algorithm can be formulated by using Dynamic game theory.

It is required to develop a rational transmission tariff system to ensure the fair participation of the players in the market. This study suggests an improved transmission tariff system which classifies the line capacity into line usage and reliability capacity based on their use and reasonably allocates the costs incurred by each of them to users. In addition, it takes the system load variations into consideration.

This paper presents a new systematic contingency selection, screening and ranking method for on-line transient security assessment. Transient stability of a particular generator is influenced most by fault near it. Fault at the transmission lines adjacent to the generators are selected as contingency. Two screening methods are developed using the sensitivity of modal synchronizing torque coefficient and computing an approximate critical clearing time(CCT) without time simulation. The first method, which considers only synchronizing power, may mislead in some cases since it does not consider the acceleration power. The approximate CCT method, which consider both the acceleration and deceleration power, worked well. Finally the Single Machine Equivalent(SIME) method is implemented using IPLAN of PSS/E for detailed stability analysis.

As electric power systems have been moving from vertically integrated utilities to a deregulated environment, the charging of reactive power management is a new challenging theme for market operators. This paper proposes a new methodology to compute the costs of providing reactive power management service in a competitive electrical power market. The proposed formulation, which is basically different from those shown in the literature, consists of two parts. One is to recover investment capital costs of reactive power supporting equipment based on a reactive power flow tracing algorithm. The other is to recover operational costs based on variable spot prices using the optimal power flow algorithm. The charging shapes resulted from the proposed approach exhibit a quite good meaning viewed from a practical sense. It turns out that reactive power charges are mostly due to recovery of capital costs and slightly due to recovery of operational costs. The method can be useful in providing additional insight into power system operation and can be used to determine tariffs of a reactive power management service.

This work deals with the compensation of the impact of highly varying loads on the power system using a static var compensator(SVC). Highly varying loads is properly modelled via deterministic approach using PSCAD/EMTDC. Also, the procedure to determine a suitable capacity of the compensator is proposed. Finally, the new online index to quantify the harmonic distortion is introduced.

본 연구에서는 전력계동의 다이나믹스를 정확하게 표현할 수 있는 기계적 시스템인 등가역학 모델(Equivalent Mechanical Model: EMM)을 제안하고, 이를 기초로 확고한 수학적 해석을 통해 에너지 함수의 유도 방법을 체계화 하고 물리적 의미를 파악함으로써 에너지 함수를 이용한 시스템 해석에 대한 이론적 배경을 마련한다. 또한 시영역 모의법을 이용한 과도안정도 해석의 간접법에서 SI법중 Trapezoidal법에서의 오차를 줄일수 있는 알고리즘을 제시한다. 먼저 수학적 이론을 바탕으로 전력계통에 적용하여 상태변수를 업데이트 시킴으로써 Trapezoidal법에서보다 더 정확한 데이터를 얻고자 한다. 본 연구에서는 명확한 수학적 이론의 적용을 위해 1기 무한대 모선을 모델로 시뮬레이션 하였으며 결과의 비교분석을 위해 Runge-Kutta법에 의한 시영역 모의와 비교하였다.

This study presents neural load disturbance observer that used to deadbeat load torque observer and regulation of the compensation gain by parameter estimator. As a result, the response of PMSM fellows that of the nominal plant. The load torque compensation method is compose of a neural deadbeat observer. To reduce of the noise effect, the post-filter, which is implemented by MA process, is proposed. The parameter compensator with RLSM(recursive least square method) parameter estimator is suggested to increase the performance of the load torque observer and main controller. The proposed estimator is combined with a high performance neural torque observer to resolve the problems. As a result, the proposed control system becomes a robust and precise system against the load torque and the parameter variation. A stability and usefulness, through the verified computer simulation, are shown in this paper.

Bi-2223 tapes have been developed for low-field power applications at liquid nitrogen temperature. When the Bi-2223 tapes are used in an application such as a power transmission cable or a power transformer, they are supplied with an AC transport current and exposed to an external magnetic field generated by neighboring tape's AC currents simultaneously. AC loss taking into account such real applications is a crucial issue for power applications of the Bi-2223 tapes to be feasible. In this paper, the transport losses for different AC current levels and arrangements of the neighboring tapes have been measured in a 1.5 m long Bi-2223 tape. The significant increase of the transport losses due to neighboring tape's AC currents is observed. An increase of the transport losses caused by a decrease of the Bi-2223 tape's critical current is a minor effect. The measured transport losses could not be explained by a dynamic resistance loss based on DC voltage-current characteristics in combination with the neighboring tape's AC currents. The transport losses do not depend on the frequency of the neighboring tape's AC currents but its arrangements in the range of small current especially.

Due to their elastic anisotropy, ultrasonic testing of austenitic welds, frequently used in nuclear power plants, is much more difficult than that of isotropic elements. For accurate testing of austenitic welds, ultrasonic wave phenomena therein must be full understood. This study uses an accurate and effective numerical model, the mass-spring lattice model, for such phenomena. By comparing the numerical results with the corresponding analytical results, it is shown that the model is capable of accurately predicting the generation, reflection, refraction, and scattering phenomena of ultrasonic waves in anisotropic austenite welds. Therefore, the mass-spring lattice model will provide a very useful tool for simulating ultrasonic testing of austenitic welds, and thus will contribute to the enhancement of reliability of such ultrasonic testing.

As 3V cathode material, a new doping spinel material, LiMn1.6Se0.4O4 powder with a phase-pure polycrystalline was synthesized by a sol-gel method. In spite of Jahn-teller distortion in 3V region($2.4{\sim}3.5V$), the LiMn1.6Se0.4O4 electrode shows no capacity loss. The material in the 3V region initially delivers a discharge capacity of 100mAh/g which increase with cycling to reach 105mAh/g after 90cycles. And 5V cathode material LiNi0.5-xMxMn1.5O4(M=Cr, V, Fe) compounds have been synthesized by sol-gel method. a series of electroactive spinel compounds, LiNi0.5-xMxMn1.5O4(M=Cr, V, Fe) has been studied by crystallographic and electrochemical methods. The material presents only one plateau at around 4.5 V vs. Li/Li+ with a large discharge capacity of 152mAh/g and fairly good cyclability.

The specific goal of this research is to develop a non-contact measurement technique of stress waves propagating in a rotating shaft. This technique will enable on-line damage detection in shafts in power-generating systems. To minimize measurement errors due to shaft rotation, we have employed magnetostrictive sensors. The sensors are not only cost-effective but also insensitive to liftoff or fill factors. Several experimental results showed the effectiveness of the present technique. The damage location in a rotating shaft was accurately predicted by the wave signal measured by the present approach.

A percentage current differential relaying algorithm is widely used for bus protection. However, it may maloperate external faults with CT saturation. This paper proposes a percentage current differential relaying algorithm for bus protection using CT saturation detecting algorithm. The CT saturation detecting algorithm uses difference of secondary current of CT and detects CT saturation. The proposed method distinguishes percentage differential relay operation caused by faults from percentage differential relay operation caused by CT saturations.

This paper presents a distance relaying algorithm based on the Discrete Fourier Transform(DFT) for elimination of DC-Offset. When the DFT is applied to current signal. the real and imaginary parts of fundamental component consist of fundamental component itself and DC-Offset. The DC-Offset is calculated by four consecutive values of the imaginary components, so that the fundamental component can be accurately estimated. Performance evaluation is presented for A-phase ground faults on 154kV 80km overhead transmission line. The proposed algorithm is inspected by software simulation and hardware simulation.

This paper presents a fault location algorithm using iterative method at unbalance condition for distribution feeder systems. Distribution feeders include single phase and three phase laterals. The proposed algorithm achieves a high accuracy by continuously updating voltage and current phasor using the phase components and admittance load model.

A reliable fault type identification (phase selection) plays a very important role in transmission line protection, particularly in Extra High Voltage(EHV) networks. The conventional fault type identification algorithm used the phase difference between positive and negative sequence current excluding load current. But, it is difficult to pick out only fault current since we can not know when a fault occurs and identify the fault type in weak-infeed conditions that dominate zero-sequence current in phase current. The proposed algorithm can identify the accurately fault type using the sum of unit vectors which are calculated by positive-sequence votage and negative-sequence voltage.

This paper discusses how to implement and verify a software relaying model which is added to RTDS model library and is then subjected to the same outputs as the actual relay.

This paper discusses the operation zone of distance relay on transmission line connected unified power flow controller(UPFC). Depending on operating conditions of UPFC, the trip characteristics of distance relay is influenced by the prefault conditions. In this paper, apparent impedance of distance relay influenced by the UPFC control of distance is calculated.

In this paper the Graphic-based Power System Simulator(GPSS) program is introduced. GPSS is a Power System Simulator that is designed to provide friendly and highly interactive Graphic User Interface(GUI). The main features of GPSS are graphical free editing, quick and fine System-Drawing and Load-Flow analysis. Most of all, mapping power system data(only pure text information) into Graphic Data is of very practical use to power system designer and analyst.

본 논문에서는 인체 조직모델을 전기적 성질을 가지고 있는 정육면체 셀로 가정하여 각 인체조직을 Impedance Network로 모델링하여 Maxwell Equation을 간단한 Circuit Equation으로 전환하는 방법을 이용하여 인체 와전류를 계산하였다. 인체에 유도되는 와전류 해석 예로써는 인체의 두부 및 복부 단면 모델을 사용하여 각 조직의 전도도에 따른 조직에 유도되는 전류를 계산하였다.

Recently transmission and distribution power facilities have been often damaged severely by fire which broke out around the facilities in forest. It causes a power failure and thus gives an economic losses to both the public and the power utilities. Sometimes the fire can happen by an electrical accident such as the electrical short circuit or the ground short circuit. In this paper, trend of breaking out the fire has been investigated and an countermeasure against the economic losses due to the fire has been studied.

This paper discusses the optimal sizes of BESS. The goal must be optimized electricity charge of the customers-side with choosing the time-of-use rates. Therefore the cost is minimized by BESS installed the customers-side. Feasible ROR that means the ratio of capital costs to economic effect owned the optimal BESS sizes is determined the suitable domestic condition based on the battery cost and power converter system cost. Payback period times can be presented by BESS through the ROR. Multi-Pass Dynamic Programming(MPDP) algorithm is applied to the customer for the optimal sizes determination in this paper. It is to solve the optimal solution under the constraints. To investigate the efficiencies of the constraints, it is applied the typical load curve to the high-voltage customer owned Time-Of-Use(TOU) whether BESS is installed or not. Well, The result is obtained that feasible BESS sizes can be achieved the suitable customers-side of meter through the ROR.

In this work, we have conducted insulation aging assessment and maintenance for submarine medium voltage power cable systems to discriminate and maintain bad cables economically. We have found that aging status of submarine cable systems are very poor and in progress. We have found that insulation status were improved with the replacement of cable terminations. We have confirmed with the electrical and structural analysis of terminations, that the poor aging status of cables are mainly caused not by the cable insulations but by the aging of cable terminations. From the above results, we have also confirmed that the domestic diagnostic system is successful and convenient for the discrimination and maintenance of the damaged cables economically.

The transformer and the OF cable are cooled and insulated by insulating oils in their body. The insulating oil expands or contracts with the heat transfer according to the operating conditions of the electric facilities. So we install the $N_2$ gas tank connected with the insulating oil system to overcome the change. The change of the insulating oil volume for the operation temperature range must be calculated to decide the $N_2$ gas volume and to set the alarm point for safe operation. It is known that this change is proportional to the temperature change and to the insulating oil volume if the temperature change is small enough.[1][11] However this proportional formula has been accepted generally in the design of electric facilities for wide operation temperature range such as $40^{\circ}C{\sim}125^{\circ}C$. Hence, it makes large errors in calculation which car result in serious damage against safe operation of the electric facilities. This paper presents a improved method of calculating the accurate change of the insulating oil volume to insure the safe operation of electric facilities.

The selection of voltage is one of the most significant factors in the design of power system for industrial plant. It is a major factor in determining over-all system cost, flexibility, and ease of future expansion. This paper presents the study results on the selection of economic voltage for low voltage power distribution system.

This paper presents a Case-Sort method to solve the unit commitment problem using database in electric power systems. The formulation of the unit commitment may be described as nonlinear mixed integer programming. However, it is hard to optimize a problem with discrete and continuous variables in a large-scale system at the same time. The Case-Sort method is based on the unit [MW] generation cost considered drive hour. Then, this paper shows effectiveness and economical efficiency of the proposed algorithm.

This paper introduces the principal pool rules of the wholesale power market scheduled to be commissioned in January 2003 in Korea. The pool rules includes electricity trading procedures such as bidding, determining and publishing of forecasted market price, and 5 minute unconstrained dispatch scheduling for generation/market price, which are required for settlement after dispatching and should be conformed by KPX and participants in the market. Detailed procedures of the rules are under development and additional provisions for stable market operation are under discussion.

This paper describes the settlement rules in the basic market design for Korean Wholesale Electricity Market. The settlement rules are to be exercised after the Bid and Offer Processes as described in the pool rules(within the market rules) and to determine the payments to Generators, charges to Energy Purchasers and charges or payments to the Transmission Asset Owner(TAO).

This paper describes the dispatch rules prepared for Korean Wholesale Electricity Market. The dispatch rules set out the procedure for the scheduling and dispatch in the operational timescale. It details the process whereby the KPX produces an operatinal schedule taking into account system and operational limitations-the constrained schedule.

This paper presents the application draft of ancillary services for Korean Wholesale Electricity Market. This application draft of ancillary services is based on technical rules for ancillary services agreements prepared by KEMA and the present conditions of KEPCO system operations and future directions.

계량규칙은 전력거래에 따른 전력량의 수수를 정량적으로 계산하기 위한 규칙이다. 계량규칙에서는 전력거래소를 포함하여 전력거래와 관계된 모든 시장참석자들의 거래 전력량을 정확하게 측정하여 이들 데이터를 정산시스템에 전달함으로써 전력거래에 따른 요금계산이 가능하도록 지원할 뿐만 아니라 계량기에 저장된 데이터를 바탕으로 시장운영자의 발전지시를 발전사업자가 잘 준수하고 있는지의 감사 근거자료를 제공하기도 한다. 본 논문에서는 이 밖에 계량설비에 요구되는 조건, 계량설비의 설치위치 계량기 설치 및 비용부담의 주체, 계량기의 교정 및 시험 등에 관련된 사항 등에 대해 각 시장 참여자가 양방향 입찰 전력시장의 효율적인 운영을 위해 지켜야할 책임과 의무 등에 대해 제시한다.

This paper presents the application draft of system frequency and reserve criteria for Korean Wholesale Electricity Market. This application draft of system frequency and reserve criteria is based on frequecy, voltage control rules and technical rules for ancillary services agreements prepared by KEMA and the present conditions of KEPCO system operations and future directions.

This paper represents planning rules which specify the technical and design criteria and procedures that apply to the transmission asset owner(TAO) and the distribution network service providers(DNSP) in the planning and development of the electricity network.

This paper describes a proposal for performance criteria for transmission system planning performance criteria of transmission system is expected to be a guideline for investment into transmission network.

The Transmission network provides physical transport, network security, and connection services. The five principles of Transmission pricing are economic efficiency, cost recovery, efficient regulation, simplicity and transparency, non-discrimination. The Transmission Charges are made up of transmission connection charge and transmission charge of network. The Transmission Losses will be considered through Marginal Transmission Loss Factors in the market operation. The transmission loss rentals are used for the reduction of the annual revenue requirement of the transmission network for the purpose of derivation of transmission use of network charge.

The Distribution Network costs are currently part of the total cost of KEPCO covered through aggregated final consumer tariffs. There is no unbundling of Power Sale and Distribution Network activities. This situation will change with the introduction of competition in supply. The Distribution Network Service Providers will have to provide access and set explicitly Distribution Service Charges in order to enable the Power Sales Businesses to convey electricity to their consumers using the Distribution Network for these purposes. The Distribution Service Charges will be made up of Distribution Connection Charge and Distribution Use of Network Charge. The Distribution Losses will be considered through Distribution Loss Factors and included in the electricity purchased by the Power Sales Businesses.

전력에서 설치 운영되는 설비나 장치들을 감시, 제어하는 시스템은 산업 현장이나 기관에서 개발 운영하고 있다. 배전계통에서도 마찬가지이다. 배전선로에 설치된 개폐기나 리클로져 등을 감시, 제어하는 배전자동화시스템 배전반 등을 감시하는 전력감시 제어시스템 발전소나 대규모 수용가에서 사용하는 전력량이나 계량정보 등을 검침하는 원격검침시스템 등이 있다. 이 중에서 배전자동화시스템과 원격검침시스템을 연계함으로써 보다 효율적인 배전계통 운영을 수행하고 나아가 그 기반 시스템에 또 다른 수용가 정보 시스템 또는 배전정보 시스템을 통합함으로써 통합 배전정보 관리 체계를 가져갈 수 있다.

This paper presents methodology to evaluate interruption cost for determination of optimal reliability level. Recently, the power interruption cost is considered one of the useful index to determine optimal reliability level. Accordingly, in this paper reports estimation results of customer interruption cost to determine optimal reliability level by the economic macro method based on the 5 years from 1995 to 1999 and various kinds of customers in Korea.

Intensive competition in the electricity market and demand for higher quality service force the utilities to change their strategies in setting price and quality combination. As cost-up by homogeneously enhancing the electricity service quality may reduce their competitiveness, differential service is to be taken into consideration. Priority Service, which provides customers with a selection of service options at a range of prices and reliability for all or portions of their loads, has drawn attention from utilities in an increasingly competitive environment. Priority Service is to enlarge service options for customers who have diverse needs for supply reliability. This paper in the light of this point reviews differentiated strategy of power quality in the U.S.A.

The protection of underground cables against transient overvoltages resulting from lightning and other causes is important in cable-tine which is connected with overhead line and underground cable. This paper investigates the failure of CCPU(Cable covering Protection Unit) and presents improved configuration method of CCPU in underground cable system EMTP(Electromagnetic Transient Program) is used in order to study the overvoltages and modeling of components of the system such as overhead lines, underground cables, CCPUs and towers in presented.

This paper describes an improved analysis method for sheath circulating current on three-underground transmission cables using EMTP(Electromagnetic Transient Program). Author studied diversely the sheath circulating current on three-underground cables depending on the various length rate, the phase arrangement, and the grounding resistance of the sheath in the cross-bonded section. It was clear that very large circulating current is generated in cable systems due to unbalanced length rate and phase arrangement in the cross-bonded section. The analysing method for two or more underground cables will be really Improved for cable system utility.

The transformer role is very important in power system operation and control; also its price is very expensive. Therefore many kinds of the efforts for transformer protection have been executed. So for as, current differential relay(87) has been mainly used for transformer protection. But current differential relaying method has several troubles as followings. Differential current can be occurred by transformers inrush current between winding1 and winding2 of transformer when transformer is initially energized. Also harmonic restrained element used in current differential relaying method is one of the causes of relays mal-operation because recently harmonics in power system gradually increase by power switching devices(SVC, FACTS, DSC, etc). Therefore many kinds of effort have been executed to solve the trouble of current differential relay and one of them is method using ratio of increment of flux linkages(RIFL) of the primary and secondary windings. This paper introduces a novel protective relay for power transformers using RIFL of the primary and secondary windings. Novel protective relay successfully discriminates between transformer internal faults and normal operation conditions including inrush and this paper includes real time test results using RTDS(Real Time Digital Simulator) for novel protective relay. A novel protective relay was designed using the TMS320C32 digital signal processor and consisted of DSP module. A/D converter module, DI/DO module, MMI interface module and LCD display module and developed by Xelpower co., Ltd.

본 논문에서는 조류해석에 관한 내용을 웹으로 구현하여 학생들로 하여금 쉽게 학습할 수 있도록 하였고, 풍부한 하이퍼링크로써 궁금한 사항에 대한 즉각적인 On-Line 참조가 되도록 하였다. 웹 문서는 HTML 태그와 자바스크립트를 이용하여 작성하였고 동적이고 양방향적으로 구현할 수 있도록 하는 프로토콜로써 CGI를 사용하여 제공된 입력 데이터를 웹에서 수정해가며 직접 조류계산을 수행할 수 있도록 하였다. 또한 학습자가 결과를 얻고 싶어하는 전력시스템에 대해서는 File Upload를 통하여 결과를 확인할 수 있도록 하였다. File Upload를 위해 qDecoder-7.0 CGI 라이브러리를 이용하였다. 전력 방정식을 풀기 위해 사용된 산법으로는 고속 분할법을 사용하였으며, 모선 서열화와 스파스 프로그래밍 기법 등을 사용하였다. CGI 프로그램에는 C++를 이용하였다.

When a wide area blackout occurres, reenergizing transmission lines should be done at first. The KEPCO(Korea Electric Power Corporation) divides whole power system grid Into seven subsystem. This paper describes the investigation of facts, such as voltage rising and system stability, which occur in case that the blackstart plant of the Honam area will be displaced from Juam H/P to Seojingang H/P.

일반거주지역의 초고속 광가입자망 구축을 위해 B-PON(Broadband Passive optical network)시스템과 이를 위한 급전방안으로 공유급전이 고려되고 있다. 한곳의 Power-Node가 최대 32개의 ONU에 전력을 공급하기 위해서는 고 전위의 구동 source가 필요하게 된다. 고압실현을 위하여 검토되는 회로는 범용으로 사용되는 linear 방식보다는 SMPS(Switching Mode Power Supply)방식의 소형경량화의 회로를 채택하며, 고 용량화에 수반되는 역률 문제를 보상하고, 고효율을 실현하여 전체시스템의 전력밀도의 극대화를 이루었다.

This paper represents the application of the Static Var Compensator(SVC) on the electric railway power supply system. The purpose of the electric equipment can be summarized as to improve electrical power quality and to maintain the voltage. This paper shows that the SVC is necessary for voltage compensation in the railway power supply system and verify effectiveness of the SVC through the simulation. In this paper, the case studies were performed with the various line length and train position.

Nowadays, small scale DGS(Distributed Generation System), as a wind power generation or photovoltaic generation, becomes to be introduced into the power distribution system. But in that case, it is difficult to properly maintain the terminal voltage of low voltage customers. So, it is necessary to determine the permissible operation limit of the introduced DGS for proper voltage in distribution system. In this paper computes permissible operation limit of DGS when the DGS is connected to power distribution system using fixed tap(without LDC operation). For this simulation, KEPCO distribution system is used.

시스템의 통합 운용 및 네트워크화로 장비간의 간섭과 노이즈에 대한 완화 및 효율적인 제거는 매우 중요한 문제로 대두되고 있다. 본 논문에서는 서지 및 노이즈의 간섭을 최소화하는 접지시스템의 구축 방안을 연구하였으며, 이를 위해 현장의 대지저항률을 실측하여 컴퓨터 시뮬레이션을 통해 정량적으로 분석하고, 현장에 최적의 접지시스템을 구축하기 위해 주파수에 따른 접지 임피던스 특성을 시뮬레이션하였으며, 접지계통으로 유입되는 서지의 경로 및 주파수 특성을 분석하였다.

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.

The reliability and probabilistic generation production cost evaluation of composite power systems are important for power system operation and expansion planning. This paper present a computer program which can evaluate the reliability and probabilistic generation production cost of composite power system using GUI(Graphic User Interface). In this computer program, Monte Carlo simulation methods and CMELDC(CoMposite power system Effective Load Duration Curve) were used.

In this paper, the fault analysis program that is convenient to analyse fault records of a digital relay and to set a digital relay is described. The key feature of this fault analysis program is as follows. - analysing fault records stored in a local PC and/or a digital relay - analysing events - setting a digital relay. This program is for a digital bus protection relay using a conventional variable percentage current differential relaying algorithm. So this program adds a function analysing the characteristic of each variable percentage current differential function and the connection state of the transmission lines at double-bus system.

The two fuzzy criteria to distinguish the internal fault from the inrush for the power transformer protection have been identified. They are based on the terminal voltage, fundamental and second harmonic component of differential current. A systemetic way to determine the associated fuzzy membership function is also proposed.

Modern power systems are very complex and to model them completly is impractical for electromgnetic transient studies. Therefore areas outside the immediate area of interest must be represented by some form of Frequency Dependent Network Equivalent (FDNE). In this paper a method for developing FDNE is presented and demonstrated. The FDNE is generated by Linearized Least Square fitting the frequency response of a z-domain formulation. The advantage of this approach is that a direct implementation occurs which dose not incur errors due to discretization inherent with implementing a fitting function in the s-domain. The developed FDNE is accurate and efficient.

전력 계통의 운용 계획을 최적화 하기 위해서 수요예측에 관한 연구가 활발히 진행되고 있다. 기존의 수요예측 기법의 최대 오차는 특수일이 토요일과 월요일인 경우와 연휴인 경우에 발생한다. 이 중 특수일이 토요일과 월요일인 경우는 퍼지 선형회귀분석법과 상대계수법을 이용하여 우수한 결과를 도출한 바 있다. 구정과 추석은 특수일 중 평일과의 부하 차이가 가장 큰 특수일이며 약 $45{\sim}50%$ 정도가 감소된다. 이러한 부하의 감소 폭은 서서히 줄어서 연휴 당일 4일 후에는 완전히 복구가 되며 연휴 전 부하가 낮아지는 시점은 연휴 당일 3일 전이다. 연휴 예측의 불확실성은 연휴 기간의 길이 변동 및 기타 다양한 변수들에 의한 유동성에 기인한다. 특히 추석의 경우 과거 데이터 이용에 더욱 신중해야 하며 타 특수일에 비해 부하 값의 예측이 힘들다. 또한 직전 평일 대비 추석 연휴의 부하는 변화가 심하게 나타나며 본 논문에서는 퍼지 선형회귀분석법을 기본으로 변형된 알고리즘으로 향상된 예측도를 제시한다.

본 논문은 2003년 한전 실계통(154kV 강진 S/S)에 적용예정인 80MVA UPFC(Unified Power Flow Controller)시스템의 동적특성을 EMTDC/PSCAD를 이용하여 분석한 결과이다. UPFC는 FACTS 기기중 전압, 임피던스, 위상각등 전력전송 제어를 위한 송전선로의 모든 파라미터를 동시에 독립적으로 제어 할 수 있는 FACTS기기[1]로서, 미국 Inez S/S, Marcy S/S에 이어 강진 S/S에 80MVA 용량의 UPFC가 실계통 적용될 예정이다. 본 논문은 과도현상 해석 프로그램인 PSCAD/EMTDC를 이용하여 80MVA UPFC 제어기와 적용 대상 계통인 강진 S/S 인근 계통을 모델링하고 상정사고에 대한 UPFC 제어효과 분석에 대하여 기술하였다. 적용된 EMTDC UPFC모델은 실제 80MVA UPFC 기기에 채용된 전력회로, 제어기, 보호시스템과 동일하게 모델링하였으며 적용 대상계통은 PSS/E 해석결과와 동일하도록 강진 S/S인근 계통을 축약 등가화한 계통모델을 사용하였다.

This paper proposes an analysis of an permissible current-carrying capability of being installed transsmission power cables and distribution power cables simultaneously.

As we move to competition, transmission cost become more and more important. At the wholesale competition market, the process of settlement must include the cost of transport. The aim of this paper is to calculate approximate transmission cost at each power sales district office using KEPCO data. We considered investment cost, transmission constraints and marginal losses as cost elements which must be taken into account in transmission cost calculation.

최근 정보통신산업의 발전에 따른 첨단 정보통신기기의 사용증가와 정밀제어기기, 연속공정기기의 증가는 이전의 고전적인 품질규제나 신뢰도 규정보다 더욱 엄격한 전력품질 관리기준을 요구하고 있으며, 또한 전력산업구조개편을 통한 경쟁체제 도입은 전력품질을 기반으로 한 전력거래와 계약을 요구하고 있다. 본 논문에서는 이러한 전력품질을 측정하기 위한 계측 장비들의 최근 기술 동향 및 새롭게 대두되고 있는 전력품질 모니터링 및 알고리즘에 대해 살펴본다. IEEE 1159표준을 중심으로 한 전력품질 표준에 대해 살펴보고 이를 측정하기 위한 소프트웨어와 알고리즘을 분석하도록 한다. 마지막으로 현재 (주)LG산전이 공동 개발하고 있는 전력품질 분석시스템과 소프트웨어의 구조와 기능에 대해 살펴보기로 한다.

This paper presents a model for short-term load forecasting using relationship of temperature and load. We made one-day ahead load forecasting model using hourly normalized load and 11 dummy variables that were classified by day characteristics such as day of the week, holiday, and special holiday.

This paper presents a fault location algorithm using current distribution factors for distribution feeder systems. When a fault occurs in distribution system, an accurate fault distance is important for fast fault restoration. The proposed algorithm achieves a high accuracy using negative sequence circuit with various fault conditions.

Identifying the fault location has to deal with multiple possible candidates. It presents a new technique to diagnosis a fault region. The proposed diagnosis scheme identifies accurately the location based on the protective device operations and load current change at the substation. An Expert system is presented using these facts.

In general, the PSS/E program based on RMS mathematical models is used for analyzing the steady state and transient stability phenomena of full-scale large power system. Whereas, the EMTDC program unlike PSS/E, studies the specific reduced small-scale power systems as a basis of instantaneous value mathematical models and used to analyze the Electro-Magnetic transient characteristics. The PSS/E provides various control models such as exciter, governor, PSS models and TGOV5 model but there are few control models in EMTDC. In this paper, we developed EMTDC model for TGOV5 of a steam turbine and boiler which represents governor action, main, reheat and low-pressure effects, including boiler effects. The EMTDC model is developed by examining PSS/E control block and using User Define Model(UDM) in addition to default.lib provided by EMTDC. We verify the correctness of developed TGOV5 model with PSS/E and EMTDC simulation results using Governor Step(GSTEP) method.

This paper deals with the analytical approach for the reliability assessment in radially operated distribution systems. The existing indexes can consider the number and configuration of the load, but can not consider the characteristics of the load which is the one of the most important factor in the investment cost for the distribution systems. Therefore, This paper presents the new indexes considering the expected interruption cost for the load section and protection systems in the cafe where the Dispersed Storage and Generation Systems are introduced to distribution systems. And this paper shows the effectiveness of the proposed methods by simulating at the model systems.

전력계통의 조류계산과 고장계산은 전력계통의 운용과 해석 및 계획의 기반이 되는 산법으로 계속 연구 개선되고 있으며, 최근에는 컴퓨터 분야의 발달에 따라 소형 컴퓨터 레벨에서도 대규모 계통을 해석할 수 있는 소프트웨어들이 개발되고 있다. 본 연구를 통하여 퍼스널 컴퓨터 레벨에서 대규모의 실계통을 해석할 수 있는 소프트웨어를 개발하였다. 산법에는 조류계산과 고장계산 모두 어드미턴스행렬을 기반으로 하였으며, 스파스 프로그래밍 기법을 도입함으로서 대규모 실계통의 해석을 가능하게 하였다. 개발된 소프트웨어는 이미 전력회사에서 그 성능을 검증받은 PTI사의 소프트웨어인 PSS/E와의 입력자료 호환성을 갖도록 하였고 사용자의 접근을 쉽게 할 수 있는 그래픽 사용자 인터페이스 환경을 구현하였다. 개발된 산법의 성능을 검증하기 위하여 PSS/E 20모선 샘플계통, IEEE 샘플계통 및 한국전력 실계통에 적용하였다.

This paper describes an interactive educational software developed at Konkuk University. This software provides an educational opportunity for electrical engineering students at the junior level to expand their knowledge about fault analysis in power systems. The developed educational software has three main modules: 1) Z-building, 2) setting the type and location of the fault, 3) displaying the calculated fault currents, according to the given simulation options. The main features of this tool are the diversification of acquisition network data, the function of learning about the z-building procedures, and the dynamic display function of state vectors-all voltage/current phasor. To verity the effectiveness of the developed educational software, some case studies are performed.

This paper represents protective management system for transmission line involving the UPFC(Unified Power Flow Controller) device, which is the most vigorous component of FACTS. The presence of the UPFC significantly affects the line parameters of transmission system, which are also influenced by the distance relay setting. Moreover, depending on the UPFC location and its parameters, zones of setting the distance relay will be changed. Therefore, established protective system should be taken into account the variable injected voltage of the UPFC and constructed data base system.

전력계통 과도현상을 모의해석 하는 실시간 시뮬레이터의 경우 계통 요소들을 자세히 모델링하여 과도 현상을 모의해석 하는 것은 아주 높은 정도의 계산 부담을 치루어야 한다. 특히 이러한 시뮬레이터는 계통 크기의 제한을 가지므로 대규모 계통에 대한 과도현상 해석이 현실적으로 불가능하다. 이러한 이유로 시스템 해석시 중요하다고 여겨지는 부분만을 자세히 모델링하고 나머지 부분은 상대적으로 간단하게 표현하는 축약 계통의 가용이 요구되어진다. 본 논문에서는 국내에서 가장 널리 사용되는 PSS/E를 이용해 얻은 다이나믹 데이터를 축약계통 구성에 그대로 이용할 수 있는 지수를 개발하고 이를 K-Means 알고리즘에 적용시켜 coherent한 발전기 그룹을 식별하였다. 마지막으로 제안하는 방법의 타당성을 검토하기 위하여 IEEE New England 10기 39모선에 대한 계통 축약이 수행되었다.

계통의 최적 조류 계산(Optimal Power Flow)을 수행한 후, 계통 전체의 ATC(Available Transfer Capability)를 구한다. 이때 계통 전체의 ATC는 어느 특정한 선로의 ATC 값으로 결정되는데, 이 선로의 전력 조류량을 조금만 줄여도 전체 계통의 ATC가 크게 증가하게 되는 경우가 많다. 따라서 본 논문에서는 계통 전체의 ATC 증대를 위하여, ATC를 제한하게 되는 관심 선로의 조류에 각각의 발전기가 미치는 민감도와 각각의 발전기의 발전비용 함수를 동시에 고려한 최적의 발전력 재분배를 통하여 발전비용의 증가와 관심 선로의 전력 조류감소 효과의 최적화를 위하여 Liner Programing 기법을 이용한다.

This paper deals with single-phase unified power quality conditioner(UPQC), which aims at the integration of series-active and shunt-active filter. The series filter is used to compensate for the voltage distortions and the shunt filter is used to provide reactive power and counteract the harmonic current injected by the load. Also, the voltage of the DC link capacitor is controlled to a desired value by the shunt active filter. The performance of UPQC under load nonlinearities conditions is investigated using simulation as well as experimental results.

This paper is to introduce a more effective and flexible restoration algorithm composed to the fault preventing and restoring system now in use. This was possible by considering the changes that can occur by the proper or the improper run of the Feeder, which the power system restoration method now using didn't consider. The new algorithm uses the method minimizing the loss with respect to the load changes occuring when the power system is restored, rather than just simply following the SOP that is only composed of a single Feeder On/off combination. This can present the more effective power system running method for the safer subway running and passenger transport, by giving the system operator the chance to choose between the SOP and the minimum loss method.

송전선에 사고가 발생하면 계전기가 동작하고 여러 가지 후속 조치가 적절히 수행되기 위해서는 빠른 시간 내에 고장의 검출, 고장 종류의 분류, 고장 위치의 판정 등이 요구된다. 신경회로망을 이용한 고장 해석은 빠르고 정확한 해석이 가능하기 때문에 최근에 각광을 받고 있다. 본 논문에서는 기존의 코호넨 신경회로망의 지도 경쟁 학습 알고리즘을 개선한 새로운 학습 알고리즘이 제시된다. 제안된 학습 알고리즘은 전력계통의 송전선 고장 종류 분류에 적용된다.

본 논문에서는 전압 sag보상을 하기 위한 DSTATCOM 제어기를 설계하고 EMTDC/PSCAD로 확인하였다. DSTATCOM의 전류성분을 d,q분해 해석을 통하여 상태방정식을 유도하고 부하모델과 네트워크의 제약조건을 결합 모델을 제시하였다. 1선 지락 사고시 PI 제어시보다 LQR 제어의 응답 특성이 우수함을 검증하고 전압 sag가 개선됨을 보였다.

This paper describes the algorithm which can not only take account of voltage suability but also consider small signal stability. As for voltage stability both CPF and PoC methods are utilized to pinpoint the exact voltage collapse point. Then, using the converged load flow results full system matrix is configured and its eigenvalues are computed. The suggested algorithm is applied to the Two-area system, and verified its usefulness. In addition this paper also deals with the results of analyzing the two-area system in terms of voltage stability and small signal stability.

This paper presents a fast and accurate contingency analysis in EHV systems for line outages, loss of generation of redispatching and loss-of-load or load management. Unlike other contingencies, line outage requires the modification of the Jacobian of the base case power flow and the calculation of its new inverse, which is substantially different from the original inverse. In this paper, we obtain the inverse of the new Jacobian from the original inverse without repeating the time consuming matrix inversion process. Numerical test results show the significant improvement in the accuracies compared with those obtained using the original inverse.

Distribution systems is consist of network in physical and radial in electrical aspect. Therefore radial operation is realized by changing the status of sectionalizing switches, and is usually done for loss reduction in the system. In this paper, we propose a optimal method for distribution systems reconfiguration. Specifically we use genetic algorithm method to solve distribution systems reconfiguration for loss minimization problem. A genetic algorithm(GA) is set up, in which some improvements are made on string coding, fitness function and mutation pattern. As a result, premature convergence is avoided.

In this paper, an algorithm for fault location in Auto Transformer(AT) Feeding Railway system is presented. If a fault occurs at the AT feeding circuits of electrical railway system, it is very important to find fault location and to remove it immediately for the purpose of ensuring safety for transportation. Because the characteristics of reactance-distance are not linear, only using one terminal signals to give fault distance is difficult. In this paper, first, using the KVL, 4 voltage equation are obtained. Secondly, eliminating voltage a distance equation which consists of currents at rail and line parameters including mutual effects.

본 논문에서는 $\alpha-\beta-0$ 변환 방식을 이용한 제어방식을 모델화 하여 DSTATCOM에 적용하였다. 이러한 변환 방식을 통해서 배전 선로상에 존재하는 역상성분, 영상성분 고조파 성분 등을 나타낼 수 있으며 이에 대한 적절한 보상신호를 연산과정을 통해 생성해 낼 수 있다. 제안된 제어기의 검증을 위해 EMTDC/PSCAD를 이용한 IEEE 13 버스 배전 계통 모델링 및 유도기 부하 모델링 및 사고 모의 및 보상 시뮬레이션을 실시하였다.

In an electrical network, electrical power are transmitted by a various of protection, isolation and control electric circuit devices. This thesis deals with the protection function between circuit-breakers. The protective coordination concerns the behaviour of two devices placed in series in an electrical network, with a short-circuit downstream circuit-breaker. It has two basic principles: First, discrimination which is an increasing requirement of low voltage electrical distribution systems. Second, which is less well known: cascading, which consists of installing a device, whose breaking capacity is less than the three-phase short-circuit current at its terminals and helped by main circuit-breaker. The important advantage of cascading is to be able to install at a branch circuit-breaker of a lesser performance without endangering the safety of the installation for more economical usage. To determine and guarantee co-ordination between two circuit breakers, it is necessary to carry out a theoretical approach, first, and then confirm the results by means of standard tests. This is illustrated in appendix A of IEC 947-2.

The sharing of common corridors by electric power transmission lines and pipelines is becoming more common place. However, such corridor sharing can result in undesired coupling of electromagnetic energy from the power lines to the near facilities. During a fault on any of the transmission lines, energization of the earth by supporting structures near the fault can result in large voltages appearing locally between the earth and the steel wall of any nearby pipeline. This paper presents the outline of the tower footings for the transmission lines having been used in KEPCO and analyzes the earth resistance for operation method of the tower footing, that is contact presence for the anchor and reinforcing rob of the tower and foundation presence of the underground wiring.

본 논문에서는 극저주파 전자계 장해의 공학적 평가에 있어 기본이 되는 송전선 주변의 3차원 자기장 예측기법에 대하여 기술하였다. 송전선 주변의 무한영역 극저주파 자기장 계산을 위해서는 Biot-Savart's law에 의한 3차원 자기장 해석방법을 사용하였으며 교류자계 벡터의 중요한 파라미터인 elliptical polarized 특성에 대하여도 고찰하였다.

This study proposes a new method for the transmission system expansion planning using the fuzzy integer programming. It presents stepwise cost characteristics analysis which is a practical condition of an actual systems. A branch and bound method which includes the network flow method and the maximum flow-minimum cut set theorem has been used in order to proceed the stepwise cost characteristics analysis. Uncertainties of the permission of the construction cost and not strict reserve rate and load forecasting of expansion planning have been included and also processed using fuzzy set theory in this study. In order to proceed the latter analysis, the solving procedure is illustrated in detail by branch and bound method which includes the network flow method and maximum flow-minimum cut set theorem. Finally, case studies on 21-bus test system show that the algorithm proposed is efficiently applicable to the practical expansion planning of transmission systems in future.

The demand of the power and gas energy have been rapidly increasing with the industralization, therefore, the area where buried pipelines run parallel with the adjacent power lines and cross them increases in Seoul as well as other cities. These situation cause AC interference from the power lines. However, there aren't any standards to preserve the pipelines from AC interference in Korea. We just use other country's criteria directly. Other developed countries have used the various AC interference mitigation methods such as lumped grounding. cancellation wires and gradient control wires etc.. This paper introduces the steel plate method which is using for AC interference mitigation method in Korea and investigates the effects of mitigation methods through case study by computer simulation.

In this paper, an analysis of electromagnetic repulsion force is presented using 3D FEM considering eddy current. It is important for the optimum design of switching device to analysis electromagnetic repulsion forces generated by the interaction of the electric current and its own magnetic field on the closed electric contacts flowing over current. The validity of our analysis is confirmed by comparing analytic and experimental results.

The oscillation is very dangerous in bundled transmission lines. But we have no data for oscillation phenomena in real transmission lines. In order to develop the control method of the osculation, we need to know the amplitude and relations between winds and other conditions. So we observed and analyzed the oscillation in some 4 bundled lines, which have high failure rate. We try to suggest the oscillation phenomena of the 4 bundled lines. In the future we will try to observe and analyze the oscillation for developing protection methods of transmission lines from the oscillation.

In this paper, we present 2-step load cycle for daily load curve of up to and including 100kVA distribution transformer in domestic. Daily load patterns are classified by two methods dependent upon possession information. In case we possess daily load profiles make use of K-mean algorithm and in case we have not daily load profiles, make use of customer information of KEPCO. As the parameters of the load pattern classification, we use are daily load profiles and customer information of each distribution transformers. Data management system is used for NT oracle. We can present peak load magnitude, initial load magnitude and peak load duration for daily load patterns by 2-step load cycle for daily load curve of up to and including 100kVA distribution transformer in domestic. We think that this paper contributes to enhancing the distribution transformer overload criterion.

In this paper, we developed the fault diagnostic expert system of silicone-immersed transformer using dissolved gas analysis. The knowledge base module consists of the knowledge using the rule: if Then . The inference engine uses the fuzzy rule for the management of uncertainty of the boundary and rule and derivate the Belief and Plausibility of the normality and fault using Dempster-Shafer theory. The expert system is connected to the database and it can manages the history of gas-data of the transformer.

Contamination flashover is responsible for insulator electrical failures. Particularly, in Korea, with its perennially dry spring, the first spring rain often cause serious line outages by forming a conductive liquid film on the insulator surface. Rainwater and fog are not normally conductive but unfortunately atmospheric dust deposited on the insulator surface contains soluble salts which may lead to bad condition of insulation by combining watery and salts. Transmission design engineers have used a contamination map drawn on the traditional paper map. But it is not convenient because it does not include the information of Geographic Information accurately. This paper explains the newly developed salt contamination map program using Geographic Information System, which provide accurate geographic information. The program is designed to use four parts of datum, salt contamination levels, 345kV & 154 kV transmission lines, power plants & substations and background map. The digital background map is composed of raster files, the others are done by vector map.

This paper describes the protection of insulation joint box in combined transmission line which is connected with the 154kV underground power cables. An actual power cable system was selected to establish modeling and to analyze. Modeling was established in EMTP and ATPDraw. Simulation was carried out according to the buried method of cable and connection method of CCPU. Results presented in this paper will be applied to another power cable systems.

Distance relay is tripped by the line impedance calculated at the relay point. Accordingly the accurate operation depends on the precise calculation of line impedance. Impedance can be accurately calculated in case of overhead line. However, in case of power cables or combined transmission lines, impedance can not be accurately calculated because cable systems have the sheath, grounding wires, and cable cover protection units (CCPUs). There are also several grounding systems in cable systems. Therefore, if there is a fault in cable system, these terms will severely be caused much error to calculation of impedance. Accordingly the proper compensation should be developed for the correct operation of the distance relay. This paper presents the distance calculating algorithm in combined transmission line with power cable using wavelet transform. In order to achieve such purpose, judgement method to discriminate the fault section in both sections was proposed using db1 coefficient summation. And also, error compensation factor was proposed for correct calculation of impedance in power cable.

The experiments were performed in model conductors under the application of ac and dc high-voltages. The results of an experimental investigation into the flashover characteristics of air dielectric strength in the presence of oil/gas flame are reported. It is demonstrated that flame can reduce by more than half, 80% in maximum the breakdown voltage of a model line. Taking a horizontal model line with a k=0.5, it can be seen from the results that the reduction of flashover levels, in comparison with the no-flame case, are 78.7[%] for h=0[cm], 59.6[%] for h=3[cm], 46.4[%] for h=6[cm], 40.4[%] for h=9[cm] and 23.2[%] for h=12[cm] when ac voltage is applied.

Occurring forest fire or burning bushes beneath overhead transmission lines have caused system disturbances in many countries. In this study, various tests in the simulated condition of power lines were conducted so as to investigate the reduction in insulation strength caused by combustion flame. The results of an experimental investigation into the flashover characteristics of air dielectric strength in the presence of oil flame are reported. It is demonstrated that flame can reduce by more than half, 80% in maximum, the breakdown voltage of a model line.

Recently, the increasing need for internet and the activation of hiring business of communication line makes the demand for OPGW cable which can construct the optical communication network in the basis of existing overhead power transmission line. Especially, the demand is focused on the high fiber count OPGW due to high capacity transmission. In step with the trend toward high fiber count cable we have developed the Stainless Steel Loose Tube type OPGW within which have 144core firstly in KOREA. This paper describes the cable design and manufacturing process which gives the stable operation in very severe conditions and the long-term reliability test results conducted in according to dominant specification IEEE Std. 1138-1194.

In this paper, 3-dimensional charge simulation method was applied to analyze electric field distributions of special conductor bundles equipped with spiral rods for reducing aeolian noise in a corona cage. Comparing electric field distributions of special conductor bundles in 765kV transmission tine with ones in corona case, we decide experimental voltages of special conductor bundles in corona cage.

This paper presents the detection method of partial discharge in metal clad switchgear(MCS) using electromagnetic technique. Two antennas are located in the inside and outside of the MCS, and electromagnetic waves detected by these antennas are analyzed and compared by FFT method in order to identify an insulation abnormality. As a result of the experiment by the proposed method, we show the detection possibility for partial discharge in the MCS. The proposed method is expected to apply to insulation condition observation and an accident prevention in the MCS effectively.

For 4-conductor bundle transmission line spacer damper are equipped so as to keep the spacing between sub conductors. For 4-conductor bundle the subspan spacing of a spacer damper is determined and applied in order that the bundle may get restored to a normal state when 4-conductor bundle is rolled by rigid body vibration due to wind. But 4 conductors of 345kV 4-conductor bundle transmission line were twisted by the angle of $315^{\circ}$ for the first time korea. In this paper, we will analyze the reason of the power line twisting of 4-conductor bundle which occurred for the first time in korea and offer the preventive countermeasures for this

This paper discusses on an optimal bidding strategy of a generator in a competitive electricity spot market using the information of predicted spot price with some assumptions. Optimal bidding strategy of a generator is derived by solving a profit-maximizing optimization problem with a constraint where the forecasted spot price is treated as a constant value. The main advantage of this methodology is that the optimal bidding strategy of each generator can be obtained independently where the gaming characteristics of generators are merged into the forecasted spot price.

This paper presents the results of power flow of North-South Korea system with interconnected cases which were proposed by various present studies PSS/E and PowerWorld Simulator were used to analyze the inter connected system with several interconnected lines alternatives. The results would be very useful to select the best alternative for interconnection with considering several evaluation terms.

본 연구에서는 경쟁적 전력시장에서 발전 사업자들이 송전망 이용료를 지불하는 방법론을 개발하고 계산하였다. 이는 현재 호주에서 시행하고 있는 부하를 중심으로 한 송전요금제도와 관련된 방법론으로서 기존의 부하에 대한 알고리즘을 변형하여 유도하였다. 현재 호주에서는 발전사업자들에 대한 송전망 이용료를 부과하고 있지는 않지만, 발전사업자에게 위치적 가격 신호를 제공하기 위해서는 적절한 가격을 부과하는 전략이 필요하다. 제안된 방법론은 샘플 및 우리나라 실계통에 적용하여 부하에 대한 송전요금 방법론의 결과와 비교 분석하였다.

Restructuring of electricity industry is going on for the purpose of introducing competition and after separation of generation and retail business and introduction of competition, substantial change is expected in overall electric power system. In other words, DSM projects are divided with public projects and private projects. Particularly for public project, it is essential to evaluate the DSM volumes by program. This paper tries to derive the ways for achieving the necessary DSM goal in the electricity industry in Korea. First of all, by analyzing the load in Korea, we forecast the standard demand and estimate the technological potentials of each program in considering DSM technological indicators. Moreover, by using economic analysis by program, we estimate economic potentials and finally, we estimate the potentials by program in considering the DSM policy. We estimate the potentials by using random method because application methodology and procedures by program are not established until now, which leads to not obtaining transparency for implementation effect by program. Therefore, this paper estimates the future potentials of DSM projects by using the logical and systematic analytic method and establishing database for DSM basic indicator. The DSM goals estimated by this method will be reflected to mid/long term nation-wide resource planning, which will mitigate anticipated power supply shortage and be applied to derive desirable energy demand/supply structure.

The methodologies of power transmission pricing are normally divided into two categories such as marginal cost method and embedded cost allocation method. This paper, first, discusses the possible problems that can occur when the marginal cost method is applied to pricing the transmission services. Next, the paper proposes a method to apply the power flow tracing to the transmission network charge. The result of the power flow tracing method is then used in MW-mile method to charge individual loads for the use of transmission network. Effectiveness of the algorithm is verified by computer simulations.

The vertically integrated power industry was divided into six generation companies and one market operator, where electricity trading was launched at power exchange. In this environment, the profits of each generation companies are guaranteed according to utilization of their own generation equipments. This paper represents on generator maintenance scheduling and efficient bidding strategies for generation equipments through the calculation of the contract and the application of each generator cost function based on the past demand forecasting error and market operating data.

This paper proposes a special-day load forecasting method with the characteristics of temperature based on fuzzy linear regression. We can obtain a linear regression model from the relation between daily peak load and daily maximum or minimum temperature. Simulation results show that the proposed method can improve an accuracy of a special-day load forecasting.

The change of the electricity charge from cost base to price base due to the introduction of the electricity market competition causes consumer to choose a variety of charge schemes and a portion of loads to be affected by this change. Besides, it is required the index that consolidate the price volatility experienced on the power exchange with gaming and strategic bidding by suppliers to increase profits. Therefore, in order to find a mathematical model of the sensitively-responding-to-price loads, the price-sensitive load model is needed. And the development of state-of-the-art technologies affects the electricity price, so the diffusion of high-efficient end-uses and these price affect load patterns. This paper shows the analysis on learning curves algorithms which is used to investigate the correlation of the end-uses' price and load patterns.