2002.07a
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If a fault occurs in the DC railway system, it is important to find fault location and to remove it immediately for prompt repair. The aim of the present paper is to locate the position of the fault by using Kirchhoff's voltage law(KVL). The DC railway system is simulated using Power System Blockset(PSB) in Matlab Toolbox.
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J.S., Jun-Seok;Lee, S.J.;Choi, M.S.;Kang, S.H.;Kim, S.T.;Lim, S.I.;Oh, S.M.;Kim, J.K.;Park, S.J. 6
In this paper present Autonomous Adaptive Digital Over Current Relay which acts autonomous setting using voltage and current measured by relay in the change of power systems. Automation of relay setting is required for distribution automation although manual relay setting is used at present. This paper presents Autonomous Relay Setting which knows change of the power system and acquires setting element using the Recursive Least Squares. Relay setting is very difficult work. But proposed relay is expected to decrease burden of relay setting using acquired information of power system change and autonomous setting. Also fast protective ability is expected according to change of power system. -
This paper proposes a percentage current differential relaying algorithm for bus protection using an advanced compensation algorithm of the secondary current of CTs. A percentage current differential relaying algorithm may maloperate in case of external faults with CT saturation. Thus, it needs an additional method to cope with CT saturation. The advanced compensation algorithm is unaffected by a remanent flux. The proposed relaying algorithm does not need any additional methods for CT saturation and is unaffected by the remanent flux and has the wide operating zone of current differential relays.
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Cho, Seong-Jin;Choi, Myeong-Song;Hyun, Seung-Ho;Kim, Joung-Wook;Lee, Joo-Wang;Cho, Bum-Sub;Yoo, Young-Sik 12
Korea Power System Protection Setting Rule was used from the rectify 1990's. Thereafter transmission voltage is raised the voltage into 765kV, and introduction to new technology of Power System, and was many of variation but, it is using. The present is using Digital type distance relay for 765kV transmission line protection. If impedance value of transmission line were to value lower than setting, this would be operating and relay setting rule is for 85% into Zone 1 self section, and Zone 2 is a 125%, Zone 3 is a 225%. Which's$15{\sim}25%$ include current transformer error 5%, potential transformer 5%, relay calculation error 5% and margin factor from the field experience. This paper is discussed transmission protective relay and relay setting rule of high voltage power system and we verify the correctness relay setting rule with distance relay using Matlab simulation. -
This paper proposes a difference-blocked current differential relaying algorithm for power transformers. The proposed algorithm observes that the shape of the differential current is changed using the difference. If the change is detected, output of current differential relay is blocked for a certain time. In this way, the algorithm distinguishes internal faults from magnetizing inrush. The proposed algorithm uses only currents and is unaffected by the remanent flux.
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This paper presents a power transfer capability calculation algorithm Considering Voltage Stability Margin. In this method, voltage stability margin constraints are incorporated into a power transfer capability formulation to guarantee adequate voltage security levels in interconnected Power System. The proposed method is applied to IEEE-24 Reliability Test Systems and the results shows the effectiveness of the method.
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This paper introduces the real-time soil thermal property analyzer and temperature measuring system which is combined with radio telecommunication technique. To measure the thermal parameters in real-time, the radio telecommunication technique are used the personal communication service (PCS) which is in the world-wide serviced commercially firstly by CDMA. The thermal property analyzer has an ability of measuring thermal resistivity, thermal diffusivity and thermal stability. To estimate the soil thermal properties, the curve fitting algorithm by means of the least square method are used. TCP/IP protocol and MTM are used to install the real-time soil thermal property and temperature measurement system at multiple locations along routes of the underground power cables and to reduce the cost of telecommunication.
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This paper describes a new economical voltage sag and swell generator suitable to the evaluations of high power custom power devices such as DVR (Dynamic Voltage Restorer) and DSTATCOM (Distribution Static Compensator). This system was designed to generate the several power quality disturbances in MVA power ratings - voltage sag and swell, under voltage, over voltage and harmonic distortions. The basic idea for voltage sag and swell is to use the voltage drop across a reactor, while the voltage swell is to use the step-up transformer and the TCR(Thyristor Controlled Reactor). In this paper, two identical 3 phase TCRs and a step-up transformer with tap changer are used. Additional harmonic filters are added to reduce the voltage distortion when TCRs are operated. Simulation results are given for several cases of voltage sag and swell generations.
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The increasing application of electronic equipment has heightened the interest in power quality in recent years because there are economic impacts on utilities, customers, and suppliers of load equipment. The power quality would impose result in severe damage on many industrial customers. As having been supplied many kinds of electronic devices such as computer and communication equipment, automation equipment and various kinds of control devices etc., it comes to be more and more difficult to maintain the clean power quality. According to the restructuring in electricity industry the power quality may be treated as goods as contract terms and regulation elements between power supplier and consumer in the near future. Under the above environment, the power quality should be monitored for all day long with appropriate devices which is possible to measure and record the associated power quality data to prove each responsibility for the impacts when disputes arise due to power quality problems power quality problems are occurred. In this paper the authors propose some functions to be considered and system configuration to monitor the associated power quality elements in developing the web based power quality monitoring system.
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It studied modelling about employing analog PSS in domestic 500MW grade standard thermoelectric power plant in this paper. Modeling and parameters were verified by simulation of PSS response characteristics measured in AVR step examination and using power plant system model parameters decided by generator characteristics test. Through this PSS modelling research, contributed in domestic electrical power system small signal stability as that do modelling to be possible exact analysis of power system.
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한전계통의 구조는 원거리 발전단에서 부하 밀집지역인 수도권 지역으로의 장거리 송전을 하고 있다. 본 논문에서는 765kV 송전선로 신가평-신태백 2회선 상정사고에 대하여 수도권 및 인근지역에 대한 순동 무효전력을 확보함으로써 계통 전압을 0.96 p.u - 1.03 p.u 사이로 전압안정도를 유지할 방안과 순동 무효전력 투입위치와 투입량 산정방안에 대하여 모의 연구하였다.
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A study on the test method and the test facilities of synthetic capacitive current tests have been very slight and the direct test method with the short-circuit generator and power transformer only used up to now. However, according to the development of analysis technique of power system and design and manufacture technique we are realized that direct testing method is not satisfactory to evaluate the performance of circuit-breaker because it is difficult to simulate precisely the conditions of power system. Therefore, in order to solve these problem this paper deals with the tests methods and the design technique of the tests facilities of the synthetic capacitive current based on the same theory with the synthetic short-circuit tests.
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전력계통 해석의 정밀도 향상을 위해서는 배전용변압기 1차측 기준의 정확한 부하역율 데이터 입력이 요구되나, 현재 역율산정을 위한 유 무효전력 측정설비가 변압기 2차측에만 설치되어 변압기 자체에서 소모되는 무효전력에 대한 보다 정확한 고려방법 모색이 필요하다. 이와 관련하여 본 고에서는 변압기 OLTC 변화에 따른 소모 무효전력 변화량 고려방법, 변압기 2차측 유, 무효전력 측정치 및 조상설비 운전실적 등 제반 요소를 고려한 변압기 1차측 기준의 역율 산정방법을 제시하고, 현재 우리계통에서 운전되고 있는 154kV 전 변전소 전 변압기 및 154kV 직거래고객에 대하여 계절별, 요일별, 시간대별로 총 44개 케이스의 부하역율 특성분석 결과를 이용 계통해석시 적용되는 부하데이터의 정밀도 향상방안과 부하역율 변경 적용시 계통해석 결과에 미치는 영향 등에 대한 우리나라 실 계통 대상 모의 결과를 다루었다.
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Service restoration following a complete or partial collapse starts with reenergize a transmission line from black-start generators. Voltage problems can arise by Ferranti effect as unloaded transmission line is reenergized. This paper presents analytical results on the primary restorative transmission system focused on the voltage problem during the early restoration process. Methodologies to handle load pick-up compensating Ferranti effect. and terminal voltage and reactive capability limitation of black-start generators about self-excitation are presented. An algorithm for static analysis about these methodologies is developed, and EMTDC simulation for verifying the efficiency of the algorithm is performed.
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현재 플리커 및 고조파는 전기공급약관의 송전용 전기선비 성능기준에서 전압품질유지 기준을 지정하여 운용하고 있다. 그러나, 전력시장 체제 하에서 전력품질은 그 자체의 상품성을 가질 것으로 예상이 되고 있으므로, 현재 우리나라의 플리커 및 고조파 실태를 조사 분석하여 이에 대비할 필요성이 있다. 본 논문은 우리나라 154kV 선로에 직접 접속하여 수전하고 있는 대형 수용가 단에서 플리커 및 고조파를 측정하여 현재의 실태를 파악하고, 이를 근거로 적정 규제 방안에 대해 논하고자 한다.
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GPSS(Graphic-based Power System Simulator) had been introduced before in an ex-thesis. GPSS is a Power System Simulator that is designed to provide friendly and highly interactive Graphic User Interface (GUI). In this Paper, GPSS was improved not for the education or the test, but as the instrument for a large-scale systematic analysis. To limit the difference between a theory and practical affairs, we reformed and added a lot of functions to the GPSS. And we have verified the real-systematic data.
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This paper presents a part of system study results for UPFC Pilot Plant application in Korea. The system study includes control limits of UPFC Pilot Plant. Expansion of control limits is studied by coordination to switched shunt capacitors in local areas. The system study is simulated by PSS/E Ver 26.
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전력계통에 대규모 발전단지가 증가함에 따라 송전선로의 전압 격상 및 송전선로 용량증대로 대처하고 있으나 중조류 선로가 고장시 인근계통에 미치는 영향이 커 이에대한 대책으로 상정고장에 대비하여 한계치를 설정하여 운영함에 따라 계통제약이 발생된다. 본 논문에서는 발전력이 집중되어있는 개소의 상정고장 시 전압안정도를 향상시키기 위한 여러 방안중에서 발전기 차단에 의한 계통전압 향상방안을 실계통을 통해 모의함으로서 전압향상 및 전력조류 운영한계치 증가등을 통해 경제적인 계통운영방안을 제시하였다.
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Before a developed digital Power System Stabilizer(PSS) is installed to real power system, an efficient trial test for installing PSS is needed. In this paper, the performance of developed digital PSS for a single hydro-turbine generator and infinite bus system has been investigated using Real Time Digital Simulator(RTDS) in order to install PSS to real power system practically. The test system was composed of RTDS, three phase voltage/current amplifier and the PSS and the test scheme provided a very efficient way to verify the design and control performance of a PSS to be applied to real power system. The trial installation test through AVR 3% step test and three fault analysis may be guaranteed to install PSS to real power system.
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본 논문에서는 북한 및 남한의 수도권 지역을 중신으로 한 부하집중지역들의 전력 부족을 해결하기 위한 대안으로서 신포에 세워질 2000MW의 원자력을 이용할 수 있는 방안을 검토하고자 한다. 특히 남한은 향후 계측적인 전력 수요의 증가로 인한 발전력의 부족을 해결할 마땅한 대책이 없으리라 여겨진다. 이러한 문제에 있어 해결책은 첫째로 북한의 2000MW KEDO 원전에서 북한의 일부 부하집중지역 (특히 평양주변)에 공급하면서 남한의 수도권지역에 전력을 공급하는 것이 가능한 대안 중의 하나로 여겨진다. 본 논문에서는 KEDO 원전의 전력을 흘려보내기 위한 시나리오 작성 및 진력 조류흐름을 파라하는 것을 목적으로 한다. 시뮬레이션은 미국 PTI사의 PSS/E 패키지를 사용하였으며, 조류 계산을 하여 그 결과를 전력흐름도로 작성하고 비교 검토하였다.
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This paper presents the statistical analysis of the circuit breaker's making current in large sacle industrical loads using EMTDC. Typically, the making current includes DC components as the phase angel of making instances varies and represents as a instantaneous valus not rms. Consequently, in this paper, the statistical analysis results of making current and steady state fault current for typical industrial loads presents.
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Utilities are trying to install the equipment of high quality to avoid deterioration of supply reliability. In addition, many sectionalizing switches which can decrease the total outage value for a fault are installed for the same reason. Therefore, utilities are interested in standards and criteria for installing switches to optimize the total cost on distribution systems. The affect of sectionalizing switches installed on distribution feeder is gradually decreased because the failure rate on distribution feeder is decreased. Also the automation for distribution systems is widely applied for the efficient operation. Therefore, the renewal for installation standards of sectionalizing switches is required to reflect the current operation situation. The variable data is used to consider the KEPCO's real situation of distribution feeder as follows; the feeder capacity, connecting rate, feeder length, failure rate of distribution feeder, the failure rate of switches, perception time of feeder fault, the restoration time for a faulted section, the transfer time to other feeders, and the switching time. In this study, We propose equations which can determine the number of sectionalizing switches for minimizing the outage and switch installation cost.
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In this study, We propose equations which can determine the number of sectionalizing switches for minimizing the outage and switch installation cost.
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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.
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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.
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This paper presents a new approach using an Improved branch exchange (IBE) technique to maximize the voltage stability as well as loss minimization in radial power systems. A suitable voltage stability index (VSI) for optimal routing algorithm is developed using novel methods both a critical transmission path based on a voltage phasor approach and an equivalent impedance method. Furthermore, the proposed algorithm can automatically detect the critical transmission path to be reached to a critical load faced with voltage collapse due to additional real or reactive leading. To develop an effective optimization technique, we also have applied a branch exchange algorithm based on a newly derived index of loss change. The proposed IBE algorithm for VSI maximization can effectively search the optimal topological structures of distribution feeders by changing the open/closed states of the sectionalizing and tie switches. The proposed algorithm has been tested with the various radial power systems to show its favorable performance.
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The SVC(Static Var Compensator) resulted from the FACTS technology can generate or absorb reactive power rapidly so as to increase the transient and voltage stability. In this paper, the SVC is applied to the power system in order to improve the total transfer capability from a viewpoint of static voltage stability and the effects of application of the SVC to the power system are analyzed. The IPLAN, which is a high level language used with PSS/E program, is employed for determining the total transfer capability.
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This paper presents the design of a Unified Power Flow Controller(UPFC) for enhancing the small signal voltage stability in the multi-machine power systems. Recently a lot of attention has been paid to the subject of dynamic stability. The paper deals with analysis of eigenvalue sensitivities with respect to parameters of UPFC Controller. The series branch of the UPFC is designed to damp the power oscillation during transients, while the shunt branch aims at maintaining the bus voltage. Comprehensive time-domain simulation studies using Pss/E show that the proposed robost UPFC controller can enhance the small signal stability efficiently in spite of the variations of power system operating conditions.
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A 765kV Transmission line system plays an important role in delivering the electric power produced at mid-western in Korea. This system will be constructed and operated normally on 2002. By doing the number of test operation in a given time, the reliability on the operation of 765kV transmission system could be secured.
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This paper is to introduce the R&D project called "System Protection with emphasis on Power System Stability". The principal objective of this project is protection aids to system stability. The objects of this project arc as follows. First, drawbacks of classical under frequency load shedding and implementation issues of the rate-of-change of frequency will be described. Secondly, the project discusses the possibilities of voltage instability in power system and how this risk will affect protective relays in real system. Lastly, special protection system is designed to preserve system stability for KEPCO.
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시각 동기화된 계통 운전데이터를 이용하여 계통의 안정성을 실시간으로 감시, 분석하는 전력계통 온라인 안정성 감시, 분석시스템을 개발하였다. 개발된 시스템은 대용량 발전소와 주요 345kV 전력소에 설치되어 GPS를 이용한 시각 동기화 된 계통 운전데이터를 측정하고, 지역사고 판단 및 사고데이터를 기록하며, 측정/기록데이터를 Master 시스템으로 온라인 전송해주는 Local 시스템과 각 Local 시스템에서 전송되어진 측정/기록데이터를 수집하고, 광역사고 판단 및 사고데이터를 기록하며. 과도안정도를 온라인으로 평가해주는 Master 시스템으로 구성되어 있다. 전력계통 온라인 안정성 감시, 분석시스템 중 Local 시스템은 울진, 영광, 고리 원자력발전소와 동서울, 신제천, 청양, 아산, 신옥천 전력소 등 8개소에 설치하고, Master 시스템은 한국전력거래소(KPX)에 설치하여 우리 계통의 안정운용을 위해 활용할 예정이다.
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This paper presents a algorithm for contingency ranking using the real power ratio. The fundamemtal cause of voltage collapse is considered due to excessive power trnsfer through the line. To obtain contingency ranking, maximum real power tansferred to the load is obtained when load impedance
$Z_r$ equal to line impedance$Z_s$ . This algorithm is verified by simulation on a 6-bus test system. -
In this paper, a fault location algorithm is suggested for line to line faults in distribution networks. Conventional fault location algorithms use the symmetrical component transformation, a very useful tool for transmission network analysis. However, its application is restricted to balanced network only. Distribution networks are, in general, operated in unbalanced manners, therefore, conventional methods cannot be applied directly, which is the reason why there are few research results on fault location in distribution networks. Especially, the line to line fault is considered as a more difficult subject. The proposed algorithm uses direct 3-phase circuit analysis, which means it can be applied not only to balanced networks but also to unbalanced networks like distribution a network. The comparisons of simulation results between one of conventional methods and the suggested method are presented to show its effectiveness and accuracy.
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In general, it is supposed that load characteristics of high and low voltage distribution line are always coincidence. But in practical distribution system, voltage variation characteristics of high and low voltage distribution line are not same. Then in this paper, we proposes a voltage regulation method considering load variation characteristics of high and low voltage distribution line in distribution system.
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Voltage drop of low voltage distribution line is closely related with proper voltage regulation. It depends on the voltage drop of pole transformer, low voltage distribution line, and low voltage customer entrance line. Using above voltage drop factors, we proposes an estimation method of voltage drop in low voltage distribution line. Proposed method has been applied to a 22.9kV practical distribution system.
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In this paper, we preposed a chaos optimization method to reduce computational effort and enhance optimality of the solution in feeder reconfiguration problem. Chaos method in optimization problem searches the global optimal solution on the regularity of chaotic motions and more easily escapes from local or near optimal solution than stochastic optimization algorithms. The chaos optimization method is tested on 15 buses and 32 buses distribution systems, and the test results indicate that it is able to determine appropriate switching options for global optimum configuration with less computation.
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The general capacitor placement problem is a combinatorial optimization problem having an objective function composed of power losses and capacitor installation costs subject to bus voltage constraints. In this paper, the method employing the chaos search algorithm is proposed to solve optimal capacitor placement problem with reducing computational effort and enhancing optimality of the solution. Chaos method in optimization problem searches the global optimal solution on the regularity of chaotic motions and easily escapes from local or near optimal solution than stochastic optimization algorithms. The chaos optimization method is tested on 9 buses and 69 buses system to illustrate the effectiveness of the proposed method.
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This paper presents a fuzzy-GA method to resolve dispersed generator placement for distribution systems. The problem formulation considers an objective to reduce power loss costs of distribution systems and the constraints with the number or size of dispersed generators and the deviation of the bus voltage. The main idea of solving fuzzy nonlinear goal programming is to transform the original objective function and constraints into the equivalent multi-objectives functions with fuzzy sets to evaluate their imprecise nature and solve the problem using the proposed genetic algorithm, without any transformation for this nonlinear problem to a linear model or other methods. The method proposed is applied to the sample systems to demonstrate its effectiveness.
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Because of the continuous growth of energy consumption and also the tendency to site power lines and pipelines along the same route, the close proximity of power lines and buried metallic pipelines has become more and more frequent. Therefore there has been and still is a slowing concern about possible hazards resulting from the influence of power lines on metallic pipelines. Underground pipelines that run parallel to or in close proximity to power lines are subjected to induced voltages caused by the time-varying magnetic fields produced by the power line currents. The induced electro- motive force cause currents circulation in the pipeline and voltages between the pipeline and surrounding earth. This paper analyzes the induced voltage on the gas pipelines buried in parallel with 22.9kV distribution lines. Their magnitude depends on the length of parallelism and on the distance between distribution lines and pipeline.
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It is raised for methodology to evaluate power system reliability using interruption cost which is converted customer loss due to interruption into cost according to power industry is rushed into competition appearance. This paper presents algorithms to evaluate reliability of distribution power system taking into consideration customer interruption cost. Customer interruption cost is considered as one of the valuable index to estimate reliability of the distribution power system from customer situation. Also. this paper estimate evaluation results regarding the reliability of distribution power system using a sample model system. Finally, evaluation results of unserved energy and system interruption cost based on customer interruption cost are shown in detail.
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In this paper, we propose the analysis method of the Double Circuit Simultaneous Fault. To improve the accuracy and the promptness of the coontingency analysis, we reformed the Peterson method and extended the Sherman-Morrison equation. We also used the table of trigono -metric factor of Jacobian matrix before the fault, to compute the inverse matrix needed in the loadflow calculation.
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This paper describes a new contingency analysis methods for small signal security assessment based on the eigenvalue perturbation. The eigenvalue perturbation with respect to MW changes can be used to find possible sources of the low frequency oscillation, and to select contingency for small signal stability. The proposed algorithm has been successfully tested on the KEPCO systems.
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전력계통망의 부하 구성에서 발생되는 갑작스런 변화는 계통의 부하 중심 사이에 전력 동요를 일으키게 되는데 계전기가 설치된 점에서 전압, 전류, 임피던스, 유효. 무효전력의 측정되는 전기량은 위상각
${\delta}$ 의 함수로 변화한다. 그러한 조건에서 거리계전기의 오동작을 방지하기 위해 계통동요 방지 장치가 자주 이용된다. 종래의 계통동요 방지 장치는 이러한 전기량의 변화로 응동 되었다. 그러나 이런 방법은 빠른 계통 동요에 대처하지 못하고, 고저항 지락 같은 고장에는 장시간지연을 피할 수 없게 된다. 본 논문에서는 계통 동요시 여러고장 식별을 위해 계전기에 직교웨이브렛(WT)을 도입하여 동요시 고장을 구별하는 방법을 제시한다. -
In this paper, the improved fault locating method using distributed parameter which calculating the reduced voltage and current according to the ground capacitance in long transmission line was proposed. For the purpose of the fault locating algorithm non influenced source impedance, the loop method was used in the system modeling analysis. To enhance the fault locating, zero sequence of the fault current which is variable according to ground capacitance was not used but positive and negative sequence. System model was simulated using EMTP software. To verify the accuracy of proposed method, in different cases 64 sampled data per cycle was used and 160km and 300km long transmission line has fault resistance
$0{\Omega}\;and\;100{\Omega}$ respectively was compared. -
Recently the demand for electrical power is significantly increased due to the life improvement of customers. Correspond to the result, the transmission capacity is larger, also the fault current is significantly larger. Within the methods of limiting this fault current, the methods of using the fault current limiter is on the rise. If the Superconducting Fault Current Limiter(SFCL) is applied, then the power delivery loss doesn't exist between the plural power systems, also the fault current can be reduce. But for applying the real system, it needs to investigate the effect of SFCL before appling to real power systems. Consequently, the fault of transmission with SFCL was simulated using EMTP. It was investigated to the effect of SFCL at the 345[kV] transmission fault according to compare with the case of appling SFCL and removing SFCL.
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This paper proposes a concept for fault diagnosis system based on the relay coordination to deal with unavoidable uncertainties imposed on fault dignosis of substation. This system uses information on the relay setting values and tripped data to identify the faulted element of power system. The proposed concept will be very useful and efficient for substation and control center operator.
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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. This study introduces the separation distance to protection of buried pipeline from arc strikes caused by power line ground fault current. And this study examines and compares the arc distance through case study.
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In this paper, we analyze about voltage sag effect at load side during fault according to change of power system condition. through the case studies, we find that there is no close connection between substation bus transfer and voltage sag during fault. however, we find that other feeder connecting with the faulted transmission is directly affected by fault type and magnitude, therefore, the main subject can be divided into the utility and customer side countermeasures, utilities concentrate their effort to prevent the faults and to modify the fault clearing practice in power system. however, the faults in power system can never be completely eliminated. therefore, customer side solutions usually involve the power conditioning equipment for sensitive loads aiso, we investigate that the several methods to reduce the number and severity of voltage sag and to dull the sensitivity of equipment for voltage sag have developed. moreover, about SEMI, the industry association for the semiconductor two voltage sag immunity standards.(SEMI F47, SEMI F42) The simulation is accomplished by PSS/E 26.
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A software, called touch-one, is developed about the determination of short-circuit values and protective co-ordination in power system. The used solution algorithm reviewed intensively, and the protective co-ordination determination technique presented by using the circuit-breaker's current-limitation characteristic. 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. With this software, we can construct a electric-power system which is reliable and economic according to user's purpose.
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In this paper a new numerical algorithm for fault distance calculation and arcing fault recognition based on one terminal data and derived in lime domain is presented. The algorithm is derived for the case of most frequent single-phase line to ground fault. The faulted phase voltage at the fault place is modeled as a serial connection of fault resistance and arc voltage. The fault distance and arc voltage amplitude are estimated using Least Error Squares Technique. The algorithm can be applied for distance protection, intelligent autoreclosure and for fault location. The results of algorithm tested through computer simulation are given.
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This paper presents a new numerical algorithm suitable for defining recloser reclaims time and blocking automatic reclosing during permanent faults on overhead lines. It is based on terminal voltage input data processing. The decision if it is safe or not to reclose is determined from the voltage signal of faulted and tripped line phase using Total Harmonic Distortion factor calculated by Discrete Fourier Transform. The algorithm was successfully tested using signals recorded on the real power system. The tests demonstrate the ability of presented algorithm to determine the secondary arc extinction time and to block unsuccessful automatic reclosing of HV lines with permanent fault.
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The western route of KEPCO's 765kV transmission line has been tentatively operating as 345kV voltage before commercial operation. After finishing the test operation of 765kV substation in 2002. KEPCO decided to operate the 765kV line for commercial operation. During the applying of 765kV voltage to the transmission line, double circuit transmission line will be operated with two voltage grades of 765kV and 345kV. Because the earthing switch is installed on both end of transmission line, we had estimated the electrostatic induction voltage and electromagnetic induction current before the line energizing in order to confirm the ratings of earthing switch. The induced voltage and current is very important for the maintenance of parallel circuit. This paper describes the simulation study of electrical phenomena such as electrostatic induction voltage from the parallel line and electromagnetic induction current from the parallel circuit. The transmission line model was developed by EMTP (Electro-Magnetic Transient Program).
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This paper proposes a new methodology for adequacy evaluation of composite power system considering an ambiguity of overload of transmission lines. Nodal arrival powers under considering an ambiguity of overload of transmission lines can be evaluated using the proposed method. Fuzzy set theory has been used in order to consider the permission level of overload of transmission lines. The problem of adequacy evaluation has been formulated using fuzzy linear programing. The effectiveness of the proposed method considering permissible overload of transmission lines has been demonstrated on the IEEE RTS.
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The use of underground transmission cables has increased continuously in densely inhabited urban and suburban for power transmission. Two or more transmission lines are outgoing from one substation in many cases, and one line comprises twin circuits. In order to meet the increasing do and for electric power, underground tables of two or fore circuits are installed in ducts in parallel for several kilometer in the same route. It, however, has not been known generally that the sheath circulating current is generated in a system where a large number of cables are laid on the same route. Therefore, this paper describes an improved analysis method for sheath circulating current on underground transmission cables using EMTP. Author propose several methods to reduce sheath circulating current. The analysing method and reduction methods for two or more underground cables will be really improved for cable system utility.
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Limitation countermeasure on harmonics occurred by power conversion installation, motor speed control equipment, and so on of power system is very important problem, and first of all, accuracy harmonics analysis in system is required for appropriate limitation counterplan. Analysis and judgement on power system harmonic by measurement are needed because analysis by mathematical model generally used for these harmonic analysis, if nonlinear ingredient is included in system, is not relatively correct. So, in this paper, system to measure and analyze harmonic by installing it in a power system, using DSP(Digital Signal Processor), is designed and developed. Also, it's performance is verified by installing it in the system that harmonics occurred.
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Complete load model of the substation not only should include the performances of the load components, but also should take into consideration the core losses of transformers, the line losses and the capacitor banks. In an actual distribution system, the control scheme of capacitor banks are so complex and is difficult to identify actual values for the reactive powers of capacitor banks. This research improves on this drawback by applying component-based modeling method including a capacitor banks in distribution systems. Initial differences between the model results and the actual values for reactive powers are later decreased by the proposed method.
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This paper presents the power swing model to dynamic test of protective relay. We propose the method of configuration of the locus of swing by change the voltage magnitude, impedance and frequency with the proposed model.
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A relaying board is developed for the study of digital relay, which is based on Digital Signal Processor(DSP). The present development is capable of understanding and application for digital relay hardware. To support the design of relaying hardware, first A/D convertor MMI and serial port for communication are embedded, and next a booting cables of three types are supplied. More particularly the relaying board that is convinient to test digital relaying algorithm. This paper concludes by implementing the distance relaying algorithm into a relaying board, the hardware test results show practically high performance.
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The industrial power distribution system is a radial system and therefore usually protected with time delayed over current relays (OCR's). Proper time dial settings are provided at the OCR's. Meanwhile, the systems, where synchronous generator, or synchronous motors, or large induction motors are operating, can not be protected with only OCR's with time grading. This paper presents a technical limit and a suitable range of time delay in applying OCR's to clearing faults in the industrial power systems for maintaining stability. Dynamic simulations are made to show them employing a real power systems of a large petro-chemical complex.
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In this paper, a communication module is proposed to be applied to communication between over current relay (OCR) agents in multi agent protection system. A multi agent system can achieve a global goal beyond the ability of each individual agent by working together, in which it is the prerequisite for each agent to be able to exchange or share information or processing status with other agent. The proposed communication module is purposed to enable not only each agent to bring about its own goal, but also the whole protective system to provide much improved coordinated protection. It is applied to a self adaptive protection system for a distribution network using multi agent concept to show its effectiveness.
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This paper represents a new approach for the protective relay of power transmission lines using a Artificial Neural Network(ANN). A different fault on transmission lines need to be detected, classified and located accurately and cleared as fast as possible. However, The protection range of the distance relay is always designed on the basis of fixed settings, and unfortunately these approach do not have the ability to adapt dynamically to the system operating condition. ANN is suitable for the adaptive relaying and the detection of complex faults. The backpropagation algorithm based multi-layer perceptron is utilized for the learning process. It allows to make control to various protection functions. As expected, the simulation result demonstrate that this approach is useful and satisfactory.
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This paper presents the new protective relaying scheme as a method for discriminating of power transform's transient state associated with magnetizng inrush state and internal fault using wavelet transforms. The simulation of EMTP with respect to different fault and inrush condition in transformer have been conducted, and the result prove that the preposed method is able to discriminate between inrush magnetizing current and internal fault.
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This paper presents the fault location estimation algorithm in transmission line using a recursive least square error method (RLSE). To minimize the computational burden of the digital relay a RLSE approach is used. Computer simulation results of the RLSE algorithm seem promising, indicating that it should be considered for further testing and evaluation.
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The transmission system is designed to be protected by 40 kA rate of circuit breaker fer 345 tV system and 31.5 kA and 50 kA rate of circuit breaker for 154 kV system. The short circuit current shows the tendency of exceeding circuit breaker duty for some substations and the tendency will continue if an appropriate countermeasure will not be applied to. In order to solve this problem from the viewpoint of system operation, the 154 kV system is under reconfiguration to be radial systems. This paper presents application effect of resistive and inductive SCFL (Superconducting Fault Current Limiter to Korea power systems. An algorithm of SCFL site decision is suggested.
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본 논에서는 기존의 무효전력 보상을 정의하고 순시 유효전력 개념들을 도입한 제어 기법을 제안하였다. 이 기법은 배전 계통에서 비선형 부하로 인한 고조파 제거 기능에 보다 효과적임을 알 수 있다. PSCAD/EMTDC를 이용한 시뮬레이션을 통하여 전통적인 무효전력 보상 기법에 근거한 제어 기법보다 좋은 성능이 있음을 보였다.
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This paper proposes an advanced compensating algorithm of the secondary current of CTs. The exiting compensating algorithm for the current transformers calculates magnetic flux using the magnetization curve. In such a case, it is difficult to compensate for distorted secondary current when a remanent flux exists in a core at the beginning of the calculation. To make up for the drawback in the existing compensating algorithm, the algorithm detects the instant of saturation using difference of the secondary current and estimates flux at the instant of the beginning of the first saturation. After that, the algorithm calculates flux and compensates for distorted secondary current.
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This paper describes the modelling method of the Superconducting Fault Current Limiters (SFCL) for Real-Time Digital Simulator (RTDS). The simulations in this paper were carried out using the R type SFCL. The R type SFCL is developed by using User Defined Component (UDC).
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DG (Distributed Generation) devices such as co-generation systems, fuel cells and photovoltaic power generation systems, etc is introducing into the distribution systems by the deregulation. In this paper, the controller of synchronous generator used for DG is newly designed in order to regulate the real & reactive power and the effect on the islanding phenomenon compared with the traditional controller.
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In this paper, we designed fuzzy legit controller(FLC) for HVDC current control using genetic algorithm. The proposed method was applied to HVDC power system simulator in Korea Electrotechnology Research Institute(KERI). We are adjusted input/output gain of FLC by real-time using genetic algorithm. Experimental results show that FLC has the better control performance than PI controller in terms of settling time, rising time.
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This paper presents a new control approach for designing a coordinated controller for static VAR compensator system. A SVC constructed by a Fixed Capacitor and a Thyristor Controlled Reactor is designed and implemented to improve the damping of a synchronous generator, as well as controlling the system voltage. A design of linear quadratic controller based on optimal controller depends on choosing weighting matrices. A coordinated optimal controller is achieved by minimizing a quadratic performance index using dynamic programming techniques. The selection of weighting matrices is usually carried out by trial and error which is not a trivial problem. We proposed a efficient method using GA of finding weighting matrices for optimal control law. Thus, we prove the usefulness of proposed method to improve the stability of single machine-infinite bus with SVC system.
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Bae, Y.J.;Lee, S.J.;Choi, M.S.;Kang, S.H.;Kim, S.T.;Choi, J.L.;Jeong, C.H.;Yoo, Y.S.;Cho, B.S. 229
The digital current differential relaying scheme is widely used for primary protection of 765(kV) power transformer. The current differential relay pickup the internal fault at the threshold which is set at 30% of rating current. Margin of 30% include current transformer error 5%, relay error 5%, on load tap changer error 7% and margin factor 140% obtained from the field experience. In this paper transformer protection relay and relay setting rule of high voltage power system are discussed. And we verify the correctness of relay setting rule with current differential relay using Matlab simulation. -
A Vacuum Circuit Breaker Model for simulation of transient overvoltages was developed by using the PSCAD/EMTDC. The Model includes the power frequency chopping current. Breaker withstand voltage, and quenching capability of High frequency currents. To verify the abilities of the breaker model, the simulation on the Lindmayer's single-phase circuit was carried out. The results show that using the proposed model, the transient overvoltages, current chopping, and multiple reignitions of vacuum breaker are properly reproduced as real phenomena. In further study, virtual chopping current will be incorporated into the model for 3 phase system.
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Whenever the large-capacitor and high-voltage pump motor is opened and closed, the power factor improvement condenser and the low-voltage equipment are often damaged by the sparking and the on-off power serge. In order to find the reason and resolve the problem, we have installed a transition wave recorder for obtaining the transient on-off power serge wave and a power disturbance analyzer for long-time monitoring. In this way we measured and analysed the condition of the high-voltage pump motor whenever it is opened and closed.
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A Study on the Design of Advanced Digital Kwh-Meter for the Remote Management of Distribution SystemThis paper proposes an advanced digital kwh-meter, which records voltage management data, load management data as well as the existing kwh data. This meter supports the requests from DRMS (Distribution Remote Management System) which include kwh meter reading, voltage management data reading, and load management data reading request, it can enhance greatly the economics of the existing remote meter reading system. Also it can improve highly the quality of power supplied to the electric customer by minimizing the voltage management cost and by enhancing the efficiency of load management.
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This paper proposes a DRMS(Distribution Remote Management System) based on the advanced digital kwh-meter. The proposed URMS is designed so as to be able to collect the voltage management data, the load management data as well as the used kwh data from advanced kwh-meter remotelly. It makes the integrated management of distribution system possible and enhances highly the economics of the existing remote meter-reading system based on the only used kwh-data. Also it can improve highly the quality of power supplied to the electric customer by minimizing the volt age management cost and by enhancing the efficiency of load management.
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전력시스템에서 설치 운영되는 설비나 장치들을 감시, 제어하는 시스템은 산업 현장이나 기관에서 개발 운영하고 있다. 배전계통에서도 마찬가지로 여러 설비와 장치들 즉, 배전선로에 설치된 개폐기나 리클로져 등을 감시, 제어하는 배전자동화시스템, 배전반등을 감시하는 전력감시 제어시스템, 발전소나 대규모 수용가에서 사용하는 전력량이나 계량정보등을 검침하는 원격검침시스템 등이 있다. 이러한 시스템에서 배전자동화시스템과 현재 나날이 발전해가는 인터넷을 접속하여 원격지에서의 보다 효율적이고 간편하게 배전계통의 운영을 수행하고, 나아가 그 기반 시스템의 데이터베이스를 관리하여 차후의 계통운용에 기초자료로 사용하며 송 배전 시스템의 전체 구성 및 향후 계획에 기초 자료로 사용할 수 있다.
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본 PowerMeter-Modem은 시스템 서버의 전단 통신 장치부의 무선모뎀과 IS-95B 망을 통해 서킷 접속을 하며 검침수행 관련정보를 수신하여 전자식 전력량계와 RS232 시리얼통신을 이용하여 전자식 전력량계의 전력량의 데이터를 취득 후 가공하여 서킷 방식이나 TCP/IP 프로토콜을 이용 패킷형태로 검침데이타를 IS-95B 망과 시스템간 프로토콜 변환장치를 거쳐 전단 통신 처리장치로 송출하는 역할을 한다.
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Since DAS(Distribution Automation System) has been typically managed for feeder automation in passive manner, it has to be managed by operator when feeder over loadings are detected therefore it may be possible for propagating the over loaded area by operator's mistake. To overcome the defect, The author proposed the feeder switch automation using active database.
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Choi, Sang-Bong;Kim, Dae-Kyeong;Jeong, Seong-Hwan;Moon, Young-Hwan;Seong, Ki-Chul;Kim, Hak-Man 253
The necessity of compact high temperature super conducting cables is more keenly felt in densely populated metropolitan areas. As the compact high temperature superconducting cables that can be installed in ducts and tunnels can reduce construction cost and make the use of underground space more effective, the effect of introducing it to power system will be huge. For this study, Seoul, Korea is selected as a review model, the loads are estimated by scenario based on a survey and analysis of 345kV and 154kV power supply networks in this area. Based on this, the following items on urban transmission system are examined. (1) A method of constructing a model system to introduce high temperature superconducting cables to metropolitan areas is presented. (2) A case study through the analysis of power demand is conducted, and the amount of high temperature superconducting cable to be introduced by scenario is examined. (3) The economy involved in expanding existing cables and introducing high temperature superconducting cables(ducts or tunnels) following load increase in urban areas is examined and compared. (4) The maximum external diameter of HTS cable to accommodate exiting ducts based on the design standards for current cable ducts is calculated. (5) The voltage level that can be accommodated by existing ducts is examined. -
This paper analyzes the sensitivity of the permissible current-carrying capability of underground power cables according to the thermal property of backfill materials and construction size of backfill materials. It is helpful for operators to determine the operating current and to design the construction of underground power cables.
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Recently, according to the spread of semiconductor applied technology like motor speed control contrivance, power conversion installation and so on, harmonic ingredients occurred in switching operation flow into a distribution system and increase voltage distortion of distribution system and bring on obstacles like damage, lowering of capability, false operation and so on of various electrical installation. So, in order to consider a countermeasure to limit occurrence quantity of harmonic source, harmonic interception and others, precision measurement and analysis on voltage, current, power, power factor, the each ingredient of harmonic order, the percentage of total harmonic distortion and so forth are needed. In this paper monitoring system to measure and analyze power quality connected with power harmonics was developed and it's performance is verified by measuring and analyzing three-phase voltage and current of R, S, T in the three-phase and four-wire system using the developed measurement system.
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This paper shows the design standard of KEPCO on the contamination design for 345 kV and 154 kV transmission tower. Up to now, because the design standard of KEPCO on the insulation design contains 154 kV transmission system only, we had investigated the 343 kV system for the revision of design standard, with respect to the contamination design, we have used the same design philosophy which were adopted to the 765 kV transmission tower. In order to determine the number of insulator discs, we had investigated the withstand voltage of discs according to the level of ESDD(Equivalent Salt Deposit Density) and kinds of disc types. The TOV(Power Frequency Temporary Overvoltage) were estimated by EMTP(Electromagnetic Transient Program) for both 154 kV and 345 kV transmission system. The overvoltage level was appeared 1.35 p.u. between phase to ground for both 154 kV and 345 kV transmission system, but finally this factor was not applied to the design standard considering current design standard and economic point of view. With regard to classification of contamination area of 345 kV transmission system, we added the clean area which was not specified in the current design practise.
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This paper deals with an I/O simulator design for performance evaluation of reactor protection systems in nuclear power plants. The I/O simulator provides input signals for the reactor protection system, and acquires output signals from the initiation circuits. The simulator is based on VMEbus system, and all VMEbus boards are developed within the country.
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신속한 고장복구를 통해서 정전시간을 최소화하고자 배전기동보수업무에 최신 정보통신기술을 접목하려는 시도는 많이 있었다. 그러나, 그간 GIS, GPS, Mobile 등 시스템 구현에 필요한 핵심요소기술들이 성숙되지 않은 상태였고, 무엇보다 기반 시스템으로서의 NDIS가 전제되지 않은 상태에서 설비종합 DB와의 체계적인 연계가 미비하여 사업소 확산에 어려움이 있었다. 그렇지만, 최근에 관련 정보기술(IT)의 발달과 NDIS DB구축사업이 사업소별로 추진되어 기동보수시스템이 현장업무에 적용될 환경이 충분히 조성되어 있다고 판단된다. 이러한 배경에서 이동보수차량의 위치를 GPS와 TRS망을 연계하여 실시간 관리함으로써 고장지점으로 신속히 출동시키게 하고, 현장에서는 고장접수정보와 계통구성정보 등 관련 설비정보를 이용할 수 있게 함으로써 고객서비스의 질을 높이고, 많은 비용과 노력을 기울인 GIS DB 구축자료의 활용성과 이용효율성을 극대화시킬 수 있을 것으로 기대된다.
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In this paper, we describe the implementation of a monitoring and diagnostic system for GIS. This system monitors operation status of GIS and transmits data from GIS to host. With this system, an operator can monitor an operating condition and judge the aging of each device, and prevent the failure or breakdown in advance.
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긴급보호제어시스템(SPS, Special Protection System)은 일반적인 보호동작 범위를 벗어난 외란에 대해서 계통 전지역의 보호를 목적으로 하는 광역시스템 보호기술이다. 따라서 SPS는 외란 시에 계통 장비의 보호보다는 계통을 보호함으로써 전력 공급능력 향상에 주안점을 두게 된다. SPS는 자주 동작하지 않고 평소에는 대기 상태로 있으며, 긴급한 동작이 요구되기 때문에 많은 경우에 그 동작이 미리 결정되어 있다. SPS는 입력변수나 전력계통에의 영향에 따라 분류할 수 있는데, 입력변수에 따라서는 계통 응답에 기초한 SPS와 사고에 기초한 SPS로 나눌 수 있다. 발전기 탈락, 부하 차단이 SPS의 주요 보호 동작이며 이 외에 가스터빈이나 양수발전기 기동, AGC 제어, HVDC 고속전력변환, 분로기기의 자동스위칭 등의 제어 동작이 있다. 우리나라의 경우에는 주로 동기탈조 방지를 위한 발전기 탈락의 동작을 하는 SPS가 설치, 운전되고 있다.
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본 논문은 UPFC(Unified Power Flow Controi)의 유효전력 및 무효전력의 제어를 통해 시스템의 레벨을 향상시키기 위한 운용 알고리즘을 제시한다. 전력 계통에서 UPFC의 효과 분석하기 위해 분리형 모델(decoupled model)을 이용하였다. 본 논문에서는 계통의 조류 및 전압을 이용한 안전도 지수가 제시되었고, 이를 반복계산(iterative method)을 통해 최소화하였다. 이를 위해 각 안전도 지수의 민감도 벡터가 최소화되는 방향으로 UPFC의 운전점을 찾고, 이로써 시스템의 안전도를 증대시킨다. 제안된 알고리즘은 다기의 UPFC를 대상으로 IEEE 30 모선에 적용하여 시스템 안전도 레벨을 검토하였다.
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This paper presents the characteristics and Real Time Digital Simulator(RTDS) model for Seo-deagu Static Var Compensator(SVC) systems installed in 1999. SVC system is a power system controller using power electronics called Flexible AC Transmission Systems (FACTS). RTDS model for Seo-deagu SVC is developed and verified, we recognize to be essential for SVC systems and understand SVC systems through simulation.
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Boiler combustion systems are large, non-linear systems with numerous interactions between its component parts. In the analysis of such complex systems. dynamic simulation is recognized as a powerful method of keeping track of the myriad of interactions. This paper shows and discusses the developed analysis model, such as the forced draft fan the primary air fan, the furnace and burner system, pulverizer, air preheater and induced draft fan, etc. in accordance with BMCR condition of boiler using the Modular Modeling System(MMS) software.
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The rapid development of measurement systems for high power tests makes it possible to measure signals as well as analyze with the help of computer. Also, methods to evaluate such measurement systems are required recently. Uncertainty has been regarding as the most important factor in evaluating the measurement systems. Because of the character of the measurement systems for high power tests. the uncertainty shall be evaluated by each component. If the uncertainty evaluated by each component, it is convenient to evaluate total uncertainty of the measurement systems according to each component setting's combination. In this paper each component of high current measurement system of high power testing Dept. II in Korea Electrotechnology Research Institute is evaluated except sensors such as shunts and CTs. The total uncertainty of the measurement systems can be determined by that of each component including uncertainty of sensors.
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When a bulk power system experiences a serious disturbance or heavy load trip, the system frequency may drop and even collapse if the total generating power does not supply the system demand sufficiently. Since an isolated power system possesses a lower inertia and comes with limited reserves, the load shedding by under frequency relay becomes an important strategy to keep system frequency. This paper presents a scheme to determine the load shedding criteria by using the rate of change of frequency when the large disturbance happens.
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Load management programs was initiated in the 1970s to actively influence customer load in the United States. Generally, load management programs can be categorized into direct load control(DLC), indirect load control(IDLC), and energy storge system(ESS). The DLC allows the utilities to shed remote customer demand unilaterally Direct load control(DLC) has lately attracted considerable attention. This paper suggests efficient promoting plans of DLC, which has a lot of advantages. The importance of DLC will be increased more and more. Therefore, various studies of DLC activation plans have to be continued.
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In this study, Genetic Algorithm(GA) is applied for voltage and reactive power control in power system. In power system, switched shunt capacitors are used to improve the voltage profile and to reduce power losses. There are many switched shunt capacitors in power system. Therefore, it is necessary to coordinate these switched shunt capacitors. A Genetic Algorithm(GA) is used to find optimal coordination of switched shunt capacitors in power system. The effectiveness of the proposed approach is demonstrated in KEPCO's power system.
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The design of a measurement system to perform Harmonic State Estimation (HSE) is a very complex problem. In particular, the number of available harmonic instruments(Continuous Harmonic Analysis in Real Time : CHART) is always limited. Therefore, a systematic procedure is needed to design the optimal placement of measurement points. This paper presents a new HSE algorithm which is based on an optimal placement of measurement points using Genetic Algorithms (GAs). This HSE has been applied to the New Zealand AC Power System for the validation of the new HSE algorithm. The study results have indicated an economical and effective method for optimal placement of measurement points using GAs in the HSE.
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The load frequency control of power system is one of important subjects in view of system operation and control. To converge within allowance load variation value the frequency and tie-line power flow deviation of each areas, we should regulate the active power output of power plant for regulation in system Applying the NFC(Neuro-Fuzzy Controller) to the model of load frequency control of 2-area power system, we prove that the control is superior to the conventional control technique through computer simulation. For verification of robustness, when we consider generator-rate constraint similar to nonlinearities of power system.
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This paper presents a new method to characterize sag event. Power quality monitoring algorithm to analyze PQ problems is described. This paper shows that conventional characterizing method which makes use of only sag magnitude and sag duration has some limitations. It characterizes non-rectangular sag as more severe one. In addition, it can't count on voltage tolerance characteristics of each apparatus. In order to solve these problems, this paper present a new characterizing method and it properly characterizes non-rectangular sag considering the voltage tolerance characteristics.
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This paper proposes an expert system, which is able to determine the problem-solving strategy for diversity events occurred on the distribution system. The events include events related to the fault, scheduled outage and optimal operating task such as feeder line fault, line scheduled outage, line overload, system load balancing, system loss minimization, main transformer fault, main transformer scheduled outage, main transformer overload, main transformer protection control. The expert system enhances the reliability of software designed by the integrated concept for the diversity events.
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The development of IEC 61400-21 provides firm basis for assessment of the impact of wind turbines on voltage quality. This paper presents analysis and modeling of the flicker emission of wind turbines. The paper concentrates on the theoretical aspects of the flicker algorithm, wind turbine characteristics and the generation of flicker during continuous operation of wind turbines. It also introduces a simplified assessment to limit the flicker emission.
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Frequency and phasor are the most important quantities in power system operation because they can reflect the whole power system situation. This paper proposes a design and implementation using phase angle difference calculation for frequency measuring in power system. The process is considered to be complicated as compared to the present proposed method. Performance test results, using signals from Excel program, indicate that the proposed technique can provide accurate estimates within 16ms.
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본 논문에서는 먼저 영남지역의 장기적인 전력부족을 해결하기 위하여 일본의 규슈지역과 남한의 부산지역을 KVDC로 계통연계를 위한 시나리오 및 전력 조류의 분포도를 분석하는 것을 목적으로 한다. 특히 경인지역과 영남지역은 부하의 중심지라고 할 수 있으며, 영남지역은 현재의 경우에도 발전량보다 부하량이 많은 것으로 나타나 있다. 이러한 추세는 향후 계속적인 전력수요의 증가로 인해 더욱 문제가 될 것이며, 이런 증가하는 발전력의 부족을 해결할 만한 마땅한 대책이 없으리라 여겨진다. 본 논문의 시나리오에서는 영남지역에 전력을 공급할 목적으로 되어있기 때문에 일본측을 컨버터로 한국측을 인버터로 하여 일본에서 한반도 방향으로 전력을 흘려보내도록 하였다. 양국의 HVDC 전력 계통연계는 가상으로 시나리오를 작성한 후, PSS/E Tool을 사용하여 조류 계산을 시행하여 전력 분포도를 살펴보았다.
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Distribution system loss minimization re-configuration is 0-1 planning problem, and the number of combinations requiring searches is extremely large when dealing with typical system scales. For this reason, the application of a genetic algorithm (GA) seems attactive to solve this problem. Although Genetic algorithms are a type of random number search method, they incorporate a multi-point search feature and are therefore superior to one-point search techniques. The efficiency of GAs for solving large combinational problem has received wide attention. Further, parallel searching can be performed and the optimal solution is more easily reached. In this paper, for improving GA convergence characteristics in the distribution system loss minimization re-configeration problem, a chromosome "Limited Life" concept is intro duced. Briefly, considering the population homogenization and genetic drift problems, natural selection is achieved by providing this new concept, in addition to natural selection by fitness. This is possible because individuals in a population have an age value. Simulations were carried out using a model system to check this method's validity.
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This paper is based on model electrode by reduced scale and theoretical background of proportion factor. use building structure and mesh electrode, we get grounding electrode of building grounding structure and grounding electrode of mesh electrode by modeling experimentation and estimation coordinate geometry, we are doing practical grounding electrode assumption.
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There are a lot errors and little accuracy when calculating the grounding resistance with the transposition methods in the equivalent surface of hemisphere electrode. Therefore we should calculate the grounding resistance by using the mesh factor. In this paper, we would estimated the grounding value of mesh electrode with water tank model & estimation method using the reduced scale ratio of mesh electrode based on the theory of model electrode & proportional factor according to the reduced scale ratio. And also we have confirmed the accuracy of the empirical formula of model electrode by using by regression analysis.
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경제 발전에 따른 생활수준의 향상과 수용가 부하용량의 증가로 인하여, 다양한 부하가 사용되고 있다. 반면, 전기사용으로 인한 안전사고와 전기재해 인한 피해가 증가하고 있으며, 이에 대한 대처방안이 요구된다. 특히 전기재해중 인명과 재산에 피해를 주는 전기화재가 대표적 피해 중 하나 일 것이다. 본 논문에서는 저압배전선 시스템에서 발생하는 전기화재 징후들에 관하여 조사하고 이를 모의, 검출하는 방안들에 관하여 제시한다. 전기화재의 두 가지 요인인 아크와 스파크의 전기적 특성에 관하여 조사하고 이들 현상이 수용가에서 사용하는 부하의 동작으로 인한 현상들과 구분되는 특징과 이들 전기화재 징후를 검출하는 방법에 대하여 제시하고자 한다.
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We improved quench properties of a superconducting fault current limiter (SFCL) based on YBCO thin films by their serial and parallel combinations. The SFCL consisted of 6 switching elements fabricated of 4 inch-diameter YBCO thin films. Simple serial connection resulted in imbalanced power dissipation between switching elements even at the quench current difference of 0.6A. On the other hand,
$2{\times}2\;and\;3{\times}2$ stack combinations produced simultaneous quenches. The$3{\times}2$ stack combination showed better simultaneous quench behavior than the$2{\times}2$ stacks. This is suggested to be because the currents between switching elements in parallel connection of the$3{\times}2$ stacks were more effectively redistributed than the$2{\times}2$ stacks. -
The remaining life of ACSR exposed to the atmosphere for a long period may rely on deterioration caused by environmental indices such as atmospheric corrosion, galvanic corrosion, crevice corrosion and fatigue corrosion. One of reduction of useful life in overhead transmission lines built on the ridge of mountain is often caused by forest fires. This paper deals with investigation of strength deterioration performance of ACSR due to fires through several testing and analyzing data for both tension load and material analysis. Test samples are ACSR
$480[mm^2]$ conductors, which are artificially fired to regular durations. As a result, it can be verified that tension load of ACSR are reduced by increasing fro duration. Hence, it is obvious that ACSR due to forest fires may lead to mechanical deterioration. -
This paper presents a new strategy to find starting points for placing optimally Phasor Measurement Units(PMUs). The performance of the starting point, initial placement set of PMUs, affect critically the computational burden and/or time, because the Optimal PMU Placement (OPP) problem is formulated the combinatorial optimization. By analyzing the properties of OPP solutions on IEEE sample systems in detail, a new strategy for initial PMU placement, in this paper, is proposed. To verify the performance of the suggested strategy, the comparison with the existing strategy and the new one, on IEEE sample systems. is performed. By using the new strategy, the numbers of search spaces to solve the OPP problem is drastically decreased.
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이 논문은 현재 지중송전 케이블에서 관로포설용 되메움재로서 널리 사용되고 있는 모래를 대신할 수 있는 개량 되메움재 연구하고, 이에 대한 송전용량 증대효과를 살펴본 것이다. 먼저, 기존 되메움재인 모래 및 개량 되메움새에 대한 토양 열특성을 비교 검토하고, 다음으로 개량 되메움재를 실선로에 적용할 때의 송전용량 증대 효과를 시뮬레이션을 통해 확인하였다.
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In the high-power tests to be performed on electrical apparatus as switchgears, transformers, insulators, cable and so on the results of tests on these apparatus are extremely important to evaluate the performance of test object. The reliability of the results depends on the reliability of measuring systems used in the laboratories where tests are performed. This paper introduces factors of uncertainty and describes estimation of uncertainty in high-voltage measuring system used in high-power testing LAB. 1 in KERI.
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Up to now the design standard of tower for overhead transmission line in KEPCO was revised four times since 1970. During last year. we had reviewed this design standard. This paper shows the design standard of tower for overhead transmission line in KEPCO. In this standard, a kind of tower was defined as standard tower and special tower. Also we had defined usage range of standard tower, tower height, arrangement of power line, design condition of tower arm and etc. On the wind pressure, we had defined basic velocity pressure per region and maximum wind pressure. For special region, design wind pressure will be considered the receded wind velocity of meteorological observatory and regional condition by this standard.
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In this paper a technical consideration is made on the AGC operation under the wholesale market in Korea in view of the signal connection between EMS and power plants for AGC. We review the market rules related AGC operation first. Then we investigate the current AGC connection to measure the level of the satisfaction for the every term in the rules.
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한국전력공사는 합리적인 전력소비를 위해 다양한 요금체계를 제공하고 있다. 그러므로, 주택용과 일반용전력(갑), 일반용전력(을), 교육용전력, 산업용전력(갑), 산업용전력(을) 등 전력사용고객의 성격에 따라 기본요금이나 계절별, 시간대별, 혹은 누진 등 차등요금제를 적용한다. 그러나, 이들 각각에 맞는 전자식 전력량계를 개발한다는 것은 경제성이 없는 일이다. 그러므로, 단일의 전자식 전력량계에서 다양한 요금체계를 수용할 수 있는 방안이 필요하며, 이를 위해 단일의 전자식 전력량계로 공통 기능은 하드웨어로 구현하고 각종 요금체계에 따른 변화를 수용하는 부분은 펌웨어로 개발하여 검침을 수행하는 것이 바람직하다. 본 논문에서는 단일의 전자식 전력량계에서 효과적으로 적용할 수 있도록 한국전력공사에서 시행하고 있는 다양한 요금제도에 부합하는 응용프로그램을 설계하고 구현하는 방안을 제시한다. 또한, 이런 응용 프로그램을 관리하는 소프트웨어를 실제로 구현한 사례를 제시한다.
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전력산업 구조개편에 따라 전력회사의 공익기능 회피로 발생할 수 있는 시장실패 요인을 보완하기 위하여 정부 주도의 공익적 기능 수행으로 전력산업의 효율향상이라는 구조개편의 근본 취지와 목표를 달성하고자 정부는 매 3년 단위의 전력산업기반조성계획을 수립하도록 전기사업법에 명시하고 있고, 본 논문은 구조개편 하에서 공정한 경쟁 환경을 조성하여 소비자의 편익을 증대시킴으로써 공익기능을 강화하기 위한 중장기적인 전력 수요관리 정책방향을 제시하고, 2003년에서 2005년까지의 전력수요관리 프로그램별 세부 추진계획을 수립하였다.
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The characteristic responds of load respect to various disturbances which can usually be occurred on actual power system is very important to analyze performance and to improve load with high-technology. The disturbance power supply is designed to provide wide range of power to testing load. This device uses PLC technology to dynamic characteristic experiment and CVVF to change frequency. Also this instrument includes data acquisition system to obtain reliable data from experiment.
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This paper presents a technique that can obtain an optimal solution for the Security-Constrained Economic Dispatch (SCED) problems using the Interior Point Method (IPM) while taking into account of the power flow constraints. The SCED equations are formulated by using only the real power flow equations from the optimal power flow. Then an algorithm is presented that can linearize the SCED equations based on the relationships among generation real power outputs, loads, and transmission losses to obtain the optimal solutions by applying the linear programming (LP) technique. Finally, the application of the Primal Interior Point Method (PIPM) for solving the optimization problem based on the proposed linearized objective function is presented. The results are compared with the Simplex Method and the Promising results ard obtained.
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기저부하조성 및 부하율 망상을 위한 심야 전력요금제도의 정착으로 최근 심야전력축열기기의 보급이 활성화되고 있다. 그러나 모든 심야전력축열기기들이 심야요금개시시간대인 22:00경에 동시에 가동됨에 따라 23:00경에 심야전력 부하가 최대에 이르러 전력피크가 발생하여 한전의 수요관리에 어려움을 주고 있다. 따라서 이 피크 부하를 심야전력 공급시간대의 저부하 시간대로 분산시킬 수 있는 심야전력기기 공급시간제어장치가 필요하게 되었으며, 이미 축열식전기보일러와 축열식 전기온수기에는 개발 보급되고 있는 실정이다. 이 논문에서는 다른 심야전력축열기기와는 달리 자연방열의 바닥축열난방방식인 축열식전기온돌의 공급시간자동제어장치 알고리즘을 실증실험을 통해서 검증하였다.
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제주-해남 HVDC 시스템의 #1, #2 Pole이 동시 운전 중에 동기조상기가 탈락할 경우, HVDC시스템의 운전모드 절체와 제주기력 #2, #3호기의 출력변화 등을 EMTDC 프로그램으로 시뮬레이션 하였다. 또한 HVDC 시스템의 AC측 보호계전기를 계전 알고리즘을 이용하여 EMTDC 모델로 구현하고 제주 교류계통에서 사고 발생시 HVDC 시스템의 보호를 검토하였다.
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This paper provides a new approach for the load-focused transmission marginal loss factors(MLF). It can be widely applied to power system operations and pricing mechanism in a competitive electricity market. The load-focused MLF is the ratio of required additional generation at a reference bus to the demand increments at a arbitrary bus. The new approach to determine the load-focused MLF was developed under some practically endurable assumptions. Although the suggested method is very similar to the conventional penaty factors in its concept, the method is more efficient than the existing heuristic method for the load-focused MLF. To show its effectiveness and efficiency, numerical test have been performed in IEEE 14-bus system.
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An important aspect of the study of power system markets involves the assessment of strategic behavior of participants for maximizing their profits. In models of imperfect competition of a deregulated electricity system the key task is to find the Nash equilibrium. In this paper, the bimatrix approach for finding Nash equilibria in electricity markets is investigated. This approach determines pure and mixed equilibria using the complementarity pivot algorithm. The mixed equilibrium in the matrix approach has the equal number of non-zero property. This property makes it difficult to reproduce a smooth continuous distribution for the mixed equilibrium. This paper proposes an algorithm for adjusting the quantization value of discretization to reconstruct a continuous distribution from a discrete one.
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2001년 4월 전력도매전력시장의 출범과 함께 공정경쟁을 확보하기 위한 시장감시기능의 중요성이 부각되고 있다. 특히, 전력은 현대 생활의 필수품으로 공급의 안정성이 크게 중요시되고 있으며, 생산과 수송 구매에 있어서 기술적 특성이 일반상품과 크게 달라, 시장감시의 역할이 더욱 크게 평가되고 있어서 이를 수행하기 위한 기술적 어려움이 문제로 제기되고 있다. 전력시장에서의 공정경쟁 화보를 위해서는 시장지배력 및 이의 행사여부, 담합행위, 법령 및 규칙의 준수여부 등이 감시되어야 하고, 전력시장가격의 이상 급등락 등 이상현상에 대안 원인규명 등의 시장감시기능이 이루어져야 한다. 본 논문에서는 아직 초보단계에 머무르고 있는 전력시장의 감시기능을 소개하고, 변화하는 전력시장에서의 시장감시기능에 대한 관심을 제고하고자 한다.
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The key objectives of this study are to develop the enhanced electricity system analysis methodologies and decision making process applicable to the analysis of the energy policies, especially the renewable energy policy, through surveying the recent trend and relevant study results. This study utilizes DECADES model, a comparative assessment tool developed by IAEA, and suggests a way to establish DECADES database required to make it applicable to Korean electricity system analysis. For this, a survey on the existing database of various organizations is performed. A case study on the economic and environmental impact of renewable energy is made using DECADES model.
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This paper presents the System Marginal Price(SMp) forecasting implementation using backpropagation Neural Networks in Competitive Electricity Market. SMP is very important term to seek the maximum profit to bidding participants. Demand and SMP that necessary data for training Neural Networks, supplied from Korea Power Exchange(KPX). Statistic analysis about predicted SMP presents a part of consideration in end of this paper.
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전력시장에서의 적정 설비예비력을 확보하는 문제는 구조개편의 진행과 캘리포니아 전력비상사태 이후 더욱 더 중요성을 가짐에 따라 이에 대한 심도 있는 논의와 분석이 필요하게 되었다. 이런 이유로 현재 해외전력시장에서 활용중인 적정 설비예비력 확보방안들을 이론적 및 실증적인 방법에 의한 비교 분석을 통하여 한국전력시장에 적합한 방안을 모색하고자 한다. 본 논문에서는 특히 미국 PJM 전력시장 등에서 활용중인 용량의무 방식과 캘리포니아 시장에서 활용중인 시장의존방식을 중심으로 적정 설비예비력 확보방안을 간략하게 비교하고자 한다.
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Recently, electric heating using midnight power has brought a rapid increase. Therefore, the increase of midnight power use has much influenced on midnight load pattern and share more than 20% of total midnight electricity consumption. Hence, the distortion of load by using midnight power apparatus is severe and made the usage pattern ineffective electricity usage pattern. This paper analyze the load pattern of midnight power apparatus and policies that can effectively build midnight load. In addition, it provides policies on shifting midnight power apparatus load.
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This paper presents long-term electricity market analysis simulation considering Genco's strategy using P-POOL. In the competitive electricity market, system operation and/or market operation is highly depended on the participants' intention and his planning. We focus on the Genco's strategy, including maintenance scheduling and bidding strategy. And we represent his profit using 3-Bus sample system.
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Transmission and Distribution(T&D) pricing has been one of keystones of ongoing deregulation and privatization process in power industries. The electricity markel has been established based on open access and nondiscriminatory use of the T&D assets. As T&D business remains as a monopoly, it is necessary to provide economic regulation. This paper focuses on the distribution pricing methods and the analysis of pricing structure of distribution-retail sale company under power system deregulation.
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전력시장에서의 공정경쟁의 중요성은 새삼 강조의 필요가 없을 만큼 중요한 것이다. 대표적인 전력시장에서의 불공정행위로는 시장지배적 사업자에 의한 시장지배력 행사와 다수 사업자에 의한 부당공동행위, 즉 담합행위를 들 수 있다. 불공정행위의 실제 행위는 시간별 가격과 용량을 입찰하는 과정에서 부당한 이익을 위한 전략적 행위를 행사함으로써 발생한다. 인위적으로 가격을 올리거나 가격이 낮은 발전기의 용량을 축소 입찰함으로써 정상적인 시장가격보다 높은 시장가격이 형성되어 이러한 부당행위의 당사자가 부당을 이익을 얻게 되는 과정이다. 이러한 행위는 상당히 은밀하고 전략적으로 행사되므로 그 적발이 용이하지 않지만 전력시장을 관찰함으로써 징후를 포착하고. 정밀조사를 통하여 부당행위를 적발, 시정하는 지속적인 활동이 필요하다. 본 연구에서는 이러한 부당행위를 적발하기 위한 기본과정으로서 입찰용량의 적정성 판정을 위한 지표개발을 시도하였다. 설비용량과 보수용량을 감안한 입찰가능용량과 실제 입찰한 용량의 상관관계를 분석함으로써 정밀조사 대상이 되는 비정상 입찰행위 식별지표인 용량철회 가능성 감지지표를 개발하였다.
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This paper proposes a process using the load shedding scenario method that determines the minimum local load shedding quantity considering the local DLC(Direct Load Control) potentials. So this method is applied to Kyung-In area and determined the load shedding of this area with comparison to its DLC potentials.
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So far, electricity rate under the midnight hour incorporates policy consideration and maintains fixed irrespective of generation cost. Therefore, the promotion of midnight power apparatus has been rapidly increased due to increasing difference in substitute heating cost. This paper estimates the power supply cost during midnight times and analyzes the rate mechanism which can promote economic midnight power apparatus. In addition it provides the alternative on the direction of policy after the restructuring.
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현재, 전세계의 전력산업은 수직통합적 독점산업에서 부문간 경쟁산업으로 변화하고 민영화를 통한 시상경쟁원리가 도입되고 있다. 이러한 전세계적 전력산업 구조개편에 발맞추고, 전력산업에서의 효율을 제고하기 위하여 우리나라도 전력산업에 시장경쟁 체제를 도입하고 발전산업에 민영화론 추진하고 있다. 2001년 4인, 전력을 거래하기 위한 한국전력거래소가 발족되었으며 6개의 발전자회사의 설립을 통하여 발전부문의 경쟁체제가 도입되었으며, 2003년부터 본격적인 도매경쟁 시장이 도입될 전망이다. 이러한 새로운 시장 환경아래에서 전력거래가 원활하게 이루어지고, 시장이 안정화되기 위해서는 정부, 전력거래소, 발전사업자 등과 같은 시장참여자들이 전력시장을 분석할 수 있는 방법론 및 모델을 확보하고 있어야 한다. 따라서, 본 논문에서는 이러한 전력시장을 분석하기 위한 방법론으로 게임이론을 적용하여 각 발전사업자의 보수전략(Maintenance strategy)을 분석하고자 한다. 이론 통해 각 발전사업자는 보수전략을 수립하는데 이용할 수 있고, 시장규제자의 측면에서는 전력시장이 효율적으로 가동되고 있는지 여부를 판단할 수 있는 유력한 도구로도 활용될 수 있을 것으로 예상된다.
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본 논문은 2001년에 도입되어 현재 시행중인 우리나라의 대표적인 부하관리 프로그램인 직접부하제어의 적정 인센티브 수준을 결정하는 새로운 방법론을 제시한다. 기존의 인센티브 수준 결정 방법론이 공급자측을 중심으로 한 회피비용에 기초하여 결정된 반면, 본 연구에서는 참여자인 수용가의 대처비용과 월간요금 지급액의 감액을 중심으로 한 인센티브 결정 방법론을 제안한다. 또한, 이러한 인센티브 결정 방법론의 수학적 정식화를 도출하여 보다 체계적인 분석이 가능하게 하였다. 이러한 접근법은 소비자의 편익 및 비용을 보다 정확하게 분석하고 이에 기초하여 인센티브 수준이 결정되기 때문에 직접부하제어의 활성화에 기여할 것으로 판단된다.
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This paper presents a methodology for the application of Unified Modeling Language (UML) to develop the new load management system. Development of new load management system in competitive electricity market is very complex since it requires too much data of power system. For the efficient and flexible design to develop of new load management system, a UML approach in applied which is composed of a class diagram, package diagram using Rational Rose Unified Process.
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Many methods about real power flow tracing have been suggested. Electric power industrials and organizations of the world use the method which is best suitable to themselves in practical aspects. In this paper we calculate the real power transfer between individual generators and loads referencing the method introduced by oversea's paper. It is considered to be significant to the wholesale competition market and transmission open access. Based on ac load flow solution and graph theory, the simulation on IEEE 30-bus system are carried out and the results are compared with that of oversea's paper. Also the simulation on the power system of Korea is carried out and the results are analyzed.
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In a deregulated power market, a load model considered the characteristics of electric consumers is required and the congestion management of transmission lines should be resolved in a point of economic benefits. It is essential that the optimal power flow algorithm is applied to manage transmission line congestion. Therefore, in this paper, we implement the optimal power flow with object function of social welfare maximization based linear programming and analysis the nodal prices for generations and loads through a numerical study.
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A Improved Network partition Technique Using Marginal Cost Sensitivity Under Transmission Congestion본 논문에서는 경쟁적 전력시장에서 송전제약에 관한 비용을 적절히 할당하는 방법을 제시하고자 한다. 혼잡비용을 할당하는 방법으로는 모든 사용자들에게 똑같이 배분하는 방법과 혼잡의 원인을 제공한 사용자에게 정도에 따라 가중하여 혼잡비용을 할당하는 nodal pricing과 zonal pricing이 있다. 계산의 신속성과 복잡성으로 인해서 zonal pricing이 유용한 방법으로 사용되고 있다. 기존의 분할 기술은 계통운영자가 설정한 한계범위의 모선들을 zone으로 형성하는 통계적인 방법을 사용했다. 이 방법은 운영자의 임의성이 반영되는 모호한 알고리즘이라는 단점을 가지고 있다. 그래서 본 논문에서는 한계비용민감도를 이용한 계통분할 방법을 제안하였다.
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Recently, electricity demand of remote islands in Korea has been rapidly increased. It's mainly due to increase of income level resulted from economic development. Electricity demand patterns and characteristics in remote islands are different from those of mainland in point of time of peak load, demographic and industrial characteristics of islands, and so on. The optimal power supply in remote islands has a important relationship with accurate analysis of island's load characteristics, the adoption of relevant load forecasting technique, and optimal power facilities reflecting local's electricity demand characteristics. This paper shows the recent load pattern and characteristics, load forecasting using probability distribution, and the perpetration of relevant power facilities in remote islands.
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This Paper presents the technical perspective on the Real Time Pricing(RTP). So far customer has no control on the electricity pricing. But the price hike in California makes changes in the electricity demand and pricing. In such environments. RTP has become an important role in Demand Side Management. Here the system configuration, advantages of RTP are described. Also the relationship between RTP and AMR is considered.
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In deregulated power market, transmission pricing methodology should maintain non-discrimination amongst all participants while ensure that TRANSCOs recover their revenue requirements. The proposed transmission pricing methodology for Korea needs cost allocation ratios, such as allocation ratio of physical transport to network security and that of generators to loads. In this paper, we studied the nodal transmission price determined by the cost allocation factors and its influence on GENCOs and DISTCOs.
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A Development Of The Window-Based Load Management System Package In A Competitive Electricity MarketThis paper presents a window-based load management system (LMS) package developed as a decision-making tool in the competitive electricity market. The presented LMS package can help the users to monitor system load patterns, analyze their past energy consumption and schedule the future energy consumption. The LMS package can also provide the effective information on real-time energy/cost monitoring, consumed energy/cost analysis, demand schedule and cost-savings. The developed LMS package can be used to establish the optimal demand schedule and consumption strategy.
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현재, 전세계의 전력산업은 수직 통합적 독점산업에서 부문간 경쟁산업으로 변화하고 민영화를 통한 시장경쟁원리가 도입되고 있다. 이러한 전세계적 전력산업 구조개편에 발맞추고, 전력산업에서의 효율을 제고하기 위하여 우리나라도 전력산업에 시장경쟁 체제를 도입하고 발전산업에 민영화를 추진하고 있다. 이러한 새로운 시장 환경아래에서 전력거래가 원활하게 이루어지고, 시장이 안정화되기 위해서는 정부, 전력거래소, 발전회사 등과 같은 시장참여자들이 전력시장을 분석할 수 있는 방법론 및 모델을 확보하고 있어야 한다. 따라서 본 논문에서는 이러한 전력시장을 분석하기 위한 방법론으로 게임이론을 적용하여 각 발전회사가 선형함수(linear offer curve)로 입찰하는 현물시장에서 각 발전회사의 최적입찰전략 및 시장균형을 분석하고자 한다. 이를 통해 각 발전회사는 현물시장에서 자신의 이익을 최대화하기 위한 최적의 입찰전략을 수립하는데 이용할 수 있게 되며 규제자 및 시장운영자는 현물시장을 예측 분석할 수 있다.
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Sheath circulating current rises from the change of sheath mutual impedance which is caused by imbalanced cable system, and different section length between joint boxes. However, mixed burying typo and imbalance section length take many parts of main reasons of sheath circulating current increment in domestic underground transmission power cables. Therefore, the increment reason and variation characteristics of sheath circulating current is analysed with simulation using EMTP/ATPDraw and measuring data of practical cable system which has a problem of exceeding sheath circulating current in this paper.
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In case the overload of an existing power line is expected as the consumption of electric power increase, we substitute STACIR/AW which has better thermal characteristic for ACSR. That can approximately double the transmission capacity. In that case the mechanical characteristics of STACIR/AW should meet the design condition of the existing tower. However, the strength of invar in STACIR/AW is lower than that of steel in ACSR, which makes it difficult to keep the safety of a conductor specially in a long span In this regard, this paper presents the new conductor model using the AMC and the analysis of its characteristics.
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가공 송전선로의 낙뢰고장은 송전설비가 국토 전 지역에 분포되어 있기 때문에 고장 점유율이 가장 높다. 또한 낙뢰가 아주 큰 전기량과 짧은 순간에 방전하는 특성뿐 아니라 다양한 구름의 변화형태에 따른 낙뢰 발생 패턴이 달라 아직까지 이를 예방하거나 제어하는 기술은 높지 않은 수준에 있다. 이 논문은 자연환경이 비슷하고 전압레벨과 전력계통이 유사한 한국전력(KEPCO)과 대만전력(TPC)의 6년간의 송전선로 낙뢰고장을 통계적으로 비교하여 낙뢰고장과 전력신의 차례각과의 관계적 원인을 도출하고자 하였다. 이에 따라 전력선의 차폐각에 따른 낙뢰고장 발생 확률을 시뮬레이션 프로그램을 통하여 도출하고 실제 양 전력회사의 차폐각별 송전선로의 낙뢰고장 발생빈도와 비교하였다.
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Ha, Bok-Nam;Oh, Jae-Hyung;Cho, Nam-Hun;Bae, Seong-Hwan;Kim, Jae-Sung;Jung, Chang-Soo;Lee, Heung-Ho 462
KEPCO enforces the development about distribution automation technology continuously for 10 years and reached in fair level present. And distribution automation system was constructed actively meantime, its establishment will be completed 100% at late 2002s. Distribution automation system had been developed also in Japan, U.S.A and Europe etc. In japan, distribution automation system was established all business office to whole county. Lately, there is examining distribution automation expansion actively in developing country including China. Therefore, we try to analyze domestic and foreign technological variance as that examine foreign distribution automation trend and the development direction of domestic distribution automation technology forward. -
In order to newly define and specify the performance and the testing method of the high-voltage circuit breaker, IEC 62271-100 was published in May, 2001 and took place of IEC 60056 which had been used since 1987. This new standard intensifies the requirement and the test method of the circuit breaker and also domestic manufacturer makes progress the new product development. And, KERI also goes on the build-up project of short-circuit testing facilities for fulfilling the testing method requirements in new IEC 62271-100. This paper introduce the limiting method of short-circuit making current by controlling the time constant of dc component.
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HVAC transmission lines must be designed to satisfy environmental regulations. Therefore it is necessary to pre-evaluate environmental problems for transmission line designer using prediction program. In this study, environment design software, TLCALC 2001 for transmission lines was developed as a comprehensive window program. It has 6 modules that are audible noise, radio noise, television noise, magnetic field, electric field and conductor surface gradient TLCALC 2001 solved a few problems in use of the existing foreign tools and took several advantages. Experienced designers can get the results of calculation within about 15 minutes. Because the use of TLCALC 2001 is easy and practical, this program will be usefully applied to the environmental friendly design and construction of HVAC transmission lines. In the future, it is expected that public complaints and social environmental cost will be reduced by the use of TLCALC 2001.
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The objective of this survey is to characterize the personal magnetic field exposure of the Korean population. The participants in the survey on magnetic field exposure were selected randomly by occupation. In this first step survey, the number of participant is 108 and for the second step, about 400 participants will be surveyed in the near future. The survey is the first significant study that quantifies the exposure of the general population for the entire day, not only for the time spent in one's bed but also for the time at work in Korea.
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본 논문에서는 765kV 송전선로의 일부구간에서 발생되고 있는 풍소음의 대책으로 개발된 저풍소음 도체를 소개하고 이 도체방식을 개발하기 위해 수행된 전기환경장해 및 풍소음 저감 영향에 대한 시험결과를 제시하고 있다. 저풍소음 도체는 우수한 풍소음 저감기능을 가지면서도 기존 전선에 비해 추가적인 전기환경 문제가 발생되지 않아야 하는데, 기존 전선과 달리 전선 주위에 돌기부가 있어서 전계 집중에 따른 환경장해 발생의 우려가 있다. 이러한 이유 때문에 전기환경 모의시험설비인 코로나 케이지를 이용한 코로나 발생 특성 시험을 수행하여 환경설계기준 만족 여부를 확인하였으며, 실규모 시험선로를 이용한 장기 실증시험을 실시하여 송전선로 주변에서 실제 발생 가능한 라디오 장해와 같은 전기환경 장해량에 대한 평가를 실시하여 풍소음 저감효과와 환경설계기준에 만족하는 결과를 얻을 수 있었다.
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Wind energy can be conversed into electrical power using wind generator. Wind farm is made up of many wind generators, and it is often interconnected into distribution system to supply power for utilities. There are many protection problems on distribution system connected with Wind farm. It can effect on power quality severely when faults are occurred on distribution line or Wind farms. Therefore the correct protective scheme must be set for distribution system which has a Wind farm. In this paper, A wind farm connected into distribution line is simulated with several fault types which can be occurred on distribution line and Wind farm using PSCAD/EMTDC. And this paper proposes necessary relays to protect both sides of distribution system and wind farm.
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In this paper, for continuously changed closing time of circuit breakers, switching overvoltage on 345kV underground transmission systems are variously analyzed using EMTP with statistical analysis method. And, switching overvoltage and closing surge occurred in conductors at sending and receiving end and metal sheath with variation of cable length are analyzed, and the reduction effects for switching overvoltage considered preinsertion resistance of circuit breakers are examined.
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In this paper, installation type is analyzed into a single and mixed burying type on burying situation of domestic underground transmission cables, and problem of underground cable is discussed with investigating the relation between burying type and sheath circulation current. Investigated cable systems are 520 T/L which have 512T/L for 154kV and 8T/L for 345kV. The authors consider that the analysis of sheath circulating current with burying type will contribute for setting reduction methods of sheath circulation current.
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Wind farm paralleled with electric power network can supply the power into a power network not only the normal conditions, but also the fault conditions of distribution network. If the fault happened in the power line with wind farm, the fault current level measured in a relaying point might be lower than that of distribution network without wind turbine generator. Consequently, it is difficult to detect the fault happened in the distribution network connected with wind generator. This paper describes the influence of wind turbine generator on the protective relaying system for detecting the fault occurred in a power line network. Simulation results shows that the fault current depends on the fault impedance, location, and the capacity of wind farm and distribution network load.
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전력시장개방에 따라 전력계통 효율적 운영에 대하여 국민적 관심이 증대하고, 경제회복으로 인하여 전력수요가 꾸준하게 증가하고 있다. 따라서 전력계통에서 발생한 고장을 정밀분석하고 문제점 파악 및 대책 등을 강구 시행하여 전기품질 향상에 일조하고자 현재 전력계통에서 운전중인 154kV이상 송변전 설비의 고장 및 보호계전기의 동작상태을 대상으로 다양한 통계방법을 이용하여 분석을 실시하였다.
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본 논문에서는 향후 우리나라에 전자계 규제가 이루어질 경우 국민이 부담해야하는 사회 경제적 비용을 추정하였다. 여기에서 사회 경제적 비용의 추정은 전자계 규제치를 만족하기 위해 선로 지상고만을 조정하였을때 추가되는 건설비용을 기준으로 한 기초적 검토 결과로써 송전선로 표준 모델을 사용하여 예측한 결과
$20{\mu}T$ 로 기준 설정시 부터 사회 경제적 비용이 발생함을 알 수 있었으며,$10{\mu}T$ 로 기준 설정 시에는 약 20조원의 추가 비용이 발생할 것으로 예상된다. -
가공선로 표지물로 사용되는 구에서 발생하는 소음의 특성을 조사하였다. 현재 한전에서 사용하고 있는 표지용 구의 크기는 직경 62cm이며 두께가 3mm인 합성수지로 만든 반구를 접합부분에 요철형상으로 결합하도록 되어있다. 현장에서 발생하는 소음 스펙트럼을 측정하여, 무향 풍동에서 측정한 구형 셀에서 발생하는 스퍽트럼과 비교하였다. 백색음을 입사하여 구형 셀의 크기에서 발생하는 기본음의 스펙트럼을 조사하였다.
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Receltly, Underground transmission system is getting increased. Therefore the design of grounding system becomes very important to discharge overcurrent of lightning and fault through earth and reduce sheath induced voltage and sheath circulation current. This paper describes fault current distribution ratio for grounding line with grounding types of normal joint box and sheath grounding resistor at line-to-ground fault of cable.
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This paper describes the symptoms with the failure causes of pole transformers analyzed at KEPCO branch offices' request in 2001, and ultimately aims for devising proper countermeasures against the failures. The failure causes are generally divided into problems in manufacturing, mounting and operating. The pole transformers encounter the failure with unique mechanisms. To verify the mechanisms to failures and help devise proper countermeasures, a flowchart is proposed based on the authors' experience and foreign case studies. The failure causes of pole transformers can be analyzed more exactly by using the flowchart.
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This study is for the development of KEPCO Safety Management System. There were so many incidents for ten years in KEPCO. So, KEPCO has been some needs to change in field of safety management. This paper presents introduction of SSM (Systematic Safety Management) of KEPCO that has procedure, checklist, computer program.
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우리나라의 지중배전선로는 가공선의 정비 차원에서 지중케이블로 공급함으로써 시작되었으며, 지금은 변전소 인출개소와 택지개발 지역에 신규공급용으로 주로 설치되고 있다. 지중배전선로는 매년 약 7%의 증가율을 보여주고 있으며 2001년말 기준으로 케이블긍장이 16,301(C-km)로 약9.4%의 지중화율을 나타내고 있다. 선로가 증가함에 따라 고장의 발생이 광역정전등 점차 많은 문제점을 내포하고 있다. 지중배전선로의 고장은 주로 케이블에서의 외상과 열화가 주요인으로 이는 환경적인 영향과 제작 시공 및 유지관리면에서의 미흡에 의한 것으로 효과적인 관리를 위해서는 지하매설물종합관리기관 설립 등의 제도적 도입과 선로제작과 시공품질의 향상을 유도하기 위한 계약 제도의 보완 및 선로의 중요도와 경제성에 따른 차별화된 관리 방법과 선로고장시 정확한 data 보고관리의 여건 마련과 아울러 정확한 선로 이력 database화 등의 체계적인 선진 예방보수 기법의 도입이 요구된다.
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본 논문에서는 전력계통 관련 기기에서 문제가 되고 있는 전자기적합성(Electromagnetic Compatibility, 이하 EMC)을 다루고자 한다. 전력계통은 서지와 같은 많은 전자기 장해를 발생한다. 그래서 최근 제정 및 개정되고 있는 전자기기 회로가 포함되어 있는 IEC 규격에서는 대부분 EMC 시험을 포함하고 있다. 본 논문에서는 전력계통과 EMC 연관성을 검토하고자 한다. 또한 주요 중전기기의 EMC 규격 동향을 소개하고자 한다. 마지막으로 국내 전력계통 기기에서 발생한 실제 EMC 문제를 소개하고자 한다.
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본 논문에서는 저전압 기기의 전자회로를 보호하는 서지보호장치(surge protective devices, SPD)의 기술에 대하여 논의하고자 한다. 먼저 저압 전력계통에서 발생하는 전원장해(power disturbance) 종류 및 서지보호장치와의 상호관계를 고찰하였다. 또한 서지보호장치의 보호소자 및 특성, 구성기법을 고찰하고, 최근 IEC 및 IEEE 규격을 소개하고자 한다. 마지막으로 국내의 문제점 및 발전방안을 제안하였다.
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The contracted electric power and the demand factor of customers are used to predict the peak load in distribution transformers. The conventional demand factor was determined more than ten years ago. The contracted electric power and power demand have been increased. Therefore, we need to prepare the novel demand factor that appropriates at present. In this paper, we modify the demand factor to improve the peak load prediction of distribution transformers. To modify the demand factor, we utilize the 169 data acquisition devices for sample distribution transformers. The peak load currents were measured by the case studies using the actual load data, through which we verified that the proposed demand factors were correct than the conventional factors. A newly demand factor will be used to predict the peak load of distribution transformers.
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In Korea, power requirement has been increasing. But the large generation unit is hardly installed because of economic and environment problem. Therefore, the concern of dispersed generation system(DGS) is growing. The power distribution system is generally operated with radial type. The protection system is composed of one directive source. But power distribution system inserted DGS changes it to two directive source system. Therefore, the insertion of DGS has the problem of protection coordination. In this paper, we argue fault current affected by interconnected DGS. We analyze fault current flow affected by DGS placement. Then, we find protective coordination problem. Consequently, we study advance point for protection scheme of power system interconnected DGS.
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In this paper, accelerated life test (ALT) models and procedures for Magnetic Switch (MS) are developed and applied to assure specified reliability of the products at development phase and guarantee the life of the products. Magnetic contactor that functions with over-current relay is called MS. Magnetic contactor closes and opens the motor load with ON/OFF switch of electronic contactor. It is also used for protecting and controlling the load. Magnetic contactor detects the over-current flow in the load with a over-current relay and disconnects the load by opening its control power. In this study, ALT models for MS are developed using the relationship between stresses and life characteristics of products. Using the ALT models, we performed life tests and analyzed the tests results. The proposed ALT models and procedures may be extended and applied to testing similar kinds of products to reduce test times and costs of the tests remarkably. Finally the results of this study will contribute to improving reliability of products and strengthening competitiveness of our products in world markets.
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This paper describes the analysis resulates on the P.T ferroresonance at 154kV GIS(Gas Insulated Substation) by EMTP(Electromagnetic transient program). We had simulated the PT ferroresonance between a potential transformer(PT) and open circuit braker's grading capacitance. The ferroresonance leads to very large power frequency overvoltage on PT bus and subsequent insulation failure. The damping circuit connected on the secondary winding were considered in the model. The actual countermeasure include a saturable inductor and a resistor series mounted, but the 2 ohms of damping resistance was used in the computational model.
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In a high power laboratory, artificial lines are used for SLF tests of circuit breakers. The line side PTRV is affected by the stray capacitances of testing and measuring equipment as well as the circuit parameters of artificial lines. The changing pattern of PTRV was examined, and the circuit parameters of artificial line for some examples were compensated using the changing pattern to satisfy test conditions specified.
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In this paper the domestic and worldwide trends of substation automation are described in order to cope with the coming new environment in this part On the world market of substation control it will be change from analog technology to digital technology. And the technology of a system integration relevant to a substation automation become more important than that of individual power apparatus. Therefore development of substation automation technology is needed.
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The cubicle type GIS rated at 25.8kV has been designed and manufactured by Jinkwang E&C eacently with their own technologies and KERI's assistances. The C-GIS has been tested to check the design capability for reference before conducting the type test. The operating characteristics test, short time withstand current and peak withstand current test, basic short circuit test duty T60 for preconditioning test, cable charging current switching test, capacitor bank current switching test, basic short circuit test duty T100s and T100a, single phase earth fault test, double earth fault test has been conducted. The test results show that the design and the manufacturing of the C-GIS has an enough capability to pass through the type test except the occurrence of 2 NSDDs in the cable charging current switching test and the instability of opening time at the minimum operating voltage. The problems shown in the tests will be improved soon and the successful pass will be expected in the following type test.
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It has little possibility that cable and cable joint causes any problem in transmission system. But when cable fault occurs, the damage is very severe. There are weak points to have potential problem due to many cable joint especially in high voltage transmission line. In this study, we propose nobel method to detect PD in cable joints and show the effectiveness of the proposed method through experiment results.
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KEPCO has been operating since March 1998 a HVDC link between Cheju Island and the mainland that it constructed to save high generation cost & ensure the system stability and the supply of electric power of Cheju island (approximately 100km from south of mainland). The purpose of this study is to consider the complete maintenance of the HVDC Submarine Cable after its construction in 1997 while proposing future direction for the stable operation of the HVDC Submarine Cable.
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This paper describes measurement and diagnosis methods for electromagnetic wave using a VHF(Very High Frequency) antenna. In the laboratory partial discharges are generated on a needle-plate and a plate-plate configuration. The detected electromagnetic wave is analyzed by FFT(Fast Fourier Transform). We propose a methode to classify creeping partial discharge and corona partial discharge that are detected in three frequency bands.
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The designed frequency compensator is proposed to make the estimation of amplitude of fundamental frequency immune to frequency variation. The designed method which has a simple structure and low calculation burden is proper to apply digital protective relay. The results of experimental demonstrate that the frequency compensator has good performance to the estimation of amplitude of fundamental frequency against frequency variation.
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In this study, the measurement part in which the Fast Fourier Transform module and orthogonal filter are included is proposed. Protection relay should has a high precision and concurrently real-time response. Because FFT routine give micro-processor heavy burden and orthogonal filter reduces precision, both FFT module and orthogonal filter are designed to have different sampling frequency.