2003.11a
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전력계통의 정상상태와 다양한 초장상태를 모의하기위한 단락시험설비는 크게 단락발전기, 보호차단기, 전류제한 리액터, 투입스위치, 단락변압기, 버스바 및 케이블, 투입피크 제한장치, 부하회로 및 측정장치 등으로 구성되어 있으며, 유효한 시험을 위해서는 이러한(변수)조합들을 적절하게 조절, 제어하여 실계통의 현상을 재현하거나 규격 또는 의뢰자의 요구에 부응하도록 하는 것이 중요하다. 이것을 위해서는 각 시험설비의 정상 및 과도 특성과 조합된 회로에 상존하는 변수(stray values)들을 찾아내고, 이들에 대한 독립성과 의존성 관계를 파악하여 계산 가능한 모델링을 도출 하여야 한다. 그러나 경험적으로 볼때 단락발전기의 과도임피던스 및 여자 특성과 변압기를 포함한 회로상의 stray values 등이 여러 변수들과 만들어내는 상관관계를 파악하는데는 좀 어려움이 있었다. 본 논문에서는 이러한 관점에서 상기 변수에 따른 변화 기여도를 가능한 한 정량적으로 분석하여 회복전압, TRV 및 전류와의 상관관계를 규명해 보고자 한다.
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계통에 발생하는 불안정 현상을 억제하기 위한 방법으로 저주파수 부하차단과 저전압 부하차단이 있다. 저전압 부하차단은 저주파수 부하차단에 비해 지역적 특성이 강하기 때문에 일반적인 기준이 제시되어 있지 않다. 본 논문에서는 정적 모의를 통하여 저전압 기준치를 결정하는 기법을 제안하고 동적 모의를 통하여 이를 검증하고 시지연값도 결정하도록 하였다.
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For four decades now KEPCO has experienced an incredible growth rate of over 10% per year in each year. This growth led to the fast development of new facilities, especially in the transmission systems field, and we also managed to gain an enormous amount of experience and technology in the construction and design. With this experience and technology we curbed the electricity demand. Experts now predict that we will enter a new phase in which our growth rate will stagnate and eventually level off. This isn't what KEPCO or any company wants. We are looking for continued growth. In the last decade KEPCO began selling its technology in the generation sector of the electricity business to overseas markets. Sales in the generation sector have been a great success. This decade marks another milestone for KEPCO as overseas sales in the transmission sector began. Our first project, "Myanmar Power System Development Study" and its subsequent successful completion gave us the ammunition necessary to expand in this line of business. This success has also given birth to this paper. KEPCO is still the People's company, but with a new vision. It now hopes to not only sustain a high growth level but to also increase the growth of domestic companies by sharing with them a piece of the proverbial pie, as it ventures forth to be a Global player on the international stage.
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Electric arc furnace has consumed plenty of power. Hence electric arc furnace can be expected to use for demand side management. When electric arc furnace use for demand side management, electric arc furnace frequently occur a starting and a stop. Electric arc furnace irregularity change consumption of power. Due to character of time-varing and non-linear, electirc arc furnace has a problem with voltage quality(flicker, harmonics). Producted harmonic in electric art furnace is different any harmonic source because of electric arc furnace peculiar operating. Accordingly, analysis for generated harmonic in electric arc furnace operating is demanded. This paper analyze effect of harmonic by arc furnace operating.
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This paper focuses on the effects of wind pressure on transmission towers. It recommends the need for an application method to strengthen some existing towers, especially those in areas regularly affected by typhoons, and to be applied to new constructions. Some considerations taken into account were modifying existing towers exposed, which can cause significant damage to the power system and the effects of damage on third parties.
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전력계통 해석용 프로그램으로 우리나라에서 주로 사용되고 있는 것은 PSS/E(Power System Simulation and Engineering) 이다. 이것은 계통해석을 위한 범용 프로그램으로 그 기능이 다양하지만, 상정고장 검토와 같이 많은 설비고장에 대하여 반복적인 과정의 모의를 하는 경우 적절한 자동화 방안이 없는 단점이 있다. 본 연구에서는 IPLAN을 활용하여 이러한 반복과정을 자동으로 수행하고 계산결과 안전도 위배사항을 요약하여 Report하므로써 전력계통 안전도평가 업무를 신속하고 정확하게 수행할 수 있는 프로그램을 개발하였다. 또한 본 프로그램은 방대한 계통DB에 대한 필요한 정보를 요약제공하므로 전체적인 DB구성에 대한 파악이 용이할뿐만 아니라 계통DB의 수정입력을 위한 툴을 함께 개발하여 제공하므로써 사용자 편의를 도모하였다.
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Probabilistic Load Flow(PLF) solution based on the method of moments is used for security assessment of bus voltages in power systems. Bus voltages, line currents, line admittances, generated real and reactive power, and bus loads are treated as complex random variables. These complex random variables are known in terms of probability density functions(PDF). Also, expressions for the convolutions of complex random variables in terms of moments and cumulants have been derived. Proposed PLF solution using the method of moments is fast, because the process of convolution of various complex random variables is performed in moment and cumulant domain. Therefore, the method is applied to security assessment of power systems in this paper. Finally, system operator also can be used information of security assessment to improve reliability of power systems.
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Power system restoration following a partial or complete blackout starts with energizing of primary transmission lines. Because system changed rapidly during early restoration process, transformer energization and load pickup is executed to maintain the power system stability. However unexpected problem such as harmonic overvoltage may be arisen during energizing transformer. The reason of harmonic overvoltage is known as transformer saturation and magnetizing in-rush current and so on, but it is difficult to estimate the condition of occurrence. This paper describes the analysis of the harmonic overvoltage while unloaded transformer is energized using PSCAD/EMTDC.
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The frequency of power system will change when the load-generation equilibrium is disturbed. Insufficiency of generation from the imbalance between load and generation decreases the power system frequency. In case of the severe emergency, the under frequency load shedding scheme is applied for the power system defense plan. In this paper, we analyzed the dynamic characteristics of under frequency load shedding using new Transient Security Assessment Tool ; TSAT. We applied the actual UFLS scheme to these studies and considered the possible contingency.
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This paper describes the integrated dynamic stability(IDS) program for tuning the power system controllers, such as PSS, AVR and so on. IDS consists of three modules; power flow module, PWRLF, to calculate large scale power system load flow solutions, IDS/PSS module to calculate eigenvalues and frequency response in the range of frequency from 0.2Hz to 2Hz, and IDS/NEA module to calculate eigenvalues in the range of frequency from 5.0Hz to 55Hz. In addition, IDS provides graphic user interface(GUI) in order to let the user handle and analyze the input data and the results of calculation with convenience.
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본 논문에서는 부하의 상태에 따라 능동적으로 추종 및 보상기능을 갖으며, 에너지절약기능 및 고품질을 유지할 수 있는 소형이면서 가격도 저렴한 전력 품질보상장치의 Prototype을 구성하고져 한다. 최근 일반 주택이나 사무실내에 반도체소자 및 전력전자기기의 사용이 급증하면서 이들 기기에서 발생하는 고조파 및 무효전력량이 증가하여 주위의 환경과 전기적 손실이 심각한 문제를 발생한다. 이런 상황 하에서 전력품질에 민감한 부하들이 급증하고 부하의 민감도에 따라 다양한 전력품질을 요구하는 장치가 점점 필요로 하게 되었다. 지금까지 국내 외적으로 이런 문제를 보상하는 소형보상장치는 가전기기 즉 세탁기 냉장고등 각기 개개로 부착하고 있는 것들은 어느 정도 개발되어 사용되고 있으나, 가정용도로 사용하기 위하여 주택전체를 보상하는 기기는 개발이 되어있지 않은 상태에 있다. 따라서 현재까지 국내 외적으로 개발되어온 기기들은 가정용 소형 전력품질의 모니터링 수준이라고 할 수 있다. 따라서 본 논문에서는 기기의 최 말단 즉, 기기자체에 부착하여 사용하는 단순형 보상형태를 확장시켜 소형이면서 에너지 절약이 가능한 가정용으로 적합한 능동 추종형 전력품질 보상장치의 기술에 대한 연구를 하는 것이 목적이다.
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At present, the Korean electricity industry is undergoing restructuring and the CBP market is being operated preparing for TWBP market open. As the circumstance of the traditional system is changed according to power system deregulation the unique market simulator is needed to analyze and study an electricity market. In this paper, we implement the main two modules of unique market simulator(PEXSIM) and introduce the characteristics of PEXSIM focused on the M-SIM and P-SIM.
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This Paper proposes the new method of Nodal Price calculation on nonoptimal condition of power system. It uses Power Flow instead of Optimal Power Flow. We propose a idea of imaginary constraints at the first. And the proposed method is applied to IEEE-30 and results show the effectiveness of the method.
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With the advancement of superconductor materials, especially in HTC YBCO(Gen II), the feasibility of SMES in power systems become much higher than previous days application[1]. Also, with the de-regulation of electricity market, it is indispensable to have a proper estimation of power quality index and power quality cost calcluation mechanism to stabilize highly industrialized society and to vitalize the investment for electric power system. This paper suggests a comprehensive algorithm[2] to determine the policy of SMES investment with the PQ Indices[3] based on aggregated load CBEMA curve reflecting the voltage characteristics such as volatge sags and interruptions which make electric load in unstable operation.
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This paper demonstrates an analysis of harmonics at the high speed railway substation and proved on this countermeasure using the PSCAD/EMTDC simulation tool. First, high speed railway feeding system is composed using PSCAD/EMTDC electrical railway feeding system model in advance. Second, This paper applications line capacitance values as feeder-trolley, trolley-rail and feeder-rail to analysis harmonics more accuracy in advance did not application. This capacitance values calculate using the EMTP(Electro Magnetic Transient Program). Third, the tractions are arranged in the section that substation supplies power, and this paper take the simulation each case(fractions composition amount) to see harmonic propagation from traction to substation. As a result, generated harmonics at traction can confirmed that harmonics did not reduce at utility source. This harmonics have an influence on bulk power system. Finally, this paper introduces the methods of harmonics effect minimum. This paper proved harmonics reduce effect through the passive filters application.
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In recent, the importance and necessity of some studies on reliability evaluation of grid comes from the recent black-out accidents occurred in the world. The quantity evaluation of transmission system reliability is very important under competitive electricity environment. The reason is that the successful operation of electric power under the deregulated electricity market depends on transmission system reliability management. This paper introduces features and operation modes of the Transmission Reliability Evaluation for Large-Scale Systems(TRELSS) Version 5_1, a program made in EPRI, for assessing reliability indices of composite power system. The package accesses not only bulk but also buses indices for reliability evaluation of composite powers system. The characteristics of the TRELSS program are illustrated by the case studies using the IEEE 25buses system.
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In recent, the importance and necessity of some studies on reliability evaluation of grid come from the recent black-out accidents occurred in the world. The quantity evaluation of transmission system reliability is very important under competitive electricity environment. The reason is that the successful operation of electric power under the deregulated electricity market depends on transmission system reliability management. The various results of many case studies for the IEEE 25buses system using the Transmission Reliability Evaluation for Large-Scale Systems(TRELSS) Version 5_1, a program made in EPRI are introduced in this paper. Some sensitivity analysis has been included. This paper suggests that the some important input parameters of the TRELSS can be determined optimally from this sensitivity analysis for high reliability level operation of a system.
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Fall-of-potential method is used usually to measure the ground impedance of large scale grounding system exactly. Because the interlinked magnetic flux between closed loops to inject test current and to measure potential rise is existed in E-P-C straight line arrangement, mutual(or inductive) coupling influences greatly on the measurement correctness. Measurement errors produced from inductive coupling could be reduced by the arrangement methods of auxiliary electrodes. Right angle or P-E-C order arrangement methods were effective to reduce the inductive coupling and the decrease degree of measurement error was analysed as quantitative through an experiment.
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전력계통의 배전계통은 수용가 직전의 배전용 변전소까지는 상당한 수준의 지능형 시스템이 도입되어 운용되고 있으나 일반 수용가 단위에서는 전기 에너지가 공급된 이후로 큰 변화가 없었다. 생활환경은 정보화 사회로 급변하고 있으며 이로 인한 전기 에너지는 여타 에너지 보다 필수적인 것으로 되었다. 따라서 정보화 시대의 필수 에너지원으로써 보다 안정적이며 능동적인 전기에너지 공급을 위해 본 논문에서는 홈 네트웍을 기반으로 수용가측 배전 시스템의 지능화에 대한 연구 내용을 다룬다.
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This paper presents development and testing of a new numerical spectral domain algorithm devoted to blocking unsuccessful automatic reclosing onto permanent faults and the fault distance calculation. The arc voltage amplitude and the fault distance are calculated from the fundamental and third harmonics of the terminal voltages and currents phasors. From the calculated arc voltage amplitude it can be concluded if the fault is transient arcing fault or permanent arcless fault. If the fault is permanent automatic reclosure should be blocked. The algorithm can be applied for adaptive autoreclosure, distance protection, and fault location. The results of algorithm testing through computer simulation are given.
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This paper presented a method to develop a relay model by the user-written model function of PSS/E. As for the voltage instability, although generator current limiters, transformer's tap-changers and dynamic loads have been considered as the dominant components, the protection system is also very important because it may influence the system's dynamic behaviour. Hence a distance relay model implemented with the suggested method was added, and then the operating characteristics of the distance relay under the voltage instability condition were investigated.
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본 논문은 2기 5모선 모의계통에 3상 단락고장을 발생시킬 경우, 해당 모선에서 각 차단기가 분담하는 고장전류를 PSCAD/EMTBC3.0을 이용하여 분석한 결과이다. 적용된 차단기 개극시간(Contact Parting Time, CPT) 및 아크시간(Arc Time) 등은 실제 차단기 제작사(효성, 현대중공업 및 LG산전)들로부터 조사/수집하여 적용하였으며, 적용 대상계통은 PSS/E 분석결과와 비교/검토하여 검증하였다. 이는 기존 혹은 신설 차단기 적정 차단용량을 선정하는데도 활용가능 할 것으로 보인다.
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In this paper, an algorithm to compensate the distorted signals due to CT(Current Transformer) saturation is suggested. Firstly, WT(Wavelet Transform) is used to detect a start point and an end point of saturation. Filter banks which can be easily realized in real-time applications are employed in detecting CT saturation. Secondly, least-square curve fitting method is used to restore the distorted section of the secondary current. Fault simulations are performed on a power system model using EMTP(Electromagnetic Transient Program). A series of test results indicate that WT has superior detection accuracy and the proposed algorithm which shows very stable features under various levels of remanent flux is also satisfactory.
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A DC railway system has low feeder voltage, The fault current can be smaller than the current of load starting. So it is important to discriminate between the small fault current and the load starting current. The load starting current increases step by step but the fault current increases all at once. So the type of
${\Delta}I$ relay(50F) was developed using the different characteristics between the load starting current and the fault current. As for the load starting current, the time constant of load current at each step is much smaller than that of the fault current. First, to detect faults in DC railway systems, an algorithm using the time constant calculated by the method of least squares is presented in this paper. Secondly, to compose a protection scheme for DC railway systems is presented in this paper. -
This paper deals with optimal voltage regulation methods of line voltage regulator(SVR : Step Voltage Regulator) in power distribution systems. In order to deliver suitable voltages to as many customers as possible, the optimal sending voltage of SVR should be decided by the effective operation of voltage regulators at the distribution feeders and substations. In this paper, a new voltage regulation method based on the existing method is presented and an optimal coordination method of multiple voltage regulators is extended. The results from a case study show that the proposed methods can be a practical tool for the voltage regulation in distribution systems.
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This paper describes a time-sequential simulation technique for the reliability evaluation of a distribution system including Photovoltaics(PV) Generation. A three-state model of a PV is presented, considering variable radiation and the forced outage rate. A test distribution system is utilized to illustrate the proposed model. The effects on the distribution system reliability of the PV parameters are examined and illustrated.
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본 논문에서는 분산전원을 포함하는 배전계통을 위한 3상 조류계산 프로그램에 대하여 소개한다. 이 프로그램은 배전계통의 방사상 구조를 가정하여 개발된 것이 아니므로 어떠한 구조로 구성된 배전계통이라도 모두 사용이 가능하며, 불평형 부하 및 불평형 선로를 포함하는 계통에 대해서도 해를 구할 수 있도록 고안되었다. Voltage regulator는 각 상별로 tap을 조정할 수 있는 3상 변압기로 모델링하였으며, 분산전원은 계통 내 다양한 위치에 배치하여 수렴특성을 확인하였다. 3상 불평형 부하와 단상 및 2상 선로를 포함하는 20모선 시험 계통을 구성하여 수행한 사례연구에서 조류계산 프로그램은 가혹한 중부하 환경에서도 훌륭한 수렴특성을 보여 주었다.
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This paper describes the various characteristics of voltage sags and temporary interruptions which can affect the functions of 3-phase induction motors. These assorted characteristics include motor speed loss, voltage recovery, motor reacceleration, and transient characteristics. An experimental study on induction motor behavior was also carried out to confirm these impacts. Besides, sequential voltage sags of short duration were considered for this paper. The results show that the occurrence of the second voltage sag after the first one may affects the induction motor adversely.
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Development of Intelligent Distribution System Service Restoration Algorithm Using PC Cluster System본 논문에서는 확률적인 전역 최적화 알고리즘인 유전 알고리즘과 경험적인 최적화 알고리즘인 타부 탐색법을 병렬화함으로써 최적해 탐색성능 및 탐색속도를 개선하는 방안을 개발하였다. 배전계통의 주변압기에서 고장이 발생한 경우에는 여러 정전구역에 대한 복구문제가 되어 매우 복잡하고 많은 연산량을 수반한다. 따라서 제안한 고장복구 알고리즘은 PC 클러스트링을 이용하여 각 프로세서별로 유전 알고리즘 또는 타부 탐색법을 사용하여 최적해를 탐색한 후 일정 기간 이후에 해를 교환함으로써 배전계통에서의 주변압기 고장발생시 최적해 탐색에 소요되는 시간을 단축하였으며 고장복구 지원시스템의 성능개선을 도모하였다. 제안한 알고리즘의 유용성을 입증하기 위하여 한전의 실 배전계통 주변압기 고장복구 문제에 적용함으로써 제안한 알고리즘이 해의 탐색속도 및 해의 성능면에서 우수함을 입증하였다.
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본 논문에서는 확률적인 전역 최적해 탐색 방식인 유전알고리즘과 경험적인 최적화 알고리즘인 Tabu 탐색법을 이용하여 실시간으로 적용 가능한 배전계통 선로 재구성 및 커패시터 용량결정 방안을 제안하고자 한다. 제안한 알고리즘은 PC Cluster System으로 병렬처리하여 배전계통의 손실 최소화를 위한 선로 재구성 및 커패시터 용량 결정문제의 최적해 탐색에 소요되는 계산시간을 단축하고, 실시간 지원시스템의 성능 개선을 도모하고자 한다. PC Cluster System은 이용자의 편의를 위해서 MS Windows 환경에서 구축하였고, Visual C++ 환경에서 개발하였다. 제안한 방법의 유용성을 입증하기 위해 참고 문헌의 예제 계통에 적용한 후 종래의 방법과 비교함으로써 제안한 방법이 해의 탐색속도 및 해의 성능면에서 우수함을 입증하였다.
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전력계통에 대해 적용되고 있는 수많은 안정화 방안으로 발전기 탈락, 부하차단, 계통분리 등의 방법 중에서, 우리나라 계통에서의 과도안정도 문제에 대한 안정화 대책으로는 주로 발전기 탈락이 많이 적용되어 왔다. 본 논문은 이러한 발전기 탈락량에 관한 주제를 다루고 있다. 이러한 발전기 탈락을 적용하기 위해서 과도안정도 취약지점에 대해 KPX 보고서를 참조하여 상정사고 지점을 선정하고, 해당지역 계통에 대해 등면적법을 적용, 적정 발전기 탈락량을 계산하였다. 이러한 사전 연산형(offline) 형 발전기 탈락 외에도 온라인 상에서의 발전기 탈락량 계산방법과 그 문제점에 대해서도 고려하였다.
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In recent, the various electric & electronic machines are newly developed everyday and the electricity supply system & environment on the process from generation to consumption of electricity also is being changed. In other words, both supplier and consumer of electricity are required to be responsible for their interruption costs. So, it is very important and meaningful work for evaluating the interruption costs in quantitative. Additionally, since the restructuring of electric industry is on going in world wide, after restructuring, most of all electric utilities and consumer have to consider the supply reliability and quality as a important element of the calculating the related costs and contract because it takes costs to keep the supply reliability and quality highly. Especially, the interruption or the supply reliability will have influence on the bilateral contract between supplier and customer as a key point to determine the once in competitive electric market. Therefore, it has very important moaning to calculate the interruption costs in the present that it is prepared to open the competitive electric market. In this paper, international standards, i.e. IEC, IEEE, are applied to the analysis on the interruption costs used in the questionnaires which are newly designed including short duration interruption by the authors instead of traditional interruption criteria. Firstly, using the questionnaires, the authors got related data from industries according to the standard industry classification which are being used in electric utility and other national statistics in Korea. However, analysis results are hard to say typical value because of the not so many samples. So, the authors are going to survey and focus on not all kinds of industry but a few kinds of them that their facilities are effected or stop by short duration interruptions, so there are large economical damages. Finally, the authors hope to find the reliable and meaningful model in interruption costs of industrial customer.
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This paper presents method of the assessment on the Influence of harmonic torque in diesel generating system by using EMTP(Electromagnetic Transient Program). The objectives is to analysis the influence on power oscillation and voltage fluctuation due to the periodically varying torque developed by the new diesel generator to be installed in existing power system.
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Recently, with the increasing use of power semiconductors and microprocessors which are very sensitive to little change of power quality and power market being formed according to the reorganization of the power market, power providers and consumers show much interest in the power quality problem. This situation makes the demand creation of integrated system for power quality analysis and monitoring based on speedy and powerful functions by the growth of computer hardware and information technology, and besides advanced corporation already have created and employed power quality analysis and monitoring system. In this papers, it will be introduced that power quality database design-database is essential to integrated system-for managing effectively and confidently data from the power quality meters(PQM).
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In this papers, it will be introduced that power quality analysis software design including investigation of mutual relation between power quality data and mechanism for getting data from power quality database according as based on object-oriented methodology. The UML which is only a language and so is just part of a software development, may be used to visualize, specify, construct, and document the artifacts of software-intensive system.
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The deregulated electricity market is operated with respect to theory of economical efficiency, and therefore, the system operator requires data with fast contingency ranking for security of the bulk power system. This paper compares the weather dependant probabilistic risk index(PRI) with the system performance index for power flow in the IEEE-RBTS. also, the system performance index for power flow presents the power system stability. The probabilistic risk index can be classified into normal weather and adverse weather. This paper proposes calculation method using the probabilistic risk index in determining contingency ranking requiring for security under the deregulated electricity market.
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Micro-Sources arc emerging as a providing environmentally friendly and reliable and effective solution. Micro-Source converter DC voltage of prime mover to AC voltage using voltage source inverter for interjecting with AC grid system. This paper studies optimal series inductance size for interjecting with AC grid system.
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배전선로에서 부하가 증가함에 따라 주상변압기의 탭 조정만으로는 모든 수용가단 전압을 규정치(
$220{\pm}6%$ ) 이내로 유지시킬 수가 없게 된다. 따라서, 수용가단 전압의 품질을 규정치 이내로 유지할 수 있는 보강공사가 필요하게 된다. 현재는 수용가단 전압품질에 문제가 발생하지 않으나, 선로의 부하가 증가 될수록 통과전류의 양이 많아져, 전압강하가 높아지기 때문에 일부 수용가에 저전압이 발생하게 될 가능성이 있게 된다. 여기서는 부하증가(부하증가율 : 1%, 2%, 3%, 4%, 5%)에 대한 대책으로 다음과 같은 3가지 대안을 고려하기로 한다. 본 연구에서는 1) 선로전압조정장치(SVR)의 설치 2) 회선증강(ACSR$95mm^2$ $\rightarrow$ ACSR$160mm^2$ ) 3) 회선신설(전압강하 5%이상 지점에 회선 추가)에 대한 경제성을 현재가치 환산법에 의해 평가해 보고, 가장 적정한 대안을 제안하여 배전계통 계획 및 운용에 대한 합리적인 투자 대안을 제시한다. -
최근 석유공급의 불안정과 에너지 소비의 급격한 증가로 인하여, 국가적인 차원에서의 에너지 절약사업이 주요 시책으로 추진 중에 있으며, 전력사업에서도 에너지 절감이라는 차원뿐만 아니라 경영에 직결되는 중요한 과제로 전력손실에 대한 관심이 높아져가고 있다. 특히, 전력시장 자유화라는 흐름 속에서 전력손실 문제는 전기요금의 산정에 있어서 합리적인 근거를 제시한다는 점에서 중요한 관심 사항이 되고 있다. 본 논문에서는 배전손실을 정확하게 산정하는 방안을 마련하여, 배전사업자가 배전망을 효과적으로 운용하여 손실을 최소화할 수 있도록 유도하며, 전력공급 전반의 효율성을 향상시킬 수 있도록 한다.
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Power demands are increased because of the growth of the economy and the improvement of a given condition life. For this reason, the fault current of the power system is largely increased and the fault current procedure for the proper interrupting capacity calculation of the existing or the new circuit breaker is essential. This paper is basis on collection of the case of foregin countries. It presented the new procedure of the fault current for the interrupting capacity of the circuit breaker. This procedure is applied to the future power system and calculates the fault current.
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This paper proposes determining a optimal number, size and allocation of DGs(Distributed Generations) needed to minimize operation cost of distribution system, obtains economic benefit in operation planning of DG and improves system reliability. System reliability is assessed whether DG install and reliability cost consider. DG optimal allocations are determined to minimize total cost with power buying cost, operation cost of DG, loss cost and outage cost using GA(Genetic Algorithm). And it was determined installed load-point and order.
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The exicting short circuit analysis calculate the current with the balance system and unbalance fault impedance. That method deal with only bus fault with the consequence that line fault study is irrational. This paper propose the line fault, shunt unbalance and series unbalance analysis method using template concept that is one of advantages for OOP(Object-Oriented Programming). This method is possible to use for calculating inductive distrubance.
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Recently, with the increasing use of power semiconductors and microprocessors which are very sensitive to little change of power quality and for coping positively with anticipating power quality disputes between power providers and consumers which are possible to occur by of power market being formed, the power quality problem has gained preponderance among the contemporary research areas. To serve these purposes, this paper is described the integrated system for power quality monitoring, which provides speedy and powerful functions by analyzing the Event data and diverse graphic interfaces for user.
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본 논문은 수도권 지역계통의 전압안정도 향상을 위한 FACTS 설비의 설치 위치를 선정하기 위해 전압-무효전력의 감도를 이용한 모드 해석(Modal Analysis) 방법의 적용 사례를 제시한다. 적용 사례는 우리나라 전력계통의 2007년, 2008년, 2009년, 2010년의 부하수준별 수도권의 중요 345kV 송전선로 상정 사고시 모드 해석 결과에 의해 각 모드별 모선 참여율을 구해 가장 효과적인 FACTS 설비 설치 후보지를 도출하였다.
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본 논문은 제주도에 신설되는 제주급전소 EMS/SCADA 기능의 일부인 자동발전제어(AGC) 기능의 설계 내용을 제시한다. 제주 EMS의 자동발전제어(Automatic Generation Control(AGC)) 기능은 지역으로 구분된 계통에서 전력수요를 만족시키기 위해 지역 내의 발전소 유효전력 출력을 제어하는 계통급전센터의 온-라인 응용 소프트웨어이다. 본 논문에서는 제주 EMS에 적용된 AGC 기본 알고리즘과 운영자 편의를 위한 MMI 설계를 보여준다.
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This study alms at analyzing a power system, in case of installing HTS cable in the system. First of all, we determine the case that HTS cable can be applied to KEPCO systems and analyze the static state of power system. Then we propose a solution of the problem resulting from the analysis.
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This paper presents a new fault location algorithm for 3 phase underground cable based on distributed parameter circuit analysis, by which we establish the basic equations for each of core and sheath currents and voltages considering cross-bonding sheaths. The proposed algorithm need simulate by EMTP, and then the EMTP data need be compared with the calculation result in Matlab.
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Kinds of most frequent faults happened on overhead distribution system are the single line-to-ground fault, the line-to-line fault and the two line-to-ground fault. Occasionally, the three line-to-ground fault and the disconnection of a wire are happened in severe conditions. In this study, the single line-to-ground fault, the line-to-line fault, two line-to-ground fault on three-phase four-wire overhead distribution system were experimentally simulated and characteristics of total leakage current of distribution arrester caused by these faults were investigated. Also, the changing aspect of total leakage current of distribution arrester caused by voltage variation was investigated. In a consequence, abnormal voltages caused by voltage variation, the line-to-line fault, the two line-to-ground fault have a little effect on total leakage current of ZnO arrester. But abnormal voltages caused by the single line-to-ground fault have an important effect on total leakage current of ZnO arrester.
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Since faults often occur on power system, relay protection has become an important part to protect the equipments of power system efficiently and safely. Database can store the data about the relay protection efficiently, and these data must be shown to users through the web. Proset2000(an overall program system to protect power system) can realize this function in some measure, but it needs to be developed. This paper is about the further development of Proset2000. In this paper, web of Proset2000 is made by ASP programming technology, and users can browse and search the useful data through the web. There are some new functions, such as the summary of setting values, the message board and the management of administrator.
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Lee, S.S.;Song, K.J.;Sohn, J.M.;Han, J.G.;Lee, T.Y.;Park, J.K.;Moon, S.I.;Kim, J.C.;Lee, S.K. 181
본 연구에서는 현재 국내-외 논문을 참조하여 배전계통에 적용된 조류계산 알고리즘의 적용사례를 조사하였다. 배전계통에 적용된 조류계산알고리즘은 Power Summation Method와 Current Summation Method가 있다. 배전계통은 선로의 구조가 거의 대부분 방사상으로 성되어 있기 때문에 Newton Raphson, Gauss Seidel, Fast Decoupled 방법을 그대로 사용하기는 문제가 있다. 그래서 DistFlow, Forward/Backward sweeping 법 등이 주로 사용되어 왔다. 그러나 미래의 계통은 현재와는 또 다른 Topology로 방사상과 루프가 혼합된 형태로 다르게 구성되어야 할 것이다. 이러한 상황에서 미래의 배전계통에 대하여 적용 가능한 알고리즘을 전망하고져 한다. -
As STATCOM is considered to be installed in bulk power system, various studios are conducted to establish strategies for system operation considering STATCOM. This paper describes control strategy for coordinating STATCOM with existing switched shunt in bulk power system.
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Service restoration following a complete or partial collapse starts with reenergizing a transmission line from black-start generators. Voltage problems can arise from Ferranti effect as unloaded transmission line is reenergized and has to be required to consider it when KPX makes a restorative plan on the massive blackout. This paper presents the investigation of seven regional blackstart lines which are chosen by KPX restorative plan and suggests the verification method for the new designed line according to the system modification.
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When generators trip on the occurrence of disturbance, the power system frequency declines by the amount of difference between demand and supply due to the imbalance between power generation and load. Even though the power system is operated with the same grid structure, generating capacity, and load, the resulting frequency decline and its recovery slope show different aspects according to the inertia constants of generators, spinning reserves, and the speed adjusting rates at the governors. From this point of view, we analysed differences of frequency decline at the various conditions in domestic power system.
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In this paper, we present the analysis results of TCSC(Thyritor Controlled Series Capacitor) operating characteristics with damping resisters. This TCSC system is designed for KERI simulator. It consists of many power system components, which are generator models, scale-downed transmission line modules, transformers, switches, FACTS(Flexible AC Transmission System) devices.
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The impacts of electric service interruption to customers depend on customer and interruption characteristics. Customer characteristics include demographic aspects(residential type, and number of household members) and power supply types whereas interruption characteristics include frequency, duration, time, and day of interruption. Accordingly evaluation of these customer interruption costs is very complicated and subjective. For residential customers, customer survey method seems most appropriate because interruption impact to residential customers is intangible. In other words, the value of housework or lost leisure due to interruption is individual. Accordingly, this paper selected the customer survey method to assess the interruption costs for residential customers.
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Han, Choong-Kyo;Park, Jong-Young;Park, Jong-Keun;Ahn, Byeong-Jin;Jo, Beom-Seop;Jang, Byung-Tae 199
전력산업의 경쟁도입 환경으로 인한 송전서비스에 대한 증가된 수요를 보여주고 있다. NERC의 1997-2000 신뢰도 평가 보고서에 의하면 과거 10년동안 대부분의 송전시스템 추가는 지역적 보강을 위해 이루어졌다. 전 계통의 시스템 능력을 강화시키는 큰 송전시스템의 증설은 거의 이루어지지 않았다. SPS는 비정상적 계통 상황을 검출하고 미리 계획된 동작을 수행함으로써 비정상적 상황을 회피하여 정상적 계통을 유지하게 한다. SPS는 계통의 송전능력을 증가시키는데 자주 이용된다. 새로운 송전설비 증설의 대안으로 비용면에서 값싼 SPS가 활용되어지는 것이다. SPS가 정확하게 동작한다면 상정사고에 대한 시스템 능력을 매우 향상된다. 그러나 미리 정의된 상황을 검출하는데 실패하거나 미리 계획된 교정동작을 수행하는데 실패한다면 매우 심각한 결과를 초래한다. IEEE-CIGRE 설문조사에서 보여주듯이 SPS 동작 실패는 비용면에서 매우 높은편으로 응답되었다. 따라서 단순 비용 평가를 통해 SPS를 도입을 결정할 수 없다. 경제적 위험 평가를 통해 SPS가 있을때와 없을때의 위험을 평가하여 의사결정에 반영하여야 한다. 본 논문에서는 SPS의 위험을 평가하는 절차를 보여주고 산업에서 SPS 경험들을 소개하도록 한다. -
This paper suggests an optimal parameter setting method by use of parametric protectability index, as the objective function. In this paper, a gradient based optimization method is used under the assumption that the initial values of a parameter is in a convex set including the optimal value, which is verified by a plenty of simulation studies. The proposed method is applied to a sample distribution network to shows its effectiveness.
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Computerized simulation is becoming an indispensable procedure in the stage of planning, design, and operation of railway systems. This paper presents result of simulation technique for describing electrical performance of the power supply system which comprises the substation, catenary, feeder, and rails where multiple trains are running using result of train performance simulation.
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Conventional PDC relaying with 2nd harmonic restraint makes some doubt in reliability. It can contain second harmonic component to a large extent even during internal fault, and shows a tendency of relative reduction because of the advancement of transformer's core material. It is, therefore, necessary to develop a new algorithm as well as a new technique for the effective and accurate discrimination. This paper deals with advanced algorithm, fuzzy logic based relaying by using flux differential, and a new fault detection criterion logic scheme by using wavelet transform. To comparative analysis of proposed techniques, the paper constructs power system model including power transformer, utilizing the EMTP, and collects data through simulation of various internal faults and magnetizing inrush.
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A voltage sag is a short-duration reduction in rms voltage, and utilities have been faced with rising numbers of complaints about the quality of power due to voltage sags. In this paper, vulnerable areas of voltage sag are determined using representative loads at the buses. The CBEMA curves of the representative loads are used to determine whether the bus is vulnerable or not. Also, the ares are displayed with geographical information in order to help operators understand the situation going on easily. The proposed simulator is applied to Jeju power system to show its capabilities.
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This paper presents a distance relaying algorithm for a transmission line protection with MAS. First, the voltage and fault current of the opposite side are represented as a function of those of the measuring end using source voltages of both ends. These voltages are assumed to be obtained from the transformers protecting agents, periodically in normal state. Then, the fault location expression, independent of fault resistance, is derived with voltage and current in only one end of faulted line used. The suggested algorithm is applied to a simple system with two power sources to show its effectiveness.
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This paper presents VSCOPF(Votage Stability Constrained Optimal Power Flow) algorithm based on SLP(Successive Linear Programming) to interpret the large scale system. Voltage stability index used to this paper is L index to be presented by function form. The objective function consists of load shedding cost minimization. Voltage stability indicator constraint was incorporated in traditional OPF formulation. as well as the objective function and constraints are linearlized and the optimal problem is performed by SLP(Successive Linear Programming). In this paper, the effect of voltage stability limit constraint is showed in the optimal load curtailment problems. As a result, an optimal solution is calculated to minimize load shedding cost guaranteeing voltage security level. Numerical examples using IEEE 39-bus system is also presented to illustrate the capabilities of the proposed formulation.
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본 논문에서는 현장측정을 통하여 수용가별(업무용, 주택용, 산업용)로 발생하는 전압, 전류고조파의 특성을 비교분석하였다. 특히 국내에서 규정되어 있지 않은 전류 고조파 종합왜형률(
$THD_i$ )과 더 향상된 방식인 전류 종합 부하왜형률($TDD_i$ )을 제시하여$THD_i$ 와 비교하였다. 또한 50조파까지의 측정을 통해 향후 국내의 실정에 맞는 고조파 한계 기준에 적합한 설정치를 제시하였다. -
본 논문은 분산전원이 기존의 배전계통상에 도입되는 경우에 대하여 전압변동해석을 수행하기 위해 제주 성산 변전소를 선정하여 MATLAB 프로그램을 이용하여 시뮬레이션 및 전압변동사항을 모의 분석하였고, 실제로 제주 행원풍력설비에서 발생하는 전압, 전류 고조파를 50조파까지 측정하여 전압 및 전류고조파 왜형률에 대한 분석을 시행하였다.
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본 논문은 최근 대체에너지원으로 각광받고 있는 주택용 태양광발전시스템에 전력변환 장치로 이용되고 있는 계통연계형 5kW 태양광 인버터에 대한 현장 실계통의 고조파를 측정하여 전압 및 전류 고조파왜형률에 대한 분석을 시행하였다.
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This paper describes a new methodology to get pareto-optimal generation planning for decision-making. To get optimal generation planning consider total quantity of contamination for the specified term, authors employ dynamic programming. And, in the course of dynamic programming, pareto optimal solution can be obtained. So, a most proper solution can be selected by derision-maker. The usefulness is verified by applying It to the test system.
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This paper proposes a method for estimating unbalance in electric railroad system PSCAD/EMTDC models for voltage unbalance analysis of electric railroad system that transfer electric power through Scott transformer from KEPCO's 154kV transmission line are developed. In order to verify model's validity, we compare simulation results with simple calculation results.
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The time domain simulation method of transient stability presents accuracy and reliability, but it demands much computational time. Therefore it is necessary to filter out very stable and very unstable cases from a large set of contingencies. Following a disturbance, the shape and magnitude of representative generator angle which is most increased after fault clearing are the measure of transient stability. This paper propose a method that is not a calculation of the exact CCT of contingency, but a fast assessment of transient stability. Also it can help operators identify transient stability immediately without analyzing the graphical results. The proposed method is applied to the KEPCO system. The PSS/E is used as a time domain simulation engine by IPLAN.
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Lee, Hong-Hak;Lee, Tae-Young;Kim, Ho-Pyo;Nho, Jang-Hyun;Kang, Kun-Soo;Jang, Sung-Hoon;Lee, Jae-Wook 242
The functional test of protection relays is divided into two kind of test types; the steady-state test and dynamic test. Because the steady-state test is comparatively easy, this test is used to test the characteristics of the relaying elements, operating values, resetting values and etc. using equipment such as Doble. But the dynamic test has to be performed on the test environment with RTDS(real time digital simulator) because of the dynamic characteristics of real protection relays. Therefore, it is not usually easy to perform dynamic test of relays using power system simulation tool based on PC(personal computer) such as PSCAD/EMTDC. This paper discusses how to develop and implement a test model and user-defined components that can be performed dynamic test using PSCAD/EMTDC. -
Zone 3 of the distance relay is used to provide the remote back-up protection in case of the failure of the primary protection. However, the risk for mal-operations under stressed conditions such as heavy loading, voltage and transient instability is usually high. Zone 3 is used in combination with the derivatives of the voltage, and current, etc to prevent mal-operations. Sometimes, the impedance characteristics that restrict the tripping area of relay are used to avoid the mal-operations due to load encroachment. This paper presents a novel zone 3 scheme based on combining the steady-state components(i.e. 60Hz) and the transient components(TCs) using a state diagram that visualizes the sequence of studies that emanate from the sequence of events. The simulation results show that the novel zone 3 distance relay elements using the proposed method operates correctly for the various events.
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Recently, electric power system's situation grows gradually so Fault Diagnosis is being complicated and is felt difficult. And ability that operator who is using electric power system must do correct judgment of power system state, and can cope at fault of power system state is required. Therefore, large size power system is divided into predefined minimum module, and define each module accident type. We use and compare defined accident type, we can know easily accident that happen forward. Therefore, large size power system using module that is defined to each section common accident type search in this paper. Therefore, large size power system using module that is defined to each section, we search for common accident type. And when accident in electric power system happens, I wish to explain about process that can do fault diagnosis in more easy and fast time, because using accident type that it is verified in front.
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A voltage stability assessment consists of the contingency screening, voltage stability analysis, and counter measures. A widely used index for the voltage stability assessment of power system is the reactive power margin. It shows some factors of voluntariness as following the status of power system and load levels for the target analyzing area. Therefore, it has a demerit that the absolute amounts of reactive power margin is not to be applied by the quantized margin criterion. This paper selects a vulnerable area by assigning the voltage instability for the particular contingency for the selection of vulnerable area in the respect of the investigation of reactive power margin or VQVI as an index of V-Q margin sensitivity in order to overcome the demerit. This will be able to grasp the V-Q margin sensitivity for the target analyzing area by presenting the ratio of power margin between the margin before and after contingency as following the calculation of reactive power margin. The presented method is applied to the voltage stability assessment for the Metropolitan area of 2003 KEPCO summer peak system.
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In this paper there are different methods used to study the voltage stability, such as the P-V curve method. Jacobian method and the voltage collapse proximity indicator(L-index) method. The P-V curve method is to check operating margin from the maximum operating point. The Jacobian method is to check the eigenvalue or the minimum singular value of the load flow Jacobian matrix. If the power system is unstable, one of the eigenvalues, at least, has crossed the imaginary axis. The L-index method is to quantify how to close a particular operating point. This paper describes these methods to select the best location of FACTS and demonstrate the effectiveness of STATCOM of voltage stability on the IEEE 9-bus system.
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오늘날 상용화되어 있는 디지털 주파수 계전기는 교차된 시스템 전압의 양단이 0 으로 되는 동안의 시간을 측정하여 주파수를 얻는다. 이러한 계전기의 동작은 왜곡된 고조파와 노이즈로 인하여 주파수 측정을 잘못하는데 이로 인해 zoro crossing이 변하거나 증가된 zero crossing이 생성된다. 최근 몇몇의 디지털 주파수 계전기 알고리즘이 제안되었다. 본 논문에서도 역시 보다 정확하면서 고속데이터 처리가 가능하도록 보호 계전기 연산에 사용되는 알고리즘을 최적화하고자 한다.
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During magnetic inrush or over-excitation saturation of the core in a transformer draws a large exciting current. This can cause mal-operation of a differential relay. This paper proposes a modified current differential relay for transformer protection. In order to cope with the remanent flux at the beginning. the start of saturation of the core is detected and the core flux at the instant is estimated by inserting the differential current into a magnetization curve. Then, this core flux value can be used to calculate the core flux. The proposed relay calculates the core-loss current from the induced voltage and the core-loss resistance; the relay calculates the magnetizing current from the core flux and the magnetization curve. Finally, the relay obtains the modified differential current by subtracting the core-loss current and the magnetizing current from the conventional differential current. The proposed technique not only discriminates magnetic inrush and over-excitation from an internal fault, but also improves the speed of the conventional relay.
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This paper proposes the Fault Location Estimation Algorithm in the parallel transmission lines. These algorithm uses a variable data window method based on least square error method to estimate fault impedance quickly. And it selects the optimal equation according to the operation situation and usable fault data for minimizing the fault estimation error effected by the zero sequence mutual coupling. After simulation result, we can see that these algorithm estimates fault location more rapidly and exactly.
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A method for calculation of mutual inductance from the parallel power-line and earth conduct to communication-line is studied in the paper. The solution for the electromagnetic field produced by an overhead power-line is derived using Maxwell's equations and treating the as a boundary value problem. Total mutual inductance from direct current and image current to communication-line is used Carson's formula for infinitely long parallel conductors.
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Distribution system reliability evaluation estimates by approach methods such as Makove modelling or Monte Carlo simulation, equation of state and failure rate that is on one basic data used to these assessment technique is described as probability of average value. because average failure rate equipment device is aged as time goes by but there is shortcoming that such used failure rate does not evaluate thing which is correct in reliability change hereafter. In this paper, failure rate displayed that apply aging to basis equipment device by passing time using Weibull distribution one of life evaluation method and for express aging of component from utility's failure database.
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This paper deals with Object-oriented Database(OODB) which is designed for power system analysis, and describes load flow analysis using OODB. Database management systems are widely used and achieve high reliability of data management in the engineering fields. However conventional database systems, relational database system, have disadvantages in application to power system analysis. This paper presents advantages of OODB for modeling complex data of a power system analysis. The OODB supports data modeling requirements of GUI applications and the performance is well acceptable for GUI applications.
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As the use of ASD due to developing of power electronics technology was increased, the failure of induction motor by switching surge also was increased. This paper presented a switching surge modeling of inverter and a induction motor modeling using EMTP program. As a output waveform of square wave inverter and PWM inverter and the input terminal waveform of induction motor were shown, the effect of switching surge was analyzed.
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In the rower systems of Korea, there is little chance of the separation of power systems as well as a blackout due to the large disturbance. However, that possibility shouldn't be ignored, and always exists. In this paper, we present the results of the analysis of transient stabilities for the case of contingencies of power systems separation in the isolated power systems where the regional concentration of supply and demand exists.
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The low load power factor causes various problems such as the Increase of the power loss and the voltage instability. The demand of reactive power increases continuously with the growth of active power and the restructuring of electric power companies makes the integrated management of ractive power troublesome, from which the systematic control of load power factor is required. In this paper, the load power factor sensitivity of the generation cost and integrated costs are used for determining the locations and capacities of reactive power compensation devices effectively and for enhancing the load power factor appropriately. It is shown through the application to a small-scale power system that the system power factor can be enhanced effectively and appropriately using the load power factor sensitivity and integrated costs.
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다모선 계통의 정확한 과도 안정도 직접해석을 위해 댐핑영향은 고려해야 할 중요한 요소 중의 하나이나 일반화가 어려워 최근까지 무시되어 왔다. 본 논문에서는 시스템을 나타내는 함수들의 적분 관계식들을 고려함으로써 다모선 계통에서의 댐핑영향을 반영한 에너지 함수를 유도하였으며 유도 과정에 있어 최근 다모선 계통에 보편적으로 적용되고 있는 관성중심(Center of Inertia :COI) 표현법으로 전개를 시도하였다. 유도된 에너지함수를 PEBS(Potential Energy Boundary Surface) 직접법에 적용하여 임계위치에너지를 산출하였으며, 임계고장제거시간을 계산함으로써 과도안정도직접해석법을 수행하였다. 제안된 에너지 함수를 WSCC 3기 9모선 샘플 시스템에 적용하여 댐핑이 고려된 에너지함수가 실제 계통을 보다 정확하게 표현하고 있음을 시뮬레이션을 통해 검증하였다.
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Energy markets of the Northeast Asia countries and in particular South Korea are perspective enough from the standpoint of export of energy resources from Russia. South Korea Power System has been rapidly growing. However, recently it has been confronted with difficulties in regard to constructing new Power Stations and especially Hydro Power Plants. Therefore it is mutually beneficial to build electric tie to South Korea in order to use highly effective Power of Northeast Asia. In this paper, we describe the maximum available transmission power through interconnected line without loss of stability in power system. For this simulation, the AC transmission system is assumed appropriate for this preliminary study. The transmission system will pass through territory of North Korea and connect to 765 kV Network near Seoul with long distance.
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Lee, S.S.;Li, S.Y.;Lee, Y.J.;Chung, W.D.;Jang, G.S.;Min, S.W.;Park, J.K.;Moon, S.I.;Lee, H.J.;Lee, K.S.;Kang, S.H. 294
본 논문에서는 우리나라 7개 지역의 시송전 선로를 구성하여 전력계통안정화장치(Power System Stabilizer)의 특성을 분석한다. Black start 발전기의 전력은 각 지역의 시송전 경로를 통하여 우선공급발전기에 공급한다. 이는 한국전력거래소(KPX)에서 규정하고 있으며, 주선로와 예비선로로 구성되어 있다. PSS의 성능 분석은 PSS1A type을 부착하여 수행하였다. 시뮬레이션 패키지는 EMTDC를 사용하여 그 특성을 검토하였다. -
This paper proposes a totally new method in the chaos characteristics analysis of power systems, the introduction of topological invariants. Using a return histogram the bifurcation graph was drawn, the periodic orbits and topological invariants the local crossing number, relative rotation rates, and linking number during the process of period-doubting bifurcation and chaos were extracted. This study also examined the effect on the topological invariants when the sensitive parameters were varied. In addition, the topological invariants of a three-dimensional embedding of the strange attractor was extracted and the result was compared with those obtained from differential equations. This could be a new way for a state detection and fault diagnosis in a dynamical system.
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본 연구에서는 발전기에 적용된 전력계통안정화장치(Power System Stabilizer)의 적용사례를 분석한다. 전력계통안정화장치에 적용된 알고리즘은 Lead-Lag 제어기가 있고, 현대 제어이론에 바탕을 둔 LQR, LQG,
$H_{\infty}$ , 슬라이딩모드 제어기, 비선형궤환제어기가 있다. 그 외에 퍼지제어기, 뉴럴 제어기, 진화연산제어기등이 있다. 이중에 전력계통안정화장치의 제어알고리즘에 대하여 대표적인 사례를 파악하고져 한다. -
각종 전력기기들에 대한 국내외 규격시험을 성공적으로 수행하기 위해서는, 측정시스템의 구축뿐만 아니라 측정결과에 대한 신뢰성을 제공하고 시험을 효율적으로 수행할 수 있는 전용 소프트웨어의 개발이 필요하다. LG산전 전력시험기술센터(PT&T)는 이러한 목적을 위해 전력시험 전용 소프트웨어를 개발하고, 부속 기능인 API 함수를 이용해 퓨즈시험 전용 프로그램 모듈들을 개발하였다. 본 논문에서는 개발된 소프트웨어의 특징을 소개하고자 한다.
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전력품질 향상기기인 DVR, D-STATCOM의 동작특성 분석을 위해서 미리 선정된 부하에 대한 PSDM(Power System Fault and Disturbance Recorder) 데이터를 근거로 ZIP모델을 구성하고 EMTDC 프로그램을 이용하여 이를 분석하였다.
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유도 전동기 보호를 위한 계전기 개발을 위해서는 유도 전동기의 내부 사고에 대한 모델링이 선행되어야 한다. 본 논문에서는 유도 전동기의 내부사고 중에서 고정자 권선의 지락 사고에 대한 모델링 방법을 제시하였으며 이를 MATLAB을 이용하여 모의하였다. 제시한 모델링 방법을 이용하여 유도 전동기의 기동 현상을 모의하였으며 이를 EMTP에서 모의한 기동 현상과의 비교를 통하여 제시한 모델링 방법의 타탕성을 검증하였다.
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Power system is becoming more and more complex and large. And power consumption increases rapidly according to the industry development. There is an ample possibility for a fault in proportion to these facts. Therefore power system engineer is requested to abilities, fault analysis and fault prevent. This paper handling result data by Object Oriented Database(OODB) because OODB has advantages abut flexibleness and recycling. Besides this paper presents fault analysis program by Graphic User Interface(GUI) to understand easily program using method.
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When power cables cross regions with unfavorable thermal conditions, conductor temperatures higher than the design value can occur. This paper studies the algorithm which is calculate the conductor temperature distribution of power cables installed in thermally dissimilar soil materials and simulate the longitudinal temperature of power cables.
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Maximum short circuit current of modern power system is becoming so large that the current should transmission capability. Although there are various kinds of method to solve this, approached from super conductivity Fault Current Limiter application viewpoint among them. High Temperature Superconductor-Fault Current Limiter(HTS-FCL) development is progressing according to HTS technology development, and system application is tried. For actual system application of such super conductivity FCL, an efficient method to find FCL locations suitable for reduction of short circuit currents of more than one fault location is developed.
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전력계통 해석의 정확도 향상을 위해서는 해석용 데이터의 정확한 입력이 필수적이나, 우리가 사용하고 있는 해석용 프로그램의 알고리즘상 한계, 실제 전력계통에 설치중인 비표준 전력설비의 데이터 적용상 문제점 둥으로 현재 우리가 사용하고 있는 계통해석용 데이터는 정확도면에서 다소 보완이 필요하다. 이와 관련하여 본 고에서는 전력계통 해석 정확도 향상을 위한 각 상별로 다른 변압기 임피던스의 합리적인 적용방법, 우리계통에 다수 설치되어 있는 기준 외 변압기 데이터 처리방법, 발전기 단자전압과 Step-up 변압기 정격전압 상이로 인한 데이터 적용상 문제의 해결대안을 모색하였고, 현재 우리가 적용하고 있는 송전선로의 선로정수 데이터를 대푯값과 비교분석을 통하여 정확성 의심개소를 제시하였으며, 기존 방식의 해석결과와 금번 개선안 적용시의 해석결과를 실계통 운전실적을 중심으로 비교하여 계통해석 정확도 차이를 나타내 보였다.
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This paper proposes an estimation algorithm for the generating power of distributed generations(DG) interconnected with distribution networks. These days, DG are rapidly increasing and most of them are interconnected with distribution networks. The DG can supply power into the distribution network, which may make significant impact on fault current and the protection scheme of the interconnected distribution networks. Generally these influences of DG is proportioned as the distributed generator's power. Therefore, it is important to forecast the output power of distributed generator in PCC(point of common coupling). This paper presents the prediction method of DG's power by monitoring the current and phase difference.
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This paper describes the effect of the interconnected wind turbine generators on fault current level of distribution networks. Distributed generator(DG) interconnected with grid 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 distribution power line with DG, the fault current level measured in a relaying point might be higher than that of distribution network without wind turbine generator due to the contribution of wind farm. Consequently, it may destroy the conventional protective devices applied in the distribution network with DG. Simulation results shows that the current level of fault happened in the power line with DG depends on the power output of DG.
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This paper describes the influences of the large scaled wind farm interconnected with 154 kV power networks on the operational characteristics of distance relay applied in the transmission line. The wind farm composed of wind turbine generators are one of the great energy sources: they can supply the power into an interconnected network not only the normal conditions, but also the fault conditions of power network. Therefore, the distance relay applied in the transmission tine may mal-operate due to the contribution of wind farm. This paper presents the operational characteristics of distance relay for the fault occurred in the transmission line interconnected with wind farm. Simulation results show that it is difficult to recognize the fault location due to the power output of wind farm.
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This paper describes the operational characteristics of protection algorithm applied in distributed generations(DG) for faults occurred in the interconnected distribution networks. The DG can be Influenced by abnormal grid conditions such as disturbances occurring in the neighboring distribution feeders as well as the interconnected power line. Particularly, in case of the fault happening in the neighboring distribution feeders emanated from the substation to which DG is connected, the protective devices in the DG might mis-operate. The mis-operation of protective devices can be varied by the fault conditions. The simulation results for Hoenggye substation model composed of five feeders using PSCAD/EMTDC showed that the number of mis-operation of protective devices applied in DG is about 0.66 times per one year.
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This paper proposes a tree-winding transformer protective relaying algorithm based on the ratio of increment of flux linkages (RIFL). The RIFL of the two windings is equal to the turns ratio for all operating conditions except an internal faults. For a single-phase transformer and three-phase transformer containing the wye-connected windings, the increments of flux linkages are calculated. for a three-phase transformer containing the delta-connected windings, the difference of the increments of flux linkages between the two phases are calculated using the line currents, because the winding currents are practically unavailable. Their ratios are compared with the turns ratio. The results of various tests show that the algorithm successfully discriminates internal faults from normal operation conditions such as magnetic inrush, overexcitation and external faults. The algorithm can not only detect internal winding faults, but reduce the operating time of a relay.
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본 논문에서는 분산전원이 기존의 배전계통상에 도입되는 경우에 대하여 전압변동해석을 수행하기 위하여, 풍력발전단지가 도입된 제주 성산 변전소를 선정하여 MATLAB 프로그램을 이용하여 시뮬레이션을 수행하고 전압변동상황을 예측, 이에 따른 문제점과 그에 대한 대책을 제시하도록 할 것이다.
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본 논문에서는 태양광-풍력 복합발전시스템의 발전용량 예측을 통한 시스템 시설투자비 및 발전단가와 경제성에 대하여 분석한다. 도시지역의 일사량 및 풍속 데이터를 기초로 하여 복합발전시스템의 일일 발전량을 구하고, 수용가의 일일부하패턴과 수요부하를 고려하여 태양전지 어레이와 풍력발전기의 용량을 산정한다. 그리고 용량 산정에 따른 복합발전시스템의 초기투자비용과 연간 발전량, 연간 소요경비 등의 요소를 고려하여 총 수명가 분석법(Total Life-Cycle Cost Analysis)에 기초한 발전단가를 계산하고 잉여전력을 계통에 판매할 경우의 경제성을 평가한다.
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Lee, S.S.;Sohn, J.M.;Song, K.J.;Han, J.G.;Lee, T.Y.;Park, J.K.;Moon, S.I.;Kim, J.C.;Lee, S.K. 351
우리나라 배전계통의 운용은 15개 지사와 수많은 지점에 의하여 관리되고 있으며 각 지역은 산악과 평지가 어우러져 복잡하고 다양한 지리적인 형상을 가지고 있다. 우리나라 고압 배전선로 구성의 특징은 도심지나 주요 시설을 제외하고는 거의 대부분이 방사상으로 되어 있다. 본 연구에서는 우리나라 배전선로의 현황 및 지리적 특징에 따른 선로 구성 방안과 해외사례를 검토한다. -
전력산업은 국가의 가장 중요한 중추적인 기간산업임에도 불구하고 최근 정보 통신 산업 등에 밀려 위기를 맞고 있다고 할 수 있다. 그러나 IT기술의 발달과 전력기기, 설비의 디지털화 기술개발이 본격화되면서 전력 IT기술과 산업은 IT 융합형의 신전력산업으로 그 가능성이 어떤 분야보다 크며 새로운 기회를 맞이하고 있다고 볼 수 있다. 특히 중전기기분야에 선진국에서는 전력산업이 퇴조를 이룬 반면 국내에는 한국전력, 각 학계, 연구소 및 업계에 많은 전문인력을 확보하고 있으며, 특히 세계적인 경쟁력이 있는 IT기술을 확보하고 있다. 그러므로 IT기술과 중전기기, 전력계통 기술을 융합하여 전력산업에서의 새로운 산업창출을 도모하고 세계적인 경쟁력을 조기에 확보하여 수출산업으로 육성하기 위하여 정부는 차세대 성장동력산업의 주력기간산업으로 전력 IT분야를 포함하기에 이르렀다. 이제 차세대 성장동력산업의 산업 기술혁신 5개년 계획에 따라 전력 IT가 전기산업 분야의 새로운 산업으로 발전할 수 있어야 하겠다.
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원자력과 같은 대용량 발전기의 갑작스런 탈락이나 하루 중 아침시간이나 점심시간과 같이 급격한 부하변동이 발생하는 특수 시간대에는 계통의 발전량과 부하량간에 심한 불균형이 발생하게 된다. 이 경우 계통 주파수가 변하여 발전량과 부하량이 자동으로 조절되어 수급의 균형이 이루어지게 되므로 계통이 안정하게 유지된다. 본 논문에서는 실계통 사고사례를 통하여 우리나라 계통에서 대용량 발전기 탈락시 주파수변동에 따른 발전량 및 부하량의 조절특성과 고장당시 계통 발전기들의 응동특성을 소개한다.
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Lee, Jae-Duck;Ryoo, Hee-Suk;Choi, Sang-Bong;Nam, Kee-Young;Jeong, Seong-Hwan;Kim, Dae-Kyeong 361
To reduce the effect of fault on underground power cable, we need exact and fast fault location detection technique. In this thesis, we describe on filter design technique that can be applied to on-line fault defection technique. To design fitter for fault location defection on Power cable, we should analysis fault signal. So we designed test bed for fault generation and measured fault signals for analysis. Through the analysis of signals, we found that ANC filter can be applied to separate fault signals and we designed a ANC filter. We tested on the designed filter through computer simulation, and we describe its results in this paper. -
345kV XLPE Cable system was constructed between Yeongseo-Yeongdeunpo at first in Korea. XLPE cable have the advantage of OF cable. it is to raise the power transmission capacity and reduce the power loss and expenses. We also applied many new technology in this project at first. One is pre-fabricated joint which can be easily assembled in the field without any hand-skill, another is PD(Partial Discharge) test for after laying test. Especially, PD measurement for after-laying test was performed to evaluate the quality of the cable joint and termination. Through the good experience of this project, we have gotten the international competitiveness of power business.
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최근까지 낙뢰에 의한 과전압으로 인해 배전설비뿐만 아니라 수용가 설비의 피해가 적지 않게 발생하고 있다. 특히 낙뢰는 호우를 동반하는 경우가 대부분이기 때문에 수용가에 미치는 피해의 파급효과는 아주 크게 나타나고 있다. 따라서 배전급 내뢰설비의 시설효과를 실제 배전계통상에서 실증적 방법으로 분석하여 최적의 운영방안을 도출함으로써 효과적인 내뢰대책을 제시할 필요성이 크다. 본 논문에서는 수용가와 직결된 주상변압기 2차측 저압선로의 내뢰설비인 저압피뢰기(Secondary Arresters, SA)의 설치효과를 특고압측 및 저압측에서의 임펄스 전압 발생을 모두 고려하여 실증시험을 수행하고, 그 시험결과를 통해 배전급 저압피뢰기의 설치효과를 분석하였다.
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As there expands the usage of Al-Cu connections to interface aluminum and copper in power distribution systems, efforts to mitigate the mechanical, electrical or electro-chemical degradation are widely spreading. The explosive bending technology, in particular, has been thought as a countermeasure for the degradation. In this paper, electrochemical analysis and optical microscopic observation are carried out in order to compare the corrosion resistivities of the commercial compression type bimetallic sleeve and the explosion type bimetallic sleeve. The results show that the explosive bonding technology can prevent the interfacial corrosion caused by the formation of crevices and pits as well as from galvanic potential difference.
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The subway, a typical electrified transit, is operated by the 1500 V DC-powered system with the overhead positive feeder and the rails negative return. This return path would bring about considerable stray current circuits, that is, from the bottom of rails to sell and then to the station ground, unless the rail-to-soil resistance is sufficiently high. The stray current can cause electrolytic corrosion of subway metallic structures and adjacent underground utilities. In this paper, we reports on-site investigation of the stray current condition, especially influenced by drainage method. The drainage method including both forced drainage and polarized drainage, extensively adopted as a countermeasure for electrolytic corrosion of underground pipelines, was found out to exert a harmful influence upon rail components as well as the pipelines.
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The first installation of long-distance underground transmission line with 345kV XLPE Cable in KoreaSince the first underground transmission line of Korea was installed between Danginri and Yongsan substations in 1974, the two types of underground transmission power cables, oil-filled and XLPE, have been applied for underground transmission lines. As the manufacturing technologies of XLPE cable have been improved and the simplicity of installation and maintenance has been focused on, the installations of XLPE cables have been largely increased since the mid 1990's. For the first time, in Korea, the 345kV XLPE cable was installed between Youngseo and Youngdeungpo substations in 2003, June. So, this paper introduces the project profile, the design of cable and its accessory, the cable system design, installation and site test.
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The sharing of common corridors by electric power transmission lines and pipelines is becoming more common place. However, such corridor sharing can result in undesired coupling of electromagnetic energy from the power lines to the near facilities. This causes induced voltages on underground metallic pipelines due to the power line currents. This could cause AC corrosion in the pipeline, which could in turn lead to disastrous accidents, such as gas explosion or oil leakage. This paper investigates for the limitation of induced voltage on the buried metal structures which is used in the inside and outside of the country. And then we measure the earth resistance and leakage current of 22.9kV distribution lines and pipe to soil potential of near pipelines in Seoul Korea. Hereby we can see the leakage current flowing through the earthing electrode have an effect on near pipelines.
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In case of parallel running with underground gas pipeline and subway, stray current of subway makes a interference on gas pipeline. This interference is one of the reason of gas pipeline corrosion. So, the high speed response rectifier was developed in order to mitigate a interference. In this paper, the field test result of proposed rectifier is presented. The effect of an alternative in stead of the forced drainage system is also presented.
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전력계통의 증가에 따라 일부 계통에서 지락고장 전류가 2010년이후 차단기 정격전류인 40[kA]를 초과할 것으로 예상된다. 이에 대한 대책으로 345kV 변압기의 중성점의 부동(Floating) 운전을 위하여 PSS/E를 이용하여 실제의 발변전소의 모델을 설정하고 EMTP를 이용하여 지락고장 발생시 건전상의 전위상승, 중성점 전위상승, 부동운전 가능 대수, 변압기 중정점 NGR 설치 효과 및 적정 임피던스 산출, 변압기 중성점 피뢰기 설치 효과 및 적정 정격 산출등을 검토하였다.
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154 kV 변전소에 설치 운전 중인 SC Bank 콘덴서 셀의 절연파괴 고장이 빈번하게 발생되어 전력계통의 운용 및 변전소 운전에 지장을 주는 사례가 많이 발생하였다. 따라서 이의 고장원인 진단을 통하여 대책수립을 하고자 EMTP(Electro-Magnetic Transient Program)를 이용하여 SC Bank의 정상상태시 과전압, 과전류에 의한 소손현상을 검토하고, 계통조건에 따른 공진점변화와 고조파에 따른 이상전압 및 콘덴서 셀 전압의 상승 현상을 검토 분석하고, 고조파 성분에 따른 과전압 및 과전류를 분석하여 대책을 제시한 사례연구의 결과이다.
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The study of electric field analyses has been conducted on two kinds of bushings for 17.5kV
$SF_6$ gas insulated recloser. In this paper, two model bushings and input conditions for the analyses are described in detail. The results of the electric field analyses are presented and compared with to find out the better design in two bushings. Finally some suggestions are given for improving the insulation characteristics of the bushings. -
최근 전력산업의 구조개편, 선로건설의 어려움, 송전선로의 노후화, 선로용량 취약개소의 상시감시 필요성 등으로 인하여 선로의 허용 전류용량을 합리적으로 평가하는 한편, 도체의 허용전류를 실시간으로 산정하여 현재 운용상태와 비교하여 그 한계 및 여유 정도를 알아보는 것이 중요한 문제로 대두되었다. 본 논문에서는 이러한 연구의 일환으로 먼저 기상모델을 중심으로 실시간 허용전류 산정 알고리즘에 대하여 살펴보고, 대전 지역의 가공 송전선로를 대상으로 선로 주변의 기온, 풍속, 지형 정보를 이용하여 동적으로 허용전류를 산정하여 그 이용 가능성을 확인하였다.
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The inductive interference can be happened on some of the communication line that is located near by paralleled transmission line. The causes of inductive interference are magnetic coupling, capacitive coupling and residual voltage at neutral point of transmission line. In this paper, after grounding the one side of communication line, we have measured the voltage to ground at the other side of it. And we also have measured the voltage to ground at the end of it without grounding. As a result, we proved that the cause of inductive interference is the difference of ground voltages.
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본 논문에서는 대전류 표준측정에 대한 STL TC의 Ad-Hoc Working Group의 최종방안에 대해 자세히 소개하여 이를 계기로 국내에서도 필요한 사전준비에 만전을 기하고자 한다. 향후 연속적으로 해야 할 업무, Shunt의 소유, 경비 지불방법 등에 대한 사항과 함께 우리나라 대전류 표준측정시스템의 구축절차를 제안하였으며, 이를 통해 대전류 측정에 있어서 국제표준과의 소급성을 확보할 수 있기 때문에 국내에서 시행하는 각종 시험에서 대전류 측정이 국제적으로 유효하게 될 것이다.
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본 고에서는 우리나라에 유일한 배전급 실증시험장인 전북 고창 시험장에 배전급 차단기 및 개폐기의 성능을 실증 평가 할 수 있는 기본 시험 시스템 구축에 관한 시험설비에 관하여 소개한다. 본 설비를 구축 활용하므로써 filed에서 발생되는 실증시험을 통해 국내 기자재의 성능 파악 및 신뢰도 향상을 제고하고자 한다.
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본 논문에서는 대전류 표준측정에 대한 STL TC의 Ad-Hoc Working Group의 최종방안에 대한 기술적 배경을 소개하여 이를 계기로 국내에서도 대전류 표준확보에 필요한 사전준비에 만전을 기하고자 한다. STL의 대전류 reference shunt 요구사항, 측정 불확도 및 각 시험소에서 교정하여야 할 사항 등에 대하여 검토하고, 우리나라 대전류 표준측정시스템의 구축필요성, 구축절차 및 방안에 대하여 기술한다.
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It is important to classily fault types, discriminate fault section and calculate the fault location by any detecting technique for combined transmission lines. This paper proposes the technique to classily the fault types and fault section using neuro-fuzzy systems. Neuro-fuzzy systems are composed of three parts to perform different works. First, neuro-fuzzy system for fault type classification is performed with approximation coefficient of currents obtained by wavelet transform. The second neuro-fuzzy system discriminates the fault section between overhead and underground with detail coefficients of voltage and current. The last neuro-fuzzy system calculates the fault location with impedance in this paper, neuro-furry system shows the excellent results for classification of fault types and discrimination of fault section.
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한국전력공사에서는 전압원 인버터형 FACTS 기기인 UFPC를 전남 강진군 강진변전소에 설치하였다. 강진 UPFC는 한전과 (주)효성이 공동으로 투자하고, 지멘스와의 기술제휴를 통해 개발하였으며, 40MVA 병럴인버터, 40MVA 직렬인버터로 구성되어 총 80MVA 용량이다. 강진 UPFC는 GTO를 이용한 3레벨 인버터 모듈 20MVA 총 4대로 구성되어 있으며, STATCOM, SSSC, UPFC의 3가지 운전모드를 갖는다. 현재 병렬인버터는 강진 모선전압 제어, 직렬인버터는 강진-장흥간의 조류제어에 기여하며, 상용운전 중이다. 본 논문에서는 강진 UPFC의 운전결과 및 효과를 분석하였다.
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송전선로에서 발생하는 전자계에 대한 관심이 증가함에 따라 이를 저감하는 방법에 대한 연구도 활발하게 진행되고 있다. 본 논문에서는 송전선로에 적용할 수 있는 전자계 저감방법중 하나인 수동루프에 대한 성능을 송전선로의 축소모형 실험을 통해 나타내고 그에 대한 결과를 이론적인 계산 값과 비교하였다. 약 1/20 크기로 축소한 송전선로 모형을 제작한 다음 몇 가지 전압, 전류를 인가하여 선로 주변 전자계를 측정하여 그 결과를 정리하였다.
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CBP market which is the first stage of competitive electricity market has been operated and the KPX has been established since April, 2001 by restructuring plan for electricity industry. Baseload unit are settled with baseload CP and BLMP in CBP market. The other unit are settled with peakload CP and SMP. The difference of settlement between two groups occurs the profit changes of the unit. This paper analyzes the profit by units under settlement rule in CBP market. It analyzes the difference between market clearing price and variable costs, and fixed cost recovery through CP income. Finally, this paper suggests the plan how market was affected by the difference of fixed cost recovery by generators and how to improve Intermediate and peak load unit's profit.
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This paper presents the cost-effectiveness evaluation of DSM programs. The purpose of this paper is to analyze the energy consumptions and peak reductions of DSM programs, evaluate the cost effectiveness for each DSM program, and identify the benefits and the costs for each California Test. The proposed approach is applicable to DSM programs post-conducting in Korea.
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Available Transfer Capability(ATC) calculation is a complicated task, which involves the determination of TTC, TRM, and CBM. This paper proposed QFA method, which can reduce the calculation time comparing with CPF method and has few errors in ATC calculation. It proved that the method can calculate ATC more fast and accurately in the case study using IEEE 24 bus RTS(MRTS).
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This paper developed the web based power flow program for education. Since a lot of users can connect and implement the web based program, the only one computer can get much evaluation burden not to compute. Using the XML technology, which supports the distributed computing technology, we have developed the web-based power flow software and system that are distributed the above calculation burden to three computers: web server, database server, application server. Also, this software was developed to get the difference of number of iteration and evaluation speed as veil as the results of state variables for each node according to the each calculation method for power flow using the chart. Therefore, users can get the physical concept of power flow in addition to the difference among the evaluation methods for power flow. We have performed the case studies with IEEE 14 bus system using the developed software.
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공급 예비력 확보와 설비투자 지연을 목적으로 운영하였던 직접 부하제어(DLC)는 경쟁, 규제 완화, 민간 자본의 참여 등으로 변화된 양방향 입찰 시장에서 시장가격결정에 수요측 의사를 반영하는 수단으로 의미가 변화되어 가고 있다. 현재 직접 부하제어 시범사업은 한전과 에너지관리공단에서 2원화하여 운영하고 있으며 에너지관리공단의 시스템 구성은 상위 시스템으로 전력부하관리센터(LMC)와 민간 사업자용 부하관리사업자시스템(LSES), 하위 시스템으로 EMD 시스템으로 구성되어 있다. 본 논문에서는 민간 부하관리 사업자인 LG 산전의 데이터 센터에 설치된 웹 기반의 부하관리사업자시스템의 구성, 주요 기능, 구현된 배분 알고리즘, 정산 알고리즘을 소개하고 시스템의 유용성 및 활용 방안을 언급하고자 한다.
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This paper resents an application of an Artificial Neural Network(ANN) technique to forecast the short-term system marginal price(SMP). The forecasting of SMP is a very important factor in an electricity market for the optimal biddings of market participants as well as for the market stabilization of regulatory bodies. The proposed neural network scheme is composed of three layers. In this process, input data are set up to reflect market conditions. And the
$\lambda$ that is the coefficient of activation function is modified in order to give a proper signal to each neuron and improve the adaptability for a neural network. The reposed techniques are trained validated and tested with the historical real-world data from korea Power Exchange(KPX). -
One of the major pending issues regarding the Kyoto Protocol is to develope the domestic policies and measures for achieving GHG emission reduction target. The Kyoto Protocol can create the change of fuel-mix in generation company. This study analyzes the impact of introducing emission trading on the change in fuel mix in Korea generation market.
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This paper deals with an allocation strategy for the resources of direct load control program, which is considered the operating states in power systems. The existing approaches, load shedding priority algorithm, curtailment payback based algorithm and mixed curtailment algorithm, are based on the uniform allocation strategy. These approaches are not taken into account the operating states in power systems. So, under the critical operating condition, direct load control resource is evaluated by introducing the congestion factor.
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In competitive electricity markets, maintenance schedule is submitted by Genco's and Transco's, and coordinated by ISO with the adequacy criterion. This paper presents an alternative coordination procedure by ISO on the maintenance schedule.
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This paper presents the estimation on Load Characteristic Factor(k) which is considered to load pattern and seasonal characteristic of consumer. We can calculate the loss of distribution networks through the equation composing of Load Factor(LF), Loss Load Factor(LLF) and load characteristic factor(k). This equation is similar to the method of Regulator-General Victoria, Australia. Generally, the conventional method for calculating the distribution losses uses k with a constant value from 0.1 to 0.3. However, the k which is a relationship between LF and LLF can be varied by load pattern and seasonal characteristics. It is necessary to estimate the k according to load characteristics. This paper shows the result for recalculating k using the KEPCO's SOMAS data measured in distribution networks.
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This paper describes a type test results of 154 kV transmission line arrester with external gap. The test was carried on surge arrester unit and line arrester with external gap, respectively. Withstand voltage test demonstrate the voltage withstand capability of the line arrester with external series gap under the dry and wet conditions. In insulation coordination test external series gap shall be discharged every time when lightning impulse voltage with the steepness of more than 1500
$kV/{\mu}s$ are applied under the wet condition. -
As a competitive power market has introduced, many energy management systems have been developed. This paper presents the web-based energy management system which is developed by our company. The users tan monitor and analysis their load information using our energy management system.
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One of many elements considered important is TR-Cost in restructed electrical power market. KEMA supposed the TR-Cost system which involved an allocation rate of groups of generator and load as 5 to 5 but it isn't based on electrical and economic theory. Also there is a defect that we cann't calculate each allocation to numerous members forming the group of generators and loads. Therefore, in this paper, we propose an allocation method by using "generator forcused TR MLF" & "load forcused TR MLF" in consideration of economic signal.
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This paper adopts the methods of dynamic programming based on priority and the objective function is to maximize the amount of priority. The Purpose of this work is to schedule the direct load control with approciate constrints. To demonstrate the effectiveness of the study, sample data is used about 54 load. And the results of sample are described in this.
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본 논문에서는 산업자원부에 의해 확정된 제5차 장기전력수급계획에 근거하여 2004년에서 2009년까지의 기간에 대해 시장지배력 사업자인 한수원의 시장지배력 행사 가능성을 분석해 보았다. 시뮬레이션은 본 연구원에서 보유하고 있는 PLEXOS로 각 해당 년도 내 임의의 하루 24시간을 선정하여 수행하였다. 시뮬레이션 결과는 2004년과 2007년을 선택하여 정리하였다. 2004년은 베스팅 계약의 비율이 100%에 가깝고 2007년에는 절반 정도로 떨어지게 된다. 2가지 경우의 결과를 비교하여 베스팅 계약이 시장에 미치는 영향과 시장지배력 행사 가능성을 분석할 수 있다.
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TWBP 도매전력시장의 개설과 더불어 도입되는 PPS&RMS 하의 계약 제도는 전력시장가격 안정화 및 발전사업자의 수익 보장 등 여러 가지 목적이 있지만 그 중에서도 시장점유율이 높은 한수원의 시장지배력 완화 역시 도입 목적 가운데 하나이다. 한수원은 설비용량 기준 30%, 공급량 기준 40%의 거대 발전사업자이므로 시장지배력 행사에 대한 잠재적 가능성이 존재하기 때문에 시장초기에 PPS&RMS를 도입하여 공급 물량의 95%를 계약으로 묶게 된다. 본 논문에서는 이러한 환경적 요인을 반영하여 현재 우리나라의 전력시장 현황을 분석한 다음, 2004년 베스팅 계약이 적용되었을 경우 한수원의 시장지배력 가능성에 대해서 분석해 본다.
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This paper presents a contains contingency constrained Optimal Power Flow(CCOPF) algorithm. The proposed algorithm maintains the nodal voltage levels within the specified limits after contingency. A case study demonstrate the proposed algorithm with the IEEE-14RTS under N-1 contingency criterion.
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본 논문에서는 쿠르노 모형을 적용한 양방향입찰 전력 풀시장에서 입찰에 참여하는 발전기가 최대 이익을 얻기 위한 입찰전략으로서 신경회로망의 오차 역전파 알고리즘을 이용하여 최적 입찰발전량과 입찰가격을 수립하는 기법에 관하여 연구한다. 전력시장 환경은 n 개의 발전기들이 참여하는 비협조적 불완전정보 시장으로 설정하고 Bayesian의 조건부 확률이론을 적용하여 상대 발전기들의 발전비용함수와 시장의 수요함수를 추정하여 발전기 상호간 쿠르노-내쉬균형점을 이루는 최적 입찰발전량을 예측한다. 그리고 이익을 극대화시키기 위해 오차 역전파 알고리즘을 이용하여 시장의 가격 탄력성과 쿠르노 시장균형가격에 연결가중치를 조절함으로써 입찰가격이 계통한계가격에 근접하도록 최적 입찰전략을 수립한다.
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The outage cost has very important position for determination of the optimal level or optimal range of reliability in power system expansion planning. Establishing the worth of service reliability is a very difficult and subjective task. This paper suggests strategies for the role, need and assessment algorithm and methodology of the outage cost in power system expansion planning. Organization, data collections and method about D/B for outage cost assessment is proposed in the this study.
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With the restructuring of the electric power industry during the past decade, operation and control strategies have undergone a shift in paradigm. Certain activities that were earlier considered as part of the integrated electricity supply(such as voltage and frequency control) are now treated as separate services and often independently managed and accounted for. This paper examines the management of reactive power services in deregulated electricity markets around the world. From the review several diverse methods for handling reactive power within the deregulated market framework emerges. While in many of the markets, proper financial compensation mechanisms exist to compensate the providers for their service, some others continue to handle reactive power through regulatory frameworks and technical operation guidelines.
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This paprer presents the evlauation method for transmission marginal loss factors(MLFs) considering the electrical distance. Generally, MLFs are represented as the sensitivity of transmission losses, which is computed from the change of generation by the change of the load. MLFs are classified as load-focused MLFs and generator-focused MLFs. The existing evaluation method for generator focused MLFs has the limit not reflecting the characteristic of power systems since the method has been introduced the assumption which the output of a generator is supplied to all of the load buses on the power system. Therefore, to overcome the limit of evaluation method for generator-focused MLFs, we have applied the process, which it approximately can find the load buses that supplied a generator to the method. We have applied the proposed method to the simple 5-bus system because the proposed method is not analytic but the hybrid method incorporated the Kirschen and Bialek's algorithm to the existing analytic method to find the load buses supplied by a generator.
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Load foretasting model used generally such as times series and econometric regression model often doesn't reflect the load characteristics of small remote islands. Therefore, in this paper load demand forecast is peformed using EGARCH-M non-linear forecasting model.
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Transmission congestion is one of the key factors to local market power in competitive electricity markets. This paper presents an alternative methodology in estimating market power under transmission congestion. The proposed methodology was demonstrated with the Optimal Power Flow(OPF).