• 대한전기학회논문지:전력기술부문A
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• 제53권11호
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• pp.604-609
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• 2004

This paper suggests a long-term distribution area load forecasting algorithm which offers basic data for distribution planning of power system. To build forecasting model, 4-level hierarchical spatial structure is introduced: System, Region, Area, and Substation. And, each spatial load can be decided proportional to its portion in the higher level. This paper introduces the horizon year loads to improve the forecasting results. And, this paper also introduces an effective load transfer algorithm to improve forecasting stability in case of new or stopped substations. The proposed model is applied to the load forecasting of KEPCO system composed of 16 regions, 85 areas and 761 substations, and the results are compared with those of econometrics model to verify its validity.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.181-183
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• 2002

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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전력기술부문
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• pp.319-321
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• 2001

When the fault occurred at distribution system, the restoration was late. There are 2 reasons The one is the error of fault location the other is multiple possible candidates of fault location. This paper presents two of new techniques for diagnosing fault regions. The proposed diagnosis scheme is capable of accurately identifying the location of fault upon its occurrence. based on the integration of information available from protective devices and measured load current change at the substation. In this paper expert system for real fault region is presented using these facts. Testing of the developed system using EMTP Simulation Model has demonstrated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 하계학술대회 논문집
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• pp.125-128
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• 1990

A program for the protection coordination of distribution systems is reported. The developed program nailed DISCO, consisting of two modules has a capability of selling the overcurrent relays, reclosers, sectionalizers, fuses which are commonly used in the primary feeder systems. Setting is performed in a downstream fashion starting from the substation, and coordination rules are applied identifying the pattern of the primary-backup devices based on the depth-first search. T/C curves of various devices are handled by digitization for accuracy and various graphics and windows are adopted for user-friendly interface.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 D
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• pp.954-957
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• 1997

In this paper, we analyze the voltage sag caused by reclosing on electric power distribution system. When a fault is on the electric system, a reclosing operation brings a voltage sag on the feeders which is supplied with a common substation transformer. By analyzing the fault wave-form measured in the field, it is showed that a voltage sag is in proportion to a fault current. Also, we propose an adaptive reclosing scheme. This scheme changes the number of reclosing as a function of the magnitude of a fault voltage and the fault type. As the proposed scheme is compared with conventional scheme in the side of voltage sag and permanent fault, it is verified that the proposed scheme is more effective than conventional scheme.

• 한국초전도ㆍ저온공학회논문지
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• 제12권3호
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• pp.39-43
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• 2010

In Korea, 22.9kV hybrid SFCL (Superconducting Fault Current Limiter) has been developed and carried out long-term field tests in Gochagn power test center of KEPCO through DAPAS program. The SFCL will be installed at a distribution line of Icheon substation in Korea. For the successful application, we have to design the specifications considering real power system operation. This paper proposes a concept of the operating current based rms value for the protection coordination with protective delays and studies a proper range of the current in Korean distribution power system.

• 대한전기학회논문지:전력기술부문A
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• 제48권10호
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• pp.1190-1197
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• 1999

The management of power factor(PF) in the distribution line is treated according to the measurement a month about the feeder unit at the substation. In Korea, we have not researched into power factor in distribution system due to it's less weight. The reactive power in advanced countries is controlled automatically by the compensative condenser switch on/off under the monitoring. This paper first presents the optimal condenser position and proper capacity by lagrangue factor ${\lambda}_{Q}$ which is the line loss index about reactive power unit. Therefore, the largest ${\lambda}_{Q}$ node is the condenser injection point and we find out the best condenser capacity when the line loss is saturated by the moderation of condenser volume. By this method, we suggest 0.6% uprising PF by injection of 15 kVA condenser. Additionally, PF is analysed into 5 areas; large city, middle city, small city, farm village, fishing village by the use of Power Platform which is classified the same concept of the low load management in KEPCO. Two feeders of each area are selected by the worst results of PF in specified areas.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 추계학술대회 논문집
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• pp.49-52
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• 2003

As the power demand has increased, it is expected that the transmission system will have more complicated problems under the influence of investment reduction for overall power system. The route length per MW demand will be reduced gradually from 0.6［C-km/㎿］ to 0.53 ［C-km/㎿］ in 2010. This comes up to a real serious problem of system planning and operation viewpoints HTS power technologies have properties to solve these complex transmission and distribution constraints, especially for metropolitan area, in the future. As the HTS technology has developed, the HTS cable technology can be the most effective alternative to solve the future expected transmission constraints as compared with other countermeasures in terms of economics, environments and system operation. This paper describes the general application methodology of developing 22.9 ㎸ HTS cable by CAST for practical distribution system, particularly, step-by-step application methodology of 22.9 ㎸ HTS cable to substitute the existing and planning 154 ㎸ cable. In this scheme, almost of the downtown 154 ㎸ substation of metropolitan city such as Seoul will be changed into 22,9 ㎸ switching station.

• 한국초전도ㆍ저온공학회논문지
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• 제12권2호
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• pp.17-20
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• 2010

A considerable amount of research material discussing designs and properties of High Temperature Superconducting Fault Current Limiter (HTS FCL) is available. However, a shortage of research concerning positioning of HTS FCL in power grid is felt. In this paper a feasibility study of HTS FCL positioning in Smart Grid through simulation analysis is carried out. A complete power network (including generation, transmission and distribution) is modeled in Simulink / SimPowerSystems. A generalized HTS FCL is also designed by integrating Simulink and SimPowerSystem blocks. The distribution network of the model has a wind turbine attached to it forming a micro grid. Three phase fault have been simulated along with placing FCL models at key points of the distribution grid. It is observed that distribution grid, having distributed generation sources attached to it, must not have a single FCL located at the substation level. Optimized HTS FCL location regarding the best fault current contribution from wind turbine has been determined through simulation analysis.

• KIEE International Transactions on Power Engineering
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• 제5A권4호
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• pp.357-365
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• 2005

This research investigates the influences of distributed generations (DG), which are interconnected to the bus by the dedicated lines, on the overcurrent relays (OCR) of the neighboring distribution feeders and also proposes a novel method to reduce the negative effects on the feeder protection. Due to the grid connected DG, the entire short-circuit capacity of the distribution networks increases, which may raise the current of the distribution feeder during normal operations as well as fault conditions. In particular, during the switching period for loop operation, the current level of the distribution feeder can be larger than the pickup value for the fault of the feeder's OCR, thereby causing the OCR to perform a mal-operation. This paper proposes the adaptive setting algorithm for the OCR of the distribution feeders having the neighboring dedicated feeders for the DG to prevent the mal-operations of the OCR under normal conditions. The proposed method changes the pickup value of the OCR by adapting the power output of the DG monitored at the relaying point in the distribution network. We tested the proposed method with the actual distribution network model of the Hoenggye substation at the Korea Electric Power Co., which is composed of five feeders supplying the power to network loads and two dedicated feeders for the wind turbine generators. The simulation results demonstrate that the proposed adaptive protection method could enhance the conventional OCR of the distribution feeders with the neighboring dedicated lines for the DG.