• KEPCO Journal on Electric Power and Energy
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• 제7권1호
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• pp.171-177
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• 2021

In terms of distribution planning, accurate electric load prediction is one of the most important factors. The future load prediction has manually been performed by calculating the maximum electric load considering loads transfer/switching and multiplying it with the load increase rate. In here, the risk of human error is inherent and thus an automated maximum electric load forecasting system is required. Although there are many existing methods and techniques to predict future electric loads, such as regression analysis, many of them have limitations in reflecting the nonlinear characteristics of the electric load and the complexity due to Photovoltaics (PVs), Electric Vehicles (EVs), and etc. This study, therefore, proposes a method of predicting future electric loads on distribution lines by using Machine Learning (ML) method that can reflect the characteristics of these nonlinearities. In addition, predictive models were developed based on actual data collected at KEPCO's existing distribution lines and the adequacy of developed models was verified as well. Also, as the distribution planning has a direct bearing on the investment, and amount of investment has a direct bearing on the maximum electric load, various baseline such as maximum, lowest, median value that can assesses the adequacy and accuracy of proposed ML based electric load prediction methods were suggested.

• Journal of Advanced Marine Engineering and Technology
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• 제26권3호
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• pp.313-319
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• 2002

Since the oil crisis in 1970, a great deal of effort has been made to develop automatic electric load sharing systems as a part of the efforts to save energy. A large scale electric generating system composes more than two generators whose characteristics may be different. When such a system is operated individually or in parallel, the lagrange multiplier's method has difficulty in achieving optimal load distribution because generators usually have the limitations of the operating range with inequality constraints. Therefore, a suitable operating mode of generators has to be decided according to the selection of the generators to meet electric power requirements at the minimum cost. In this study, a method which solves the optimal electric load distribution problem using the dynamic programming technique is proposed. This study also shows that the dynamic programming method has an advantage in dealing with the optimal load distribution problem under the limitations of the operating range with inequality constraints including generator operation mode. In this study, generator operating cost curve of second order equation by shop trial test results of diesel generators are used. The results indicate that the proposed method can be applied to the ship's electric generating system.

• Journal of Advanced Marine Engineering and Technology
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• 제24권3호
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• pp.106-112
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• 2000

Since the oil crisis, we have been concerned about the energy saving techniques of electric generating systems. As a part of the effort to save energy, automatic electric load sharing device was developed. Usually, ship's electric generating system consists of two or three sets of generator. And, electric generating system is operated as single or parallel operation mode according to the demanded electric power. Therefore, it is important to investigate generators operating mode for the supply of required electric power in the ship in order to decrease the operating cost. So, this paper suggests the method to solve the optimal electric load distribution problem by dynamic programming. And, this thesis indicates that the proposed method is superior to the lagrange multiplier's method in obtaining optimal load distribution solution in the ship's electric generating system.

• Journal of Electrical Engineering and Technology
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• 제12권5호
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• pp.1743-1753
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• 2017

Since there are multiple random variables in the probabilistic load flow (PLF) calculation of distribution system containing distributed generation (DG) and electric vehicle charging load (EVCL), a Monte Carlo method based on composite sampling method is put forward according to the existing simple random sampling Monte Carlo simulation method (SRS-MCSM) to perform probabilistic assessment analysis of voltage quality of distribution system containing DG and EVCL. This method considers not only the randomness of wind speed and light intensity as well as the uncertainty of basic load and EVCL, but also other stochastic disturbances, such as the failure rate of the transmission line. According to the different characteristics of random factors, different sampling methods are applied. Simulation results on IEEE9 bus system and IEEE34 bus system demonstrates the validity, accuracy, rapidity and practicability of the proposed method. In contrast to the SRS-MCSM, the proposed method is of higher computational efficiency and better simulation accuracy. The variation of nodal voltages for distribution system before and after connecting DG and EVCL is compared and analyzed, especially the voltage fluctuation of the grid-connected point of DG and EVCL.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.495-497
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• 2000

The KEPCO is developing the load forecasting sysetm using land use simulation method and distribution planning system. Distribution planning needs the data of presents loads, forecasted loads sub-statin, and distribution lines. Using the data, determine the sub-station and feeder lines according to the load forecasting data. This paper presents the method of formulation processfor the long term load forecasting and optimal distribution planning and optimal distribution planning. And describes the case study of long term distribution planning of Kwangju city accord to the newly applied method.

• 산업기술연구
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• 제25권A호
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• pp.15-22
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• 2005

In order to evaluate seismic performance of multi-degree-of-freedom bridge structure, moderate lateral load distribution methods using the pushover analysis were developed by many researchers. One of important variables to improve an accuracy of pushover analysis is lateral load distribution. In this study, pushover analyses were performed using the five types of lateral load distribution and seismic performances were evaluated by capacity spectrum method (CSM). To verify an accuracy of suggested lateral load distribution, the maximum displacement estimates by the CSM were compared to those by inelastic time history analysis.

• 조명전기설비학회논문지
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• 제18권1호
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• pp.98-104
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• 2004

본 논문에서는 사고나 계획정전 등으로 인한 건전 정전구간에 신속하게 전원을 공급하는 방안을 제시하였다. 제시한 부하복구방안은 연계개폐기로부터 공급피더 방향으로 계통을 역방향으로 탐색하고 탐색시 저장된 경로와의 조합을 이용하여 구해짐으로써 계통의 탐색공간이 대폭 줄어들게 되어 신속한 복구방안의 제시가 가능하다. 또한 공급 여유량을 미리 확보하는 2단계의 부하복구, 모든 구간에 대한 복구가 불가능한 경우 부하를 차단하는 방안 등이 포함되어 있으므로 광역정전이나 다중사고 및 중요수용가를 고려한 부하복구, 배전자동화시스템과 연계된 부하 복구에도 이용할 수 있다.

• 한국멀티미디어학회논문지
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• 제7권8호
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• pp.1097-1106
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• 2004

전형적인 웹 클러스터 시스템은 여러 대의 실제서버와 클라이언트에 작업을 분배하는 가상서버로 구성된다. 본 논문에서는 고 가용성 웹 클러스터를 구성하기 위한 부하예측방식을 사용한 동적 작업 분배 방식을 제안하였다. 가상서버는 적절한 주기로 상태요청 메시지를 실제서버에 전송하여 부하 상태를 알아낸다. 하지만 작업분배 과정에서 실제의 부하상태의 변화를 정확히 알 수 없으므로 클라이언트의 요청에 대하여 실제서버의 부하상태를 예측하여 최소 부하상태 인 서버에 작업을 할당한다. 제안된 작업 분배방식은 실제서버의 부분적 고장과 무관하게 동작하며 부분적인 고장이 발생하여도 전체 시스템에 영향을 주지 않고 계속적인 서비스를 제공한다. 또한 다양한 성능평가를 수행하여 실제서버 확장에 따른 성능확장능력과 작업처리능력이 향상되었음을 보였다.

• 산업기술연구
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• 제15권
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• pp.33-40
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• 1995

This paper presents a new method for load distribution in a single-level tree network equipped with front-end processors. This method focuses on effective data distribution over a number of processors minimize job processing time. Optimal multiple installment load distribution algorithm is presented. Minimum number of processors that maximizes efficiency is decided theoretically.

• 전기학회논문지
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• 제58권9호
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• pp.1681-1688
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• 2009

This paper proposes a new fault restoration method which adopts the recloser as top agent to release the problems of the data concentration and fault processing delay of the existing DAS(distribution Automation System) under the ubiquitous distribution system. In proposed method, top agent collects the data based on the multi-casting communication with the tie switches of the interconnection point, and then selects a closed switch(tie switch) to transfer the sound outage load to other feeders based on the heuristic search strategy step by step until the load transfer work is finished. Here, a new heuristic rule is developed which can guarantee the relational load balancing and line loss from the collected voltage data. Finally, the several faults are simulated for typical multi-section and multi-interconnection distribution system to prove the effectiveness of the proposed strategy, in particular, for each simulation cases, the load balancing index and line loss index of the obtained solution from the proposed method is compared with those of all of feasible solutions.